Workflow for digitizing MF B/W negatives - focus stacking & pano stitching

[MichaelEzra]

I finally offloaded this workflow from my head into a diagram, so I would not forget what it is.
I would like to share, as perhaps this can be useful to others.

I used to scan 6x7 BW film with Nikon LS-8000 scanner. That scanner has a phenomenal lens and is able to deliver extremely uniform level of sharpness, as long as subject is flat. That, however is a problem with film - it is not flat. I tried using a anti-newton glass negative carrier/holder. This keeps film sufficiently flat, but still causes newton rings for fine grain film.

To solve this problem, I resorted to using Nikon Z7 with Nikon Z MC 105mm f/2.8 VR S Macro Lens, while doing focus stacking to capture non-flat film in perfect focus and also combining this with panoramic stitching in order to not be constrained by the resolution of Z7 sensor.

There are great benefits to using the new Nikon 105mm S lens:
 - Lens' optical performance is very high
 - At F5.6 this lens rivals the sharpness of LS-8000, perhaps exceeds it when used with glass carrier.
 - ACR provides calibrated lens corrections
 - it allows very accurate and quick autofocusing on the BW negative
 - can image the negative at a greater magnification/resolution than LS-8000, even without the extension tubes.



Camera settings:
 - RAW
 - 1/200 sec F5.6 ISO 64
 - electronic shutter ON
 - silent photography ON

Light: video LED light, non flickering (Genaray LED-7100T)

Negative Holder / lens adapter:
 - https://www.amazon.com/Camflix-Digitizing-Adapter-120-Negatives/dp/B08122RLLV
 - Tube extension, to move the negative further away from the lens: https://www.amazon.com/gp/product/B06XKD62ST

Helicon Remote:
I programmed a shortcut in MacOS Automator to set a focusing range (steps 2,3,4,5):
1. manually AF
2. Step back 1 medium step
3. Step forward 2 medium steps
4. Step forward 1 small step
5. Shoot the batch
This simplified things a lot - less clicks / user actions per each focus stack sequence.
I set the size of Medium step to 6 in Preferences and shooting with Auto DOF checkbox ON (this automatically calculates the number of frames required based on the F-stop and the +/- displacement from the focused position).

It is helpful to AF in the same area while sliding the negative into new position (for panoramic stitching).

Helicon Focus:
Default settings work great: B / 8 / 4
On M1 Max eight TIF-16 grayscale frames are rendered and saved into a fully focused TIF-16 grayscale image in just 1 second!

In AutoPano:
 - I forced images to be recognized as 1000mm lens, thus bypassing any distortion correction, which is handled by ACR.
 - Autopano can only process RGB images, this caused a small detour from grayscale into RGB. One could do everything in RGB of course, if preferred.
 - Camera RAW can also handle panoramic merge of images in ~2 seconds, as opposed to 30-60 sec for Autopano, but it would require greater overlap than AutoPano, thus more stacks. Generally, I am getting better detection of overlaps and more accurate merging from Autopano.

As a result of this workflow, I am getting uniformly very sharp images of 6x7 BW film in resolution of 90+ megapixels. Every grain is clearly and uniformly visible across each frame.

[Boris Pasman]

Dear Michael,

What a fantastic workflow, thank you very much! How long does it take to digitize one capture?

[MichaelEzra]

Hi Boris!

In order to speed up the process, I minimized all delays, including - no exposure delay in camera (tethering with computer shortcuts eliminates shakes as naturally a few seconds pass after negative is loaded and shooting starts), setting all review delays in Helicon remote to the minimum.

Net time for shooting a sequence of 8 frames stack is ~30 seconds.
Average time for tethering 9 negatives (from a 3x3 archival storage sleeve), 2 sections per each, 8 frames per section is about 45 minutes.
This time includes all manual handling of the negatives, blowing off dust, loading, unloading, repositioning, initiating AF and all shooting sequences.
The result is 144 frames tethered into the computer.
When a greater magnification is needed and suitable (as this crops the film edges), I do 3 sections, thus 50% more frames.

Runtime of using ACR (RAW->TIF-16-G) for 144 NEF files (Z7 14 bit lossless compressed) is ~3min 30 sec on M1 MAX 64 GB 32 GPU 4 TB.
This computer is pretty fast, and the slowest part is Autopano Giga, which is not (and will never be, as Kolor closed) optimized for M1, its about 1 minute per negative. On my 9 year old PC that runs in 30 secs. But frankly that does not make much difference, as I do it in batch. The real downside of running Autopano on M1 would be setting control points manually. Normally I happen to avoid that and automatic detection is excellent.

Another thing is, while camera is shooting, it gets boring quickly, once one figures out all the steps, naturally one wonders into image processing of what was shot previously.
With that I am able to shoot one film, while processing a previous one through subsequent steps in the workflow. Overall that shortens the total time per final MF digital capture, but  as I haven't specifically measured it yet, I cannot accurately quote.

In this workflow a case of a 2-section pano / 8 frames focus stack each involves a bit over 5 GB of processing per each negative and perhaps about 7-10 minutes per negative when batch processing a large number of negs (up to the step of creating a composite TIF-16G file and before all manual steps of retouching and creative processing).

Hope this helps:)

P.S.
I don't shoot more than 18 negs per day so far.. but I did once digitize 900 slides from the 1970-s.. and I must say that that just makes you dizzy, doing that in a single session:)

[fdisilvestro]

Thanks so much for sharing this workflow!