NikonGear'23

Gear Talk => Lens Talk => Topic started by: Michael Erlewine on April 12, 2023, 21:17:27

Title: Can We Do Focus Bracketing with Extension Tubes?
Post by: Michael Erlewine on April 12, 2023, 21:17:27
Can You do Focus Bracketing with Extension Tubes

Are there any extension tubes for the Nikon Z cameras and lenses that work with Focus Bracketing?
Title: Re: Can We Do Focus Bracketing with Extension Tubes?
Post by: Birna Rørslett on April 12, 2023, 22:29:10
AF works with extension tubes such as those from Fotodiox and Meike. Thus the answer to your question should be 'yes'. However, the focus range will be narrow.

An example; with the 35mm Fotodiox, the AFS 400/4.5 covers approx. 1 to 4m.
Title: Re: Can We Do Focus Bracketing with Extension Tubes?
Post by: Michael Erlewine on April 13, 2023, 05:45:06
AF works with extension tubes such as those from Fotodiox and Meike. Thus the answer to your question should be 'yes'. However, the focus range will be narrow.

An example; with the 35mm Fotodiox, the AFS 400/4.5 covers approx. 1 to 4m.


Thanks much. I will look into that, such as it is.
Title: Re: Can We Do Focus Bracketing with Extension Tubes?
Post by: Michael Erlewine on April 13, 2023, 13:24:50
Does anyone make an ultra-thin extension ring for Z cameras that is able to allow auto-focus?
Title: Re: Can We Do Focus Bracketing with Extension Tubes?
Post by: Birna Rørslett on April 13, 2023, 13:36:01
Meike has a 11mm Z ring that will do what you require.  Don't know any thinner.
Title: Re: Can We Do Focus Bracketing with Extension Tubes?
Post by: Bernard Delley on April 13, 2023, 14:08:08
how useful is focus bracketing actually ?
I have done some experiments on focus accuracy using MTF. You can get an idea about it in my MTF thread here, and the mention on a nerd use of AF tune also there.
With my Z7 II , I find that one AF-tune step corresponds to about 6 micro meters shift of the focal plane at the sensor for fast lenses. The might be also the smallest possible step for bracketing. On top of that come statistical focus mis-placements ranging  3-15 micro meters RMS at the sensor depending on the lens model and lens sample. For example with my AF-S 105mm f/1.4 on FTZ it is RMS = 3 and for the Z 24-120 f/4 it is about RMS = 10, which is OK for the lens speed.
The geometrical optics DoF at the sensor  is: circle of confusion diameter times F-number : for example  10 micro-meter x 1.4 = 14 micro meter for the fast lens.
Title: Re: Can We Do Focus Bracketing with Extension Tubes?
Post by: Hugh_3170 on April 13, 2023, 15:27:20
In Z-mount, Kenko make a 10mm and a 16mm.  About $US200 - so more expensive than Meike.  I have yet to determine whether they are metal bodied.

Meike has a 11mm Z ring that will do what you require.  Don't know any thinner.