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Question about Sigma 18-125

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Anonymous
January 8, 2005 3:31:12 PM

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

I was reading reviews of this lens. Not many I could find. But one
reviewer said that as this lens is for digital cameras only, its 18mm
focal length setting is true 18mm for digital cameras. That is, it is same
as 18mm on a film camera rather than being converted to 28mm as normally
happens with other lenses.

Is that true ? Has anybody in the group used it and found that to be
correct ?

--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com

More about : question sigma 125

Anonymous
January 8, 2005 3:31:13 PM

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

"Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
>I was reading reviews of this lens. Not many I could find. But one
> reviewer said that as this lens is for digital cameras only, its 18mm
> focal length setting is true 18mm for digital cameras. That is, it is same
> as 18mm on a film camera rather than being converted to 28mm as normally
> happens with other lenses.
>
> Is that true ? Has anybody in the group used it and found that to be
> correct ?

Sigma manufactures lenses that are made for digital SLRs - noted by the "DG"
moniker. However, there is still the multiplication factor involved. It is
not a "true" 18mm on a digital camera as it would be a true 18mm on a film
camera. With this lens on my DSLR, it would be 28.8 mm (the mulitiplication
factor for my DSLR is 1.6) and unless you have a DSLR with a full frame
sensor then there is also a multiplication factor involved.
Related resources
January 8, 2005 6:14:51 PM

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

"Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
>I was reading reviews of this lens. Not many I could find. But one
> reviewer said that as this lens is for digital cameras only, its 18mm
> focal length setting is true 18mm for digital cameras. That is, it is same
> as 18mm on a film camera rather than being converted to 28mm as normally
> happens with other lenses.
>
> Is that true ? Has anybody in the group used it and found that to be
> correct ?
>
> --
>
> Gautam Majumdar
>
> Please send e-mails to gmajumdar@freeuk.com

Hi there.

The Focal Length of any lens is defined by the Laws of Optics. So an 18 mm
is an 18mm, irrespective of the size of the Camera to which it is attached.

On a Digital Camera that will produce a Wide Angle view of the subject. On
a 35 mm it would produce an extreme Wide Angle View, and on a 120 Roll Film
Camera it would produce a Fish Eye Type Image, (probably just a small
circular image on the film).

The confusion arises because Camera and Lens manufacturers compare the View
effect of Lenses between Digital and 35mm. Saying that an 18mm on a Digital
produces a similar view to a 24mm lens on 35mm Film Cameras.

It is exactly the same situation as comparing 35mm Camera lenses to 120 roll
film Camera lenses. A 50mm lens on a Roll film Camera is a Wide Angle Lens,
on a 35mm Camera it is a Standard Lens, and on a Digital Camera it is a
Short Tele Lens.

It has all to do with the sizes of the Image and Angles - big 120 Negative,
smaller 35mm Negative, even smaller CCD

Lenses produced specifically for Digital Cameras do not need to produce as
large a Circle of Light at the CCD, as lenses for 35mm Cameras, because the
CCDs are smaller than the 35mm Frame. BUT the Focal Length will be the Focal
Length.

God help us all if Camera Manufacturers start applying Hype and Distorting
the Truth about Focal Length of Lenses.

Roy
January 8, 2005 8:32:28 PM

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

"Peter A. Stavrakoglou" <ntotrr@optonline.net> wrote in message
news:InTDd.49319$Hr4.31778@fe10.lga...
> "Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
> news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
>>I was reading reviews of this lens. Not many I could find. But one
>> reviewer said that as this lens is for digital cameras only, its 18mm
>> focal length setting is true 18mm for digital cameras. That is, it is
>> same
>> as 18mm on a film camera rather than being converted to 28mm as normally
>> happens with other lenses.
>>
>> Is that true ? Has anybody in the group used it and found that to be
>> correct ?
>
> Sigma manufactures lenses that are made for digital SLRs - noted by the
> "DG" moniker. However, there is still the multiplication factor involved.
> It is not a "true" 18mm on a digital camera as it would be a true 18mm on
> a film camera. With this lens on my DSLR, it would be 28.8 mm (the
> mulitiplication factor for my DSLR is 1.6) and unless you have a DSLR with
> a full frame sensor then there is also a multiplication factor involved.
>
Oh. Yes it is!

An 18mm Lens is an 18mm Lens irrespective of whether it is fitted to a 35mm
Film Camera, a Digital Camera or is fitted to nothing.

When you talk about Multiplication Factor, you are discussing the Image
Size, not the Focal Length of the Lens. The Image Size is what would change
if you fitted this Lens to a 35mm Camera. It is still an 18mm Lens.

As I said an 18mm on a Digital Camera is a wide Angle Lens. On a 35mm
Camera it is an Very Wide Angle.

On Peter's Camera it will give the same Image Size as a 28.8mm Lens would on
a 35mm Camera. Hence his use of the multiplier of 1.6.
On a Nikon D70, it would give the same Image Size as a 27mm Lens on a 35mm
Camera, multiplier of 1.5.

BUT --- It is still an 18mm Lens, and can only be described as 18mm.

Those multipliers are only enabling us to mentally visualise the Image
Sizes, because we know (or should do) what Image Sizes a 28mm and a 24mm, or
whatever, on a 35mm Film Camera will produce.

Could you imagine what would happen if Sigma started to describe this lens
as a Nikon Fit 27mm, and Canon Fit 28.8mm. Every time a new size of CCD was
produced, every existing lens would have yet another Focal Length
description applied to it.

Lens makers should stick to actual Focal Lengths, and we can use
"Multipliers" in our Imagination until we get used to Digital Cameras with
relatively small CCDs, and start to know what Image Size an 18mm lens will
give.

BUT -- That 18mm Lens is still a True 18mm Lens, and will always be a
True 18mm Lens.

Roy
Anonymous
January 8, 2005 8:32:29 PM

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

"Roy" <royphoty@iona-guesthouse.co.uk> wrote in message
news:MOUDd.186$fH1.156@newsfe2-gui.ntli.net...
> "Peter A. Stavrakoglou" <ntotrr@optonline.net> wrote in message
> news:InTDd.49319$Hr4.31778@fe10.lga...
>> "Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
>> news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
>>>I was reading reviews of this lens. Not many I could find. But one
>>> reviewer said that as this lens is for digital cameras only, its 18mm
>>> focal length setting is true 18mm for digital cameras. That is, it is
>>> same
>>> as 18mm on a film camera rather than being converted to 28mm as normally
>>> happens with other lenses.
>>>
>>> Is that true ? Has anybody in the group used it and found that to be
>>> correct ?
>>
>> Sigma manufactures lenses that are made for digital SLRs - noted by the
>> "DG" moniker. However, there is still the multiplication factor
>> involved. It is not a "true" 18mm on a digital camera as it would be a
>> true 18mm on a film camera. With this lens on my DSLR, it would be 28.8
>> mm (the mulitiplication factor for my DSLR is 1.6) and unless you have a
>> DSLR with a full frame sensor then there is also a multiplication factor
>> involved.
>>
> Oh. Yes it is!
>
> An 18mm Lens is an 18mm Lens irrespective of whether it is fitted to a
> 35mm Film Camera, a Digital Camera or is fitted to nothing.
>
> When you talk about Multiplication Factor, you are discussing the Image
> Size, not the Focal Length of the Lens. The Image Size is what would
> change if you fitted this Lens to a 35mm Camera. It is still an 18mm Lens.
>
> As I said an 18mm on a Digital Camera is a wide Angle Lens. On a 35mm
> Camera it is an Very Wide Angle.
>
> On Peter's Camera it will give the same Image Size as a 28.8mm Lens would
> on a 35mm Camera. Hence his use of the multiplier of 1.6.
> On a Nikon D70, it would give the same Image Size as a 27mm Lens on a 35mm
> Camera, multiplier of 1.5.
>
> BUT --- It is still an 18mm Lens, and can only be described as 18mm.
>
> Those multipliers are only enabling us to mentally visualise the Image
> Sizes, because we know (or should do) what Image Sizes a 28mm and a 24mm,
> or whatever, on a 35mm Film Camera will produce.
>
> Could you imagine what would happen if Sigma started to describe this lens
> as a Nikon Fit 27mm, and Canon Fit 28.8mm. Every time a new size of CCD
> was produced, every existing lens would have yet another Focal Length
> description applied to it.
>
> Lens makers should stick to actual Focal Lengths, and we can use
> "Multipliers" in our Imagination until we get used to Digital Cameras with
> relatively small CCDs, and start to know what Image Size an 18mm lens will
> give.
>
> BUT -- That 18mm Lens is still a True 18mm Lens, and will always be a
> True 18mm Lens.

Of course you are correct, I knew that but perhaps I haven't explained it
properly. I have heard people say that if you take an 18mm lens made for
digital (such as a Sigma DG) then there is no multiplication factor - the
image on a DSLR would be 18mm just like it would on a 35mm SLR. That is not
true and that is the point I was making. We all know that if you shop in
the wrong places you can get some really bad information from salespeople,
like I've heard in Circuit City and Best Buy.
Anonymous
January 8, 2005 9:01:42 PM

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

On Sat, 8 Jan 2005 12:55:00 -0500, Peter A. Stavrakoglou wrote:
> Of course you are correct, I knew that but perhaps I haven't explained it
> properly. I have heard people say that if you take an 18mm lens made for
> digital (such as a Sigma DG) then there is no multiplication factor - the
> image on a DSLR would be 18mm just like it would on a 35mm SLR. That is not
> true and that is the point I was making. We all know that if you shop in
> the wrong places you can get some really bad information from salespeople,
> like I've heard in Circuit City and Best Buy.

In any case, how could the lens "know" whether it was using a crop factor of
1.5, 1.6, 1.7... Obviously silly.

As you say, 18mm is 18mm...

--
John Bean

Idealism is what precedes experience; cynicism is what follows (David T.
Wolf)
Anonymous
January 8, 2005 9:01:43 PM

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

The lens doesn't "know" what the multiplication factor is...that's
determined by the size of the imaging sensor in the camera.
A smaller sensor will give you a narrower field of view than a larger
sensor.
This mental experiment should help... take a picture with a 35 mm film
camera and a 35 mm lens, then print an 8 x 10. If you crop the center of
the negative then enlarge the center to print an 8 x 10, it will look like
you took the second picture with a 50 mm or longer lens. The lens focal
length hasn't changed, the field of view has changed. That's what happens
when CCD or CMOS sensors are smaller than a 35 mm negative.

The OP question wasn't answered completely... The 18 mm lens on a Nikon D70
dSLR is still 18 mm, but it will give you the same field of view as a 27 mm
lens on a 35mm film camera. This lens only works properly on dSLRs with
sensors that are no larger than the APS size, like the D70. On film
cameras, or dSLRs with full frame sensors, the image will be severely
vignetted. This is because the physical size of the image projected by the
lens on the sensor is smaller than lenses designed for 35 mm or full frame
sensors. It's the same thing as putting a 35 mm lens on a medium format
camera...it may work and produce an image on the film, but it'll be a small
circular image in the center of the negative.

....MTB


"John Bean" <waterfoot@gmail.com> wrote in message
news:c77dpjacwfdw.dlg@waterfoot.net...
> On Sat, 8 Jan 2005 12:55:00 -0500, Peter A. Stavrakoglou wrote:
> > Of course you are correct, I knew that but perhaps I haven't explained
it
> > properly. I have heard people say that if you take an 18mm lens made
for
> > digital (such as a Sigma DG) then there is no multiplication factor -
the
> > image on a DSLR would be 18mm just like it would on a 35mm SLR. That is
not
> > true and that is the point I was making. We all know that if you shop
in
> > the wrong places you can get some really bad information from
salespeople,
> > like I've heard in Circuit City and Best Buy.
>
> In any case, how could the lens "know" whether it was using a crop factor
of
> 1.5, 1.6, 1.7... Obviously silly.
>
> As you say, 18mm is 18mm...
>
> --
> John Bean
>
> Idealism is what precedes experience; cynicism is what follows (David T.
> Wolf)
Anonymous
January 8, 2005 9:15:03 PM

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

> Sigma manufactures lenses that are made for digital SLRs - noted by the
"DG"
> moniker. However, there is still the multiplication factor involved.

I believe it's "DC", not "DG". Are you sure that the crop-factor is still
present? Sigma isn't entirely clear, but does say that " Image circle is
designed to match the size of the image sensor of digital SLR cameras ".
While it isn't perfectly clear, it sounds like they had the APS-C sensor
size in mind when designing it, which would eliminate the crop factor - or
at least reduce it from something like 1.5/1.6 to 1.05 or so, depending on
whether you've got a D70 or a DigiReb.

steve
Anonymous
January 8, 2005 9:55:41 PM

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

On Sat, 08 Jan 2005 15:49:50 +0000, Peter A. Stavrakoglou wrote:

> "Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
> news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
>>I was reading reviews of this lens. Not many I could find. But one
>> reviewer said that as this lens is for digital cameras only, its 18mm
>> focal length setting is true 18mm for digital cameras. That is, it is
>> same as 18mm on a film camera rather than being converted to 28mm as
>> normally happens with other lenses.
>>
>> Is that true ? Has anybody in the group used it and found that to be
>> correct ?
>
> Sigma manufactures lenses that are made for digital SLRs - noted by the
> "DG" moniker. However, there is still the multiplication factor
> involved. It is not a "true" 18mm on a digital camera as it would be a
> true 18mm on a film camera. With this lens on my DSLR, it would be 28.8
> mm (the mulitiplication factor for my DSLR is 1.6) and unless you have a
> DSLR with a full frame sensor then there is also a multiplication factor
> involved.

Thanks very much. That is what I thought. But the reviewer specifically
mentioned that it is a true 18mm equivalent on DSLR, so I asked for
confirmation.

By the way, are you happy with the performance of this lens ? I am
thinking of buying it as the standard lens to remain on my 300D most of
the time.

--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com
Anonymous
January 8, 2005 9:55:42 PM

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

Gautum:
There's a full page ad for this lens in the December issue of Popular
Photography...page 57. The copy specifically states that this lens should
not be used with cameras having sensors larger than APS-C equivalent or with
35mm film cameras.
This lens is 18 mm at the widest, but it will give you an image with the
same field of view of as a 27 mm lens on a film SLR.
....MTB

"Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
news:N0WDd.33220$C8.25191@fe3.news.blueyonder.co.uk...
> On Sat, 08 Jan 2005 15:49:50 +0000, Peter A. Stavrakoglou wrote:
>
> > "Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
> > news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
> >>I was reading reviews of this lens. Not many I could find. But one
> >> reviewer said that as this lens is for digital cameras only, its 18mm
> >> focal length setting is true 18mm for digital cameras. That is, it is
> >> same as 18mm on a film camera rather than being converted to 28mm as
> >> normally happens with other lenses.
> >>
> >> Is that true ? Has anybody in the group used it and found that to be
> >> correct ?
> >
> > Sigma manufactures lenses that are made for digital SLRs - noted by the
> > "DG" moniker. However, there is still the multiplication factor
> > involved. It is not a "true" 18mm on a digital camera as it would be a
> > true 18mm on a film camera. With this lens on my DSLR, it would be 28.8
> > mm (the mulitiplication factor for my DSLR is 1.6) and unless you have a
> > DSLR with a full frame sensor then there is also a multiplication factor
> > involved.
>
> Thanks very much. That is what I thought. But the reviewer specifically
> mentioned that it is a true 18mm equivalent on DSLR, so I asked for
> confirmation.
>
> By the way, are you happy with the performance of this lens ? I am
> thinking of buying it as the standard lens to remain on my 300D most of
> the time.
>
> --
>
> Gautam Majumdar
>
> Please send e-mails to gmajumdar@freeuk.com
January 9, 2005 1:12:56 AM

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

They are referring to the size of the image circle rather than the focal
length. In the case of this lens it would simply not adequately cover the
24x36mm of a 35mm negative but will cover the smaller size (APS and smaller)
of most digital sensors in bodies based on 35mm prototypes. There are a few
cameras with full 24x36 sensors (or close to that) which would not be good
choices for this lens. If you own Canon I would suggest you avoid Sigma
products as they will not license the mount and therefore have later
compatibility problems - which they claim they will fix but won't.
In general Sigma is for temporary.

--
http://www.chapelhillnoir.com
home of The Camera-ist's Manifesto
The Improved Links Pages are at
http://www.chapelhillnoir.com/links/mlinks00.html
A sample chapter from "Haight-Ashbury" is at
http://www.chapelhillnoir.com/writ/hait/hatitl.html

"Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
news:koQDd.28462$C8.1732@fe3.news.blueyonder.co.uk...
> I was reading reviews of this lens. Not many I could find. But one
> reviewer said that as this lens is for digital cameras only, its 18mm
> focal length setting is true 18mm for digital cameras. That is, it is same
> as 18mm on a film camera rather than being converted to 28mm as normally
> happens with other lenses.
>
> Is that true ? Has anybody in the group used it and found that to be
> correct ?
>
> --
>
> Gautam Majumdar
>
> Please send e-mails to gmajumdar@freeuk.com
Anonymous
January 9, 2005 12:36:24 PM

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

"Steve Wolfe" <unt@codon.com> wrote in message
news:34c7o9F477i28U1@individual.net...
>> Sigma manufactures lenses that are made for digital SLRs - noted by the
> "DG"
>> moniker. However, there is still the multiplication factor involved.
>
> I believe it's "DC", not "DG". Are you sure that the crop-factor is
> still
> present? Sigma isn't entirely clear, but does say that " Image circle is
> designed to match the size of the image sensor of digital SLR cameras ".
> While it isn't perfectly clear, it sounds like they had the APS-C sensor
> size in mind when designing it, which would eliminate the crop factor - or
> at least reduce it from something like 1.5/1.6 to 1.05 or so, depending on
> whether you've got a D70 or a DigiReb.
>
> steve

It is "DG" and there is still the crop factor.
Anonymous
January 9, 2005 12:49:00 PM

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

On Sat, 08 Jan 2005 21:01:46 +0000, Bill Tuthill wrote:

> Gautam Majumdar <gmajumdar@xspamfreeuk.com> wrote:
>> I was reading reviews of this lens. Not many I could find.
>
> Did you see the one comparing to the Canon 18-55mm, Canon 17-85mm?
> Favorably.
>
> http://forums.dpreview.com/forums/read.asp?forum=1029&m...
>
> More links to reviews here:
>
> http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00...

Thanks for the links Bill. Those are very encouraging.

--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com
Anonymous
January 9, 2005 12:51:51 PM

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

"Steve Wolfe" <unt@codon.com> wrote in message
news:34c7o9F477i28U1@individual.net...
>> Sigma manufactures lenses that are made for digital SLRs - noted by the
> "DG"
>> moniker. However, there is still the multiplication factor involved.
>
> I believe it's "DC", not "DG". Are you sure that the crop-factor is
> still
> present? Sigma isn't entirely clear, but does say that " Image circle is
> designed to match the size of the image sensor of digital SLR cameras ".
> While it isn't perfectly clear, it sounds like they had the APS-C sensor
> size in mind when designing it, which would eliminate the crop factor - or
> at least reduce it from something like 1.5/1.6 to 1.05 or so, depending on
> whether you've got a D70 or a DigiReb.
>
> steve
>
>

No, it doesn't eliminate the crop factor. What is meant by it being
designed for digital is that it is designed to project the image circle on a
APS sized sensor. To do that, the lens is smaller & lighter, but the crop
factor remains. If you were to use it on a 1.3x or full-size sensor camera,
you would get vignetting.

Mark
Anonymous
January 9, 2005 6:08:26 PM

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

On Sun, 9 Jan 2005 09:36:24 -0500, Peter A. Stavrakoglou wrote:

>> I believe it's "DC", not "DG".
>
> It is "DG"

http://www.sigma-imaging-uk.com/a_pages/dc18-125.htm

DC. Unless you know better than Sigma.

--
John Bean

Bacchus hath drowned more men than Neptune (Thomas Fuller)
Anonymous
January 9, 2005 6:51:51 PM

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

"John Bean" <waterfoot@gmail.com> wrote in message
news:c6y45qs3m0qx$.dlg@waterfoot.net...
> On Sun, 9 Jan 2005 09:36:24 -0500, Peter A. Stavrakoglou wrote:
>
>>> I believe it's "DC", not "DG".
>>
>> It is "DG"
>
> http://www.sigma-imaging-uk.com/a_pages/dc18-125.htm
>
> DC. Unless you know better than Sigma.

It appears that we are both correct, according to the Sigma lens catalogue I
am holding in my hands on first reading. It reads "DG (Digital) Lenses" and
also "DC (Digital) Lenses". However, you win this one because further
reading of the catalogue under the "DG (Digital) Lenses" section states that
these lenses "are equally suited for digital and analogue cameras". If you
could see it you would note how confusing the catalog is on this matter.
Anonymous
January 9, 2005 11:57:50 PM

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

On Sun, 09 Jan 2005 14:51:51 +0000, Mark B. wrote:

> "Steve Wolfe" <unt@codon.com> wrote in message
> news:34c7o9F477i28U1@individual.net...
>>> Sigma manufactures lenses that are made for digital SLRs - noted by
>>> the
>> "DG"
>>> moniker. However, there is still the multiplication factor involved.
>>
>> I believe it's "DC", not "DG". Are you sure that the crop-factor is
>> still
>> present? Sigma isn't entirely clear, but does say that " Image circle
>> is designed to match the size of the image sensor of digital SLR
>> cameras ". While it isn't perfectly clear, it sounds like they had the
>> APS-C sensor size in mind when designing it, which would eliminate the
>> crop factor - or at least reduce it from something like 1.5/1.6 to 1.05
>> or so, depending on whether you've got a D70 or a DigiReb.
>>
> No, it doesn't eliminate the crop factor. What is meant by it being
> designed for digital is that it is designed to project the image circle
> on a APS sized sensor. To do that, the lens is smaller & lighter, but
> the crop factor remains. If you were to use it on a 1.3x or full-size
> sensor camera, you would get vignetting.
>
Sigma's website tells that the angle of view is 69.3º - 11.5º which
corresponds to ~30 - 210 mm lens for a film camera. So the 1.6
multiplication factor is there.


--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com
Anonymous
January 9, 2005 11:57:51 PM

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

"Gautam Majumdar" <gmajumdar@XSPAMfreeuk.com> wrote in message
news:iVgEd.91592$48.25995@fe1.news.blueyonder.co.uk...
> On Sun, 09 Jan 2005 14:51:51 +0000, Mark B. wrote:
>
>> No, it doesn't eliminate the crop factor. What is meant by it being
>> designed for digital is that it is designed to project the image circle
>> on a APS sized sensor. To do that, the lens is smaller & lighter, but
>> the crop factor remains. If you were to use it on a 1.3x or full-size
>> sensor camera, you would get vignetting.
>>
> Sigma's website tells that the angle of view is 69.3º - 11.5º which
> corresponds to ~30 - 210 mm lens for a film camera. So the 1.6
> multiplication factor is there.
>


Is there an echo in here?
!