Wratten Numbers and Rosco Gels

Matty

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Hello, I am new to this forum, and I'm hoping someone here has some knowledge of filters.

I'm attempting to experiment with additive light theory a-la Prokudin Gorski, and James Clerk Maxwell, and I need red, green and blue filters to make three different exposures.

I talked with my teacher, and he said I would probably need #29 red, #61 green, and a #47 blue Wratten numbers.

I'm not likely to use these filters for much else and I don't want to spend 200+ dollars on filters. Is there some way to determine an equivalent color of Rosco gel? Any suggestions would be very welcome.

Thanks!
 

samcomet

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Matty - While I do not think that there is any specified filter equivalencies between Rosco/Lee etc. and Wratten, the gel swatch books supplied by those two companies also provide the spectral distribution charts of the gels. I did a short search by the well know search engine for images of the three filters you were enquiring about and came up with pics of their spectral charts. A simple comparison of the charts might help you out there. The names of the gels also might be a good start too i.e "primary red, blue and green". I am a retired film lighting technician and have a whole bunch of these swatch books lying around. If you cannot glean one from somewhere local send me a PM and I will have a look for you myself for the matches tomorrow my time. Hope this helps. cheers. sam
 

ic-racer

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Check the Rosco site. They do have sheets in the "primary" colors (or at least named "primary").
 

nick mulder

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You might want to keep that in mind that Wratten filters have better optical qualities than your average gel. So those free swatch books of every filter you could want aren't so attractive after all (if you're using the filters in the standard 'technicolor' fashion).

But report back your findings and also find the optimal CMY gels too - extra credit ! (I need them for a project also)
 

AgX

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seperation filter sets

There are two sets given (Wratten numbers):

-) 25, 58, 47

-) 29, 61, 49


The first set is the standard, brought band, one, to be used on natural colours.
The second one consists of filters with a more narrow spectral transmission. It is used for objects made for a colour synthesis process, like colour ink prints and colour photographic prints.
 

nick mulder

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Anyone have the CMY colors also ? - 'narrow spectral transmission' (dim) ones would be ideal
 

Nicholas Lindan

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The Rosco filter numbers are often 1:1 with the wratten/photographic numbers. Rosco publishes the curves for their filters - they are near to identical to the curves in Kodak's wratten filter book.
 

Mike1234

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I believe I have all six of these... genuine Kodak Wratten and all in individual Kodak metal filter frames. Bought years ago, stored in climate controlled environment, and never used.

Anyone want to make a reasonable offer?


 
OP
OP

Matty

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Thank you all for the advice. I believe I may have found some Rosco gels that will work.

#27 medium red
#91 primary green
#80 primary blue

For some reason, Rosco does not have (or doesn't advertise) a primary red, but they recommend the medium red, which is a stop different from the other two. I don't think that will be much of an issue though. The scenes I'm going to shoot are going to have to be very controlled.
 

Nicholas Lindan

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From http://www.markerink.org/WJM/HTML/wratt_nr.htm, which has tables of wratten filters:

Color separation filters:
Filter no. low wavelength high wavelength domin. wl lum. transm. %
47 blu 400 475 464 2.8
58 grn 490 600 540 23.7
25A red 590 700 615 14

Wish there was a way to have tables in the posts...
 

Mustafa Umut Sarac

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For CMYK Transparent films , you can get small cut pieces to 70 x 105 centimeters films from prepress offices who have prepress proof systems from Fuji or Kodak.
I worked at prepress house for a long time at mid 90s and there were such things. May be today they print with laser or inkjet printer
Another option is to print these inked flat transperencies with inkjet printer.

Best ,

Mustafa Umut Sarac

Istanbul
 
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