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Digital vs 35mm lenses

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June 23, 2005 2:06:07 AM

Archived from groups: rec.photo.digital (More info?)

Please can anyone tell me if this is correct?


35mm camera with 105 mm lens to Digital with 105 mm lens.

Is this 1 to 1.5 or 1.5 to 1??????

Any and all help will be greatly appreciated.

Thanks in advance,
Chuck.

More about : digital 35mm lenses

Anonymous
June 23, 2005 2:06:08 AM

Archived from groups: rec.photo.digital (More info?)

"Faz" <chuckfaz@shaw.ca> writes:
> Please can anyone tell me if this is correct?
>
>
> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>
> Is this 1 to 1.5 or 1.5 to 1??????

We can pretty safely say the 105mm lens will achieve a narrow field of
view on the digital body (kinda sorta, very sloppily saying the lens
will appear to be something longer than 105mm), but whether it's 1.0x,
1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
than 105mm in it's field of view, or whatever depends on which
specific camera because different dSLR's have different size sensors,
and hence have different field of view crop numbers.


--
Todd H.
http://www.toddh.net/
Anonymous
June 23, 2005 2:06:08 AM

Archived from groups: rec.photo.digital (More info?)

As the replies have already shown it's 1.5:1 (for Nikon, Canon is
1.6:1)...the reason WHY it's that way is because the actual sensor is
smaller than 35mm film. So the image projected through the lens into
the body is larger than it has to be (it's projecting a full 35mm+
image, yet the digital sensor is smaller so it's only looking at the
center of that image). So one would figure out that if the sensor only
uses a part of the usuable image it's getting then why give a digital
sensor so big of an image...and that's exactly what Nikon and Canon did
with their lenses specifically designed for digital cameras, the
projected image to the sensor when using a lens specifically for a
digital SLR is the exact size the sensor needs, nothing more, therefore
the overall lens can be smaller, lighter, etc.

I would say though that since you are essentially taking the center 2/3
of a 35mm eqiv image and creating your image from that, then the
digital clarity of the center of the lens is even more paramount, if
for example a 'normal' 35mm lens was sharper around the outside (don't
think that ever happens, but for argument's sake), it would do you no
good with a cropping-factored dSLR because you are only using the
center of the lens.

There are dSLRs that do not have a cropping factor, the top Canon one,
the name escapes me but the 16MP one, it uses a full-frame sensor, so
it needs a full-size image projected back to it...and therefore the
'special' dSLR lenses Canon has made, will not work for that camera, it
needs a normal SLR lens. The top Nikon (12MP I think) is not
full-frame, so it's getting 12MP out of a sensor the size of the
D70's...

Clear as mud huh? :) 

Good Luck,
-Mark
Related resources
Anonymous
June 23, 2005 2:06:08 AM

Archived from groups: rec.photo.digital (More info?)

The 'designed for digital' comes in more importantly in designing
lenses at the wide angle side of the focal lengths. Normally wide
angle lens rear lens element is placed at greater distances greater
than the focal length would other specify. Since wide angle lenses on
digital can have lenses a shorter distance than same focal length for
full frame 35mm, the rear most element is designed to be placed close
to the focal plane on digital. That permits easier design task for
digital, with their smaller digital camera format reflex mirrors, than
if the same focal length had to be kept farther away for FF cameras.
And since the format is smaller, the lens design does not have to cover
as large an image circle, again making the design simpler to correct
for abberations, etc.

--Wilt
Anonymous
June 23, 2005 2:06:09 AM

Archived from groups: rec.photo.digital (More info?)

"Todd H." <t@toddh.net> wrote in message news:847jgm143o.fsf@ripco.com...
> "Faz" <chuckfaz@shaw.ca> writes:
>> Please can anyone tell me if this is correct?
>>
>>
>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>
>> Is this 1 to 1.5 or 1.5 to 1??????
>
> We can pretty safely say the 105mm lens will achieve a narrow field of
> view on the digital body (kinda sorta, very sloppily saying the lens
> will appear to be something longer than 105mm), but whether it's 1.0x,
> 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
> than 105mm in it's field of view, or whatever depends on which
> specific camera because different dSLR's have different size sensors,
> and hence have different field of view crop numbers.
>
>
> --
> Todd H.
> http://www.toddh.net/


http://www.lookbefore.wading-in.net/lookbefore/Digital_...

Jim
Anonymous
June 23, 2005 2:06:10 AM

Archived from groups: rec.photo.digital (More info?)

"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> writes:
> "Todd H." <t@toddh.net> wrote in message news:847jgm143o.fsf@ripco.com...
> > "Faz" <chuckfaz@shaw.ca> writes:
> >> Please can anyone tell me if this is correct?
> >>
> >>
> >> 35mm camera with 105 mm lens to Digital with 105 mm lens.
> >>
> >> Is this 1 to 1.5 or 1.5 to 1??????
> >
> > We can pretty safely say the 105mm lens will achieve a narrow field of
> > view on the digital body (kinda sorta, very sloppily saying the lens
> > will appear to be something longer than 105mm), but whether it's 1.0x,
> > 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
> > than 105mm in it's field of view, or whatever depends on which
> > specific camera because different dSLR's have different size sensors,
> > and hence have different field of view crop numbers.
>
>
> http://www.lookbefore.wading-in.net/lookbefore/Digital_...

Now there's a picture that says a thousand words!

--
Todd H.
http://www.toddh.net/
Anonymous
June 23, 2005 2:06:10 AM

Archived from groups: rec.photo.digital (More info?)

On 22 Jun 2005 18:41:47 EDT, "jimkramer"
<Sophomoric1_jim@NOSPAMjlkramer.net> wrote:

>"Todd H." <t@toddh.net> wrote in message news:847jgm143o.fsf@ripco.com...
>> "Faz" <chuckfaz@shaw.ca> writes:
>>> Please can anyone tell me if this is correct?
>>>
>>>
>>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>>
>>> Is this 1 to 1.5 or 1.5 to 1??????
>>
>> We can pretty safely say the 105mm lens will achieve a narrow field of
>> view on the digital body (kinda sorta, very sloppily saying the lens
>> will appear to be something longer than 105mm), but whether it's 1.0x,
>> 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
>> than 105mm in it's field of view, or whatever depends on which
>> specific camera because different dSLR's have different size sensors,
>> and hence have different field of view crop numbers.
>>
>>
>> --
>> Todd H.
>> http://www.toddh.net/
>
>
>http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>
>Jim
>
Why did you complicate this with the bit about the 'viewfinder'?
Why not use what counts, the field of view in the image?
The Canon doesn't have a 1.6x viewfinder, although it may have a 1.6
crop factor.
--
Bill Funk
replace "g" with "a"
Anonymous
June 23, 2005 2:06:11 AM

Archived from groups: rec.photo.digital (More info?)

"Todd H." <t@toddh.net> wrote in message news:84fyva83nr.fsf@ripco.com...
> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> writes:
>> "Todd H." <t@toddh.net> wrote in message news:847jgm143o.fsf@ripco.com...
>> > "Faz" <chuckfaz@shaw.ca> writes:
>> >> Please can anyone tell me if this is correct?
>> >>
>> >>
>> >> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>> >>
>> >> Is this 1 to 1.5 or 1.5 to 1??????
>> >
>> > We can pretty safely say the 105mm lens will achieve a narrow field of
>> > view on the digital body (kinda sorta, very sloppily saying the lens
>> > will appear to be something longer than 105mm), but whether it's 1.0x,
>> > 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
>> > than 105mm in it's field of view, or whatever depends on which
>> > specific camera because different dSLR's have different size sensors,
>> > and hence have different field of view crop numbers.
>>
>>
>> http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>
> Now there's a picture that says a thousand words!
>
Maybe 2,000, there are two birds. :-)

> --
> Todd H.
> http://www.toddh.net/
June 23, 2005 4:01:38 AM

Archived from groups: rec.photo.digital (More info?)

Thanks guys....as you say its as clear as mud although the photo explains
quite a bit. Many thanks again.


Chuck.

"Faz" <chuckfaz@shaw.ca> wrote in message
news:jhlue.1778874$6l.259376@pd7tw2no...
> Please can anyone tell me if this is correct?
>
>
> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>
> Is this 1 to 1.5 or 1.5 to 1??????
>
> Any and all help will be greatly appreciated.
>
> Thanks in advance,
> Chuck.
>
Anonymous
June 23, 2005 5:18:10 AM

Archived from groups: rec.photo.digital (More info?)

"Faz" <chuckfaz@shaw.ca> wrote in news:jhlue.1778874$6l.259376@pd7tw2no:

> Please can anyone tell me if this is correct?
>
>
> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>
> Is this 1 to 1.5 or 1.5 to 1??????

Put it this way: put the 105mm lens on the Digital body, and a 157.5mm lens
on the 35mm film body, and your shots would frame exactly the same.

Help?
Anonymous
June 23, 2005 12:53:10 PM

Archived from groups: rec.photo.digital (More info?)

Faz wrote:
> Please can anyone tell me if this is correct?
>
>
> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>
> Is this 1 to 1.5 or 1.5 to 1??????
>
> Any and all help will be greatly appreciated.
>
> Thanks in advance,
> Chuck.
>
>
Depends on camera. All 35 mm cameras have same image format size- 24 x
36 mm rectangle. There are a number of different sized chips used on
digicams, and the size of the chip (format size) determines what actual
angle a given focal length size will cover.

A small chip makes any given lens to appear longer, ie. compared to same
lens on 35 mm. Big chip makes it appear more like it does on 35mm camera.
Anonymous
June 23, 2005 5:15:04 PM

Archived from groups: rec.photo.digital (More info?)

"Bill Funk" <BigBill@there.com> wrote in message
news:5kekb1510h3pp6pll4juuv7h4ggiudcs9s@4ax.com...
> On 22 Jun 2005 18:41:47 EDT, "jimkramer"
> <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:
>
>>"Todd H." <t@toddh.net> wrote in message news:847jgm143o.fsf@ripco.com...
>>> "Faz" <chuckfaz@shaw.ca> writes:
>>>> Please can anyone tell me if this is correct?
>>>>
>>>>
>>>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>>>
>>>> Is this 1 to 1.5 or 1.5 to 1??????
>>>
>>> We can pretty safely say the 105mm lens will achieve a narrow field of
>>> view on the digital body (kinda sorta, very sloppily saying the lens
>>> will appear to be something longer than 105mm), but whether it's 1.0x,
>>> 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
>>> than 105mm in it's field of view, or whatever depends on which
>>> specific camera because different dSLR's have different size sensors,
>>> and hence have different field of view crop numbers.
>>>
>>>
>>> --
>>> Todd H.
>>> http://www.toddh.net/
>>
>>
>>http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>
>>Jim
>>
> Why did you complicate this with the bit about the 'viewfinder'?
> Why not use what counts, the field of view in the image?
> The Canon doesn't have a 1.6x viewfinder, although it may have a 1.6
> crop factor.

Actually it doesn't have either. The term "crop factor" is a misnomer,
notwithstanding its current popularity among the language-challenged.

Nothing is cropped, in the usual photographic sense of that term. If
anything *were* cropped it certainly could not be cropped by a factor of
1.6, since no one and no device can crop 160% of any photo. If you crop 50%
of it it's half gone. Crop 100% of it and it's *all* gone and there's no
more you can crop.

The term "focal length multiplier" has been objected to on the grounds that
the focal length isn't actually changed, which of course is correct but
somewhat irrelevant. If the reduced sensor size results in a 50mm lens
having the same field of view as an 80mm lens, then that's what the 1.6 *is*
as far as the user is concerned, a focal length multiplier. Field of view is
the chief reason for selecting a focal length in the first place, and it's
convenient to think of focal length in the 35mm terms that most of us are
familiar with. What other use would the number 1.6 *have* in this
application anyway?

The number 1.6 is used here as a multiplier, not a "crop factor." If "focal
length multiplier" offends some because of the fear it may mislead the tiny
fraction of one percent of users so ignorant of photographic optics that
they think digital cameras actually do change the f.l. of the lens used,
then make it "35mm focal length equivalency multiplier" or some such thing.

The fact is that these equivalencies (and the multipliers used to arrive at
them) are commonly used in the literature, by camera manufacturers, photo
magazines, and reviewers both in print and on the Web. And they have been
even before digital cameras became popular consumer items (e.g., APS cameras
were reviewed in magazines usually mentioning the 1.25 multiplier for 35mm
equivalency).

N.

N.
Anonymous
June 23, 2005 5:15:05 PM

Archived from groups: rec.photo.digital (More info?)

On Thu, 23 Jun 2005 13:15:04 -0400, "Nostrobino" <not@home.today>
wrote:

>
>"Bill Funk" <BigBill@there.com> wrote in message
>news:5kekb1510h3pp6pll4juuv7h4ggiudcs9s@4ax.com...
>> On 22 Jun 2005 18:41:47 EDT, "jimkramer"
>> <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:
>>
>>>"Todd H." <t@toddh.net> wrote in message news:847jgm143o.fsf@ripco.com...
>>>> "Faz" <chuckfaz@shaw.ca> writes:
>>>>> Please can anyone tell me if this is correct?
>>>>>
>>>>>
>>>>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>>>>
>>>>> Is this 1 to 1.5 or 1.5 to 1??????
>>>>
>>>> We can pretty safely say the 105mm lens will achieve a narrow field of
>>>> view on the digital body (kinda sorta, very sloppily saying the lens
>>>> will appear to be something longer than 105mm), but whether it's 1.0x,
>>>> 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
>>>> than 105mm in it's field of view, or whatever depends on which
>>>> specific camera because different dSLR's have different size sensors,
>>>> and hence have different field of view crop numbers.
>>>>
>>>>
>>>> --
>>>> Todd H.
>>>> http://www.toddh.net/
>>>
>>>
>>>http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>>
>>>Jim
>>>
>> Why did you complicate this with the bit about the 'viewfinder'?
>> Why not use what counts, the field of view in the image?
>> The Canon doesn't have a 1.6x viewfinder, although it may have a 1.6
>> crop factor.
>
>Actually it doesn't have either. The term "crop factor" is a misnomer,
>notwithstanding its current popularity among the language-challenged.
>
>Nothing is cropped, in the usual photographic sense of that term. If
>anything *were* cropped it certainly could not be cropped by a factor of
>1.6, since no one and no device can crop 160% of any photo. If you crop 50%
>of it it's half gone. Crop 100% of it and it's *all* gone and there's no
>more you can crop.
>
>The term "focal length multiplier" has been objected to on the grounds that
>the focal length isn't actually changed, which of course is correct but
>somewhat irrelevant. If the reduced sensor size results in a 50mm lens
>having the same field of view as an 80mm lens, then that's what the 1.6 *is*
>as far as the user is concerned, a focal length multiplier. Field of view is
>the chief reason for selecting a focal length in the first place, and it's
>convenient to think of focal length in the 35mm terms that most of us are
>familiar with. What other use would the number 1.6 *have* in this
>application anyway?
>
>The number 1.6 is used here as a multiplier, not a "crop factor." If "focal
>length multiplier" offends some because of the fear it may mislead the tiny
>fraction of one percent of users so ignorant of photographic optics that
>they think digital cameras actually do change the f.l. of the lens used,
>then make it "35mm focal length equivalency multiplier" or some such thing.
>
>The fact is that these equivalencies (and the multipliers used to arrive at
>them) are commonly used in the literature, by camera manufacturers, photo
>magazines, and reviewers both in print and on the Web. And they have been
>even before digital cameras became popular consumer items (e.g., APS cameras
>were reviewed in magazines usually mentioning the 1.25 multiplier for 35mm
>equivalency).
>
>N.
>
>N.
>

Well,thanks, but I think most understood what I was saying. As you
pointed out, "crop factor" is a de facto term for the charasteristic
we are referring to.

Still, my question stands.

--
Bill Funk
replace "g" with "a"
Anonymous
June 23, 2005 5:33:30 PM

Archived from groups: rec.photo.digital (More info?)

"Faz" <chuckfaz@shaw.ca> wrote in message
news:jhlue.1778874$6l.259376@pd7tw2no...
> Please can anyone tell me if this is correct?
>
>
> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>
> Is this 1 to 1.5 or 1.5 to 1??????

1 to 1.5, assuming of course that 1.5 is the multiplier for the particular
digital camera you're considering. E.g., a 105mm lens on that digital camera
would be 157.5mm in 35mm equivalency.

N.
Anonymous
June 23, 2005 6:55:37 PM

Archived from groups: rec.photo.digital (More info?)

"Bill Funk" <BigBill@there.com> wrote in message
news:ndvlb1tsllr2hu2d9afaemenu0ljlof9nm@4ax.com...
> On Thu, 23 Jun 2005 13:15:04 -0400, "Nostrobino" <not@home.today>
> wrote:
>
>>
>>"Bill Funk" <BigBill@there.com> wrote in message
>>news:5kekb1510h3pp6pll4juuv7h4ggiudcs9s@4ax.com...
>>> On 22 Jun 2005 18:41:47 EDT, "jimkramer"
>>> <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:
>>>
>>>>"Todd H." <t@toddh.net> wrote in message
>>>>news:847jgm143o.fsf@ripco.com...
>>>>> "Faz" <chuckfaz@shaw.ca> writes:
>>>>>> Please can anyone tell me if this is correct?
>>>>>>
>>>>>>
>>>>>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>>>>>
>>>>>> Is this 1 to 1.5 or 1.5 to 1??????
>>>>>
>>>>> We can pretty safely say the 105mm lens will achieve a narrow field of
>>>>> view on the digital body (kinda sorta, very sloppily saying the lens
>>>>> will appear to be something longer than 105mm), but whether it's 1.0x,
>>>>> 1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
>>>>> than 105mm in it's field of view, or whatever depends on which
>>>>> specific camera because different dSLR's have different size sensors,
>>>>> and hence have different field of view crop numbers.
>>>>>
>>>>>
>>>>> --
>>>>> Todd H.
>>>>> http://www.toddh.net/
>>>>
>>>>
>>>>http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>>>
>>>>Jim
>>>>
>>> Why did you complicate this with the bit about the 'viewfinder'?
>>> Why not use what counts, the field of view in the image?
>>> The Canon doesn't have a 1.6x viewfinder, although it may have a 1.6
>>> crop factor.
>>
>>Actually it doesn't have either. The term "crop factor" is a misnomer,
>>notwithstanding its current popularity among the language-challenged.
>>
>>Nothing is cropped, in the usual photographic sense of that term. If
>>anything *were* cropped it certainly could not be cropped by a factor of
>>1.6, since no one and no device can crop 160% of any photo. If you crop
>>50%
>>of it it's half gone. Crop 100% of it and it's *all* gone and there's no
>>more you can crop.
>>
>>The term "focal length multiplier" has been objected to on the grounds
>>that
>>the focal length isn't actually changed, which of course is correct but
>>somewhat irrelevant. If the reduced sensor size results in a 50mm lens
>>having the same field of view as an 80mm lens, then that's what the 1.6
>>*is*
>>as far as the user is concerned, a focal length multiplier. Field of view
>>is
>>the chief reason for selecting a focal length in the first place, and it's
>>convenient to think of focal length in the 35mm terms that most of us are
>>familiar with. What other use would the number 1.6 *have* in this
>>application anyway?
>>
>>The number 1.6 is used here as a multiplier, not a "crop factor." If
>>"focal
>>length multiplier" offends some because of the fear it may mislead the
>>tiny
>>fraction of one percent of users so ignorant of photographic optics that
>>they think digital cameras actually do change the f.l. of the lens used,
>>then make it "35mm focal length equivalency multiplier" or some such
>>thing.
>>
>>The fact is that these equivalencies (and the multipliers used to arrive
>>at
>>them) are commonly used in the literature, by camera manufacturers, photo
>>magazines, and reviewers both in print and on the Web. And they have been
>>even before digital cameras became popular consumer items (e.g., APS
>>cameras
>>were reviewed in magazines usually mentioning the 1.25 multiplier for 35mm
>>equivalency).
>>
>>N.
>>
>>N.
>>
>
> Well,thanks, but I think most understood what I was saying. As you
> pointed out, "crop factor" is a de facto term for the charasteristic
> we are referring to.

Well, "frequently encountered misnomer" is the phrase I would prefer to "de
facto term." :-)

Many misusages become fairly common. That doesn't necessarily make them
correct, even if the "language is dynamic" set thinks it does.


>
> Still, my question stands.

Sure, and I agree with you. As you said, the Canon doesn't have a 1.6x
viewfinder, and there's no good reason to complicate things by saying it
does.

N.
Anonymous
June 23, 2005 7:01:30 PM

Archived from groups: rec.photo.digital (More info?)

On Thu, 23 Jun 2005 08:53:10 -0500, Don Stauffer
<stauffer@usfamily.net> wrote:
>All 35 mm cameras have same image format size- 24 x
>36 mm rectangle.

Most, not all. Some can even be altered on a frame by frame
basis (Xpan, 36x24 or 65x24) or have built-in masks to crop
in the camera (some Pentax SLRs). Not to mention half-frame
cameras (18x24), sub-miniature using 35mm film (Tessina,
14x21), various stereo cameras (usually 23x24)...


--
Regards

John Bean
Anonymous
June 23, 2005 7:01:31 PM

Archived from groups: rec.photo.digital (More info?)

"John Bean" <waterfoot@gmail.com> wrote in message
news:mrflb110pponqrjr2ac717ulegpohuntu6@4ax.com...
> On Thu, 23 Jun 2005 08:53:10 -0500, Don Stauffer
> <stauffer@usfamily.net> wrote:
>>All 35 mm cameras have same image format size- 24 x
>>36 mm rectangle.
>
> Most, not all. Some can even be altered on a frame by frame
> basis (Xpan, 36x24 or 65x24) or have built-in masks to crop
> in the camera (some Pentax SLRs). Not to mention half-frame
> cameras (18x24), sub-miniature using 35mm film (Tessina,
> 14x21), various stereo cameras (usually 23x24)...

Yes. Also many (if not most) of the old Robot cameras were 24x24, and I
think some of the Agfa Rapid system cameras were that size and also 24x30.
It's sort of surprising that the latter format never became more popular,
since it's a perfect fit for 4x5 and 8x10 paper.

N.
Anonymous
June 23, 2005 8:06:25 PM

Archived from groups: rec.photo.digital (More info?)

On 23 Jun 2005 16:06:24 EDT, "jimkramer"
<Sophomoric1_jim@NOSPAMjlkramer.net> wrote:

><Snip>
>
>http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>
>More understandable?
>
>Jim
>
You still are using a viewfinder referrence. There's no need to.
Simply use the type of overlay you're using, and call it a difference
in the recorded image.
Forget the viewfinder. The viewfinder has nothing to do with the
subject at hand.
It could read:

Below is an image demonstrating the "Digital Crop." The full image is
a print from a typical 35mm camera. The highlighted image is the crop
from a Digital Canon (1.6 crop) camera. Wide lenses become less
"wide" and Telephotos become "longer." Depth of field remains the
same. The actual magnification of the image on the sensor/film
remains the same.
--
Bill Funk
replace "g" with "a"
Anonymous
June 23, 2005 9:20:02 PM

Archived from groups: rec.photo.digital (More info?)

"Faz" <chuckfaz@shaw.ca> writes:
> Please can anyone tell me if this is correct?
>
> 35mm camera with 105 mm lens to Digital with 105 mm lens.
> Is this 1 to 1.5 or 1.5 to 1??????
> Any and all help will be greatly appreciated.

I assume you talk about the effect caused by some digital
cameras have a smaller sensor than a 35mm film frame?

In that case, take a look at the following web page:
http://folk.uio.no/gisle/photo/crop.html
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
------------------------------------------------------------------------
Kodak DCS460, Canon Powershot G5, Olympus 2020Z
------------------------------------------------------------------------
Anonymous
June 24, 2005 12:45:49 AM

Archived from groups: rec.photo.digital (More info?)

"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
news:D 9f4o0$t42@dispatch.concentric.net...
> <Snip>
>
> http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>
> More understandable?

Jim, it's exactly as understandable as the first time I read it, neither
more nor less. Understandability is not the problem here. Terminology is the
problem.

Incidentally, that page contains a faulty statement in addition to the bad
terminology. It says "Depth of field remains the same." That is either
wrong, misleading or meaningless depending on how you look at it.

Depth of field is dependent on degree of final magnification among many
other things. For example, a contact print has more depth of field than an
enlargement made from the same negative. The image on a camera's LCD monitor
has more depth of field than when it's on a computer monitor. To say a small
partial print has "the same depth of field" as the full print (which is
essentially what is done there in that linked example) is obviously true but
irrelevant. We do not make proportionally smaller prints just because we use
smaller sensors. If the same size print were made from both, the one made
from the shot with the 1.6 multiplier would have less depth of field because
it *is for most practical purposes* a 1.6x longer focal length lens.

N.
Anonymous
June 24, 2005 1:19:37 AM

Archived from groups: rec.photo.digital (More info?)

"Nostrobino" <not@home.today> wrote in message
news:lY6dnUiW3bxdyibfRVn-sQ@comcast.com...
>
> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
> news:D 9f4o0$t42@dispatch.concentric.net...
>> <Snip>
>>
>> http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>
>> More understandable?
>
> Jim, it's exactly as understandable as the first time I read it, neither
> more nor less. Understandability is not the problem here. Terminology is
> the problem.
>
> Incidentally, that page contains a faulty statement in addition to the bad
> terminology. It says "Depth of field remains the same." That is either
> wrong, misleading or meaningless depending on how you look at it.
>
> Depth of field is dependent on degree of final magnification among many
> other things. For example, a contact print has more depth of field than an
> enlargement made from the same negative. The image on a camera's LCD
> monitor has more depth of field than when it's on a computer monitor. To
> say a small partial print has "the same depth of field" as the full print
> (which is essentially what is done there in that linked example) is
> obviously true but irrelevant. We do not make proportionally smaller
> prints just because we use smaller sensors. If the same size print were
> made from both, the one made from the shot with the 1.6 multiplier would
> have less depth of field because it *is for most practical purposes* a
> 1.6x longer focal length lens.
>
> N.
>
I think I'm am going to simply disagree with you except on one point,
"Terminology is the problem." If you believe what you stated then we have a
very fundamentally different definition of Depth of Field.

I will state unequivocally that on film camera and a digital camera; the
same lens, at the same focus distance and aperture will produce the same
DoF. Only the portion of the real image that is "captured" on either media
is different.

http://www.luminous-landscape.com/tutorials/understandi...

Jim
Anonymous
June 24, 2005 3:54:27 AM

Archived from groups: rec.photo.digital (More info?)

On 22 Jun 2005 16:19:55 -0500, t@toddh.net (Todd H.) wrote:

>"Faz" <chuckfaz@shaw.ca> writes:
>> Please can anyone tell me if this is correct?
>>
>>
>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>
>> Is this 1 to 1.5 or 1.5 to 1??????
>
>We can pretty safely say the 105mm lens will achieve a narrow field of
>view on the digital body (kinda sorta, very sloppily saying the lens
>will appear to be something longer than 105mm), but whether it's 1.0x,
>1.4x, 1.5x, or 1.6x more "apparent magnification" (sloppy language)
>than 105mm in it's field of view, or whatever depends on which
>specific camera because different dSLR's have different size sensors,
>and hence have different field of view crop numbers.

No it won't a full frame digital like the Canon 1DsMkII.


*********************************************************

"I have been a witness, and these pictures are
my testimony. The events I have recorded should
not be forgotten and must not be repeated."

-James Nachtwey-
http://www.jamesnachtwey.com/
Anonymous
June 24, 2005 3:55:23 AM

Archived from groups: rec.photo.digital (More info?)

On Thu, 23 Jun 2005 01:18:10 GMT, Eric Gill <ericvgill@yahoo.com>
wrote:

>"Faz" <chuckfaz@shaw.ca> wrote in news:jhlue.1778874$6l.259376@pd7tw2no:
>
>> Please can anyone tell me if this is correct?
>>
>>
>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>
>> Is this 1 to 1.5 or 1.5 to 1??????
>
>Put it this way: put the 105mm lens on the Digital body, and a 157.5mm lens
>on the 35mm film body, and your shots would frame exactly the same.

Not on all digital bodies. Look at Canon's full frames.


*********************************************************

"I have been a witness, and these pictures are
my testimony. The events I have recorded should
not be forgotten and must not be repeated."

-James Nachtwey-
http://www.jamesnachtwey.com/
Anonymous
June 24, 2005 2:42:19 PM

Archived from groups: rec.photo.digital (More info?)

"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:

> I think I'm am going to simply disagree with you except on one point,
> "Terminology is the problem." If you believe what you stated then we have
> a very fundamentally different definition of Depth of Field.
>
> I will state unequivocally that on film camera and a digital camera; the
> same lens, at the same focus distance and aperture will produce the same
> DoF. Only the portion of the real image that is "captured" on either media
> is different.
>
> http://www.luminous-landscape.com/tutorials/understandi...

If you define DOF as a occurring when an observer looks at a print, then you
have to come to the conclusion that the DOF for the same lens, same subject,
same distance, same f stop, and _same print size_ changes with the format,
because the degree of enlargement changes. More enlargement from the
film/sensor reduces the DOF.

That is, one has to determine the COC required on the print (for the print
size and viewing distance), and then back calculate the COC required at the
film sensor. When one does that, one sees that a smaller COC at the
film/sensor plane is required for the smaller format.

Of course, it may be hard to see the difference (or come up with examples
where the difference is clear) for a 1.6x times difference in format size.
But from a COC calculation, there is a difference.

David J. Littleboy
Tokyo, Japan
Anonymous
June 24, 2005 2:42:20 PM

Archived from groups: rec.photo.digital (More info?)

On Fri, 24 Jun 2005 10:42:19 +0900, "David J. Littleboy"
<davidjl@gol.com> wrote:

>
>"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:
>
>> I think I'm am going to simply disagree with you except on one point,
>> "Terminology is the problem." If you believe what you stated then we have
>> a very fundamentally different definition of Depth of Field.
>>
>> I will state unequivocally that on film camera and a digital camera; the
>> same lens, at the same focus distance and aperture will produce the same
>> DoF. Only the portion of the real image that is "captured" on either media
>> is different.
>>
>> http://www.luminous-landscape.com/tutorials/understandi...
>
>If you define DOF as a occurring when an observer looks at a print, then you
>have to come to the conclusion that the DOF for the same lens, same subject,
>same distance, same f stop, and _same print size_ changes with the format,
>because the degree of enlargement changes. More enlargement from the
>film/sensor reduces the DOF.

Of course it does, as you rightly say. If this were not the
case the engraved scales on a (say) 150mm lens would be the
same as on any other 150mm lens. But they are not, if one is
for 35mm film and the other for rollfilm for example. If I
mount the rollfilm lens on my 35mm camera I'll find it's DoF
scales to be hopelessly optimistic - for exactly the same
reason as when I use the 35mm version on a digital camera
with much smaller sensor. The *size* of the sensor/film has
been taken into account when calculating the DoF scale, as
it must if it to be any use to the photographer.


--
Regards

John Bean
Anonymous
June 24, 2005 2:59:20 PM

Archived from groups: rec.photo.digital (More info?)

"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
news:D 9fn39$kt1@dispatch.concentric.net...
> "Nostrobino" <not@home.today> wrote in message
> news:lY6dnUiW3bxdyibfRVn-sQ@comcast.com...
>>
>> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
>> news:D 9f4o0$t42@dispatch.concentric.net...
>>> <Snip>
>>>
>>> http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>>
>>> More understandable?
>>
>> Jim, it's exactly as understandable as the first time I read it, neither
>> more nor less. Understandability is not the problem here. Terminology is
>> the problem.
>>
>> Incidentally, that page contains a faulty statement in addition to the
>> bad terminology. It says "Depth of field remains the same." That is
>> either wrong, misleading or meaningless depending on how you look at it.
>>
>> Depth of field is dependent on degree of final magnification among many
>> other things. For example, a contact print has more depth of field than
>> an enlargement made from the same negative. The image on a camera's LCD
>> monitor has more depth of field than when it's on a computer monitor. To
>> say a small partial print has "the same depth of field" as the full print
>> (which is essentially what is done there in that linked example) is
>> obviously true but irrelevant. We do not make proportionally smaller
>> prints just because we use smaller sensors. If the same size print were
>> made from both, the one made from the shot with the 1.6 multiplier would
>> have less depth of field because it *is for most practical purposes* a
>> 1.6x longer focal length lens.
>>
>> N.
>>
> I think I'm am going to simply disagree with you except on one point,
> "Terminology is the problem." If you believe what you stated then we have
> a very fundamentally different definition of Depth of Field.
>
> I will state unequivocally that on film camera and a digital camera; the
> same lens, at the same focus distance and aperture will produce the same
> DoF. Only the portion of the real image that is "captured" on either media
> is different.

Well, I will state unequivocally that you are wrong, unless you are assuming
the same degree of final enlargement and viewing distance--which there is no
reason to assume.

For example, on some small digital cameras using the so-called 1/2.5"
sensor, the short end of the zoom range is 5.7mm, which is usually taken to
be about 35mm in full-frame 35 equivalence. Thus, a 35mm (actual f.l.) lens
mounted on such a camera, if that were possible, would have about a 6.1
multiplier, i.e. it would be about equivalent to a 215mm lens on a
full-frame 35.

Now are you saying you really believe that lens would have the same DoF on
the small digital as on the full-frame 35?

If course it *would* if you made prints from the digicam one-sixth the size
of prints from the 35 and viewed them from the same distance. But that is a
nonsensical condition. We make prints the size we want, not smaller and
smaller when using cameras with smaller sensors.


>
> http://www.luminous-landscape.com/tutorials/understandi...

Skimmed the article quickly. The author appears to be referring to 35mm
photography only, not any smaller format such as most digital cameras have.
Even so, he manages to confuse himself when he gets into wide-angle lenses,
which remarkably he *denies* have greater DoF than longer lenses. His
reasoning is specious.

N.
Anonymous
June 24, 2005 3:19:27 PM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:D 9fof7$h22$1@nnrp.gol.com...
>
> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:
>
>> I think I'm am going to simply disagree with you except on one point,
>> "Terminology is the problem." If you believe what you stated then we
>> have a very fundamentally different definition of Depth of Field.
>>
>> I will state unequivocally that on film camera and a digital camera; the
>> same lens, at the same focus distance and aperture will produce the same
>> DoF. Only the portion of the real image that is "captured" on either
>> media is different.
>>
>> http://www.luminous-landscape.com/tutorials/understandi...
>
> If you define DOF as a occurring when an observer looks at a print, then
> you have to come to the conclusion that the DOF for the same lens, same
> subject, same distance, same f stop, and _same print size_ changes with
> the format, because the degree of enlargement changes. More enlargement
> from the film/sensor reduces the DOF.
>
> That is, one has to determine the COC required on the print (for the print
> size and viewing distance), and then back calculate the COC required at
> the film sensor. When one does that, one sees that a smaller COC at the
> film/sensor plane is required for the smaller format.
>
> Of course, it may be hard to see the difference (or come up with examples
> where the difference is clear) for a 1.6x times difference in format size.
> But from a COC calculation, there is a difference.
>
> David J. Littleboy
> Tokyo, Japan

Exactly. And at the risk of redundance, allow me to stress for other readers
that your very first comment, to the effect that DoF is something defined
when an observer looks at a print, is really the crux of the whole thing.
For a given viewing distance, anything that enlarges the CoC must must
reduce the DoF, and vice versa. Many people seem to believe that DoF scales
engraved on lenses must be correct in any and all circumstances just because
they are engraved on the lens, and likewise for equally arbitrary DoF
formulas. That just ain't so.

N.
Anonymous
June 24, 2005 4:16:05 PM

Archived from groups: rec.photo.digital (More info?)

"Nostrobino" <not@home.today> wrote in message
news:kt2dnQskHvBXgiHfRVn-uw@comcast.com...
>
> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
> news:D 9fn39$kt1@dispatch.concentric.net...
>> "Nostrobino" <not@home.today> wrote in message
>> news:lY6dnUiW3bxdyibfRVn-sQ@comcast.com...
>>>
>>> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
>>> news:D 9f4o0$t42@dispatch.concentric.net...
>>>> <Snip>
>>>>
>>>> http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>>>
>>>> More understandable?
>>>
>>> Jim, it's exactly as understandable as the first time I read it, neither
>>> more nor less. Understandability is not the problem here. Terminology is
>>> the problem.
>>>
>>> Incidentally, that page contains a faulty statement in addition to the
>>> bad terminology. It says "Depth of field remains the same." That is
>>> either wrong, misleading or meaningless depending on how you look at it.
>>>
>>> Depth of field is dependent on degree of final magnification among many
>>> other things. For example, a contact print has more depth of field than
>>> an enlargement made from the same negative. The image on a camera's LCD
>>> monitor has more depth of field than when it's on a computer monitor. To
>>> say a small partial print has "the same depth of field" as the full
>>> print (which is essentially what is done there in that linked example)
>>> is obviously true but irrelevant. We do not make proportionally smaller
>>> prints just because we use smaller sensors. If the same size print were
>>> made from both, the one made from the shot with the 1.6 multiplier would
>>> have less depth of field because it *is for most practical purposes* a
>>> 1.6x longer focal length lens.
>>>
>>> N.
>>>
>> I think I'm am going to simply disagree with you except on one point,
>> "Terminology is the problem." If you believe what you stated then we
>> have a very fundamentally different definition of Depth of Field.
>>
>> I will state unequivocally that on film camera and a digital camera; the
>> same lens, at the same focus distance and aperture will produce the same
>> DoF. Only the portion of the real image that is "captured" on either
>> media is different.
>
> Well, I will state unequivocally that you are wrong, unless you are
> assuming the same degree of final enlargement and viewing distance--which
> there is no reason to assume.
>
> For example, on some small digital cameras using the so-called 1/2.5"
> sensor, the short end of the zoom range is 5.7mm, which is usually taken
> to be about 35mm in full-frame 35 equivalence. Thus, a 35mm (actual f.l.)
> lens mounted on such a camera, if that were possible, would have about a
> 6.1 multiplier, i.e. it would be about equivalent to a 215mm lens on a
> full-frame 35.
>
> Now are you saying you really believe that lens would have the same DoF on
> the small digital as on the full-frame 35?
>
> If course it *would* if you made prints from the digicam one-sixth the
> size of prints from the 35 and viewed them from the same distance. But
> that is a nonsensical condition. We make prints the size we want, not
> smaller and smaller when using cameras with smaller sensors.
>
>
>>
>> http://www.luminous-landscape.com/tutorials/understandi...
>
> Skimmed the article quickly. The author appears to be referring to 35mm
> photography only, not any smaller format such as most digital cameras
> have. Even so, he manages to confuse himself when he gets into wide-angle
> lenses, which remarkably he *denies* have greater DoF than longer lenses.
> His reasoning is specious.
>
> N.
>
>
I suggest that you reread what was said; that being that on a film camera
and a digital camera; the
same lens, at the same focus distance and aperture will produce the same
DoF. Only the portion of the real image that is "captured" on either media
is different. I said nothing of digital equivalences nor was I talking
about different lenses. Same physical lens, two different camera bodies,
same set of focus and aperture settings = same depth of field.

Jim
Anonymous
June 24, 2005 10:59:19 PM

Archived from groups: rec.photo.digital (More info?)

"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
news:D 9hbk5$t3n@dispatch.concentric.net...
>
> "Nostrobino" <not@home.today> wrote in message
> news:kt2dnQskHvBXgiHfRVn-uw@comcast.com...
>>
>> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
>> news:D 9fn39$kt1@dispatch.concentric.net...
>>> "Nostrobino" <not@home.today> wrote in message
>>> news:lY6dnUiW3bxdyibfRVn-sQ@comcast.com...
>>>>
>>>> "jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote in message
>>>> news:D 9f4o0$t42@dispatch.concentric.net...
>>>>> <Snip>
>>>>>
>>>>> http://www.lookbefore.wading-in.net/lookbefore/Digital_...
>>>>>
>>>>> More understandable?
>>>>
>>>> Jim, it's exactly as understandable as the first time I read it,
>>>> neither more nor less. Understandability is not the problem here.
>>>> Terminology is the problem.
>>>>
>>>> Incidentally, that page contains a faulty statement in addition to the
>>>> bad terminology. It says "Depth of field remains the same." That is
>>>> either wrong, misleading or meaningless depending on how you look at
>>>> it.
>>>>
>>>> Depth of field is dependent on degree of final magnification among many
>>>> other things. For example, a contact print has more depth of field than
>>>> an enlargement made from the same negative. The image on a camera's LCD
>>>> monitor has more depth of field than when it's on a computer monitor.
>>>> To say a small partial print has "the same depth of field" as the full
>>>> print (which is essentially what is done there in that linked example)
>>>> is obviously true but irrelevant. We do not make proportionally smaller
>>>> prints just because we use smaller sensors. If the same size print were
>>>> made from both, the one made from the shot with the 1.6 multiplier
>>>> would have less depth of field because it *is for most practical
>>>> purposes* a 1.6x longer focal length lens.
>>>>
>>>> N.
>>>>
>>> I think I'm am going to simply disagree with you except on one point,
>>> "Terminology is the problem." If you believe what you stated then we
>>> have a very fundamentally different definition of Depth of Field.
>>>
>>> I will state unequivocally that on film camera and a digital camera; the
>>> same lens, at the same focus distance and aperture will produce the same
>>> DoF. Only the portion of the real image that is "captured" on either
>>> media is different.
>>
>> Well, I will state unequivocally that you are wrong, unless you are
>> assuming the same degree of final enlargement and viewing distance--which
>> there is no reason to assume.
>>
>> For example, on some small digital cameras using the so-called 1/2.5"
>> sensor, the short end of the zoom range is 5.7mm, which is usually taken
>> to be about 35mm in full-frame 35 equivalence. Thus, a 35mm (actual f.l.)
>> lens mounted on such a camera, if that were possible, would have about a
>> 6.1 multiplier, i.e. it would be about equivalent to a 215mm lens on a
>> full-frame 35.
>>
>> Now are you saying you really believe that lens would have the same DoF
>> on the small digital as on the full-frame 35?
>>
>> If course it *would* if you made prints from the digicam one-sixth the
>> size of prints from the 35 and viewed them from the same distance. But
>> that is a nonsensical condition. We make prints the size we want, not
>> smaller and smaller when using cameras with smaller sensors.
>>
>>
>>>
>>> http://www.luminous-landscape.com/tutorials/understandi...
>>
>> Skimmed the article quickly. The author appears to be referring to 35mm
>> photography only, not any smaller format such as most digital cameras
>> have. Even so, he manages to confuse himself when he gets into wide-angle
>> lenses, which remarkably he *denies* have greater DoF than longer lenses.
>> His reasoning is specious.
>>
>> N.
>>
>>
> I suggest that you reread what was said; that being that on a film camera
> and a digital camera; the
> same lens, at the same focus distance and aperture will produce the same
> DoF. Only the portion of the real image that is "captured" on either media
> is different.

But that's the part of your argument that begs the question. You're assuming
that that smaller portion must remain the same size, rather than being made
the same size which would be the reasonable way to compare them for DoF.

In effect, that's the same as saying that cutting out some portion of a
print would not change the DoF of that portion. Obviously that's true,
assuming viewing distance remains the same, but it's meaningless. Again,
people do not make proportionately smaller prints just because their cameras
have smaller sensors.


> I said nothing of digital equivalences

Then to what does your so-called "crop factor" refer? Of course you are
speaking of equivalences as soon as you mention that multiplier, by whatever
name you prefer to call it. The multiplier has no purpose at all except to
establish some equivalence with full-frame 35, isn't that so?


> nor was I talking about different lenses. Same physical lens, two
> different camera bodies, same set of focus and aperture settings = same
> depth of field.

Not unless the degree of final enlargement is also the same, which as
already noted more than once, would simply not be the case. You continue to
duck this point.

N.


>
> Jim
>
Anonymous
June 25, 2005 12:12:19 AM

Archived from groups: rec.photo.digital (More info?)

"Nostrobino" <not@home.today> wrote in message
news:14GdnRBrjfLWDSHfRVn-qw@comcast.com...
[ . . . ]
>>>
>> I suggest that you reread what was said; that being that on a film camera
>> and a digital camera; the
>> same lens, at the same focus distance and aperture will produce the same
>> DoF. Only the portion of the real image that is "captured" on either
>> media is different.
>
> But that's the part of your argument that begs the question. You're
> assuming that that smaller portion must remain the same size, rather than
> being made the same size which would be the reasonable way to compare them
> for DoF.

Not as crystal clear as I should have made it. What I meant of course was,
"You're assuming that the smaller portion must remain the same small size,
rather than being made the same size as the image from which it was taken."

N.
Anonymous
June 25, 2005 1:38:08 AM

Archived from groups: rec.photo.digital (More info?)

Bill Funk <BigBill@there.com> writes:

> Below is an image demonstrating the "Digital Crop." The full image
> is a print from a typical 35mm camera. The highlighted image is the
> crop from a Digital Canon (1.6 crop) camera. Wide lenses become
> less "wide" and Telephotos become "longer."

So far, fine.

> Depth of field remains the same.

This is wrong.

Depth of field (DOF) depends both on the size of the circle of
confusion - which is normally considered a fraction of imager size
(e.g 1/1740) and actual focal length (shorter focal lengths give
deeper DOF).

The interaction of these two effects gives the result that if we
keep the focal length constant, DOF /decreases/ with imager size,
but if we keep the FOV constant, DOF /increases/ with imager size.
The latter effect is clearly illustrated here:
http://www.toddwalker.net/doftest/

For a longer explanation, see:
http://folk.uio.no/gisle/photo/crop.html#dof
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
------------------------------------------------------------------------
Kodak DCS460, Canon Powershot G5, Olympus 2020Z
------------------------------------------------------------------------
Anonymous
June 25, 2005 1:45:02 AM

Archived from groups: rec.photo.digital (More info?)

Bill Funk <BigBill@there.com> writes:

> Below is an image demonstrating the "Digital Crop." The full image
> is a print from a typical 35mm camera. The highlighted image is the
> crop from a Digital Canon (1.6 crop) camera. Wide lenses become
> less "wide" and Telephotos become "longer."

So far, fine.

> Depth of field remains the same.

This is wrong.

Depth of field (DOF) depends both on the size of the circle of
confusion - which is normally considered a fraction of imager size
(e.g 1/1740) and actual focal length (shorter focal lengths give
deeper DOF).

The interaction of these two effects gives the result that if we
keep the focal length constant, DOF /increases/ with imager size,
but if we keep the FOV constant, DOF /decreases/ with imager size.
The latter effect is clearly illustrated here:
http://www.toddwalker.net/doftest/

For a longer explanation, see:
http://folk.uio.no/gisle/photo/crop.html#dof
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
------------------------------------------------------------------------
Kodak DCS460, Canon Powershot G5, Olympus 2020Z
------------------------------------------------------------------------
Anonymous
June 25, 2005 5:29:39 AM

Archived from groups: rec.photo.digital (More info?)

"jimkramer" <Sophomoric1_jim@NOSPAMjlkramer.net> wrote:
>>
> I suggest that you reread what was said; that being that on a film camera
> and a digital camera; the
> same lens, at the same focus distance and aperture will produce the same
> DoF. Only the portion of the real image that is "captured" on either media
> is different. I said nothing of digital equivalences nor was I talking
> about different lenses. Same physical lens, two different camera bodies,
> same set of focus and aperture settings = same depth of field.

The DOF looks the same when you look at the image _at the same magnification
on the screen_, but when you actually make prints _of the same size_, the
cropped image will be magnified further, and have less DOF.

(Comparing prints of the same size (and viewing at the same distance) is the
usual assumption when talking about DOF comparisons.)

David J. Littleboy
Tokyo, Japan
Anonymous
June 25, 2005 5:50:49 PM

Archived from groups: rec.photo.digital (More info?)

John A. Stovall <johnastovall@earthlink.net> wrote in
news:D uimb1tgi63tu68gi42870o9n7dod1ojk6@4ax.com:

> On Thu, 23 Jun 2005 01:18:10 GMT, Eric Gill <ericvgill@yahoo.com>
> wrote:
>
>>"Faz" <chuckfaz@shaw.ca> wrote in
>>news:jhlue.1778874$6l.259376@pd7tw2no:
>>
>>> Please can anyone tell me if this is correct?
>>>
>>>
>>> 35mm camera with 105 mm lens to Digital with 105 mm lens.
>>>
>>> Is this 1 to 1.5 or 1.5 to 1??????
>>
>>Put it this way: put the 105mm lens on the Digital body, and a 157.5mm
>>lens on the 35mm film body, and your shots would frame exactly the
>>same.
>
> Not on all digital bodies. Look at Canon's full frames.

*THE* digital body that he specified, John. Whatever 1.5 factor it happened
to be.
!