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TDM_Canon_User Mar 6, 2005 9:45 PM



Heres a link to some focus tests I just did (after a very dissatisfying trip to Yosemite).

http://www.tmargeson.net/FocusTests/index.htm

These are all Canon EF-L lenses purchased at a local pro camera store.

Body:
Canon 1D mark II

Lenses:
16-35 f2.8L
24-70 f2.8L
70-200 f2.8L

I just had the body and all lenses at Canon for "adjustment" (in January).

Some history:


The 24-70 had broken a few months back (Error-99) and had to be repaired. Prior to the repair the focus was very good as far as I could tell. The 70-200 was out of focus from day one. Shipped to Canon and the focus came back okay. The 16-35 always seemed sharp enough, but once in a while an image was just plain out of focus.

I was at Yosemite last week to get a few wintery images. When I reviewed them today I was absolutely aghast. Hence this focus test.
9' backdrop, about 8' away. White masking tape on blue-chroma key drop.

I am looking at focus, not distortion. Ignore the wiggles in the tape. The camera was leveled and made square to the drop.
One image was taken at each step. f2.8 Av.

Autofocus, center spot:
16mm, 25mm, 35mm;
24mm, 35mm, 50mm, 70mm;
70mm, 100mm, 135mm, 200mm;

Autofocus, full zone:
16mm, 25mm, 35mm;
24mm, 35mm, 50mm, 70mm;
70mm, 100mm, 135mm, 200mm;

These are undoctored right from the camera.


The center spot tests generally are better than the zone focus - but quality isn't worth taking anything more than snapshots with. The full zone autofocus has no chance of focus - and instamatics can take better images.

Comments?
http://www.tmargeson.net/FocusTests/index.htm

NHL Mar 7, 2005 6:14 AM

IMO the test 'target' is flawed - Most cameras will have problem with this (a newspaper has more details for the camera AF to work on) and it needs more light (not enough contrast)...
http://www.wlcastleman.com/equip/reviews/35mm/meth1.htm

This test also does not tell wether the camera front or back focus which helps to isolate the problem (ie randomness or consistency of the issue):
http://md.co.za/d70/focus20.pdf

TDM_Canon_User Mar 7, 2005 10:41 AM

The target represents hazy mountains against a blue skyline - very real world. Please remember that I did teh test as a result of 392 poorly focused images.

http://www.tmargeson.net/FocusProblem/index.htm

Try this link and tell me again why the camera would have problems on these? There are about 200 more images that exhibit this focus quality. And look at the meta data if you think it's operator error. 160s f5 at 16mm does not equate to camera shake.



TDM_Canon_User Mar 12, 2005 3:09 AM

Added a PDF to show the focus problem a little more clearly:

I did a side by side of the 1DmkII versus my D60... hard to contest the subject or methods and say the problem doesn't exist.

http://www.tmargeson.net/FocusProblem/ImagesOnly.pdf

Since this is my second 1D mk II to go nuts like this, I just wonder how many others are seeing this problem.



NHL Mar 12, 2005 7:10 AM

I highly doubt it's the camera - This 45-points AF systems has been perfected since my EOS-3 eons ago, and now after two generations of dSLR and they still can't get it right... Can Canon QC be that bad for two high-end cameras to fail??? ;)

Try to shoot a newspaper @ 45 degree (under good lighting) and report back :idea:
-> Regardless of how good a system is, there's always conditions where the AF might not work, or work on one camera and not the other (since they have a different AF sensor/pattern) - It can't be 100% (even if you throw all the $$$ at it) all the time!

peripatetic Mar 12, 2005 8:02 AM

Have you run the test on the charts NHL gave you links to?

For the samples you gave it seems that there are too many variables.

In my opinion, some of the comparisons don't necessarily show a lack of focus they might show instead a difference in sharpness between the RAW files between a 1D and a 30D, with the 30D images being sharper. I'd expect that.

I'm certainly not claiming you don't have a problem with your camera, just that all the stuff you've posted isn't really that convincing.

What is clear is that you've spent a ton of money and are very unhappy with the results you're getting - which is the main point.

Have you tried some alternative lenses? Would you be able to rent some of the Sigma lenses for example? Take some side-by-side shots of test charts. Because if the problem is in the body then you should have similar problems there.

Can you do some side-by-side shots with manual focus where you are happy with the results? It's not really clear whether you think you have an autofocus problem or that you simply cannot get an in-focus image out of the camera-lens combo at all.

And finally of course - if Canon aren't responding to your needs - either in terms of quality or after sales service then perhaps you'd be better off selling the lot and going for another brand.

The Nikon D2X is now a very creditable alternative to the 1 series Canons. Also I get the impression that really crisp images are very important to you - the Leica digital back might be more to your taste if you do end up ditching Canon. Or perhaps the Mamiya ZD.

TDM_Canon_User Mar 12, 2005 11:47 AM

1 Attachment(s)
First - I take photos of real life objects, not test targets. I need my camera to focus on real life targets. My D60 does fine - my 1D once did, now is broken, just like my first 1Dm2 body was (from teh factory no less). It's probably sonmething simple like the focus screen position has shifted (testing that and manual focus today with a split image screen).

Second - did you actually look at the PDF file? If not, look at the images then make the statement its a sharpness problem (then I'll know to ignore such comments).

I've been using cameras for over 30 years. I know defocus - I know motion blur - I know circles of confusion caused by lens obstructions - I know focal plane flatness vs. depth offieldvs. depth of field range -I know software based "sharpness" deconvolution algorithms (amongst other software adjustments).

By the way - what's not shown are images that ARE in focus, one of about 20 repeated shots in that very same setup - the only difference being the number of times I pushed the shutter release. And I don't think the traffic on the freeway made a difference.

Here's a side by side of two 24-70f2.8L images taken seconds apart, same camera, same lens, same tripod, same person pushing the shutter release.


24-70 f2.8L at 24mm - two sequential shots (on tripod):

TDM_Canon_User Mar 12, 2005 11:51 AM

1 Attachment(s)
Another series, this one my 16-35f2.8 and 70-200f2.8 on the 1D and the D60... the 70mm does okay at 200mm, slightly worse at 70mm. At 200 it is a toss whether its true defocus or artifacts of resolution differences or image creation artifacts. If ALL my images were as sharp as the 200mm - I wouldn't be complaining. But EVERY other len I have gives images like the 16-35and 24-70 shown above.



TDM_Canon_User Mar 12, 2005 1:40 PM



Late breaking news:

I just installed and tried a split image screen to ensure focus was where I wanted it. Autofocus ALWAYS matched manual focus - amazingly well - so the algorithm and lens control is working as expected.

But the images? Much better than with the original screen, but still soft and blurry. Seems it's a mirror problem...it doesn't always return to where it should. That or two other possibilities: the focus screen is rattling around or the sensor is rattling around. Anyway - a mechanical problem in the body.

This started after about 2500 shots... plus one professional sensor cleaning at Canon... hmmm.

Suggest anyone witha broken-in1Dmk2 check focus quality, just in case.

Tim



NHL Mar 12, 2005 11:55 PM

TDM_Canon_User wrote:
Quote:

I just installed and tried a split image screen to ensure focus was where I wanted it. Autofocus ALWAYS matched manual focus - amazingly well - so the algorithm and lens control is working as expected.

But the images? Much better than with the original screen, but still soft and blurry. Seems it's a mirror problem... it doesn't always return to where it should. That or two other possibilities: the focus screen is rattling around or the sensor is rattling around...
The AF sensors are actually at the bottom in the base of the mirror box :idea:
... and not by the focus screen where you actually see (and compared). i.e. the camera's AF doesn't see what you see

Check the back of the mirror... there's a smaller mirror (which is folded up against the main mirror when you are in the sensor cleaning mode). The image pass though the main semi-transparent mirror and is folded toward the bottom of the body for the AF sensors by the smaller mirror behind it! - Here's how it's done on most Canon:

http://www.imaging-resource.com/PRODS/D30/ZCUTSIDE.JPG


-> Bottom line the type of focusing screen used is irrelevant!!! ;)




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