Proposed Methodology for Processing Copied Negatives

[Mrdavie]

Lightroom Version Number

8.4.1

Operating System

1. Windows 10

This negative copying project is at its beginning. It would be nice to get off to a solid start with regard to cataloging and processing copied negatives because it is so easy for the Lightroom catalog to get out of hand and detract from the goal of creating new photo artistry from old negatives. This methodology will be different from the one utilized for original digital images taken with the camera. That method consists of importing the raw files and converting immediately to DNG, and then processing the DNG files. The original raw files get backed-up by the import check box to" make a second copy." The proposed methodology for copying negatives is thus:

1. Import images into Lightroom without copying to DNG.
2. Apply a preset that simply reverses the tone curve.
3. Export the image to TIFF with the option checked to add that image to the LR catalog.
4. Proceed with processing the TIFF image. The reasoning for not processing the raw file, is that after reversing the tone curve, some of the development sliders work in reverse. That does not happen with the TIFF file. Do you like this plan or have any other suggestions?

 

[Mrdavie]

I like Linwood's use of the term Acuity. When converting film to digital you are converting grain to pixels Pixels are uniform and a regular grid. Grain is random in both size and position. When developing a film negative to print, you focus the enlarger on the grain. If you do that, then the printed image is as sharp as the focus if the camera when the image was captured. I think the same holds true when converting old negatives or slides to digital. If you are using the camera, then you probably have one of the film attachments that fits on the front of the lens. Ideally, you want a true 1:1 Macro Lens that has a minimum focus distance at or in front of the position of the image. Then you can focus on the grain rather than the general image. All of my film to digital efforts have used this approach. (I will also add that I have not been entirely satisfied with my work in this regard. However, I do have the equipment including the Macro Lens and this is the approach I've used .

Some important considerations are DoF and shutter speed. You want a large DoF such that the minimum in focus distance is in front of the film and the maximum in focus distance is behind it. With slow shutter speeds, mirror flop (on SLRs) can cause enough vibration to blur the result. I have not tried this with a Mirrorless camera yet So, I can't say if shutter curtain movement causes enough vibration to affect the image "acuity".

Right now I’m struggling a little at the early stages of this project. The camera is attached to a copy stand and negatives placed in holder on LED light tablet. Used Nikkor 55mm macro lens with adaptor for MFT mount. Hard to focus because lens mechanism not real smooth. Also, there seems to be a lot of latitude for exposure with this setup. I did not want to drop $300 for a new auto focus lens. I’m still experimenting with histogram exposure support and understanding ideal utilization of Lumix GX9 camera with “dumb” lens attached. There is a lag for the camera to catch up with focus adjustments.

 

[Umberto Cocca]

Well, maybe I'll get ambitious and try some experiments with different formulae, but it won't be -1, since the values are 0..2^14 or 0..2^12 I think. What is much less obvious is how scaling works, since a gamma curve is usually applied as well during the process and whether you have to allow for that in some fashion (e.g. change scaling of light and dark) I have no idea. But might be fun to experiment with. When I get some time I'll search because there's a ton of open source raw processing routines out there, so there may be something already made.

I the correct operation is not subtracting one but getting the complimentary bits. Example for a 8 bit photosite that can be either of RGB:
1111 1111 is max luminosity for the photosite
0000 0000 is minimum (negative)
Therefore if a photosite has a value of
1011 1010 in negative becomes
0100 0101

Then of course comes the antialiasing.

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[Linwood Ferguson]

I got some interesting responses over in another forum that's aimed at my scientific aspects of photography, if you want to read it here. I decided to give up.