10D focus issue demystified

I'm quite happy with my 10D but I do remember the long wait before canon admitted to problems with the case cracking on black G2's, fortuanately mine was ok...but now find myself checking it everytime I get it out, much as I'm now paranoid about sensor dust on the 10D.

I got my 10D on 4/15/03 and 2 Canon lenses to get myself started. Both are not "L" lenses. That was relatively close to when they were introduced I beleive so I think I got an early one. I suspected a focusing problem early on but figured it was mostly due to user error as I am NOT a professional photogrpaher. During these past few months I've read as much as I could about this issue and did numerous tests. In most cases I was getting pictures that were not focused on the intended target, a good example was at my daughters soccer game where I took about 100 shots. Using the center focusing square you could see in the grass an area in focus that was usually just in front of the kids. I use shooting mostly around 50mm @ 1/250 - 1/750. Lens was wide open in most cases but even with the kids standing still this was still a problem. I now added a Canon 75-300 IS and with all three Im still seeing this. I setup and did tests with the lines on paper and with all three lenses I was front focusing.
So I called my local shop that sold me the body and they swapped me for a new one, which had firmware 1.0.1 in it and the old one didnt so Im guessing its newer.
I've taken a few shot with it, but they sure seem alot better. Next soccer game will be the true test.

I'll try and keep you all posted.

Spike

Thanks Spike, it is good to hear shops are giving no trouble on this issue.

BTW: Everyone should have have a look at image http://www.pbase.com/i​mage/18920257 which shows how big 10D AF sensors really are related to focus screen rectangles - it is very useful to be aware of this when focusing.

Humm, I think it should be EF50mm f/1.0 L USM.


Griffin.

Pekka,

I strongly suggest you "pin" this thread on the top of this forum, if it is possible.


Griffin.

Hello,

Sorry to bring this one up again.

I am close to buying my 10D. Well, after searching back the posts here and there, I am still wary about how I setup the test environment, say, placing the test ruler at a 45-degree angle. How could I know it is a 45-degree angle?

Thanks for all your help and input so far.

Wish me luck!


Griffin.

P.S. This is kinda "undercover" kinda of "bump", you know.

Griffin,

Not sure whether you are seriously asking about how to set a 45-deg angle or not, but I'll assume you are.

It doesn't matter. You aren't trying to assess how much the focus is off, only that it is off. The key points are to make sure the camera is focussing on a completely flat target and that the angled ruler does not enter the focus area at all. If this happens, the camera might legitimately pick part of the ruler away from the intended point of focus. That's why all those picture aimed at the 6 inch mark of a ruler or complete cobblers.

Before pfaffing around with a complicated set-up, you might like to read this article. http://www.rogercavana​gh.com/helpinfo/23_foc​uscheck.htm, which describes how Canon Germany say to test focus. It's a lot less hassle to set up, although it will only tell you whether focus is off, not if you are getting front or back focus. But off is off, and if you do need to have the camera calibrated I don't think the Canon service technicians will care what you found.

Regards,

bump ( only admin can bump here )

Roger_Cavanagh wrote:

Before pfaffing around with a complicated set-up, you might like to read this article. http://www.rogercavana​gh.com/helpinfo/23_foc​uscheck.htm, which describes how Canon Germany say to test focus. It's a lot less hassle to set up, although it will only tell you whether focus is off, not if you are getting front or back focus. But off is off, and if you do need to have the camera calibrated I don't think the Canon service technicians will care what you found.

Regards,

Thank you Roger. Your site is one of the best Canon DSLR support sites out there. I have done some of my research before posting. I am still not sure about the ruler thing. BTW, the city here runs out of 10D appearently. I think I am taking time to try your hints out first.


Griffin.

Hi Pekka.

I'm new to this board, so sorry if this has been posted and I missed it, but where can I dl the Canon Finland's focus test you used in the above example. Thanks.

It's not available for download AFAIK. This info only tells how Canon does it - I don't know if they share the actual chart copies (I'll have to call and ask it one of these days).

Using method as on Roger_Cavanagh's site. I run several tests with EF50mm f/1.4 USM, EF100mm f/2.8 Macro and EF70-200mm f/2.8 L USM. No problem exhibitied on my new 10D so far...

Which is good!


Griffin.

What's within spec? (Re: 10D focus issue)

How much error is "allowable" or within spec for AF?

With my zoom lens at wide angle (28mm) the error is barely noticeable at f3.5. But at telephoto (135mm, f5.6) with a close-up test shot, there is a discernable 8mm-10mm front focus error.

For general shooting this may not be a problem, but it seems that for macro shots it would be very problematic. Also, if I had a faster lens, I think it would be even more evident. Is it time to pack it off to Canon, or is this level of error not something to worry about?

Hope I didn't miss the info in a previous post.

Thank Pekka! My test was right on the target.

The best info I've seen in this article http://bobatkins.photo​.net/info/faq30/eos3af​.html by Atkins with intput from Canon's Chuck Westfall.

He writes:

The 10D has, AFAIK, normal precision sensors, but I doubt this standard could be applied to macro work.

Regards,