Focus issues

[DonnaM]

I am not sure if this is equipment or technique so this may be in the wrong forum, if so then Mods please move.
I have just splashed out on a Nikon 300mm f/2.8 and I bought a 1.4 TC as well.
The lens / combination is pin sharp when it focuses correctly but it invariably front focuses by 2-3 cm. I have done an AF fine adjustment and under controlled indoor conditions the focus is spot on. There is a little variation if the focus is coming back from infinity or if it is going forward from 2m but hey as a retired engineer I am well aware of tolerances.
In the field however, I focus on the body of a bird, hit (and hold) the AF-ON button, lens focusses take the shot and bird is on the edge of focus with foreground foliage pin sharp! If this happens only occasionally then I would suspect movement or technique but it happens more often than not. So guys what am I doing wrong?

 

[simonedgar]

Maybe post some photos some *** can comment

 

[DonnaM]

Maybe post some photos some *** can comment

OK, one of too many. The camera recorded focus point achieved on the wing shoulder of this bird. No foliage was in the way.

As you can see the bird is not sharp but the foreground foliage is.

Camera settings:
Continuous servo AF
AF area: single point (NOTE I have tried 9,21 & 51 point but no better)
AF-C priority: Release
a4: focus tracking OFF
a5: AF Activation AF-ON only

Lens & TC combo set to +10 on AF fine tune.

This was the last of a low speed continuous set. I manually pre-focussed before holding down the AF-ON button. The rest of the set have similar focus issues, some shots have the focus point recorded, and some do not. Oh and it was a calm day!

 

[Martyn...]

I have done an AF fine adjustment and under controlled indoor conditions the focus is spot on.

The indoors bit concerns me, I have never done this myself, but have read a few threads on it and I am sure I remember comments regarding a minimum distance that should be employed to carry this out successfully, I am sure this was a fair distance, garden territory rather than in house (unless you have a large ballroom)

May be worth a Google on lens micro adjustment, see what turns up

 

[HoppyUK]

I am not sure if this is equipment or technique so this may be in the wrong forum, if so then Mods please move.
I have just splashed out on a Nikon 300mm f/2.8 and I bought a 1.4 TC as well.
The lens / combination is pin sharp when it focuses correctly but it invariably front focuses by 2-3 cm. I have done an AF fine adjustment and under controlled indoor conditions the focus is spot on. There is a little variation if the focus is coming back from infinity or if it is going forward from 2m but hey as a retired engineer I am well aware of tolerances.
In the field however, I focus on the body of a bird, hit (and hold) the AF-ON button, lens focusses take the shot and bird is on the edge of focus with foreground foliage pin sharp! If this happens only occasionally then I would suspect movement or technique but it happens more often than not. So guys what am I doing wrong?

Edit: crossed post with Martyn above

Normally I would start by asking more questions, but it sounds to me like you have adjusted the AF using a close-distance target indoors.

I hate tests that do not accurately reflect real world picture taking - brick walls, 2-dimensional resolution test targets, small bits of paper print shot close up at 45 degs - for all sorts of reasons, and they often cause a lot of problems. I would start by recalibrating your AF to a realistic focusing distance that it was designed for. You really shouldn't be having any problems with quality equipment like that.

I use a line of three cerial packets side by side for simple checks, but it should also be quite good for fine adjustments too. A subject like this usually forces a decent focusing distance, and there's plenty of bright detail for the AF to latch on to, and the AF target is flat. Have the middle packet square to the camera, and angle the other two a bit, with part of the box in front of the middle one, and part behind so that you can see where the focus hits if it is not spot on. Use centre point AF.