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Nikon Focusing Step Size

Posted: 15.09.2014 03:14
by dkperez
I thought there was a topic somewhere in here that specified the focusing step size for cameras. I have a Nikon D810, and the preferences for the current version of Helicon Remote lists "15" as the focusing step size... A couple questions:

Does the step size change with different lenses?
If not, does anyone know the correct focusing step size for the D810 (or, if it's actually 15, cool, let me know)
How does focusing step size relate to the focusing A-B done in Helicon Remote? If I go "50" in HR, is it 50 * the 15 focusing step size or what?
How do focusing steps relate to distance? What IS "15"? When I press the ">>>" and move "25", how far is that in actual distance?
I'm curious because I often know how far I need to focus to get the whole item in focus, so it would be useful to know if what I'm seeing as the A-B distance is actually getting the whole item sharp...

Anyhow, I'd like to make sure I get the focusing step size right, but I"d like a better understanding of focusing step versus distance... Thoughts?

Re: Nikon Focusing Step Size

Posted: 15.09.2014 15:40
by Stas Yatsenko
The focusing steps can't be correct or incorrect, it's just a multiplier. Yes, if you make a movement of 50 in HR it will actually be 50*15. It does not relate to distance, it's probably an angular unit, not linear. In other words, distance is related to the number of focus steps in a complex, non-linear way and depends on the current position, not just how many steps you've travelled. Even if we would derive this relation (a formula or just a table of know values) it would be useless since there's no way of knowing the current position programmatically. Bottom line - the only way to know which distance the lense is currently set to is to look at its distance scale, if the lense has one.

Re: Nikon Focusing Step Size

Posted: 16.09.2014 00:11
by dkperez
Thanks, Stas.

This morning, I manually focused at the nearest point and the furthest point, and looked at the distance scale. Then made sure my number of units covered the near to far distance on the distance scale. For that particular stack, it was a distance of about "100", and the stack appears to have covered the desired range.

One of these days I'll have to try the test to see how much I can set the DOF distance to without getting bands of out-of-focus image.