Nikon Fine Tune AF Advice

[Pitvar]

Hello all, hope someone can advise - just bought a new to me 300mm f2.8 VR I to use on my D300s - my old 300mm non VR was as sharp as anything but on reviewing the shots from the new lens I really though they were slightly soft - having a close look led me to believe it was focusing slightly in front of the focus point I'd chosen.

I've googled AF fine tune and have dialled in +8 after doing a test with a ruler at 45 degrees to a fixed focus plane f2.8 ISO 200 shutter speeds about 200]. I'm happy that focusing is much better now but is this normal/anything to worry about?

Thanks

 

[realspeed]

PitVar
Quote " I've googled AF fine tune and have dialled in +8 after doing a test with a ruler at 45 degrees to a fixed focus plane f2.8 ISO 200 shutter speeds about 200]. I'm happy that focusing is much better now but is this normal/anything to worry about? " unquote

What you havn't mentioned at what distance the test was done at as this can make a difference. You do need to test with the subject at different distances then take a mean average. I use Spyderlenscal to check this

I set the camera on one tripod and Spyderlenscal on another at the same height from the ground at do the checks at different distances. The rule and angle method can't really give a true idea of focus you do need the proper test equipment.



Just a quick example hand held camera 12-24mm @ about 2 feet away. I did find back focus on this and adjusted to compensate

Before






Anyway thats what I have found
Realspeed

 

[Bristolian]

Hi Pitvar,

I've owned several lenses in the past that needed some fine adjustment and it's obviously a common enough occurrence that both Nikon and Canon include the feature in (some of) their bodies.

There is often an enthusiastic discussion on how to actually check the focus

 

[HoppyUK]

+8 sounds fine enough to me. That's what AF microadjust is for.

Comment about testing distance is relevant, though I'd be surprised if a prime of that quality wasn't cock-on at all distances, but I'd check it at 5m minimum.

 

[Pitvar]

Thanks all - I hadn't picked up on the relative distance issue - I tested with and without TCs at around 5 metres - I'll do some more testing I think!

 

[HoppyUK]

Thanks all - I hadn't picked up on the relative distance issue - I tested with and without TCs at around 5 metres - I'll do some more testing I think!

You'll almost certainly find a differen adjustment is needed with/without TC, but your camera should recognise the TC and apply a separate setting for that.

DIY Spyder Lenscal

 

[Pitvar]

I was using a house brick with a tape marker and a spirit level at 45 degrees with ruler marking on the side