d300 af fine tune test question

[wing8]

My question is at what distance do you test for front or back focus on your

lenses? Or does it even matter? Any real experiences with zooms or primes

appreciated.

[ellis_vener_photography]

BTo do this mount the camera and lens combination you think are mis behaving o na very solid tripod you'll need to shoot frames of a subject i ngood strong light that isn't moving at all of the settings and then ,very carefully while reviewing at100% all of those frames pick the three that work best and then test those setigns again before settling on what setting works best for that individual lens and body combination. again.

 

Vety few lenses actually need the AF fine tune setting.

[jose_angel]

Just for fun I have checked my 24-70 and 17-55 time ago; as my most used distances are usually between the closest to three meters, I tested this lenses at 1, 2.5 and 7 meters on a D300. Check your lenses under the conditions you will use them. I made the test under one studio strobe, reflected on the wall, with a PDF printed USAF target.

 

Other than the longest focal lenghts were pretty difficult to test. I take conclusions only from 50 to 70mm. The shortest focals were difficult to distinghish. Also, the desk-jet laser printed A4 target didn`t have enough quality for testing. To save time, I shot JPEG, I must have used RAW.

 

My conclusions were not so reliable under that crappy conditions, but I think that I found somekind of backfocusing issue (between 10 and 20mm) on both lenses, at their longest focals (50 to 70mm) when focusing at a scarce one meter. At 2.5 and 7 meters, focus on both lenses were dead on. Shorter focals were so difficult (almost impossible) to check under that conditions.

 

Also, notice that zooms are not macro lenses, focusing issues (if so) could be mixed with somekind of softness dued to the short focus distance, thought.

 

I set the AF fine focus to +10mm and used my lenses for a time. I didn`t found any improvement with this setting but perhaps a bad focus on some shots. Finally I returned the camera to zero values. I think Ellis is right, up to now I haven`t found a lens who needs fine tune setting.

[wing8]

Thank you Ellis and Jose.