DIY BW Contrast Viewing Filter
Since my upgrade to 4x5, I have been rereading a few of my books to gleam some technical skills on work flow when shooting. One of the things that popped up again was a contrast viewing glass to help visualize a scene. I have never needed such a filter when visualizing a scene shooting 35mm or medium format, but setting up a 4x5 and the extra cost of everything, Id like to get it in one or two shots, and I thought maybe it was time to try out this filter. So there is the wratten #90 filter made just for this, as well as premade filters such as the tiffen viewing filters in 3 grades for film types. Seeing as this is just all gels, Id like to make my own with 35mm snap locking plastic slides and a rosco swatch book. I am thinking of just cutting it to size, and drilling a small hole to attach it, maybe sandwich the gel between a slightly thicker piece of clear plastic.
What would be the equivalent filter for the wratten 90? I looked through the set, and it seems the closest is #3406, Roscosun 85N.6 Its the darkest amber type rosco has.
Also, I have read that perhaps a dark blue filter my also work, something like the #80 or 83 primary blue/medium blue filters.
Does anyone have experience with viewing filters and can provide some insight?
The viewing filters of different film manufacturers were different.
I understand that different companies made different filters but i wanted to figure out an approximate gel that was close to whichever company be it wratten, tiffen or whoever. I just dont have any type at all to test against. I cobbled up a few tests just to see if this would work and it looks promising.
Left to right:
Two pieces of developed porta 120vc film unexposed end.
Roscosun 85n.6 with 17% light transmission
Rosco medium blue with 4% light transmission.
I tried sandwiching protective sheets of thicker transparency sheets and thinner glassine sheets(that uncut film is wrapped in) over the gels but they reduced clarity too much. The double layer of film is not that clear but useable, the gels are very clear. I heated up a metal awl to easily melt through the plastic where i mounted a split ring to string these together. They will probably be stored in a simple plastic pouch.
Ill test them out on a sunny day and see if they help me at all.
To make it worse:
Originally Posted by AgX
I checked with a 50's Agfa/Orwo filter list: There were even 4 different pre-viewing filters for b&w films depending on sensitization and lighting (all different from Wratten #90), and one nearly-grey filter for colour films.
You can get a Kodak 3 x 3" #90 Dark Gray Amber Wratten 2 Optical Gel Filter from B$H for 34.50. This is probably your best bet, as you can cut down and place the rest in a cool storage area for spare material.
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The main idea for a viewing filter is to render contrast similar to what normal film developing would render and to remove or mask color saturation in a similar manner to the film's spectral response so one can spot mergers (areas of similar grey tone that are different colors in the scene and therefore not so apparent).
Your approach is certainly low-tech and cheap, so try it out and see how it works for you.
Kodak Wratten #90 filters are designed to work for conventional panchromatic films. They are likely a bit "off" for the newer T-Max films and may not exactly match the spectral response of films from other manufacturers. That said, it may be just fine for general viewing purposes, and your Rosco filters may be also.
Zone VI solved the problem of using bare gels by sandwiching the #90 between two pieces of glass. You can often pick up their viewing filters used
see here http://www.ebay.com/itm/Zone-VI-Cont...item2333e84efc for a current listing.
They usually go for much more than the original retail price now. I have three that I paid about $18 apiece for years ago. I'm glad I have them and use them lots.
Thanks for the responses, its interesting to see how much prices have jumped for the wratten 90 and even used viewing filters. With their prices so close together id probably be better off just buying a premade filter. The rosco gels have spectral curves on their website and when i have a bit more time ill try comparing them to one of a wratten 90 if i can find one that is posted.
Archive.org has an old Kodak manual on filters at https://ia600809.us.archive.org/16/i...lters_text.pdf It includes the curves and transmission values for a huge range of filters. It's from the 1950s, but will give you a good idea of what to expect.
I have a Zone VI Studios, Newfane, Vermont viewing filter. I bought it many years ago so don't know what's available now or on ebay. It contains a Wratten 90 filter between two pieces of glass to protect the filter which is gel. There's a neck lanyard to wear it as well. Here's a thread and covering it back it 2006. Mine is a 6x7 for my RB67 120 6x7mm.
The guy who produced it worked with Ansel Adms in 1965. Ansel gave them the 90 wratten fileter but they would get damaged hence his design with the glass. Andsel advised squinting when looking throuhg it to get a feeling for the tonal arrangements and balances of the scene You need to practice co,mparing it to your prints over time to get feedback. I'll try to photograph and post the full intructions and device picture. Personally I stopped using it since I shoot color. But it was also useful to seeing which lens to use. ie 90, 180 360 etc. to catch the scene I wanted even for color.
Grip supply houses also have color and B&W viewing filters, if you aren't satisfied with whatever you come up with DIY.