Alignment for Film Digitization

[silvergelatin]

Wanted to see if anyone has any tricks for alignment of a copy stand film scanning rig, beyond the usual “mirror trick”.

I have a Negative Supply Pro 35 carrier, and am finding that my alignment is slightly off if I put the mirror on top of the carrier. I am using a scientific supply front surface mirror that does not move the lens image when rotated, so that’s not the issue. I tried all sorts of tests with rotating lenses and rotating the carrier, etc, and have determined that the top of the carrier simply is not parallel to the film. I am verifying the alignment by shooting Vlad’s Test Target after the mirror step.

So next I tried running two pieces of thick Ilford film into the carrier sandwiched together to create a stable base for another little 20mm laser mirror I picked up, and it was much, much closer. I plan to try using a thin metal shim material next, as it should be flexible enough to slip into the S channel, but rigid enough for supporting the mirror without sag. But worst case scenario, the film sandwich trick is usable, if slightly awkward.

I wanted to open this up to get other ideas, though. Has anyone been down this rabbit hole and have any insight?

I was hoping to use the Focus Meter feature in Capture One, but my A7RII live view feed just isn’t clean enough for that to work. Has anyone used that feature or other software with a newer camera (with better live feed tethering) like the A7RIV?

 

[xkaes]

Please give us more information. If you are using a copy stand, please explain why you are using a mirror? What magnification are you needing? What is your light source?

 

[originalwinslow]

What! This is disappointing to hear. I've scanned thousands of negatives aligning from the top of the carrier...your laser mirror technique sounds like a pain.

It seems crazy that the NS carrier is one of the most professional/expensive on the market yet they wouldn’t have considered this. Have you contacted them?

 

[isaac7]

Wanted to see if anyone has any tricks for alignment of a copy stand film scanning rig, beyond the usual “mirror trick”.

I have a Negative Supply Pro 35 carrier, and am finding that my alignment is slightly off if I put the mirror on top of the carrier. I am using a scientific supply front surface mirror that does not move the lens image when rotated, so that’s not the issue. I tried all sorts of tests with rotating lenses and rotating the carrier, etc, and have determined that the top of the carrier simply is not parallel to the film. I am verifying the alignment by shooting Vlad’s Test Target after the mirror step.

So next I tried running two pieces of thick Ilford film into the carrier sandwiched together to create a stable base for another little 20mm laser mirror I picked up, and it was much, much closer. I plan to try using a thin metal shim material next, as it should be flexible enough to slip into the S channel, but rigid enough for supporting the mirror without sag. But worst case scenario, the film sandwich trick is usable, if slightly awkward.

I wanted to open this up to get other ideas, though. Has anyone been down this rabbit hole and have any insight?

I was hoping to use the Focus Meter feature in Capture One, but my A7RII live view feed just isn’t clean enough for that to work. Has anyone used that feature or other software with a newer camera (with better live feed tethering) like the A7RIV?

Since there hasn’t been a general outcry about this I suspect either you have slightly out of spec carrier or it just doesn’t matter enough to show up in the captures. What is the impact on your scans? Are you seeing sharpness issues?

 

[silvergelatin]

What! This is disappointing to hear. I've scanned thousands of negatives aligning from the top of the carrier...your laser mirror technique sounds like a pain.

It seems crazy that the NS carrier is one of the most professional/expensive on the market yet they wouldn’t have considered this. Have you contacted them?

Not yet. I have been running a few tests to make sure that that is the actual cause, and I can't see any other explanation since the lenses don't appear to be de-centered and the film plane itself is not bent.

If you are shooting with a 60mm lens and stopping down, you might not see any unevenness. My 55 Nikkor does not show it very well, but moving to the 70mm Sigma or my new 75mm Rodagon amplifies small errors a bit more. It looks fine by f8 for practical purposes, but it bothers me that I am not actually aligned 100%.

 

[silvergelatin]

Since there hasn’t been a general outcry about this I suspect either you have slightly out of spec carrier or it just doesn’t matter enough to show up in the captures. What is the impact on your scans? Are you seeing sharpness issues?

There is some softening of grain in the affected corners, but if stopped down, it is not severe. I still want to get it right for those edge cases where it might show up. Agreed that there may be some sample variation on the carrier. The outer chassis is solid, but the inner cassette part feels like it's 3d printed.

 

[silvergelatin]

Please give us more information. If you are using a copy stand, please explain why you are using a mirror? What magnification are you needing? What is your light source?

The "mirror trick" is where you place a mirror over your film carrier (presumably parallel to your film plane) and then center the image of your stopped-down lens aperture in the mirror. The idea is that it will only line up if you are perfectly parallel.

 

[originalwinslow]

It is definitely 3D printed. For the price one would hope that they would be solid mold but that's not the case. I also have a warping issue with the 120 carrier where I now have to depress one side while balancing the mirror. They still work better than the Valoi or essential film holder.

 

[silvergelatin]

It is definitely 3D printed. For the price one would hope that they would be solid mold but that's not the case. I also have a warping issue with the 120 carrier where I now have to depress one side while balancing the mirror. They still work better than the Valoi or essential film holder.

I just tried alignment again and discovered that if I put a metal ruler across the carrier lengthwise, I get pretty good alignment with the same mirror on top of the ruler. But if I put that mirror directly across the carrier opening, it shifts a bit. So it seems the outer edges are not optically level?

 

[originalwinslow]

I have definitely noticed some softness in the grain at the very edge of the frame. But it is only visible at 200%+ crop and for a very short distance so I ignore it. I appreciate your pursuit of perfection, though. Is it not resolved with FFC?

 

[silvergelatin]

I have definitely noticed some softness in the grain at the very edge of the frame. But it is only visible at 200%+ crop and for a very short distance so I ignore it. I appreciate your pursuit of perfection, though. Is it not resolved with FFC?

Does FFC affect focus? I didn't think it did.

I never suspected that I might be OCD until started this camera scanning thing. Decades in a darkroom and never had to obsess over alignment. Lucky, I guess.

 

[silvergelatin]

Ran another test - removed the Neg Supply carrier entirely and put my Vlads target into a simple clamshell film holder (from the Nikon ES-2 I had buried in the closet). Put my mirror on top, aligned, focused, and shot at various apertures. Finally this expensive Rodagon is behaving as expected - evenly resolved corners wide open, and no visible improvement from stopping down. The NS carrier made it behave like a macro lens - curvature wide open, improved on stopping down. My NS carrier is not flat, and it doesn't seem to be just an alignment issue

 

[silvergelatin]

They still work better than the Valoi or essential film holder.

What specifically did you not like about these?

I’m going to need something to replace this NS, unless everything else is just as bad. I emailed NS to see if this is their idea of normal, so we’ll see if maybe I just got a bad one.

 

[originalwinslow]

To me the valoi system was flimsy and felt even more 3D printed. I also had some issues with light vignetting. The 120 holder did not keep the film particularly flat, either.

As far as I know the NS holder is the premium option. Disappointing that it still has a flaw as basic as this.

 

[silvergelatin]

To me the valoi system was flimsy and felt even more 3D printed. I also had some issues with light vignetting. The 120 holder did not keep the film particularly flat, either.

As far as I know the NS holder is the premium option. Disappointing that it still has a flaw as basic as this.

Yeah, I think all of the transport-focused carriers sacrifice flatness on cut strips. I ordered a Lobster Holder, but I am a little concerned that it will be slow and inconvenient for high quantities. We will see.

 

[DanielCTracht]

Given that you have Vlad's Test Target, why not use it to align? That's generally the approach I take: tethered shooting wide open at 400% and some shim stock under the feet. It was extremely tedious the first time, but I've found the Valoi holders to be dimensionally stable over time.

 

[silvergelatin]

Given that you have Vlad's Test Target, why not use it to align? That's generally the approach I take: tethered shooting wide open at 400% and some shim stock under the feet. It was extremely tedious the first time, but I've found the Valoi holders to be dimensionally stable over time.

Tedious indeed. But since the NS holder wasn't flat, it didn't matter - the film plane shifted on each shot for cut strips. The solution was to buy a Lobster Holder, which I got yesterday and scanned 12 cut rolls through last night. Problem solved!