I was very kindly welcomed to this forum and was advised to create a “separate topic”. I would never have dared to do it on my own. So here it is.
Trained in professional silver printing in one of the best Parisian B&W laboratories in the 60s, I sought to achieve the best possible results when digitizing 135 negative films. However, I was disappointed by the results I obtained with the various processes I tested. Digitization with a DSLR seemed the most promising method, yet something wasn’t right…
My research on the internet helped me understand that the cause of my disappointment was the diffuse light, which is nonetheless used, more or less discreetly, by all processes. Collimated point light thus became the only possible recourse, even though it is well established that its use is not without drawbacks. Would I be able to master it?
Spoiler alert: yes! But it’s anything but a simple and quick solution. On the other hand, what a pleasure to obtain A3+ prints that I am not ashamed of
Q: Do you actually use Negative Lab Pro to convert your negative scans? I see that you used darktable and would be interested in reading about reasons to use one over the other, apart from licensing cost.
Using monochromatic (green) light for scanning greyscale negatives seems like a smart move to me, even though the influence of the red and blue photosites on apparent quality of the grain and image is unclear to me at the moment. They might amplify or attenuate the grittiness, depending on how the file is de-mosaiced. Do you have any information about that? (Changing algorithms in darktable might reveal differences)
I chose Darktable because it’s Open Source. Thanks to this, we know exactly what it’s doing. It’s not a black box that develops our images as it sees fit without telling us what it’s doing.
The developers and the community have always answered my questions. Without them, I wouldn’t have been able to improve my results.
This is a very important question, which I was able to answer only with their help.
In fact, the photosites never gave me any problems during my tests, as soon as I switched from a 12 MPX to a 36 MPS. For 135 mm film at 400 ISO B&W, such a resolution is more than sufficient and glosses over the problem. If I chose green light, as I explain in detail in my documents, it’s essentially to get rid of chromatic aberrations, which have proved to be very penalizing due to my condensers and my APO RODAGON lens, neither of which are coated
And on this subject, Aurélien PIERRE, one of Ansel/Darktable’s developers, came to my aid. Here’s the configuration we ended up with.
In Preferences/Processing/Pixel interpolation select: bicubic.
** Optimize use of green light only :
** In the Dematrixing module, change the PPG method (default) to VGN4.
**Download the IdentityRGB-elle-V2-g10.icc2 profile and place it in
Windows - C:\Users[YourName]\AppDataLocal\Ansel\colorin\ and
Linux: ~./config/ansel/color/in/ and /out/
In the Input Color Profile module, select this new profile as input color profile AND working profile.
In the Color Calibration module, CAT tab, select Adaptation None and in the Gray tab, set the Green channel to 1, and the other two (R and B) to 0.
And to conclude : "[Configured this way] if you scan under quasi-monochromatic green light, the sharpness of your scan will be maximum because only the green photosites of the camera sensor will be used. In practice, this is equivalent to completely removing trichromy from the graphic pipeline”.
