Gelatin filters?? What am I looking for?

tkamiya · Nov 27, 2014

I have a Sigma 15mm Fisheye lens. This lens takes an "Insertion-type gelatin filter" into rear of the lens. It's quite small at less than 1" square. The lens came with a template to cut this filter myself.

I am only familiar with front-of-the-lens screw type filters and Cokin type filters.

Where do I buy these gelatin filters and what do I look for? I am only interested in yellow, orange, and red B&W "contrast" filters. Basically, what am I looking for?

Looking at B&H site, I see Kodak has lots of these but they are $73 and up. (some are way up...) Are these what they are?? Are the thickness standardized? How do I cut these without damaging them??

BrianShaw · Nov 27, 2014

They cut easily with scissors.

It has been a long time since I've bought Kodak gel filters. I recall that they came in two sizes: 3 inch and 4 inch. At one time they were expensive but not crazy expensive like they are today.

At one time Lee had a swatch book that would have been perfect for you. Not gel but polyester and a lot cheaper to try before investing in gel. I don't know if they offer that swatch book anymore or not. The swatches were about 1 x 3 inches. Somewhere I have one but it might take a long time to find it.

This ---> http://www.leefilters.com/lighting/lighting-resources.html

tkamiya · Nov 27, 2014

I just got the template out. It's exactly 1 inch square. It seems such a waste to buy 3 inch square piece and use that little.... If you find what you have, it'll be great. I'd be interested in buying it from you.

Photo Engineer · Nov 27, 2014

At one time, these filters were made in 2", 3" and other sizes up to 8x10" which was the largest I ever saw. Larger ones did exist. And, they were dirt cheap, but today they are part of a dying market and are quite pricey.

Now, if you want to tell us the filter type you want, I have a complete set of CC filters and the separation R/G/B filters. I might part with a 1" square if you are in dire need. If not, (and here is the secret) any old filter can go in front of the lens if you are careful, but with a fisheye, being careful doesn't cover it at all. The curvature of the lens is what kills you.

So, you might make do by cutting any old filter to 1" size as it will work. Gelatin filters are not mandatory.

PE

BrianShaw · Nov 27, 2014

I just looked through the "logical place it would be" and didn't see it. There is one more "next logical place" it may be. I'll check in the AM. Right now I'm engaging in pleasant distraction when I really should be cleaning up after the Thanksgiving feast. All of the guests ate, drank, and ate some more... and now went home for a nap. I'll let you know if I have success in finding it.

paul_c5x4 · Nov 28, 2014

BrianShaw said:
At one time Lee had a swatch book that would have been perfect for you. The swatches were about 1 x 3 inches.

I picked up one of these swatch booklets quite recently from a local stage lighting company - The gels are 1½"x3½" (usable area, 1½"x3") and come with a transmission curve for each one. The Lee reference numbers do not match up with Kodak/Wratten numbers, so you'd need to do some leg work to compare the transmission curves along with a bit of testing.

Nicholas Lindan · Nov 28, 2014

Rosco also sells swatch book. The filter numbers often match the common numbers - i.e. #25 is red, #11 is yellow...

http://www.bhphotovideo.com/c/product/45189-REG/Rosco_950SBLUX0103_Roscolux_Swatchbook.html - $2.50.

The books come in several series and sizes. Any of them will do.

tkamiya · Nov 28, 2014

Are these suitable for photographic lens use? I can see it would be just fine for lighting but would scratches and defects be a concern? I just don't know anything about these types of filters.

tkamiya · Nov 28, 2014

I found some NOS Kodak on eBay for (really) cheap. I hear they fade, so I guess that's why they are cheap....

Photo Engineer · Nov 28, 2014

They are as good (or bad) as any other color filter.

PE

ic-racer · Nov 28, 2014

Not much to offer that has not already been posted. However, If you can't find Wratten filters and decide to go with Optiflex filters, my experience with those is that they crack and chip when trying to cut them to size. I actually did cut two of them to size for various projects, but it was a matter of chipping away at the edges to make the shape. Very difficult to work with for projects like this.

Old-N-Feeble · Nov 28, 2014

tkamiya said:
I found some NOS Kodak on eBay for (really) cheap. I hear they fade, so I guess that's why they are cheap....

I have many VERY old Kodak Wratten gel filters and all of them are in excellent condition (not faded). The only ones in bad shape were abused... poorly handled with scratches or fingerprints or they got wet. If properly stored and handled carefully they last a very long time. They are EXTREMELY delicate though and cannot be cleaned other than very careful use of canned pressurized gas (Dust-Off).

The bright side is gels can be used behind the lens with zero focus shift or image degradation... unlike plastic or glass filters.

tkamiya · Nov 28, 2014

Old-N-Feeble said:
They are EXTREMELY delicate though and cannot be cleaned other than very careful use of canned pressurized gas (Dust-Off).

That's good to know. Then, are they considered a "disposable" item? I'll be dealing with a one inch square piece with no handling area. I don't know how long I can successfully keep finger prints or other contaminants (that doesn't blow away) away.

Just trying to gather as much information as I can before buying one and screwing it up.

Old-N-Feeble · Nov 28, 2014

tkamiya said:
That's good to know. Then, are they considered a "disposable" item? I'll be dealing with a one inch square piece with no handling area. I don't know how long I can successfully keep finger prints or other contaminants (that doesn't blow away) away.

Just trying to gather as much information as I can before buying one and screwing it up.

Just handle it carefully by the corners and it'll be fine... and don't sneeze on it.

tkamiya · Nov 28, 2014

Got it, thanks.

Paul Cunningham · Dec 1, 2014

I would use the Rosco swatches. They are about $3. for a complete set.

tkamiya · Jan 27, 2015

Thanks everybody.

M Carter · Jan 28, 2015

Just curious - are plain old lighting gels just fine behind the lens? I had a sheet of clear UV gel (roscoe) back in the day I used for light diffusion - it smeared the image up a bit.

Not crazy like the go-to 4x5 film sleeves from the lab, but still… lighting gels as camera filters? I'd shoot a test roll and compare before committing!

Old-N-Feeble · Jan 29, 2015

I don't think lighting gels are optical quality... but some may be better than others.

BrianShaw · Jan 29, 2015

Technically they probably are not, but in practice they often work just fine in an optical application.

Patrick Robert James · Jan 29, 2015

I have had a few lenses over the years that required gel filters in the back. Cine filters like the Lee and Rosco just didn't cut it. On wide lenses the edges were often smeared. I tried them in front of a pinhole camera once and you could distinctly see the imperfections in the filters which showed up as lines right through the image. That was especially telling about their optical quality. I haven't used the Lee polyester filters that are like the Kodak but I did read once from someone who would know that they cause focus shift with telephoto lenses IIRC. Your best bet would be to stick with Kodak gels.

I don't know what your template for cutting them looks like, but I always cut them in the shape of a house so I have something to hold on to when placing and removing them. I also used Compact Flash card holders to hold the gels so they wouldn't get scratched. They worked perfectly.

Hope that helps you.

Gelatin filters?? What am I looking for?

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