Dichroic separate RGB channel DSLR scaning

Has anyone experiemted with things like dichroic filter RGB DSLR scaning?
Or perhpas creating a IR channel with the removal of IR cutoff filter in the camera?

Thank for sharing your experiences.


There’s a rather old thread here:

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I’ve been using a Nikon D800 on a modified Beseler Duplicator Deluxe (built on an inverted enlarger head) for a good few years now & the colour filters work well. I always do my final colour correction in Photoshop. Mostly little is needed although really major colour changes are possible so I don’t fuss too much, I just have standard settings for transparencies & for C41.

Thank you for alerting me to that!

Do you see any improvement over single pass RGB scan?

A digital exposure is always & only a single pass exposure. I sometimes make 2 or 3 different exposures to HDR a high contrast original.

I wasn’t talking about multiple exposures but multiple passes as in multiple shots being roughly equivalent multiple linear sensor passes.

I don’t know what you mean by ‘passes’ when using a camera to digitise.

Do you mean that you attempt to neutralise the orange mask for colour negative by adding broadly cyan filtration? If so have you found that effective?

I’m wondering if you might be referring to use a dichroic enlarger to try and produce separate RGB exposures, I’m not sure that would be possible, the only solutions that I’ve seen use individually controlled (and specially selected) LEDs as in this thread:

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From memory, for C41 I’ve been using Y36, M0, C44 but the illumination is from an underrun (so quite yellow) tungsten lamp so other illuminants would need very different settings.

I meant making 3 photos – R, G and B separately and compositing the channels in PS …

Halogen is great in terms of Colour rendering index.

Oh yes, though as that post suggests maybe a bit warm for conversion with a digital camera so some filtration is possibly preferable as with @DavidHoffmanuk above. I was thinking that you might mean combining 3 different exposures with different filtration dialled in. Clearly colour printing paper was used with a tungsten light source in an enlarger but it was designed that way.

Sorry, just read this, so you did mean 3 separate exposures! Never read of anyone doing that, it’s difficult enough with individually controlled LEDs I think.

Thanks, I wondered if that was the basic principle and presumably you’ve found it beneficial over no filtration, pure tungsten as it were.

It does give a file that converts well & is mostly usable (news, books & mags but not exhibition or print sales) straight from NLP with no additional correction. When I’ve been digitising BW & forget to switch the filtration in I get very orange files but even those can be easily fixed in P’shop. Same with transparencies that come out very blue, surprisingly easy to sort out later. It’s just quicker to get it close straight off - & quick is what I like as this is a production setup so time is a major consideration.

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I’ve never tried that. Why would you?

If you used a monocrome DSL w/o a Bayer array you would get 3x time as much color information potentially making it comparable or suprassing scanner line scan sensors …

A scaner makes 3 exposures with the line sensor. Using monochrome DSLR and separate color exposures could potentially benefit the scan. How much and is it viable is questionable, this is why I am asking if somone has experience with it.

Servicing pro scanners is becoming a nightmare and DSLR repro scanning still can’t catch up. I heard the new Fuji 100MP medim makes great scans but thats an above 10k rig.