5D3 + 50L + Outer AF points = Much Sadness

Started Dec 1, 2012 | Discussions thread
OP DFPanno Veteran Member • Posts: 5,489
Re: So I tested again today.....

Glassfish wrote:

DFPanno wrote:

Oxheart wrote:

Hi -

I am one of the people on the POTN thread that had a bad 5D3 (w/ 35L). I returned it and got a different one - and it's spot on with 35L and 50/1.4 using the outer points on the right side now. So in my case, at least, it wasn't just an issue with fast primes - it was clearly the camera body.

And yes, the fastest way to see the problem is to setup a tripod, mirror lockup and all that good stuff, and just shoot a small set. Tape up a newspaper or whatever is convenient for a target and make sure lighting is very even and good (10 EV+). Shoot an image with each of your points that are level with your center point (I am all for not moving the camera, just change the focus point so you can easily compare pictures in LR). If you compare images and the area that you focused on goes completely fuzzy and OOF, you will be able to see it very clearly and it will be 100% reproducible.

It doesn't take more than 15 minutes to test, once you know what you are looking for.

- Michelle

I spent some time this am testing the 50 1.2 and a 50 1.4.

Tested both lens at max aperature, base ISO, high speed (2500) and very good light.

On and off a tripod. With and without mirror lock-up.

In some cases I keep the camera in on position and simply moved the point to each lateral edge (with lens squared up); on others I swung the camera.

Results were pretty consistent:

1.2 had more variation than 1.4

Best focus on the 1.2 was with the center point. Worst on the right. Left equal to or slightly worse than center.

So. Send the camera in? Camera and lens? Or don't bother and try to get another copy of lens?

(I am slightly out of B&Hs deadline but maybe they will goodwill the situation)

I like the lens overall but I want to use it for portraiture and I shoot grip up in vertical mode. Having the right side AF off is worse than having the left out.

Thanks to all!

The result is interesting. I use the lens with 7D. I did not do the test in more controlled way that you did but casually test right most and left most AF points in horizonal position. I found the right most AF produces more errors than the left as well (@f/1.2).

Don't take my result serious as I mentioned, I did test in more controlled way as you did.

Regardless of this, I also like the lens a lot.

Thanks for posting your test result.

BTW, does your copy makes loud noise some time during AF? When it is quiet it is quiet.

No, very quiet.

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