November 24, 2017, 03:36:10 PM

Author Topic: Canon EOS 3 autofocus issue with modern lenses  (Read 846 times)

Jesse

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Canon EOS 3 autofocus issue with modern lenses
« on: November 10, 2017, 07:23:00 PM »
I've tried two EOS 3 35mm film camera bodies now and they both have the same autofocus issue. At a certain point, once wide enough, they begin to back-focus, up to infinite, which becomes totally unusable. The lenses I've been using are the Canon 35L II, 24-70L II, Sigma 50 Art. It focuses fine when up close but becomes more inconsistent for wide shots and unusable at infinite. Anyone have any idea what the issue might be or how to fix it?

Here's an example at infinite. Focus was one shot autofocus on the pole at the back in the center. The same shot I took with a different body looks the same. This is with the 35L II
5Ds, 5D3, 8-15 f/4 L, 24L II, 35 f/2 IS, 24-70 f/2.8 II L, Sigma 50 f/1.4 Art, 70-200 f/4 IS L, 85L, 90 TS-E, 100 f/2.8 L, 135 f/2 L, 600EX-RT x2, CS6, LR5

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Canon EOS 3 autofocus issue with modern lenses
« on: November 10, 2017, 07:23:00 PM »

Valvebounce

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Re: Canon EOS 3 autofocus issue with modern lenses
« Reply #1 on: November 11, 2017, 04:04:38 AM »
Hi Jesse.
I see there are lots of people reading this but no responses, so I thought I might as well throw my idea into the ring, this is based on very little except that nearly all the manuals mention that the focus points are actually bigger than the box in the viewfinder.
So in light of the above, is it possible that the AF point although on the post was actually reading the far background?
Do you have this same shot taken with an EOS 3 and older lenses that worked?
Are you basing the comparison on one of your digital cameras with more densely packed (finer?) AF points (with 20 years of evolution to the electronics and the firmware driving them) nailing the focus?

Cheers, Graham.
7DII+Grip, 1DsIII, 7D+Grip, 40D+Grip, EF 24-105 f4L EF-S 17-85, EF-S 10-22, EF 70-200 f2.8 L IS II, EF 1.4xIII, 2xIII, EF 100-400 f/4.5-5.6l IS II, Σ17-70 f2.8-4 C, EF 50mm f1.8, YN600EX-RT, YN-E3-RT, Filters, Remotes, Macro tubes, Tripods, heads etc!

1DsIII, 20D, 24-105, 17-85, Nifty 50 pre owned

Mt Spokane Photography

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Re: Canon EOS 3 autofocus issue with modern lenses
« Reply #2 on: November 11, 2017, 05:41:30 PM »
With the issue happening at wide focal lengths, I'd suggest that you try a shot without other close subjects that the AF sensor may be picking up.  Its a fairly large area that it covers, even though the spot in the viewfindes is small.

If you can find a area where the entire frame is of a distant subject, see if it still has the issue.

It may very well have a problem, but thats the way to be sure.

johnf3f

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Re: Canon EOS 3 autofocus issue with modern lenses
« Reply #3 on: November 12, 2017, 04:43:42 PM »
Interested in your observations. I have only used my EOS3 on the Canon 24-105 F4 L IS,600 F4 L IS and my 800 F5.6 L IS and in all cases it delivered superb results. AF was quick and accurate and it tracked moving subjects well. No it was not as good as my 1DX but it did give my 7D2 a run for it's money! Not bad for an "Old" camera :D

Which lens were you using?
Canon 1DX, 7D2, 16-35 F4 L IS, 24-70 F2.8 V2, 100 F2.8 Macro, 100-400 L IS Mk2, 300 F2.8 L IS, 800 F5.6 L IS, Holga Pinhole lens.

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Re: Canon EOS 3 autofocus issue with modern lenses
« Reply #3 on: November 12, 2017, 04:43:42 PM »