This question likely overlaps with another active thread on here but my purpose is different so rather than divert the other thread…
I’m working on a setup for digitising my collection of mainly Kodachrome 35mm transparencies. My current setup uses a Canon EOS 70D DSLR, bellows and an 80mm enlarger lens.
Previous attempts using two different flatbed and one PlusTek film scanner and have all produced disappointing results - none of the scanners has been able to capture the detail in the darker areas in spite of my messing with exposure settings. From reading others’ experiences I am not alone.
The DSLR setup has already proved that it is able to do much better by using bracketed exposures and HDR techniques. I’m now trying to optimise an HDR workflow to produce decent results without requiring so many steps that it becomes impractical to do more than a handful of slides.
Noise is still evident when zooming in to the dark areas of the HDR output (but still much better than the scanner results).
Some sites advise that it is best to perform noise reduction on the original images before starting the HDR merge. This reduces the likelihood that the HDR process will treat the noise as ‘valuable detail’.
I’m not clear whether this is possible with Darktable. I’m trying both Darktable’s built in HDR and also an external merge using Luminance HDR.
Using the Darktable merge… if I apply a noise reduction module to the raw files first will the data passed into the HDR merge have the noise reduction applied?
With Luminance HDR, I’m loading the raw files from the file system so I’m pretty sure that these will be untouched regardless of what I do in Darktable beforehand. Is there a better way? Presumably I could export the noise reduced raws but what would be the best file format to use without losing information? Is there a way to do this that doesn’t require lots of manual steps?
I also do some astrophotography and regularly use multiple exposures at the same settings as a way of reducing noise. I have not found many references to using the same technique for non astro photos. Could it be done in Darktable? For example would the HDR merge be able to make use of multiple exposures at the same settings to reduce noise? … or would another module be able to do it?