Near and far point shift with Nikon 60mm

[E_C_Marsupilami]

Hi Stas,
Speaking about Helicon Remote on a laptop USB connected to Nikon D3s with AFS Micro Nikkor 60mm f:2.8 G ED.

1) As another member of the forum noticed (with a D800 I think) the max f: reported is 3.0, not 2.8. This is not a problem for me but it seems odd. Is this a difficulty of communication between the lens and the software?

2) My real problem is the shifts of Near and Far points for shorter values. I have tweaked the size of focusing steps and the maximum amount of focusing steps in the continuous focus movement without much improvement. This lens looses steps even when moved step-by-step (only with > or <) in both directions.

For one single depth scan it is ok, I just do it longer than needed and get all planes in focus. But I need about 80 time-lapse shots with focus stacking and after 3 or 4 time-lapse shots the object is out of the bonds of the focus stack.

The question/s:
(i) Is this a known issue with the Nikkor 60mm f:2.8 G ED? Would it be fixed by sending the lens to the Nikon repair service for lubrication/fixing?

(ii) I would like to know of Nikon macro lenses that have been fully tested and proved not to lose steps.

I assume it is not an issue with the 3Ds because in my setup it is externally powered and even from battery it has more than enough juice to drive the lens motor. I had no opportunity to test the lens/camera focusing mechanism in Camera Control Pro2 but I am expecting that the same will happen.

Thanks for your help

[Stas Yatsenko]

1. That's a question for Nikon, really, not for us. The application merely displays the f value as reported buy the camera body.

2.1. We can't really answer that because the specific cause of the issue is unclear. You could ask the service guys if they're familiar with this issue, I suppose.

2.2. Can't say. We don't have enough statistics to draw conclusions. Besides, people rarely inform us when everything's working fine.

You can of course try Nikon Camera Control to rule out a software issue, but I doubt such a serious programming bug could go unnoticed with us.

[E_C_Marsupilami]

Hi,
Many thanks for your answer.

1. Mystery solved. The lens is only f:2.8 when focused at infinite. When focused closer the effective f:# increases for the same physical aperture. This variation is known as the bellows-extension factor. Dumb me!

2.1. Tested today, Camera Control gives exactly the same focal shifts as observed with Helicon Remote. So, the lens is to blame, not the software.

2.2. I was hoping that someone at HeliconSoft used one Nikon macro lens to test the program. At least that particular lens works perfectly, what does not guarantee that an “identical” one will do, due to sample variation.

[Stas Yatsenko]

We use 100mm Nikkor, but it also drifts as you keep making focus adjustments.

[E_C_Marsupilami]

That means that time lapse + focus stacking with Nikon is not feasible. Even a simple focus stacking must be programmed taking into account that some drift for shorter distances is predictable. Very frustrating…

I was hoping that the 105mm Micro, since 2006 the flagship of Nikon macros, could outperform my 60mm, that is more recent but a bit cheaper. Anyway I will borrow a brand new 105mm to test ASAP and report the result.

Thanks for your clarification.