lens fine tuning - saved values vs. default

roombarobot

A friend and I worked on fine tuning our prime lenses yesterday. It was fun and a bit challenging. We were both using Spyder LensCal setups. It was interesting and I think we learned a lot.

One question I have... My 50/1.8g, 85/1.8g, 60/2.8, & 24mm/2.8 all have negative correction values (-8, -8, -14, -20 respectively). I have put these numbers into the stored value, but since they are all negative, should I instead use a negative default, then re-calibrate for that? For instance, could I put in a -10 for the default, then change my values to 2, 2, -4, and -10? How does the "default" value work?

Because all of my lens numbers are negative, I wonder if my D800E body is back-focusing. If that is true, then if I added a default -8 or -10, might that improve my focus for my zoom lenses? (which I did not try to calibrate yet)

Would one of you who knows more about this help me understand, please? Thank you!

Golf007sd

I would leave the default value on the body as is. Your D800E will know which lens is mounted to it and use the setting you have given each lens.

Zoom lenses are quite a different story. For those to be properly calibrated, I highly recommend you sending it to Nikon with your body. Moreover, I would recommend you consider doing that with all your lenses. Just make sure you package then properly.

Killerbob

You are perfectly right in your assumption. If you change the default value in the settings, that will affect lenses you have not calibrated for. Hence, if your camera is backfocussing -10, setting that as the default value, will make an adjustment ror all lenses of -10. However, I do not know if it also affects already finetuned lenses...

But why don't you try it out? As you said it just takes some time, and you learn from it. See what the result is if setting default at -10, with one of the primes you already adjusted for.

I do agree with Golf though, taking it all to Nikon for a service and adjustment. A zoom like the 24-70mm has some 5 points they adjust for, and that value is then stored in the FW, something you cannot do yourself.

Ironheart

My understanding and experience is that the default value is used for lenses that don't already have an entry. Once you create an entry for a lens, the absolute value, not relative to the default, will be used.

Nuke

My understanding and experience is that the default value is used for lenses that don't already have an entry. Once you create an entry for a lens, the absolute value, not relative to the default, will be used.

I don't know but Thom Hogan agrees with you.

Msmoto

@Ironheart

This is the way I understand it as well.

roombarobot

Thank you all, it looks like that is correct, that the SAVED values override the DEFAULT value, it is not additive.

http://nps.nikonimaging.com/technical_solutions/d4s_tips/af_fine-tuning/
Default = Choose the AF tuning value used if no previously saved value exists for the current lens (CPU lenses only).

spraynpray

My understanding and experience is that the default value is used for lenses that don't already have an entry. Once you create an entry for a lens, the absolute value, not relative to the default, will be used.

Excellent reply Ironheart.

I wonder if the OP has a good point - it looks like the trend indicates that a -8 default actually may improve chances of a closer set-up with an uncalibrated lens.