Team,
thank you for this interesting thread.
I have been reading this forum for quite a while, even registered, but hardly posted anything.
I am mostly a medium format shooter, although I have a Zeiss Ikon ZI which I use from time to time.
Here is my experience with DSLR scanning. Remember, I only express my opinions based on my
experience. Your experience and therefore your opinions may vary. Disclaimer: do not flame me
if you disagree
😀
General considerations
DSLR scanning seems to be a valid method - have a look at this video, even pros use it:
https://www.youtube.com/watch?v=UD12e8Gb_Jw
Obviously, those guys use a rig whose price is way above what mere mortals like us can afford.
But this convinced me that DSLR scanning, even if it does not reach the quality of Hasselblad X1
or drum scanning, is still a valid method - at least from some use: social media, small-size printing, etc.
In the rare occurrences when I want to print big I have the film scanned on a Hasselblad scanner.
Hardware
The ideal hardware is, in my opinion, a repro stand allowing to easily adjust the height of the camera
to maximize the usage of the sensor.
I have been successful with an LED light box from Kaiser, similar to this one:
http://www.kaiser-fototechnik.de/en/produkte/2_1_produktanzeige.asp?nr=2450
(mine is an older model). Illumination is even. Do not use an iPad or a computer screen: you will
see the pixel structure on your scans!
I use a Nikon DSLR but I guess that anything can work here.
A flat field macro lens is a must. I use a Micro-Nikkon 60mm AF-D. Although I have owned mine for decades,
those are available used for a few hundred $/€. I use the camera in live view and autofocus on each scan
somewhere in the middle of the frame. I do an exposure bracketing from -2 to +2 EV and select
the best exposed frame in post. (Auto exposure with aperture-priority mode).
I use the lowest possible ISO (for maximum dynamic range) and the optimal aperture
of the lens e.g. f/8 or f/11. Under these conditions exposures range from 1/2s to a couple seconds
depending on the brightness of the scanned picture.
I realized that the lens is very sensitive to flare from light coming from outside the scanned frame.
I thus created a mask out of black cardboard. I also scan in a dimmed room to avoid light reflections
on the film.
Scanning glass-mounted slides is the easiest. I place them onto the light box, "black side" of the GEPE mount
facing up. This is the "anti-newton" side of the glass mount facing the screen when projecting the slides.
Scanned pics are left-right reversed but this is easily corrected in post.
Scanning unmounted film might be marginally trickier, you have to ensure film flatness.
Software / Post-processing
This is in my opinion the trickiest part of the game.
There is a special edition of Capture One which is dedicated (among others) to film scanning.
Dubbed "Capture One Cultural Heritage", it is the ideal software for this task with auto-crop,
auto-rotate, negative-to-positive conversion, etc.
It also costs $5000 so forget it. It would be great if Digital Transitions, the editor of the software,
would propose a reduced version without a few pro features for a few hundred $ maybe.
But if I were to fork out $5000, I'd rather put that money towards a Hasselblad X1.
Here is the workflow I use:
1) starting from the RAW files, I select the best exposed frame.
(in the future I plan to play with HDR. I am not there yet)
I use Capture One for this but here again, I guess any software will do.
2) For slides: crop, levels and curves adjustment, (left-right flip if necessary, see above).
Pretty straightforward. Do not forget to adjust the color temperature to the color temp of your light source!
(5300K in my case)
For BW negatives: similar process. Crop, invert using the levels tool, brightness/contrast/curves adjustment.
Quite straightforward too.
Color negatives: this is the tricky part. Color negative film has a color cast which
cannot be removed
by just changing the color temperature.
The rest of the workflow description applies to color negatives only.
3) Export the best exposed frame from Capture One into a 16-bit TIFF. Ensure there is no clipping
in the histogram as this will have an influence on the color rendition.
4) I am developing a small Matlab script which does the following:
- open all TIFF files in a directory
- remove the color cast due to film die
- invert the picture
- perform histogram equalization
- save the resulting pictures as TIFF files.
The (commercial) Matlab software has great image processing functions. There are open-source alternatives (Scilab, Octave)
with similar functionality, so I guess it can be done with those too. My script is still under development but
it already brings usable results. Still a lot of work to be done here, and many ideas for improvement:
e.g. auto-crop/auto-rotate. Auto-detection of the color cast. Better automatic color correction etc.
5) A final adjustment is done in photoshop. The Auto Color feature does wonders here.
Hope this helps - let me know if you want further info!
Thanks
Etienne
