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DIY Focus Stacking for Macro Photography

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mawyatt:

--- Quote from: Dave on July 02, 2020, 03:45:50 pm ---
--- Quote from: mawyatt on July 01, 2020, 08:41:35 pm ---The effective aperture (EA) generally follows as Lens Aperture, or LA, as LM(1+M), where lens aperture is the normal "reading" on most cameras (Nikon shows the EA, not LA). When you get an EA that's beyond about F20 or so, diffraction begins to eat your lunch if your images are viewed at larger sizes. Normal lenses this doesn't matter, since shooting a bird at 100 feet or a portrait at 10 feet, M is very small, so M+1 ~ 1 and EA ~ LA. However when shooting macro this becomes a problem, example shooting at 1X the EA is twice the LA, so one would begin to see diffraction effects around LA of just f11 (in very high quality work this is below f8!!). So "stopping down" the aperture to increase the depth of focus has a limited range.
[...]

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Thanks for the explanation, knew there had to be some sort of catch behind it.

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Unfortunately there's no free lunch  :-\

Although, lately some research work has filtered down and folks are using what's called "blind deconvolution" algorithms to help remove some of the effects of diffraction. We haven't used these algorithms (yet) but others have shown good image improvements.

Best,

mawyatt:

--- Quote from: Mechatrommer on July 02, 2020, 03:32:20 pm ---
--- Quote from: Rerouter on July 02, 2020, 12:26:09 pm ---I feel I have missed it, but are there any free focus stacking programs anyone can recommend to give it a try?

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there are few in the list... i used Enfuse as one of the tools to do HDR stitching, it seems now to support focus stacking as well...
https://en.wikipedia.org/wiki/Focus_stacking

ps: for keen programmers, you can start with edge detection algorithm https://en.wikipedia.org/wiki/Edge_detection. where more edges information in the picture (higher spectral content or less compressible a particular portion of the image), thats where the focus should be, thats where to give more weight (or to put less mask) on the image, i guess this is how classic software based "contrast detection" auto focus in digital cameras work. blur the mask to avoid nasty result and then overlap them all. it should be not that difficult for a simple stitcher.


--- Quote from: fcb on July 02, 2020, 11:31:07 am ---Gorgeous images!! - any chance you can post these in high res so I can get one made into a poster for my lab wall. :)

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few replies up is the link in nikonimages.....

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PS has this capability built-in. It works OK, but has problems with involved macro stitching. Used it for a few simple stitching efforts, but it choked on some more complex stitches, so we ended up getting PTGui which works very well. PTGui has a somewhat long learning curve, but handled massive stitches rendering over 1/2 gigapixel (from 16~19 stacking session, stacked images rendered from ~300 images per stack at 36Mpixel per image, a total of over 200 gigapixels collected).

Best,

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