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FORUMS Photography Talk by Genre Macro Talk
Thread started 24 Aug 2017 (Thursday) 05:58
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D850, stacking mode

2,218 posts
Joined Jul 2016
Aug 24, 2017 05:58 |  #1

"the finest gradation (a setting of 1) equates to a focus step equal to the lens focal length divided by 30. So with a 100mm lens, the smallest step would be a distance of 3.3mm, and the largest one 30mm. "

Oh dear!
This may be inappropriately applied maths, but, approximately:
100mm FL lens,
Choose "1" = 3.3mm focus increments.

Assuming you want to be not diffraction limited, that's
Repro ratio 1:4 ie 0.25x
Aperrture f/8
Pixels/CofC 2.5
DOF (matching difraction blur) 3.5mm.

Field of view minimum 4 x (24 X 36) = 96 x 144mm.
Hand sized.. not bug sized.

Your subject can be 3 x 300 = 900 mm deep though, plus 20mm or so for the extra DoF at 900mm.

It would be more bug-friendly if it did 0.3mm focus steps, near 1:1.
Perhaps a firmware update may address that.
One obvious workaround would be to use coupled lenses ( a short one reversed on the front of the long one), but you may not get 45MP resolution.

If you create 24MP images, (ie less resolution) you can change to f/16 and get about half life size.

Could someone check the maths, please? I'd like to be wrong.


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D850, stacking mode
FORUMS Photography Talk by Genre Macro Talk

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