Is there a table/formula for extension tube calculations?

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deednets Forum Pro • Posts: 11,584
Is there a table/formula for extension tube calculations?

I just had a look at some extension tubes for Fuji. Found the following:

  • Commlite 10 and 16mm
  • MEIKE 10 and 16mm
  • JJC 11 and 16mm


  • Is there a difference when choosing from the above mentioned brands? A preference?
  • Some sources say that you cannot mount both in particular combinations e.g. the 11+16 for the 23/2.0. Why not?

Only shows you that I know diddly-squat about extension rings ... have an inkling that the larger the extension the higher the magnification but then maybe already running out of a "usable" DOF. My gut feeling tells me that I would possibly use the 10mm more than the 11 or the 16mm, but again: what do I know about this?

A website I found is possibly one of the more accurate ones:

So just for the sake of it, using - as an example - the 50/2.0 with a minimum focusing distance of 39cms:

So there you have the 50mm 39cms and 11mm extension tube. Anything in between 18.6 and 27.7cm is in focus? Or does it mean the focus range in total is only about this "wide"??

Also: any idea what "Near" and "Far" refers to? The further away the higher the magnification? Really?

My guess is that I am reading this wrongly, but since I don't have any extension tubes yet I thought i would ask for some enlightenment here.

Here is a shot taken with the 50/2 which is already quite large in my book:

X-PRO3 69 frames



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Sony RX1R II Fujifilm X-Pro3 Sony a7C Fujifilm XF 35mm F1.4 R Fujifilm XF 14mm F2.8 R +9 more
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