Topic: Buying an IR filter gel

[Urban Hafner]

So, all these recent IR images are making my jealous and I want to give it a try, too. But just for fun, I want to "convert" one of my (three) Konica Big Minis. They already have a protective filter in front of the lens and adding an IR filter gel (together with hacking the DX coding of the films) would allow me to shoot IR film with it. At least that's the plan.

Unfortunately my Google skills are failing me. I just don't seem to find such a filter gel. Any tips on where to get some?

Urban

[Late Developer]

Hi Urban.

Something liek this?

http://www.bhphotovideo.com/c/product/503590-REG/Kodak_1602143_3x3_75mm_87C_Opaque.html

[Urban Hafner]

Holy c**p, that's expensive! Also wouldn't 88A be the equivalent to a R72 filter?

[DonkeyDave]

I got an IR filter off ebay for £6 - could you hack something like that - even a non permanent version with some tape etc

how long an exposure time can you get - might be limiting with a P+S

[Urban Hafner]

That sounds more like it Dave! As I'm planning to use it in broad daylight I assume the 3.6s exposure time will be enough. BTW, what did you search for on eBay? "infrared filter gel" doesn't work for me. I assume I'm missing something (English is not my native language).

[Pete_R]

If you drop the 'gel' from 'infrared filter gel' you'll get lots of hits but depends if you definitely want a gel filter. I bought a couple of Zomei R72 filters which are pretty cheap and work OK.

[Urban Hafner]

Thanks Peter. I realised just after posting that Dave probably meant real filters. The problem is that the smallest filter I could find was 25mm and that's already a bit too big, as it will probably cover the metering cell. I'll have to measure more exactly later on to see that's really the case.

[imagesfrugales]

Hi Urban, not sure about the meaning of a filter gel, my online-translator says that gel means the same as the german Gel and I wouldn't smear that on a lens :-D

I also have a Big Mini, the BM-201, alas kaputt. When the lens is out, simply unscrew the 2 little screws at the side of the barrel and you can remove it without touching any lens element. Maybe you want to substitute the skylight filter. Or get rid of it for regular photography, because you always have your fingerprints on it.  But: with an AF-camera you can not adjust the focus for the IR-light, so manual focussing is a must imho. If dof will do the job? I doubt.

Best - Reinhold

[Urban Hafner]

Reinhold, gel filter is short for gelatin filter because historically filters in sheets were made from gelatin. But more importantly, how bad is the focus shift with IR? I always thought that it wasn't that big of a problem and could be ignored with small enough apertures.

[imagesfrugales]

PS: with my Hi-Matic 7s I can use the light meter or automatic exposure with the big 55mm filter covering the CDS-cell, but the negs are widely overexposed if you don't adjust the meter accordingly. Seems that the CDS-cell is not very sensitive for IR-light. With the RR400s = RR 400 infrared = ASP 400s etc, IR720 filter and the meter set to ISO 800 I get perfectly exposed negs. Ymmv though......

[imagesfrugales]

how bad is the focus shift with IR? I always thought that it wasn't that big of a problem and could be ignored with small enough apertures.

May be, or not. You don't know what the Big-Mini does, it will probably open the aperture fully most times. I guess p+s are more or less useless for this purpose.

[Urban Hafner]

Thanks Reinhold. I didn't expect that to work. Good to know! However the lens of Big Mini retracts and the light meter is really close to the edge so I'm not sure how easy it would be to cover the meter cell, too. So I'm thinking of just hacking the DX coding of the film canisters instead (to something like ISO 16).

As for the focus shift: I guess I'll just have to give it a try.

[Pete_R]

Thanks Peter. I realised just after posting that Dave probably meant real filters. The problem is that the smallest filter I could find was 25mm and that's already a bit too big, as it will probably cover the metering cell. I'll have to measure more exactly later on to see that's really the case.

If you get a glass filter and take it out of its mount you can cut them with a glass cutter quite easily to get the size/shape you want then just stick it to the front of the camera.

[Pete_R]

I don't worry about the focus shift when using SFX200 but other 'proper' IR films might be different.

[Urban Hafner]

Thanks Peter. I'll see in a few weeks (I guess thats ground shipping from China?) if the filter is small enough to fit with the mount. And about the film? Is there even "proper" IR film produced? I guess the Rollei 400S doesn't differ that much from the SFX.

[imagesfrugales]

I don't worry about the focus shift when using SFX200 but other 'proper' IR films might be different.

That's a good point! RR400s and SFX seem to be very similar, as far as the results can be seen here and elsewhere.

The BM-201 sets the Iso to 25 if no DX code is present. Maybe important to know. I expose the RR400s for ISO 25 with filter but measured without filter at late afternoons. I'm very curios about your findings, Urban, didn't want to disencourage you.

[Urban Hafner]

Oh really? I had assumed that it would set it to ISO 100 like most cameras. That's even easier then.

[Francois]

Well...
You could incorporate in the camera a Kodak Wratten No.25 gelatin filter (or equivalent). But then you'd have to stick to using pure infrared films, not the Ilford SFX.
The Wratten 25 blocks all visible light. When you hold it up, it looks like a black piece of plastic and it's pretty unbelievable that it is totally transparent to infrared. The sheets are quite thin and easy to cut... but are sensitive to humidity.

If you want the meter to expose correctly, you could also replace the camera's photo resistor by one that's only sensitive to IR rays. That would give you the best performance possible.

Thing is, infrared sensitivity doesn't have a direct relation to the ISO setting which is devised only for visible light applications. That means you'll have to do a bit of guess work.

I have somewhere a plan for building from scratch an infrared lightmeter. If someone wants it, I can scan it.

[Urban Hafner]

Thanks Francois. But that's just too technical for me. I'll just wing it and we'll see what happens

[Late Developer]

Holy c**p, that's expensive! Also wouldn't 88A be the equivalent to a R72 filter?

Hi Urban.

I wasn't suggesting that one in particular - just asking whether it was "something like this" you're looking for....

There'll be loads on the big auction site, no doubt.

[Urban Hafner]

No problem Paul. I was just a bit shocked I've now ordered a cheap 25mm R72 filter and we'll see what I can do with it once it arrives.

[Francois]

Thanks Francois. But that's just too technical for me. I'll just wing it and we'll see what happens

You know, nerdiness does have its drawbacks 

[jojonas~]

if you're cheap you can always use a bit of unexposed and developed slide film or welders glass. might be even less predictable then though

[Francois]

For what it's worth, I made a digital contraption last year...
I took a kid's digicam (it was an awful High School Musical model), opened it and replaced the infrared filter with two layers of the dark part you get on color negatives. I also covered the flash... it took a few more layers than for the lens. Now the camera only sees in infrared.

[imagesfrugales]

if you're cheap you can always use a bit of unexposed and developed slide film or welders glass. might be even less predictable then though

Jonas, you make my day. I have welders glasses here since my last model shooting, I have to give them a try.

[Urban Hafner]

if you're cheap you can always use a bit of unexposed and developed slide film or welders glass. might be even less predictable then though

Ah, yes! I should be able to find some bits of unexposed slide film around here. I had even read about it yesterday, but somehow it didn't cross my mind to actually try it. Maybe I'll grow impatient and try that instead

[Pete_R]

Hmm. Never heard of using slide film.

The welder's glass I have is green so I wouldn't have thought that would work unless you can get different types. OK as a crude ND filter though (except that it's not neutral).

[Urban Hafner]

A website from the RIT comes up first when searching for it: http://people.rit.edu/andpph/text-infrared-filter.html I assume it will work with Fuji slide film, too. But of course I'm not sure.

[Francois]

I haven't tried it but I figure that a bunch of layers of the darkest red filters from a Rosco sample pack should also work fine.

I don't think that color does matter much. What you want is a product that is transparent to IR and not light. Most plastics should fall into this category.

As for the welding glass, I have some reservations. It is made to block out most light, UV and some infrared in order to protect the eyes from burning, cooking and overexposure that could cause blindness...

[imagesfrugales]

As for the welding glass, I have some reservations. It is made to block out most light, UV and some infrared in order to protect the eyes from burning, cooking and overexposure that could cause blindness...

My welding glasses are also greenish and if they are made to block UV and IR it makes really sense.

The dye of color film is IR translucent, otherwise the IR dust removal in scanners wouldn't work.

[Francois]

Exactly

[jojonas~]

hm.. might have confused the welding glass for when I was looking up cheap ND filters. when you mention the coloured tint I think I remember the discussion about that too -that it was better for bw.

sorry guys!

I'll make it up later by showing some results from this setup I prepared and shot with today

[imagesfrugales]

Looks scary. Could need a sunshade 

[jojonas~]

Looks scary. Could need a sunshade 

I'm shooting for an unpredictable star

[jojonas~]

well, results are in and they are looking good


lc-a  r400s ir test by jojonas~, on Flickr


lc-a  r400s ir test by jojonas~, on Flickr

just don't shoot it straight into the sun

[Francois]

Well, this is not half bad for a test!

[tani.P]

Here's a pretty cheap IR option: http://www.bhphotovideo.com/c/product/102762-REG/lee_filters_87p3_3x3_infra_red_87.html

I have to get one of those, too, as I have a roll of Efke IR 820 laying around....

[Francois]

And the good thing with Lee filters when compared to Wratten is that the color is waterproof and won't come off when handling them.