1ds3 autofocus inconsistenies

[AbsN]

Hi

I bought a secondhand 1ds3 a couple of months ago and I'm struggling to get consistent results with the focus of my fast primes. I'm using it with 35 f/1.4, 50 f/1.2, 85 f/1.2, 135 f/2.

I've calibrated the lenses - they needed a lot of adjusting. The 85 (mk1) for example needed +20, it's not even close until +18. Other lenses didn't need quite so much.

When focusing it just seems a bit hit and miss - even on static high contrast subjects such as a test chart. Occasionally it is spot on but for the most part it is out.

Moving from a 5dii I feel a bit let down as I used the 1.2 lenses most often at 1.2 and had a very high keeper rate of getting the focus spot on by using the center point focused on eye and re-composing.

Is the Af tech of the 1d3 not as good as the center point of 5d2? By this I mean accuracy - not speed or anything. I'd rather have a slow accurate AF than a fast and inaccurate one. Is it likely the body just needs servicing?

Any thoughts much appreciated. I cant afford a 5diii at the moment but am wondering if I'd be better with a 6d for it's accurate center AF point ....

Regards,
AbsN

 

[privatebydesign]

You have an issue.

The 1Ds MkIII AF is much more accurate than the 5D MkII, my main 1Ds MkIII focuses my 50 f1.4 wide open, spot on, exactly, well over 90% of the time in One Shot. I have played with Micro adjustment but it makes little difference, in my case, and it messes with varying subject distance sharpness, if I shot in one place at one distance I'd micro adjust, as I don't I leave it off as my two 1Ds MkIII bodies return IQ that doesn't need it.

If I was you I'd send in the body with example shots of your lenses set to zero, they almost certainly will not look at them, but they will test the AF alignment and make sure it is within specs, a solid knock is all it needs to misalign it.

 

[AbsN]

Many thanks for the reply. I'm considering sending in for a service but wanted to run further, more thorough tests to see if I'm just not calibrating it right.

I've now managed to get the focus on the 1ds3 pretty much bang on after some serious testing. I set up a resolution chart, camera on tripod and photographed it from about 2 meters away. With each lens I racked it out of focus, focused and took the pic in single shot mode with center AF point. I did this 20 times with each lens with the micro adjustments set from 0 to +20.

Some of the lenses, such as the 50 1.2 varied across the micro adjust range - in out of focus up to 5, perfect at 5, out of focus for another 10, in focus for 1 or 2, then out again. I checked this a few times and it seems to be right as I got the same results several times. It's no wonder I could not quite adjust it perfectly.

So all the lenses seem spot on with the center AF point. I've not tested other points extensively but if I use an outer point they are all wrong again (not massively - but a good about for 1.2 aperture). Now does anyone know if this is a calibration issue or is it because of lens aberrations - the outer points surely must not be going through the sweet spot of optics.

I must stress again that I'm being very picky here - I've now got the center point perfect at f/1.2 and the depth of field at this aperture is millimeter(s) thick - and I'm focusing for pretty close portraits (for exact focus on eye). Am I asking too much that all the AF points should be as exact as the center point after calibration at such extreme apertures? Is this even possible on 5diii etc? At smaller apertures you'd not know there was a problem...

Any thought much appreciated.

 

[Mt Spokane Photography]

Look into the bottom of the battery compartment and see if there are two paint dots. Cameras that received the Canon fixes for AF issues have them unless they were made after the fix.

Your problem does not seem to sound like the one that the fix corrected, but you might want to check in any event.

AF systems are only consistent in very bright light, EV 13 or better is best, which is bright daylight, or high powered studio lights. If the light is not very good, there will be variations in AF.

 

[privatebydesign]

The trouble with adjust everything to 2 meters is that that is where they will work best, but they won't be optimal at other distances.

Recommendations are to do the adjustments at either >50x focal length, or your predominant working distance.

 

[phoenix7]

Make sure you have firmware v1.2.3. That is the last one and it came out last year.
http://usa.canon.com/cusa/support/professional/professional_cameras/eos_digital_slr_cameras/eos_1ds_mark_iii#DriversAndSoftware

Also there are 3 product advisories for the 1ds3, you can find them here about half way down:
http://usa.canon.com/cusa/support/professional/professional_cameras?pageKeyCode=prdAdvViewAll&categoryCid=0901e02480069fb4
One specifically about soft AF.

 

[AbsN]

Many thanks for the replies. I shall re-calibrate with the 50x lens focal length. I have done this for the 50 1.2 L already and have attached the results - a series of pics focusing on the same part of the chart with the most common AF points I use. The lens was calibrated to the center point. Positioned 2.5 meters from chart (50 x 50mm), camera on tripod with 2 second timer. Chart is mounted on a window so had strong back light. I ran this test twice and got the same results both times so I don't think it is a matter of inconsistent focus - it's consistent for the calibrated point and simply consistently out by different amounts on the other points.

The product advisory on AF sounds to be describing the issue. There are no painted dots in the battery compartment and the firmware is 1.2.0 so I'll upgrade that for the next tests too. I'm kind of wondering if one of those has more consistent AF then it may be better to switch rather than potentially always being unsure about AF point accuracy on this body. Even if it's fixed by Canon it may only take a slight bump to knock it out again? Does anyone know of any AF accuracy tests for the 5d3 or 6d using 1.2 lenses?