+15 AFMA on a New 24mm f/1.4L II - Keep or Return

[neuroanatomist]

I test all my lenses at 25x and 50x the focal length (and I also tested the 100L Macro near the MFD with the small FoCal target).

Rick, you say test wider than f/2.8 - do you mean narrower? Lenses should be tested wide open, f/1.4 in this case (which is wider than f/2.8). Wide open gives the thinnest possible DoF for the test, which should mean more accuracy. Normal AF is always done with the lens wide open.

If a narrower aperture shows backfocus, that indicates the lens has focus shift (e.g., the 50/1.2L). In that case, you can actually use AFMA to compensate for the focus shift. Not really 'on the fly', but if you're shooting a series of shots at the same aperture (say, f/1.6 on the 50L) and subject distance, and you have determined the AFMA for those conditions (which would be different than the f/1.2 AFMA with a close subject).

[HDNitehawk]

Widest equals F/1.4

I thought focal had chosen f/2.8 as a default when I tested my copy.
Is this not the case John?
Maybe these were the settings I had and I started there.

From 1.4 through 2.0 I had near identical results. From 2.0 and on only slight variations.
No indication of focus shift.

[neuroanatomist]

FoCal always tests at the widest aperture, unless you've altered the settings from default.

[Jonathan Huyer]

Update: I retested my 1DX - 24 f/1.4LII combo using LensAlign, and it seems my original adjustment of +3 worked better than the FoCal recommendation of +12. So I changed it back. With the 5D3, the FoCal result was +7, with LensAlign giving me a +5. I'm guessing the differences are due to the extreme subtleties involved here, and my testing procedures which I'm sure are not up to laboratory standards. Most of the time I'll be using this lens in manual focus mode with live view anyway.

[conropl]

I set up and tested again this evening. I tested at 50X and 25X the focal length (47" and 23.5"). The results ended up better, but boarder line. The results were:

At 50X focal length test distance I tested it 4 times with the following results:
+11
+12
+9
+10
Avg = 10.5

At 25X focal length test distance I tested it 3 times with the following results:
+10
+14
+11
Avg = 11.7

The 25X was much harder to get set up, and the set up has more effect on the results at that distance (obviously). I got a positive target set up, but kept getting errors. So I went back to the target set up program, and got it set up better. That caused the readings to drop from the 17-20 range (with many errors) to what you see above (avg around +12) and it ran very quickly with no errors. With the two averages at 10.5 and 11.7, it looks like a good place to set it is at +11.



Edit: Now I need to do a little shooting to verify that is where it should be.

[Jonathan Huyer]

....Now I need to do a little shooting to verify that is where it should be.

After spending the better part of a day testing my lenses with both camera bodies, I am thinking the same thing! The real world is the best test there is.