Pan film with 87 filter

[stephen hazelton]

Has anyone tried using standard black and white films (not infrared)

with an #87 filter?

 

I have read numerous places that an 87 filter is "opaque". Having

just bought a Tiffen #87 filter, I find that I can see strong light

sources through it (looking through the filter, not mounted on the

camera). In sunlight, with outside light shielded, after my eye

adjusts, I can see the surroundings, including the "white foliage"

effect. This causes me to wonder if there is enough visible light

coming through to expose conventional films.

 

In looking at Kodak and Ilford spectral sensitivity charts, I find

that the Tmax and Tech Pan sensitivites extend right up to the

Infrared region, whereas the older films, Plus-X and Tri-X, etc.,

don't.

 

Any experiences or comments from anyone?

[wickedmartini]

While the T-Max and Tech Pan films do have an an extended red sensitivity, there is not really enough sensitivity in that region to make it worth your while. I have experimented with this a little bit. Exposures can be extremely long, reciprocity is certainly a factor and the results didn't seem to me to be worth the trouble.

 

I hope that helps.

 

Michael D. D'Avignon

[stephen hazelton]

Well, being the curious type, I just had to try!

 

I already had Ilford HP5+ in the camera, so I tried a sequence there, starting at 5 minutes at f/4, and going down. On the 5 minute exposure there is a bit of picture, nothing worthwhile photographically, but a recognizable image. Ilford shows the sensitivity of this film extending to about 660 nm, and the 87 filter starts transmitting at about 700 nm. Nonetheless, there is apparently some overlap in the curves. By the way, the image I got DID show the "white foliage" effect. (Developed in D76 per Ilford's recommended time for 400 speed, by the way).

 

Next, I tried some Kodak T-max 3200. I started off with exposures of 6 minutes at f/8, and worked down, and then developed 15 min in D76, as shown on data sheets for 3200 speed. The sensitivity curve shows the response of this film going down to 700 nm, so I expected better results. The lens was stopped down 2 stops, but film speed was 3 stops higher, so I expected equal or better results there. What I got was Nothing. Zilch. Can't see a trace of a shadow anywhere on that portion of negatives. (Some later shots exposed 1-2 minutes at f/11 by moonlight came out pretty good, though). Either the sensitivy curve is off for one or the other film, or reciprocity is overwhelming the Tmax 3200.

 

I did have an unexpected event with the Ilford film, though. I got some fogging on the top part of the negative (which should have been dark sky). I suspect very teensy light leaks around or through the filter threads, or through the lens mount or focusing rings. Normally, this would never be noticeable, but with the camera setting in the sun for 5 minutes with the shutter open, it was there. With the second test, I shielded the camera, and didn't see that effect. (This was a Tokina 17 mm (non-ATX) on Pentax K1000).