RGB Tricolor filters for separation photography

Everything about the availability of RGB camera filters that you were afraid to ask …..

 

Wratten (original Eastman Kodak)

Tricolour photography suggested set for ‘one-shot tricolour cameras’ with B&W negatives

#25 Red; #58 Green; #47 Blue - Early nomenclature ‘A’ (Red); ‘B2’ (Green); ‘C5’ (Blue)

Tricolour set for direct separation (‘in camera’) B&W photography

#25 Red; #61 Green; #47 Blue;

Tricolour set for colour separation copy from colour transparencies

#29 Red; #61 Green; #47B Blue

These were the Kodak standards but photographers devised their own sets depending on film types and Daylight or Tungsten lighting set ups.

 

Harris Shutter 1971 (Kodak AE-90)

Mounted gelatin filters in a drop shutter #25 (Red); #61 (Green); #38A (Blue)

 

Wratten 2 (contemporary Kodak)

#25, #26, #29 Red; #58, #61, #99 Green; #47, #98 Blue

#99 (#61+#16 Yellow/Orange); #98 (#47B+#2B Pale Yellow)

Loading site please wait...

Tiffen

Glass filters

#25, #29 Red; #58, #61 Green; #47, #47B Blue

https://tiffen.com/film-enhancement/

 

Lee Filters for 100mm system

Polyester Tricolour Red #25; Green #58; Blue #47B (0.1mm thickness)

The tricolor polyester filters have been designed for tricolor photography and work well for that purpose.

Dichroic filters (or any filters designed to go over lights) are not optically pure and would compromise sharpness when used over a camera lens.

http://www.leefilters.com/index.php/camera-directory/camera-dir-list/category/tricolour

 

Kenko

The SP Color Set contains Red, Green, Blue filters for ‘factorization photography’ - similar to

a set by Prisma released in the 1970s.

SP Color Set- Kenko Global Site

 

Cokin

Cokin P Filter kit has a Red P003, Green P004 not suitable for tricolour work. (Needs clarification)

https://cokinfilter.com/collections/black-white

 

 

Formatt HiTech

Various filters in #25 Red; #61 Green; #47 Blue

Not listed on their website ? but available special order through B&H Photo NYC

https://www.formatt-hitech.com/filters/

Formatt Hitech 67mm 47 Dark Blue Camera Filter HT67BW47 B&H

Nikon

R60 (Red #25); X1 (Green #11); B12 (Blue #80B)

The X1 and B12 are unsuitable for true tricolour work

B+W

090M is equivalent to #25 Red; 091M is a #29;

061 is #13 Green (No longer available?); 081 is a medium Blue (No longer available?)

All are listed in their handbook but the 061 and the 081 are unsuitable for tricolour work

https://www.schneideroptics.com/pdfs/filters/BWHandbook.pdf

 

Moderator Note:

Please see Post #37 by OP containing revised information.

Edited September 19, 2019 by William Michael

Everything about the availability of RGB camera filters that you were afraid to ask …..

 

Nikon

R60 (Red #25); X1 (Green #11); B12 (Blue #80B)

The X1 and B12 are unsuitable for true tricolour work

 

Hmm... there go all my

dreams up in smoke...

http://bayouline.com/o2.gif

Maybe not quite everything.

 

For still life/studio work you can use gels over flash or hot lights for separation. In which case the Lee theatrical 'gels' are quite suitable. And in the absence of anything else, I recently used a piece of Lee dark blue gel over a camera lens with very little detriment to the image quality. Just don't get your fingerprints all over the gel!

 

Actually, I'm pretty sure that the manufacturing technique for theatre lighting polyesters has improved greatly of late, and that it can be used as a make-shift camera filter reasonably safely. Just eyeball it for obvious blemishes before use.

Who needs red, green or blue when you have Orang?

I'm still confused. - I'd be interested in an ability to create color work in a pinch and have a Kodak sensored Monochrom and some film stuff. Do I want the

Tricolour set for direct separation (‘in camera’) B&W photography

#25 Red; #61 Green; #47 Blue;

? - And how am I supposed to generate my K-film for printing?

I'm still confused. - I'd be interested in an ability to create color work in a pinch and have a Kodak sensored Monochrom and some film stuff. Do I want the

? - And how am I supposed to generate my K-film for printing?

If only, and duly noted ... probably should of said 'using this set on the camera for photography rather for copy/rostrum work'.

Maybe not quite everything.

 

For still life/studio work you can use gels over flash or hot lights for separation. In which case the Lee theatrical 'gels' are quite suitable. And in the absence of anything else, I recently used a piece of Lee dark blue gel over a camera lens with very little detriment to the image quality. Just don't get your fingerprints all over the gel!

 

Actually, I'm pretty sure that the manufacturing technique for theatre lighting polyesters has improved greatly of late, and that it can be used as a make-shift camera filter reasonably safely. Just eyeball it for obvious blemishes before use.

 

'Everything about the availability of RGB camera filters that you were afraid to ask ….. '

 

And yes - you can use some theatrical gels but they are generally not dyed to match the spectral response of their comparison lens filters and do not match the optical quality of glass.

Great for experimentation - I once even used 'prime' Red, Blue and Green acrylic plastic (Plexiglass, Perspex) cut to 4" x 5.6" when I could not afford the glass filters. Gave an acceptable result.

Edited July 14, 2018 by matt_t_butler

"...they are generally not dyed to match the spectral response of their comparison lens filters."

 

- That may not matter terribly much. There seems to be no specification for the exact film spectral response to match a given set of separation filters, nor a specific illumination CT. And since B&W negative film is the target 'sensor', then processing will play a large part in the transfer function of the end image.

 

I suspect that anyone doing colour-seps these days will be combining and re-colouring them after scanning and in an image editor. In which case there's immense flexibility in the complementary CMY 'dyes' that can be applied.

 

It's not like you'd have to carefully match 3 or 4 colour positives to a specific set of SWOP colours.

 

In short, I'm pretty sure that with current technology any old reasonably dense RGB filters could be made to render acceptably faithful colour in the re-combined image.

'In short, I'm pretty sure that with current technology any old reasonably dense RGB filters could be made to render acceptably faithful colour in the re-combined image.'

Absolutely correct!

Makes one appreciate the craftsmanship (craftspersonship?) applied to dye transfer and multi-colour print reproduction processes in the days before computers.

As colour is fairly subjective and photograhic post-production applications are all encompassing, then modern RGB compositing is a matter of personal expression.

If only, and duly noted ... probably should of said 'using this set on the camera for photography rather for copy/rostrum work'.

Sorry, Matt I don't get your sentence there. And also sorry, if I sound(ed) confusing. Yes, I am a press man by trade and for that reason somewhat interested in reproduction technology. That's why I'd seriously love to understand how K-films get (or got?) generated reprographically and outside the digital darkroom.

I don't get the difference between photography and copy work, as far as separation is concerned. Doing single camera triple shot color seems quite limited to really static subjects if perfection is the goal? The alternative would be artsy fun.

Even if I'll end dabbling with multi Monochrom shot color, I'd love to avoid

any old reasonably dense RGB filters could be made to render acceptably faithful colour in the re-combined image.

and rather have something I could send almost straight to the laser printer at work.

I don't get the difference between photography and copy work, as far as separation is concerned.

Back in the day Kodak suggested using two different filter sets - one for photography and the other for separation work.

The camera filters were 'broadband' spectrum filters used in early 'one shot tricolor cameras' while the separation set were 'narrow cut' filters used to produce RGB copy B&W negs from Kodachrome and Ektachrome transparencies.

Edited July 14, 2018 by matt_t_butler

RGB on Kodachrome 35mm film

 

"..and rather have something I could send almost straight to the laser printer at work."

 

- How?

To the best of my knowledge, there's no laser printer that can take 3 B&W negatives or positives as the input files for colour output.

 

There's never been a bullet-proof separation process. All of them have to be tailored to the final CMY(K) dyes used, or printing paper, film or whatever medium; either by trial and error, or careful densitometer readings, or dot measurement and dot-gain compensation.

 

Not only that, but electronic scanning of transparencies has been used since at least the 1970s in the printing industry. And before that there were 'one shot' separation cameras using beam-splitter prisms and built-in filters, for both still and cine cameras.

It was never really "easy"

kit from October, 1939 Popular Photography

Erratum for moderator

In the original opening post there is a line: 'Tricolour set for direct separation (‘in camera’) B&W photography'

Should read : Tricolour set for direct separations from original B&W photography.

 

The words 'in camera' - as pointed out suggests the process can be done entirely in camera.

From earlier post: 'Cokin P Filter kit has a Red P003 (Wratten #25).

Green P004 not suitable for tricolour work. (Needs clarification)'

 

Edited August 4, 2018 by matt_t_butler

And yes - you can use some theatrical gels but they are generally not dyed to match the spectral response of their comparison lens filters and do not match the optical quality of glass.

 

Some lenses-esp. UWs-have a gel clip at the rear since a front screw-on is impractical. Of current production lenses, the AF-Nikkor 14mm f/2.8D has this. Many super-teles either come with or have available as an accessory a gel holder for the filter drawer(although that's less less relevant since at least on Nikon lenses you can fit a Nikon brand screw in filter of the proper diameter).

 

What sort of gel would you suggest in those situations where glass is not possible?

What sort of gel would you suggest in those situations where glass is not possible?

 

Kodak still market their optically clear filters branded Wratten 2.

I don't know how thin these 'new' filters are but one can buy second-hand and generally unused original gelatin Wrattens on Ebay for reasonable prices.

If anyone on the forums knows the thickness of Wratten 2 filters please let me know.

 

Try Googling ' WRATTEN 2 FILTERS' for photographic outlets that stock them - they are used by cinematographers as well.

 

Kodak link : Loading site please wait...

Edited August 9, 2018 by matt_t_butler

Messing about with tricolour filters.

 

Dumbo photographers and tourists.

Canon 5D2, FD 50mm/f1.8, (Effective 63mm/f2.4 with FD to EOS 1.25x adapter) @ f11, 1/30sec, ISO 320, triple exposures using Wratten #25 Red; #58 Green; #47 Blue.

Composite frame grab from FCP X.

"..and rather have something I could send almost straight to the laser printer at work."

 

- How?

To the best of my knowledge, there's no laser printer that can take 3 B&W negatives or positives as the input files for colour output.

 

(snip)

 

As three separate files, it would take some tricks, but concatenated appropriately with the right Postscript code, I think it could be done.

 

The Postscript colorimage operator has enough options that it is hard to say what could be done with it.

Messing about with tricolour filters.

 

[ATTACH=full]1274553[/ATTACH]

Dumbo photographers and tourists.

Canon 5D2, FD 50mm/f1.8, (Effective 63mm/f2.4 with FD to EOS 1.25x adapter) @ f11, 1/30sec, ISO 320, triple exposures using Wratten #25 Red; #58 Green; #47 Blue.

Composite frame grab from FCP X.

 

- Why would you even bother with physical filters for something shot digitally like that Matt?

 

You could simply colourise desaturated shots and recombine as layers, or extract the separate RGB channels from any three full colour exposures.

 

There's already a set of tri-colour filters in (nearly) every digital camera, in the form of a Bayer array.

Hi [uSER=2403817]@rodeo_joe|1[/uSER] The shot your refer to is a composite frame grab from a 4K time lapse short edited with a minimum of post production processing.

 

Rather than mess about with the process to 'colourise desaturated shots and recombine as layers, or extract the separate RGB channels from any three full colour exposures' I simply exposed for balanced respective RGB triple layers that 'blended' into a colour sequence without any need to colour grade in a video edit timeline.

I was following the technique of Sergey Prokudin-Gorsky an early 20th century Russian photographer.

 

Link : Sergey Prokudin-Gorsky - Wikipedia

 

LINK to short:

 

Each camera manufacturer uses different densities of RGB dyes in the micro filters over the pixel sites in a Bayer array with twice as many Green in ratio to the Red and Blue. The respective dematrixing/demosaicing algorithms of particular camera brands give them their 'look'.

Hi [uSER=2403817]@rodeo_joe|1[/uSER] The shot your refer to is a composite frame grab from a 4K time lapse short edited with a minimum of post production processing.

 

Rather than mess about with the process to 'colourise desaturated shots and recombine as layers, or extract the separate RGB channels from any three full colour exposures' I simply exposed for balanced respective RGB triple layers that 'blended' into a colour sequence without any need to colour grade in a video edit timeline.

I was following the technique of Sergey Prokudin-Gorsky an early 20th century Russian photographer.

 

Link : Sergey Prokudin-Gorsky - Wikipedia

 

LINK to short:

 

Each camera manufacturer uses different densities of RGB dyes in the micro filters over the pixel sites in a Bayer array with twice as many Green in ratio to the Red and Blue. The respective dematrixing/demosaicing algorithms of particular camera brands give them their 'look'.

 

- A nice short, but extracting the RGB layers would keep the 'correct' colour in stationary parts of the scene without tri-colour exposure balancing or grading. An action in PS would make short work of the process.

 

Maxwell's famous shot of tartan ribbons shouldn't have worked in the absence of panchromatic sensitisers apparently. It appears that UV sensitivity took the place of the red exposure.

 

"Each camera manufacturer uses different densities of RGB dyes in the micro filters over the pixel sites in a Bayer array with twice as many Green in ratio to the Red and Blue."

 

- I think the filters used are more alike than they are different. Apart from Fuji, that does its own weird thing with array geometry. Still not sure how their supposed sampling of a 6x6 array of photosites is supposed to improve things. I suspect they're just lying about the real geometry to get around a patent, or to get the competition chasing their tails. It wouldn't be the first time Fuji had told porkies about its sensors.

Edited January 11, 2019 by rodeo_joe|1

- A nice short, but extracting the RGB layers would keep the 'correct' colour in stationary parts of the scene without tri-colour exposure balancing or grading. An action in PS would make short work of the process.

 

I guess so, but it was an experiment to see if one could reproduce Prokudin's technique with modern gear, without recourse to PS with which I am not familiar and instead use the traditional compositing effects available in the video edit program FCP X to emulated his process.

What I also discovered was the recommended filter factors suggested for exposure compensation for each filter when used with 35mm stills film cameras did not apply.

Different digital camera brands required different exposures when using the prime RGB filters - perhaps a result of the different sensors and de-matrixing algorithms used by each camera manufacturer. .... Interesting.

What I also discovered was the recommended filter factors suggested for exposure compensation for each filter when used with 35mm stills film cameras did not apply.

Different digital camera brands required different exposures when using the prime RGB filters - perhaps a result of the different sensors and de-matrixing algorithms used by each camera manufacturer. .... Interesting.

 

- As you say; interesting.

It's been my opinion for years that the Bayer filters in all modern digital cameras are too narrowly 'cut'. Missing spectral yellows and cyans altogether from their sensitivity. Therefore it's hardly surprising that there can be a clash between external narrow-cut filters and the Bayer array.

 

Could you tell us what filters you ended up using, and the factors you needed to apply?

 

Coincidentally, I came across this website that lists almost every colour process ever invented, along with some details of each process.