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peterhoward
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Order of Events

Post by peterhoward »

Hi,

I've recently started experimenting with focus stacking and have a query about what order I should be doing things in. (I'm using Zerene Stacker, but I'm not sure that's very relevant to my question.)

My typical workflow consists of the following fairly standard steps:

1) Take some photographs with various focus settings, using Raw format.
2) Convert these to .tiff format.
3) Feed them into the focus stacking software and produce composite output(s).
4) Retouch the composites if necessary and output them in .tiff format.
5) Produce .jpeg files for printing, projecting, uploading as needed.

There's one other step I need to take at some point, which is to make development adjustments to the photographs. Otherwise, because I'm starting with Raw files, the results will be very bland. My question is where is the best place to do this. I could do it after step 1, in which case I'd probably best make the adjustments on one of the files, and then copy those to all the others. Or I could leave it until after step 4.

I've experimented with both techniques, and I haven't found one to be obviously better than the other. I just wondered if anyone with more experience knew of any theoretical or practical reasons to choose one over the other. Or even adopt a different work flow entirely.

Thanks for any responses.

Cheers,

Peter

Charles Krebs
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Post by Charles Krebs »

Nothing wrong with the 5 steps you listed.

I always shoot raw plus jpg, and frankly, I can be a little lazy and if the camera jpgs look very good I will use them. If, on the other hand, they have a "problem" I'll convert the RAW files and use them.

One thing to keep in mind. If you use PMax in Zerene, (or method "C" in Helicon) the output image will show a significant increase in contrast. So (at least for me) a goal is to have source files that do not have highlights or very bright areas so light that they are on the verge of losing detail. Give yourself a little extra "headroom" at both extremes, but especially highlights. This could mean that you initially process the RAW source files a little "flatter" than you want to final image to appear.
Otherwise, because I'm starting with Raw files, the results will be very bland.
If you find that you really need to make heavy tonality changes to the completed, stacked image you should consider converting the RAW to 16 bit images before stacking (your step 2). You can also experiment with RAW conversions that are not as flat as it sounds like you might be using right now (just keep an eye on the highlights).

ChrisR
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Post by ChrisR »

Peter - A slight hesitation here but
If you're using Zerene, do NOT tick the box which says "Retain full dynamic range".

Rik (who wrote the software) will be along with a link and explanation, but as I understand the issue, that compresses the tones to make sure every single brightest and darkest pixel is allowed for. Erratics mean you compress all your image info as a result.
Try reprocessing the stack :)
Chris R

peterhoward
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Post by peterhoward »

Thanks very much, Chris and Charles. Those are both very useful posts, and give me lots more to think about and experiment with.

rjlittlefield
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Post by rjlittlefield »

Peter, welcome aboard!

From a theoretical standpoint, I know of two main considerations.

First is that stacking algorithms do a better job on images that have a high ratio of actual detail to random noise. To the extent that sharpening and noise reduction can improve that ratio, you are better off doing those operations before stacking.

Second is that most image transformations can (in theory) be performed more accurately before conversion to nonlinear color spaces, which includes all the common ones like sRGB, Adobe RGB, and so on.

Both of these considerations argue for setting the raw conversion parameters in step 2 so as to make the images look pretty close to what you eventually want in the end. Just be sure not to over-do anything, because if you do, there may be no recourse except going clear back to the raw files and starting over.

As Charles mentions, it's a good idea to leave the contrast a bit low so that there's headroom for incidental increases. Such increases can be introduced either by some of the stacking algorithms (PMax, Method C) or simply by exposure correction if that's enabled (Options > Preferences > Alignment > Brightness, in Zerene Stacker).

In your steps 2 and 4, it's best to use 16-bit TIFF so as to preserve the most ability to adjust levels & curves without introducing artifacts like posterization.
ChrisR wrote:If you're using Zerene, do NOT tick the box which says "Retain full dynamic range".
If you've downloaded the software within the last year or so, that option will now appear as "Retain extended dynamic range" (emphasis added). The old title was actively misleading, because why on earth would you not(!) want to retain "full" dynamic range?? Problems with this have dropped way off since I renamed it. See http://www.zerenesystems.com/cms/stacke ... range_mean for some more information.

--Rik

peterhoward
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Post by peterhoward »

Thanks very much, Rik. That's really helpful. I've had much more detailed information than I'd dared to hope for. Excellent!

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