Nicely done. Few people would be willing to tackle such a project and fewer would have the skill to make it work properly. Congratulations!
Nicely done. Few people would be willing to tackle such a project and fewer would have the skill to make it work properly. Congratulations!
This is encouraging. I need a blade for a #4 ilex shutter and you've provided a solution. I'll need to give it a shot.
Just a thought ( and don't ask how I know this ), but not all black plastic is perfectly opaque. You might try shining a laser pointer through a piece.
Charley
Black non-metallic shutter blades can pass the infrared that IR films are sensitive to.
Nonsense! The Rollei carbon fiber blades have/had no problem with IR transmission.Originally Posted by Jim Jones
I didn't know if the black polystyrene would be opaque, so when I received the sheets, I took one and covered the lens of my Sekonic L-758DR. I took readings in bright sunlight and also directly illuminated by a flood lamp. In both cases there was no measurable light, so I'm satisfied on that score.
However, polystyrene is a thermoplastic polymer. I suppose that if I leave the shutter in a hot car for a long enough time my carefully crafted blade might deform. I don't intend to expose the shutter to conditions like that. At least now it's usable. I've mounted the 14" Ektar cells and soon I'll take some shots with it.
Only time will tell.
Scott
That is not sufficient to discover if the material passes the IR light. A much better test is to sandwich a piece of film between two layers of the material and let it be for some time in sunshine. You would be surprised how many plastics are more or less transparent to the IR light. I had bad experiences with plastics that you would not suspect to be bad in this regard.
To your point - it really cannot matter if a shutter leaf is somewhat transparent to IR in LF for two reasons: In LF the film is not present during composition; second it is unlikely the film has significant IR sensitivity.
That is why for real 4x5 infrared I used a magnesium alloy body and telescoping steel extension (bellows) and aluminum lens board. The time between loading film to shutter exposure was short. No problem. First version. I lost interest when 4x5 Kodak High Speed IR became unavailable. (I recently built an all new concept and have some very old Kodak IR film - waiting on a deal for a big lens filter. I believe the prognosis is poor due to the age of the film.)
Last edited by Jac@stafford.net; 6-May-2018 at 17:05.
Black non-metallic shutter blades can pass the infrared that IR films are sensitive to.
Not nonsense, there are many cameras other than Rolleis. The older ones intended for use with blue sensitive film worked fine in their day, but sometimes easily passed IR.
Yes, your post was nonsense, you stated non metallic blades. There might be other cameras besides Rollei and other shutters besides Rollei but their shutter blades did not pass IR, I believe that the faster Rodenstock eShutter also uses blades that are not metal and doesn’t pass IR. This becomes particularly important to some people as there are not current manufacturers of mechanical view camera shutters
We can also take this to a further extent with all of those manufacturers of 35mm and MF cameras that also had cloth focal plane shutters. There were lots of Leica, Canon, Nikon, etc. users that shot IR!
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