Focus Stacking Results

[DelawareJim]

This is very cool. Thanks for the info Ron.

Cheers.
Jim

[ronaldhanko]

You are welcome, Jim. If you download it and use it I would suggest using the instructions provided on the web.

[tropterrarium]

Originally Posted by Connie Star

I've had a lot of fun with this- 4 seems to be the limit and the progra is very slow. I use a tripod, set the exposure as a constant and then very carefully move from front to back. Small aperture helps, too.
http://www.orchidboard.com/community...-stacking.html

I use heliconfocus for the same, mainly on stereomicroscope, but will work with any image input. Alignment is critical, so tripod is a must, or you should pre-align images in photoshop. Heliconfocus has no problem with larger number of slices. I've used at least 20. With 72 MB 16 bit .tif files from Zeiss Axiocam HRc it takes about a minute. Tweaking with the parameters may be necessary.

Re small aperture, I have to disagree. The issue is image degradation due to diffraction when stopping down quite far. It gets exacerbated in macro because the the effective f-stop at the imaging plane is f-set multiplied by the magnification plus 1. So at 1:1 with set f/22, the effective f-stop is 22 x ((1:1)+1) = 22 x 2 = 44/45. Depending on final enlargement of the shot this could be quite a bit too much and make the image appear blurry. Standard value is f max = 32 for 8x10 print viewed at 2-3 feet. Ray has a nice discussion of this in Applied Photographic Optics.

Shooting all open is not ideal either, because some residual lens errors (chromatic aberration, spherical aberration, lateral color) are not ideally corrected. In general, the sweet spot of a lens is 2-3 f-stop down from fully open. So that is the ideal f-stop for stacking. Adjust focus increments and number of slices accordingly.

[tropterrarium]

Forgot: if you stack doing macro, don't change focus, but move the camera & lens on a macrofocusing stage.