They Didn't Ask Me (dr_phil_physics) wrote,
They Didn't Ask Me

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By What False Light Do We See?

The Difference Between Digital and Film Cameras

It's the film, of course. You can put all kinds of film into any 35mm camera -- and get all kinds of results. Digital also gives you all kinds of results, but they are from either changing settings or post-processing. Ultimately, the recording sensor in the digital camera is going to control what range of results you can get -- the camera itself just comes along for the ride.

Back when I did yearbook shooting in high school and college, we used to buy a roll or two a year of infrared film, using Ektachrome Infrared color slide film. Turns out that the sensors in many digital cameras are sensitive to IR light, so they have to have an IR blocking filter mounted to keep the images restricted to visible light.

I read up on places that replace the IR filter with a visible light filter, converting the digital camera to IR use only. Alas, that requires a spare camera body AND a couple of hundred dollars.

But... it turns out that those IR blocking filters are not 100% effective. So if you're willing to use a tripod and long exposures, you can still do digital IR photography if you have a visible light blocking filter for the lens. AND, one source says that the Nikon D1 Series DSLRs are very good for this, because they use a CCD instead of a CMOS sensor.

Plus I had an infrared filter.

I remember seeing this totally black filter in Wendy's camera bag amongst a group of filters. Paul had used it way back in the 70s when he played with some of the Kodak High Speed Infrared black & white film.

Tiffen Wratten No. 87 Series VIII filter.

The glass Wratten filters take the gelatin filter and sandwich it between two pieces of glass. This filter suffers from some deterioration. (Click on photo for larger.)

Alas, it's a Series VIII filter and I haven't found a Series VIII to 52mm adapter. But, there was an old Nikon HR-1 rubber lens hood, and I found that I could loosely hold the larger Series VIII filter in the rubber and attach it onto a 52mm thread.

So I picked out a 24mm f2.8 AI converted Nikkor lens, because it has an IR focusing index, closed the eyepiece shutter, set the ISO to 400 and the aperture to f5.6, as recommended, and did a handheld shot at about 1/3rd of a second. Just to see if I got anything.


This is lightly manipulated. (Click on photo for larger.)

Next I broke out the tripod and set the camera up by the open back deck door.

Oops, this is what happens when you pan the tripod head and you've got a black filter over the lens -- next time I'll use a level. (Click on photo for larger.)

I've ordered a cheap Opteka 52mm R72 filter from Amazon -- it's supposed to be more of a 780nm cutoff, rather than 720nm, but it'll attach to a lot of my lenses -- all of my AI Nikkors from my old camera bag and several of my AF Nikkors. Amazingly, with the R72 filter, the autofocus should actually work.

This should be fun.

Oh, and the D1 Series? They also see into the UV spectrum. Lenses are a problem, but you can use EL Nikkor enlarging lenses, apparently -- and I have one or two of them. Need a helical mount, for focusing, and a UV pass filter... don't know what that'll cost. But that'll be for later.

Dr. Phil
Tags: cameras, nikon, photos

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