Stacking step for microscope objective

harisA · Post by **harisA** » Mon Sep 26, 2011 5:22 am

I'm sure this has been answered before but i did'nt manage to find.
What i want is the mathematical formula for calculating the optimal step for a given objective (magnification and n/a) and sensor size.

Also a little theory regarding the logic of calculations will be very helping.

Thank you in advance.

Haris.A

ChrisR · Post by **ChrisR** » Mon Sep 26, 2011 7:04 am

Google Nikon Microscopyu - don't forget the "u"!

This recent thread is relevant ...
http://www.photomacrography.net/forum/v ... hp?t=14527

rjlittlefield · Post by **rjlittlefield** » Mon Sep 26, 2011 11:40 am

Adding to Chris's comments...

I know two pages at microscopyu that are particularly relevant here.

http://www.microscopyu.com/articles/for ... depth.html has a general discussion, some formulas, and some examples.

http://www.microscopyu.com/tutorials/java/depthoffield/ has an interactive calculator that lets you plug in various parameters and see the calculated DOF that results.

Of the two, I'd put more faith in the calculator. Both pages show the same formula. The calculator tracks the formula exactly, but the values on the first page vary randomly -- sometimes low, sometimes high, by amounts that are large enough to matter. (I have no idea where the values come from. I asked the web site maintainers about this a few years ago, but never got an answer.)

Anyway, as noted in the thread that Chris linked, the calculations are only a rough guide to "optimal". Values from the calculator with minimum e should be safe for most purposes, but you should test in your own situation if it's important to be dead on.

--Rik

seta666 · Post by **seta666** » Sat Oct 01, 2011 5:52 am

I normally use that microscope DOF calculator they have suggested, using the formula when the lens or magnification I need is not there
For Field work I take with me a small table in mm based on Lefkowitz Formula
2*CoC*f*(m+1)/(m*m) I use a CoC of 0,030

Regards
Javier

ChrisLilley · Post by **ChrisLilley** » Sat Oct 08, 2011 1:28 pm

seta666 wrote: For Field work I take with me a small table in mm based on Lefkowitz
2*CoC*f*(m+1)/(m*m) I use a CoC of 0,030

Javier

The value for 5x f/8 appears to be out by a factor of 10 (0.10 not 0.01) compare adjoining 0.09 and 0.16.

seta666 · Post by **seta666** » Wed Oct 12, 2011 10:23 am

ChrisLilley wrote: The value for 5x f/8 appears to be out by a factor of 10 (0.10 not 0.01) compare adjoining 0.09 and 0.16.

Thank you Chris, the values are wrong, it should read 0.10 but it is easy to see that is a keyboard input mistake ;-)
Regards