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20D Canon focus advice



 
 
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  #11  
Old August 22nd 05, 12:51 AM
Randall Ainsworth
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In article , pixby
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.
  #12  
Old August 22nd 05, 12:57 AM
Cockpit Colin
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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" wrote in message
...
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




  #13  
Old August 22nd 05, 01:29 AM
Steve Dell
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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" wrote in message
.. .
In article , 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



  #14  
Old August 22nd 05, 01:58 AM
Colin D
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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.
  #15  
Old August 22nd 05, 02:32 AM
David Littlewood
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In article , Colin D
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
  #17  
Old August 22nd 05, 03:42 AM
Slack
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Default

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
  #18  
Old August 22nd 05, 04:17 AM
nick c
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Default

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.

  #19  
Old August 22nd 05, 04:29 AM
nick c
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Default

Randall Ainsworth wrote:
In article , pixby
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.
  #20  
Old August 22nd 05, 08:08 AM
pixby
external usenet poster
 
Posts: n/a
Default

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" wrote in message
...

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!
 




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