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Old 07-01-2017   #121
jzagaja
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First digital cameras 17 years ago were appying only gamma to linear capture but later they tried to simulate slide film and now even negative film (high dynamic range) so transfer function is rather unknown unless you use RAW converter and set to proper transfer function. Tonality/contrast is a one thing but color variations are much stronger and depend on light spectra used for illumination, camera colorimetry and RAW converter. Inversion curve you presented is for standard jpeg output from camera with assumption it is true gamma 2,2 without slope limiting. Was generated in my plugin. I tried 80A filters with tungsten on drum scanner but there was little difference. When you have good sensor with high dynamic range than you can correct in post without problem.
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Old 07-02-2017   #122
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what's the dichro head + flash + camera setup look like?
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Old 07-02-2017   #123
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Quote:
Originally Posted by aizan View Post
what's the dichro head + flash + camera setup look like?
I am using a Beseler Dual-Mode Duplicator. Has an illumination system with dials for color equivalent to a DiChro color head. Also had incandescent or flash illumination.

I use flash and +50 Cyan +15 Magenta to almost neutralize the orange mask in unexposed areas (e.g., rebate between frames).

Here's the setup:



DiChro controls are below, out of the frame. The gizmo "Vello" is a remote cord to trigger the flash in the Beseler.
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Jack's Curve (Transform & Invert) is a Winner!
Old 07-02-2017   #124
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Jack's Curve (Transform & Invert) is a Winner!

Quote:
Originally Posted by ColSebastianMoran View Post
Over next couple days will make some comparisons, but initial tests appear promising, possibly better than the other's I've tried.
Here's the process
- Illuminate a color neg with +50 Cyan +15 Magenta using 5000K flash
- WB from rebate (it is 4350K and -8 tint with my setup, with one typ film)
- RAW conversion with default settings in LR, Adobe "Camera standard" calibration
- Set White and Black points in PS (Levels)
- Compare a) Simply Invert vs. b) Transform and Invert with Jack's curve (Curves, custom preset in PS)
- Curves Option-Auto with Huss's options: Find Dark/Light, Snap Neutrals

With simply Invert:



With Transform and Invert using Jack's curve:



My conclusions:
- Note: this is a test of automatic processing; neither is a finished image
- I can fix either one to be a pretty good image
- The first will require more adjustments and selected area adjustments to fix the strange tonality (e.g., granite is simply wrong and has color cast)
- The second is the closest I've seen to a good automatic result from color neg film.

Thanks again to Jack and Huss. I encourage others to try Jack's custom Transform & Invert curve for PS.
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Old 07-02-2017   #125
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Quote:
Originally Posted by jzagaja View Post
First digital cameras 17 years ago were appying only gamma to linear capture but later they tried to simulate slide film and now even negative film (high dynamic range) so transfer function is rather unknown unless you use RAW converter and set to proper transfer function. Tonality/contrast is a one thing but color variations are much stronger and depend on light spectra used for illumination, camera colorimetry and RAW converter. Inversion curve you presented is for standard jpeg output from camera with assumption it is true gamma 2,2 without slope limiting. Was generated in my plugin. I tried 80A filters with tungsten on drum scanner but there was little difference. When you have good sensor with high dynamic range than you can correct in post without problem.
Jack, I cannot argue against any of that.

In my experiments with Camera-scan of color negative, there are some color issues and tonality issues. Your curve seems to help a lot with the tonality issues.

As for color, every film is different, so is every camera. I had been ignoring this, using the simple "Adobe Standard" calibration. In the past couple days, I've learned that "Camera Standard" or a custom camera profile are better, but there is still room for personal preference.

You say your curve was created for jpg at Gamma 2.2 and I'm using it to transform and invert from a RAW conversion in Photoshop. Do you think my use of your curve is consistent and OK, or would you recommend a different curve.
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Old 07-02-2017   #126
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Quote:
Originally Posted by ColSebastianMoran View Post
I am using a Beseler Dual-Mode Duplicator. Has an illumination system with dials for color equivalent to a DiChro color head. Also had incandescent or flash illumination.

I use flash and +50 Cyan +15 Magenta to almost neutralize the orange mask in unexposed areas (e.g., rebate between frames).

Here's the setup:



DiChro controls are below, out of the frame. The gizmo "Vello" is a remote cord to trigger the flash in the Beseler.
interesting piece of equipment. looks like prices are all over the place ($50-$550). i take it you're using a small flash unit that can fit in the space where the incandescent bulb goes? do the filters let you correct the color even if you don't use a flash?
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Old 07-02-2017   #127
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My curve sets middle grey correctly and if your camera adds S-curve you will detect it visually. Idea behind my plugin was to automatically batch scan negatives with predefinded white/black point and if necessary correct each frame later in post. It was used in one DTP studio for many years with Sony scanners. It could be now improved with AI algorithms, scopes etc. used in grading soft like Davinci Resolve but must be rewritten in another language.

From my experience Porta was the only film I had troubles with grading. Now it is improved with Kodak Vision cine film.
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Old 07-02-2017   #128
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Quote:
Originally Posted by aizan View Post
interesting piece of equipment. looks like prices are all over the place ($50-$550). i take it you're using a small flash unit that can fit in the space where the incandescent bulb goes? do the filters let you correct the color even if you don't use a flash?
Aizan, it's an interesting and flexible device created originally for slide copying. The "Dual" in the name is presumably incandescent vs. flash.
- Good, solid fixtures for camera mounting
- Illuminates a 6x6cm opening
- Mount a plate that takes Beseler enlarger negative carriers
- Mount a box that nicely illuminates a 4x5" opening for 6x9 or large format
- DiChro filters
- Switchable illumination: either incandescent (3000K) or flash (5000k)

Note the flash is high voltage. Use a Wein Safe-Sync.

I thought I would just mount a small modern flash in the base, but that looks very difficult. You need to continuous illumination to focus and position.
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Old 07-02-2017   #129
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Here's one more sample, shot in Tokyo on an overcast and rainy day in 2010.

Simply Invert, then Curves Auto w/options:



Transform and Invert using Jack's curve, then Curves Auto w/options:



My take:
- Note: these are just "auto" not finished images. Both start with 16 bit file.
- Could make a finished image from either; I worked on the first one to produce a usable image (not shown), but that was quite difficult, the tonality is simply "off" and needs a lot of correction.
- Second (w/Jack's curve) is much closer to "right" and quite close to the mini-lab scan for color. For tonal range, the second is better than the mini-lab scan. Already "close enough" for some uses and much easier to create a finished image from this one.
- While the dark areas are about the same, the midtones and bright areas are much different. That's result of the transform curve.

Conclusion: With these two tools (Jack's curve and Curves Option-Auto Find Dark&Light and Snap Neutral Midtones), I can make "auto" processed camera scans that will be quite usable. Close to and perhaps better than mini-lab scans.

Edit: ColorPerfect PS filter does the same job of non-linear inversion as Jack's curve. At this point, I recommend either Jack's curve or ColorPerfect for camera-scans of color-neg. See this thread.
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Named "Best heavy-game shooter in the Eastern Empire." Clubs: Anglo-Indian, Tankerville, and Bagatelle Card Club.
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