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20D Canon focus advice

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Anonymous
August 21, 2005 11:07:31 PM

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

Hi all,

I have a nagging suspicion that the focus on my new 20D isn't all that it
should be. Do any of you have any suggestions on the best way to test this?
I was thinking of photographing a sheet of A4 "Math - graph" type paper.

If the camera's focus is out, will it be out consistently when focusing on
close and distant objects? Should I have the lens wide open or stopped down
for the test. Is it possible for an image to be in focus through the
viewfinder, and yet be out of focus at the CMOS sensor? Any other thoughts
(I only have the one kit lens at this time, so I can't do any lens
comparisons).

Thanks for your input.

Cheers,

CC

More about : 20d canon focus advice

Anonymous
August 21, 2005 11:07:32 PM

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

Cockpit Colin wrote:
> Hi all,
>
> I have a nagging suspicion that the focus on my new 20D isn't all
> that it should be. Do any of you have any suggestions on the best way
> to test this? I was thinking of photographing a sheet of A4 "Math -
> graph" type paper.

Try printing this:

http://www.photo.net/learn/focustest/scale45.jpg

Place it at 45 degrees and focus on the line in the middle.

> Should I have the lens wide
> open or stopped down for the test.

A large aperture will show the results more clearly.

> Is it possible for an image to be in focus through the viewfinder,
> and yet be out of focus at the CMOS sensor?

Yes, but IMO that would mean a major physical problem
which I would expect to show up as other symptoms as well.

-Mike
Anonymous
August 21, 2005 11:07:32 PM

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

> Hi all,
>
> I have a nagging suspicion that the focus on my new 20D isn't all that it
> should be.


Hi Colin...

Not sure what you mean about the focus...whether you are talking about
through the lens or the actual results.

Don't mean to be condescending here...but if you are talking about the focus
through the lens, have you checked the diopter adjustment on the viewfinder.
The only reason I ask is that I had a friend with the same complaint and the
diopter just got knocked a fraction.

Cheers
Steve
Related resources
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August 21, 2005 11:07:32 PM

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

"Cockpit Colin" <spam@nospam.com> wrote in message
news:yIVNe.4335$iM2.444359@news.xtra.co.nz...
> Hi all,
>
> I have a nagging suspicion that the focus on my new 20D isn't all that it
> should be. Do any of you have any suggestions on the best way to test
> this?
> I was thinking of photographing a sheet of A4 "Math - graph" type paper.
>
> If the camera's focus is out, will it be out consistently when focusing on
> close and distant objects? Should I have the lens wide open or stopped
> down
> for the test. Is it possible for an image to be in focus through the
> viewfinder, and yet be out of focus at the CMOS sensor? Any other thoughts
> (I only have the one kit lens at this time, so I can't do any lens
> comparisons).
>
> Thanks for your input.
>
> Cheers,
>
> CC
>
>

I'm probably teaching old dogs new tricks but always ensure you know which
AF point the camera is focusing on, I always lock it to the center one, and
remember the AF sensors maybe bigger than the markings in the viewfinder.

take a look at http://www.knighttrain.freeserve.co.uk/400.htm where you can
see 10D AF markings and sensor sizes.

This is based on 10D info but probably holds true for the 20D.
Anonymous
August 22, 2005 12:05:40 AM

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

In article <de9e7d$lu0$1@newsg4.svr.pol.co.uk>, no@nowhere.com says...

> I'm probably teaching old dogs new tricks but always ensure you know which
> AF point the camera is focusing on, I always lock it to the center one, and
> remember the AF sensors maybe bigger than the markings in the viewfinder.
>
> take a look at http://www.knighttrain.freeserve.co.uk/400.htm where you can
> see 10D AF markings and sensor sizes.
>
> This is based on 10D info but probably holds true for the 20D.

Also, try the test with different lenses and versus your own manual
focusing ability.

I thought my camera was poor on focus, then I tried beating it with my
own eye. The AF wasn't perfect, but I wasn't anywhere close!

If you still have problems, send the camera with your lenses to a Canon
repair facility. People have reported success after the techs re-
calibrated their body and lenses.
--
http://www.pbase.com/bcbaird
Anonymous
August 22, 2005 12:05:41 AM

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

You might check out a software called "Imatest" This allows you test various
lens for a variety of quality issues.

www.imatest.com

The test procedure is long and detailed but not necessarily difficult. I
recently did it with a couple of new lens, a Canon 17-85 EF-S IS and a Canon
70-300 EF IS DO. Both came out with good results. What was interesting, the
shorter lens' quality measurement went down about 5% with a high quality
(and clean) filter. With the "DO" lens, the image quality actually improved.
I ran the test twice over a couple of days taking two measurements each
time. The data were consistent.

I think what it told me is that my lenses are high quality and if my images
are bad, it's probably the photographer and not the equipment.

Steve
"Brian Baird" <no@no.thank.u> wrote in message
news:MPG.1d72a89d63b77e48989911@news.verizon.net...
> In article <de9e7d$lu0$1@newsg4.svr.pol.co.uk>, no@nowhere.com says...
>
>> I'm probably teaching old dogs new tricks but always ensure you know
>> which
>> AF point the camera is focusing on, I always lock it to the center one,
>> and
>> remember the AF sensors maybe bigger than the markings in the viewfinder.
>>
>> take a look at http://www.knighttrain.freeserve.co.uk/400.htm where you
>> can
>> see 10D AF markings and sensor sizes.
>>
>> This is based on 10D info but probably holds true for the 20D.
>
> Also, try the test with different lenses and versus your own manual
> focusing ability.
>
> I thought my camera was poor on focus, then I tried beating it with my
> own eye. The AF wasn't perfect, but I wasn't anywhere close!
>
> If you still have problems, send the camera with your lenses to a Canon
> repair facility. People have reported success after the techs re-
> calibrated their body and lenses.
> --
> http://www.pbase.com/bcbaird
Anonymous
August 22, 2005 4:02:22 AM

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

In article <MPG.1d72a89d63b77e48989911@news.verizon.net>, Brian Baird
<no@no.thank.u> writes
>In article <de9e7d$lu0$1@newsg4.svr.pol.co.uk>, no@nowhere.com says...
>
>> I'm probably teaching old dogs new tricks but always ensure you know which
>> AF point the camera is focusing on, I always lock it to the center one, and
>> remember the AF sensors maybe bigger than the markings in the viewfinder.
>>
>> take a look at http://www.knighttrain.freeserve.co.uk/400.htm where you can
>> see 10D AF markings and sensor sizes.
>>
>> This is based on 10D info but probably holds true for the 20D.
>
>Also, try the test with different lenses and versus your own manual
>focusing ability.
>
>I thought my camera was poor on focus, then I tried beating it with my
>own eye. The AF wasn't perfect, but I wasn't anywhere close!

Unfortunately, current AF bodies (except top-of-range models like
Canon's 1-series) are stuck with screen almost totally unhelpful for
manual focussing. This is, BTW, a major problem with using DSLRs for
photomicrography, one of my main interests.

It (interchangeable screens) is also one of the more exciting (to me)
features of the EOS 5D, if the leaks prove accurate (and if one of the
screens is a useful one with clear spot and cross-hair).
>
>If you still have problems, send the camera with your lenses to a Canon
>repair facility. People have reported success after the techs re-
>calibrated their body and lenses.

David
--
David Littlewood
August 22, 2005 4:02:23 AM

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

David Littlewood wrote:


>
> Unfortunately, current AF bodies (except top-of-range models like
> Canon's 1-series) are stuck with screen almost totally unhelpful for
> manual focussing. This is, BTW, a major problem with using DSLRs for
> photomicrography, one of my main interests.

I agree and this was one of my "shopping criteria" when buying a dSLR,
something the review sites NEVER even mention. Most dSLR's assume you will
ALWAYS use AF, have no idea how to focus a camera yourself so they design
the focus screen to be as bright as possible (to brighten the view with the
slow kit lens?) at the expence of manual focusing ability. And not all
camera makers screens are like this. Some models get "blasted" by the
reviewers for having a dimmer focus screen when the fact is, they designed
the screen so you can actually see the focus plane for manual focusing.

Just another thing people should check out when camera shopping. If you
can't focus the camera well, it really doesn't matter how great the other
features are.

--

Stacey
August 22, 2005 4:02:23 AM

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

David Littlewood wrote:

> Unfortunately, current AF bodies (except top-of-range models like
> Canon's 1-series) are stuck with screen almost totally unhelpful for
> manual focussing. This is, BTW, a major problem with using DSLRs for
> photomicrography, one of my main interests.
>
>
> David


That should've read, come stock with an AF screen >>
http://www.keoptics.com/Canon20D.htm

Although, it will add some $$ to the orig purchase price, at least there
is an option available.
--
Slack
Anonymous
August 22, 2005 6:32:03 AM

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

In article <43092328.B8096D40@killspam.127.0.0.1>, Colin D
<ColinD@killspam.127.0.0.1> writes
>
>The lens stops down to f/22 at 18mm, and f/38 at the 55mm end - where
>you had the lens set - and at that aperture the image will be badly
>affected by diffraction, so it will not be anywhere near as sharp as at
>f/11 or f/8. Basically, that sort of aperture is unusable for normal
>photography.
>>
True-ish; f/38 will be very much below optimum for anything other than a
pinhole or bottle end. However, it may well be obligatory to get the
depth of field required in high ratio macro work (don't forget that that
diffraction is determined by effective aperture (which is measured
aperture x (1+m)).

Also, in large format work, f/45 is quite routine. Yes, it is
sub-optimum, but at least you have a lot of resolution to spare.

Finally, a ^good^ lens should be best (in resolution terms) at something
a lot wider than f/11. F/5.6 for a really well corrected lens, f/8 is
not bad.

David
--
David Littlewood
Anonymous
August 22, 2005 11:54:27 AM

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

Cockpit Colin wrote:
> Hi all,
>
> I have a nagging suspicion that the focus on my new 20D isn't all that it
> should be. Do any of you have any suggestions on the best way to test this?
> I was thinking of photographing a sheet of A4 "Math - graph" type paper.
>
> If the camera's focus is out, will it be out consistently when focusing on
> close and distant objects? Should I have the lens wide open or stopped down
> for the test. Is it possible for an image to be in focus through the
> viewfinder, and yet be out of focus at the CMOS sensor? Any other thoughts
> (I only have the one kit lens at this time, so I can't do any lens
> comparisons).
>
> Thanks for your input.
>
> Cheers,
>
> CC
>
>
Using an angled scale is not the best way to test your focus. 20D's have
a really tight tolerance to distance from the rear element to the film
plane (sensor). They are much less tolerant to errors than a 35mm camera
is due to the closeness of these 2 points.

According to Canon: correct focus is anywhere within the depth of field
of the lens. If you bought a camera with a "Kit lens", the focus point
could be anywhere within a inch of the centre at about 2 feet and still
be within acceptable factory tolerances. Pretty poor stuff when you
decide to shoot some flowers or small animals!

The most common focus error on 20Ds is called "back focus" which is
independent of lenses. All three of my 20Ds had back focus errors which
only became evident when I used a 50mm f1.4 lens at close range. Canon
fix it by plugging in a computer and making a few adjustments, no lens
attached. Try to get the software yourself and see how friendly and
cooperative Canon are not!

You can get an *IDEA* of the error by using the chart Mike Warren posted
a link to but the process of using a chart at an angle becomes imprecise
when you use a wide angle lens or a wide aperture lens designed for full
frame cameras (like a 50, f1.4 or 1.8). Sort of self defeating unless
the error is substantial.

All canon (non macro)lenses exhibit barrel distortion or a pincushion
effect at close quarters so your results might *indicate* a back focus
error but they cannot quantify it.

Canon will take very little time in fixing the problem. You might
discover a relapse of the problem if you have to remove the camera's
"stay alive" battery when it dies on a lens change or from connecting
your Speedlight when it's switched on, but inside 12 month, they'll do
it free as many times as you need it.

Just make sure the error is consistent between lenses or you need to
take all the lenses in as well! In all the years I used Nikon cameras, I
never saw one instance of faults or reliability relating to quality
control during manufacture at any of the newspapers I worked on.

Since buying Canon gear I've seen many photographers with 20D problems
and experienced some severe problems with my own gear which should not
have happened. People seem to think quality is related to price. Canon
have disproved that with their 20D. Those who don't get the faults,
don't push their cameras.

--
Douglas,
You never really make it on the 'net
until you get your own personal Troll.
Mine's called Chrlz. Don't feed him, he bites!
Anonymous
August 22, 2005 11:54:28 AM

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

In article <4308f82f@dnews.tpgi.com.au>, pixby_douglas@hotmail.com
says...
> Those who don't get the faults,
> don't push their cameras.

Translation:

Measurebators will always find faults with their cameras.
--
http://www.pbase.com/bcbaird
Anonymous
August 22, 2005 11:54:28 AM

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

In article <4308f82f@dnews.tpgi.com.au>, pixby
<pixby_douglas@hotmail.com> wrote:

> Since buying Canon gear I've seen many photographers with 20D problems
> and experienced some severe problems with my own gear which should not
> have happened. People seem to think quality is related to price. Canon
> have disproved that with their 20D. Those who don't get the faults,
> don't push their cameras.

There are too many people with money who buy cameras like the 20D and
have no knowledge of photography.
Anonymous
August 22, 2005 11:54:28 AM

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

pixby wrote:

> Snip
> Since buying Canon gear I've seen many photographers with 20D problems
> and experienced some severe problems with my own gear which should not
> have happened. People seem to think quality is related to price. Canon
> have disproved that with their 20D. Those who don't get the faults,
> don't push their cameras.
>

Problems with the 20D? I haven't experienced any problems with my 20D. I
use my cameras in ways that I've always used my cameras. I had problems
with the BG-E2 battery pack not being usable with AA batteries, but that
problem took about 15 minutes to go away. I drove to the Canon repair
center and told them about the problem. They took my camera to their
repair lab and before I had the chance to finish reading a magazine
article while waiting, they came back with a NEW BG-E2 battery pack.

While there, they asked to see my equipment and updated firmware and
accomplished a series of checks on my camera bodies and lenses.
August 22, 2005 11:54:29 AM

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

Brian Baird wrote:

> In article <4308f82f@dnews.tpgi.com.au>, pixby_douglas@hotmail.com
> says...
>> Those who don't get the faults,
>> don't push their cameras.
>
> Translation:
>
> Measurebators will always find faults with their cameras.


Actually you're the one who said you can't even manually focus your camera
so how would you know?
--

Stacey
Anonymous
August 22, 2005 11:54:29 AM

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

Randall Ainsworth wrote:
> In article <4308f82f@dnews.tpgi.com.au>, pixby
> <pixby_douglas@hotmail.com> wrote:
>
>
>>Since buying Canon gear I've seen many photographers with 20D problems
>>and experienced some severe problems with my own gear which should not
>>have happened. People seem to think quality is related to price. Canon
>>have disproved that with their 20D. Those who don't get the faults,
>>don't push their cameras.
>
>
> There are too many people with money who buy cameras like the 20D and
> have no knowledge of photography.

There are many people who buy expensive cars who have no interest in
lifting the engine hood. When the DOD was dumping aircraft into the
civilian market, I know people who bought T-28 North American built
trainers, who didn't know how to fly. But the price was right, so they
learned how to fly.
Anonymous
August 22, 2005 2:06:52 PM

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

Stacey <fotocord@yahoo.com> wrote:

>Brian Baird wrote:
>
>> In article <4308f82f@dnews.tpgi.com.au>, pixby_douglas@hotmail.com
>> says...
>>> Those who don't get the faults,
>>> don't push their cameras.
>>
>> Translation:
>>
>> Measurebators will always find faults with their cameras.
>
>
>Actually you're the one who said you can't even manually focus your camera
>so how would you know?


Poor Brian. He's not actually very bright.

;-)
Anonymous
August 22, 2005 2:48:46 PM

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

Randall Ainsworth <rag@nospam.techline.com> wrote:

>In article <4308f82f@dnews.tpgi.com.au>, pixby
><pixby_douglas@hotmail.com> wrote:
>
>> Since buying Canon gear I've seen many photographers with 20D problems
>> and experienced some severe problems with my own gear which should not
>> have happened. People seem to think quality is related to price. Canon
>> have disproved that with their 20D. Those who don't get the faults,
>> don't push their cameras.
>
>There are too many people with money who buy cameras like the 20D and
>have no knowledge of photography.


'Twas ever thus.

A great many people bought high end 35mm SLRs like the Canon EOS 1N/V
and the Nikon F5, only to use them with lousy 28-200mm lenses for
taking family snapshots.

It's like people who buy a Porsche and use it only for shopping trips.

It's called "freedom".

;-)
Anonymous
August 22, 2005 3:57:43 PM

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

Thanks all,

My suspicions were aroused when I took a photo of a stream and surrounding
vegetation whilst on a walking track (hand held) - it just looked plain
blury. I went back later on that day and set the camera up on a tripod. On
my 20D with kit lens (zoomed all the way out) At 100 ISO and F29? (or there
abouts - stopped down as far as it would go) I ended up with a exposure of
2.5 sec (not a breath of wind, so not worried about anything moving in the
breeze).

Back on the PC EVERYTHING just didn't appear to be as sharp as I would have
expected (shot in RAW too). The whole thing just appeared hard on the eyes -
it wasn't until I ran an unsharp mask at 200% over it that it started to
look "normal". Not sure if this is the camera, or if I'm expecting too much.
I did take some photos of some graph paper later on that night, and it "sort
of" appeared OK (difficult to tell).

I could send it in for checking, but it probably means doing without it for
a couple of weeks :( 

Cheers,

CC



"Cockpit Colin" <spam@nospam.com> wrote in message
news:yIVNe.4335$iM2.444359@news.xtra.co.nz...
> Hi all,
>
> I have a nagging suspicion that the focus on my new 20D isn't all that it
> should be. Do any of you have any suggestions on the best way to test
this?
> I was thinking of photographing a sheet of A4 "Math - graph" type paper.
>
> If the camera's focus is out, will it be out consistently when focusing on
> close and distant objects? Should I have the lens wide open or stopped
down
> for the test. Is it possible for an image to be in focus through the
> viewfinder, and yet be out of focus at the CMOS sensor? Any other thoughts
> (I only have the one kit lens at this time, so I can't do any lens
> comparisons).
>
> Thanks for your input.
>
> Cheers,
>
> CC
>
>
Anonymous
August 22, 2005 3:57:44 PM

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

In article <zv8Oe.4460$iM2.462021@news.xtra.co.nz>, spam@nospam.com
says...
> Back on the PC EVERYTHING just didn't appear to be as sharp as I would have
> expected (shot in RAW too). The whole thing just appeared hard on the eyes -
> it wasn't until I ran an unsharp mask at 200% over it that it started to
> look "normal". Not sure if this is the camera, or if I'm expecting too much.
> I did take some photos of some graph paper later on that night, and it "sort
> of" appeared OK (difficult to tell).

IF you're shooting at really small apertures things aren't going to be
as sharp due to diffraction.

Running an unsharp mast will help a bit, and in general all DSLR images
need some final sharpening to achieve optimum results.
--
http://www.pbase.com/bcbaird
Anonymous
August 22, 2005 3:57:45 PM

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

Or you can just turn up the in-camera sharpening...

....Did you ever bother to look at the custom functions, Doug?
--
http://www.pbase.com/bcbaird
Anonymous
August 22, 2005 4:43:25 PM

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

In article <J_-dnUNXlPo6ppTeRVn-vg@giganews.com>, Slack
<slacker7_ReMoVe_ThIs@scglobal.net> writes
>David Littlewood wrote:
>
>> Unfortunately, current AF bodies (except top-of-range models like
>>Canon's 1-series) are stuck with screen almost totally unhelpful for
>>manual focussing. This is, BTW, a major problem with using DSLRs for
>>photomicrography, one of my main interests.
>> David
>
>
>That should've read, come stock with an AF screen >>
>http://www.keoptics.com/Canon20D.htm
>
>Although, it will add some $$ to the orig purchase price, at least
>there is an option available.

Thanks for this. Unfortunately, split prisms and micro-fresnel screens
are not much improvement for what I want to do. The only satisfactory
screen is the clear spot/cross hair type, which gives precise focussing
in extreme macro and photomicrography. The "I" screen in the 1-series
film cameras is the one I use in those.

If it doesn't have a changeable screen, bugger.

David
--
David Littlewood
Anonymous
August 22, 2005 4:50:20 PM

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

In article <4309AAA2.F342B595@killspam.127.0.0.1>, Colin D
<ColinD@killspam.127.0.0.1> writes
>
>
>David Littlewood wrote:
>>
>> In article <43092328.B8096D40@killspam.127.0.0.1>, Colin D
>> <ColinD@killspam.127.0.0.1> writes
>> >
>> >The lens stops down to f/22 at 18mm, and f/38 at the 55mm end - where
>> >you had the lens set - and at that aperture the image will be badly
>> >affected by diffraction, so it will not be anywhere near as sharp as at
>> >f/11 or f/8. Basically, that sort of aperture is unusable for normal
>> >photography.
>> >>
>> True-ish; f/38 will be very much below optimum for anything other than a
>> pinhole or bottle end. However, it may well be obligatory to get the
>> depth of field required in high ratio macro work (don't forget that that
>> diffraction is determined by effective aperture (which is measured
>> aperture x (1+m)).
>>
>> Also, in large format work, f/45 is quite routine. Yes, it is
>> sub-optimum, but at least you have a lot of resolution to spare.
>>
><snip>
>
>True also, but the lens the OP is talking about is a zoom 'macro', not
>capable of high-ratio work,

True

> and of course f/45 in a 150mm lens is
>entirely different from f/45 in a 50mm lens, for two reasons; one, that
>diffraction is a function of the actual diameter of the aperture, and a
>longer lens has a larger aperture for the same f-number than a short
>lens;

Not true. I used to think this until I actually went and studied the
physics behind it, but diffraction is purely a function of f-number, not
absolute diameter.

> and two, there is less magnification of the image required from
>the larger negative.
>
True, which is why I said "but at least [with LF] you have a lot of
resolution to spare". This is probably why you think (and I used to
think) resolution depends on diameter: the lower magnification factor
for a large film means that a higher f-number will be satisfactory.
Rules of thumb exist, along the lines of "anything above 4mm (i.e. f/38
on a 150mm lens) is fine". They don't entirely cover the position
though.
--
David Littlewood
Anonymous
August 22, 2005 4:58:16 PM

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

Cockpit Colin wrote:
>
> Thanks all,
>
> My suspicions were aroused when I took a photo of a stream and surrounding
> vegetation whilst on a walking track (hand held) - it just looked plain
> blury.

Depending on what active focus point was looking at, the camera might
have misfocused for the scene. IMHO using all seven focus points can be
a trap if one of the outer points happens to be the one chosen by the
camera, and it's looking at an object that is not representative of the
scene distance. For this reason I always have my camera set for the
centre point only.

> I went back later on that day and set the camera up on a tripod. On
> my 20D with kit lens (zoomed all the way out) At 100 ISO and F29? (or there
> abouts - stopped down as far as it would go) I ended up with a exposure of
> 2.5 sec (not a breath of wind, so not worried about anything moving in the
> breeze).

The lens stops down to f/22 at 18mm, and f/38 at the 55mm end - where
you had the lens set - and at that aperture the image will be badly
affected by diffraction, so it will not be anywhere near as sharp as at
f/11 or f/8. Basically, that sort of aperture is unusable for normal
photography.
>
> Back on the PC EVERYTHING just didn't appear to be as sharp as I would have
> expected (shot in RAW too). The whole thing just appeared hard on the eyes -
> it wasn't until I ran an unsharp mask at 200% over it that it started to
> look "normal". Not sure if this is the camera, or if I'm expecting too much.
> I did take some photos of some graph paper later on that night, and it "sort
> of" appeared OK (difficult to tell).
>
> I could send it in for checking, but it probably means doing without it for
> a couple of weeks :( 
>
Set it up on the tripod - is it a sturdy tripod, or a $30 model that
vibrates like a tuning fork? {:-) - and take a shot of the houses across
the street from your front porch, or similar, at f/8 and again at f/11
using the Av option, at 100 ISO, using the delayed action to fire the
camera, and then have a look at the resultant images. A Canon rep
somewhere advocated using an unsharp mask at 300% and 0.3 pixels, no
threshold. I use this setting, and the images fair leap off the paper at
A4, even with Large Fine jpeg images, though I use RAW for all my
serious stuff.

Regards,

Colin D.
Anonymous
August 22, 2005 8:01:12 PM

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

"Cockpit Colin" <spam@nospam.com> wrote in message
news:zv8Oe.4460$iM2.462021@news.xtra.co.nz...
> Thanks all,
>
> My suspicions were aroused when I took a photo of a stream and surrounding
> vegetation whilst on a walking track (hand held) - it just looked plain
> blury. I went back later on that day and set the camera up on a tripod. On
> my 20D with kit lens (zoomed all the way out) At 100 ISO and F29? (or
> there
> abouts - stopped down as far as it would go) I ended up with a exposure of
> 2.5 sec (not a breath of wind, so not worried about anything moving in the
> breeze).
>
> Back on the PC EVERYTHING just didn't appear to be as sharp as I would
> have
> expected (shot in RAW too). The whole thing just appeared hard on the
> eyes -
> it wasn't until I ran an unsharp mask at 200% over it that it started to
> look "normal". Not sure if this is the camera, or if I'm expecting too
> much.
> I did take some photos of some graph paper later on that night, and it
> "sort
> of" appeared OK (difficult to tell).
>
> I could send it in for checking, but it probably means doing without it
> for
> a couple of weeks :( 
>
> Cheers,
>
> CC
>
>
>
> "Cockpit Colin" <spam@nospam.com> wrote in message
> news:yIVNe.4335$iM2.444359@news.xtra.co.nz...
>> Hi all,
>>
>> I have a nagging suspicion that the focus on my new 20D isn't all that it
>> should be. Do any of you have any suggestions on the best way to test
> this?
>> I was thinking of photographing a sheet of A4 "Math - graph" type paper.
>>
>> If the camera's focus is out, will it be out consistently when focusing
>> on
>> close and distant objects? Should I have the lens wide open or stopped
> down
>> for the test. Is it possible for an image to be in focus through the
>> viewfinder, and yet be out of focus at the CMOS sensor? Any other
>> thoughts
>> (I only have the one kit lens at this time, so I can't do any lens
>> comparisons).
>>
>> Thanks for your input.
>>
>> Cheers,
>>
>> CC
>>
>>
>
>
At F29 or so almost any lens will be un-sharp. This is due to diffraction
from the small aperture. It is not a lens defect, it is a law of physics. At
F29 or so the depth of field really means "every thing is fuzzy". The best
aperture to check for focus errors would be wide open or if the lens not of
the highest quality, at 1 or 2 stops down from the maximum aperture. Also
with a zoom lens use the longest focal length available. If your basing the
possible focus problem on a shot at the smallest possible aperture of your
lens, I would expect it to be fuzzy.


--
John Passaneau
State College Pa.
w3jxp@adelphia.net
Anonymous
August 22, 2005 8:26:30 PM

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

In article <mc5jg1tsat29dbshb40b6b7dnpltbk587g@4ax.com>, tp@nospam.co.uk
says...
> >Actually you're the one who said you can't even manually focus your camera
> >so how would you know?
>
>
> Poor Brian. He's not actually very bright.

Look you guys, if you're going to troll you'll just have to do a better
job.
--
http://www.pbase.com/bcbaird
Anonymous
August 22, 2005 9:08:10 PM

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

Cockpit Colin wrote:
> Thanks all,
>
> My suspicions were aroused when I took a photo of a stream and surrounding
> vegetation whilst on a walking track (hand held) - it just looked plain
> blury. I went back later on that day and set the camera up on a tripod. On
> my 20D with kit lens (zoomed all the way out) At 100 ISO and F29? (or there
> abouts - stopped down as far as it would go) I ended up with a exposure of
> 2.5 sec (not a breath of wind, so not worried about anything moving in the
> breeze).
>
> Back on the PC EVERYTHING just didn't appear to be as sharp as I would have
> expected (shot in RAW too). The whole thing just appeared hard on the eyes -
> it wasn't until I ran an unsharp mask at 200% over it that it started to
> look "normal". Not sure if this is the camera, or if I'm expecting too much.
> I did take some photos of some graph paper later on that night, and it "sort
> of" appeared OK (difficult to tell).
>
> I could send it in for checking, but it probably means doing without it for
> a couple of weeks :( 
>
> Cheers,
>
> CC
>
>
>
> "Cockpit Colin" <spam@nospam.com> wrote in message
> news:yIVNe.4335$iM2.444359@news.xtra.co.nz...
>
>>Hi all,
>>
>>I have a nagging suspicion that the focus on my new 20D isn't all that it
>>should be. Do any of you have any suggestions on the best way to test
>
> this?
>
>>I was thinking of photographing a sheet of A4 "Math - graph" type paper.
>>
>>If the camera's focus is out, will it be out consistently when focusing on
>>close and distant objects? Should I have the lens wide open or stopped
>
> down
>
>>for the test. Is it possible for an image to be in focus through the
>>viewfinder, and yet be out of focus at the CMOS sensor? Any other thoughts
>>(I only have the one kit lens at this time, so I can't do any lens
>>comparisons).
>>
>>Thanks for your input.
>>
>>Cheers,
>>
>>CC
>>
>>
According to Canon (again) application of an unsharp mask of 300% with a
radius of 0.3 is required to offset the effects of their anti-alias
filter (on a 10D) The AA filter on a 20D is less aggressive but still
needs about 200% at 0.2 to reach the out of camera sharpness of a Nikon
or Olympus image.
--
Douglas,
You never really make it on the 'net
until you get your own personal Troll.
Mine's called Chrlz. Don't feed him, he bites!
August 22, 2005 11:49:22 PM

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

David Littlewood wrote:



>
> Thanks for this. Unfortunately, split prisms and micro-fresnel screens
> are not much improvement for what I want to do.

If this page explains how to remove the factory screen, send to to Maxwell
precision optics and have him make you a new screen. I'm don't know if
you've ever used one of his screens, they are amazing. Very easy to see the
focus plane yet still is a very bright screen. I doubt you'd need any kind
of focus aide with it. Give him a call and tell him what your needs are,
I'm sure he can come up with a very good solution.

--

Stacey
Anonymous
August 23, 2005 2:36:18 AM

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

David Littlewood wrote:
>
> In article <43092328.B8096D40@killspam.127.0.0.1>, Colin D
> <ColinD@killspam.127.0.0.1> writes
> >
> >The lens stops down to f/22 at 18mm, and f/38 at the 55mm end - where
> >you had the lens set - and at that aperture the image will be badly
> >affected by diffraction, so it will not be anywhere near as sharp as at
> >f/11 or f/8. Basically, that sort of aperture is unusable for normal
> >photography.
> >>
> True-ish; f/38 will be very much below optimum for anything other than a
> pinhole or bottle end. However, it may well be obligatory to get the
> depth of field required in high ratio macro work (don't forget that that
> diffraction is determined by effective aperture (which is measured
> aperture x (1+m)).
>
> Also, in large format work, f/45 is quite routine. Yes, it is
> sub-optimum, but at least you have a lot of resolution to spare.
>
<snip>

True also, but the lens the OP is talking about is a zoom 'macro', not
capable of high-ratio work, and of course f/45 in a 150mm lens is
entirely different from f/45 in a 50mm lens, for two reasons; one, that
diffraction is a function of the actual diameter of the aperture, and a
longer lens has a larger aperture for the same f-number than a short
lens; and two, there is less magnification of the image required from
the larger negative.

regards,

Colin D.
August 23, 2005 4:17:33 AM

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

"Cockpit Colin" <spam@nospam.com> wrote in message
news:yIVNe.4335$iM2.444359@news.xtra.co.nz...
> Hi all,
>
> I have a nagging suspicion that the focus on my new 20D isn't all that it
> should be. Do any of you have any suggestions on the best way to test
> this?
> I was thinking of photographing a sheet of A4 "Math - graph" type paper.
>
> If the camera's focus is out, will it be out consistently when focusing on
> close and distant objects? Should I have the lens wide open or stopped
> down
> for the test. Is it possible for an image to be in focus through the
> viewfinder, and yet be out of focus at the CMOS sensor? Any other thoughts
> (I only have the one kit lens at this time, so I can't do any lens
> comparisons).
>
> Thanks for your input.
>
> Cheers,
>
> CC
>
>

Stop worrying. If you cannot tell from normal shots then it is fine. But
'geek and ye shall find' ;)  However if the measurebator urge is too strong,
then go on over to www.dpreview.com and search on bf and ff and you'll find
your comrades. Indeed there is a lot of very useful information on dpreview
also try www.photozone.de . There are plenty of charts on dpreview which you
can get off on - shoot. ;)  You should know that it if there is a problem it
could be the lens, the camera or both. Some wide angles lenses do not focus
too well at a distance. Things look sharper in the viewfinder than on a PC
screen on which they tend to look soft and even unsaturated and using a
wide-angle cheapo lens will make them look even softer and duller. Also, you
MUST post process the images to reveal their potential - that is an art in
itself.

You need some original images from the *same* camera and lens to compare
with yours. Try on www.pbase.com use their search function - look for
full-size unprocessed images.

Stop worrying. It is most likely you simply don't know much yet...
Anonymous
August 23, 2005 2:10:11 PM

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

"John Passaneau" <w3jxp@adelphia.net> wrote in message
news:U9GdnQnkxseUspfeRVn-3w@adelphia.com...
> At F29 or so almost any lens will be un-sharp. This is due to diffraction
> from the small aperture. It is not a lens defect, it is a law of physics.
At
> F29 or so the depth of field really means "every thing is fuzzy". The best
> aperture to check for focus errors would be wide open or if the lens not
of
> the highest quality, at 1 or 2 stops down from the maximum aperture. Also
> with a zoom lens use the longest focal length available. If your basing
the
> possible focus problem on a shot at the smallest possible aperture of your
> lens, I would expect it to be fuzzy.

Thanks for that. Unfortunately the "nature scene" wasn't intended as a focus
test - it was one nice scene that I wanted as a "keeper". I wanted the best
possible DOF so I went for smallest aperture - lowest ISO - shot in RAW -
put the camera on a tripod - and set the camera for a delayed shot.

I knew that a large aperture means poor DOF - I didn't know that small
aperture has issues as well (something else to add to my bucket of wisdom!).

So far, using an unsharp mask @ 300% @ 0.3 as suggested by Colin D seems to
be producing a good result (I didn't know you could select anything under 1
pixel).

I'll have to do some more tests to see it F8 to F11 are any better for me.

Cheers,
August 23, 2005 2:10:12 PM

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

"Cockpit Colin" <spam@nospam.com> wrote in message
news:H0sOe.4804$iM2.490793@news.xtra.co.nz...
>
> "John Passaneau" <w3jxp@adelphia.net> wrote in message
> news:U9GdnQnkxseUspfeRVn-3w@adelphia.com...
>> At F29 or so almost any lens will be un-sharp. This is due to diffraction
>> from the small aperture. It is not a lens defect, it is a law of physics.
> At
>> F29 or so the depth of field really means "every thing is fuzzy". The
>> best
>> aperture to check for focus errors would be wide open or if the lens not
> of
>> the highest quality, at 1 or 2 stops down from the maximum aperture. Also
>> with a zoom lens use the longest focal length available. If your basing
> the
>> possible focus problem on a shot at the smallest possible aperture of
>> your
>> lens, I would expect it to be fuzzy.
>
> Thanks for that. Unfortunately the "nature scene" wasn't intended as a
> focus
> test - it was one nice scene that I wanted as a "keeper". I wanted the
> best
> possible DOF so I went for smallest aperture - lowest ISO - shot in RAW -
> put the camera on a tripod - and set the camera for a delayed shot.
>
> I knew that a large aperture means poor DOF - I didn't know that small
> aperture has issues as well (something else to add to my bucket of
> wisdom!).
>
> So far, using an unsharp mask @ 300% @ 0.3 as suggested by Colin D seems
> to
> be producing a good result (I didn't know you could select anything under
> 1
> pixel).
>
> I'll have to do some more tests to see it F8 to F11 are any better for me.
>
> Cheers,
>
>
>

Try www.bobatkins.com Dr Atkins has lots of info on lenses, dslrs, etc....
or try www.photo.net which he now runs.
Anonymous
August 23, 2005 3:31:18 PM

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

David Littlewood wrote:

<snip>
> > and of course f/45 in a 150mm lens is
> >entirely different from f/45 in a 50mm lens, for two reasons; one, that
> >diffraction is a function of the actual diameter of the aperture, and a
> >longer lens has a larger aperture for the same f-number than a short
> >lens;
>
> Not true. I used to think this until I actually went and studied the
> physics behind it, but diffraction is purely a function of f-number, not
> absolute diameter.
>
Very interesting. I dug out my old Ilford Manual of Photography (that
shows how long I've been involved in this caper!) and looked up Airy
Disc calculations, and you're right. I am guilty of not reading the
formula correctly umpteen years ago. Since d, the aperture diameter, is
a component of the equation, I assumed that diffraction was simply
proportional to d - but I overlooked that v (image distance) is also in
the equation. Since v/d is focal length over diameter, and v/d =
f-number, then diffraction is indeed purely a function of F-number.

My old Dad used to say "the more you know, the more you know you don't
know." After 50 years, I am still learning ... thanks.

Colin D.
!