HIE and Pressure Plate

[lyle_gordon]

Im going to be shooting some HIE and ive heard that the lack of an

anti-halation layer can cause problems with a non-flat pressure plate.

The pressure plate im going to use (Nikon) has a waffle like pattern

is there something I can do (put tape over it) to eliminate the

problem or is it nothing to worry about?

 

Thanks,

[stephen hazelton]

Lyle, my K1000 has a dimpled pressure plate, and after a half dozen rolls of HIE, I have yet to spot the slightest trace of dimple pattern on my pictures. I won't say it can't be a problem, but doesn't seem to be near the problem it's made out to be.

 

If you're in the experimental stage anyway, I'd say, don't do anything, just shoot the film and see if there's any effect.

 

The "fix" I've read of, is to take a piece of thin black paper, like the backing paper off 120 film, and tape it over the pressure plate- being careful not to get things gummed up where you don't want it. I haven't tried this, and won't till I actually see a problem.

[chris_waller]

Avoid over-exposure and you should avoid any artefacts from reflection off the pressure plate. There are those who advise bracketing when shooting IR but since the film has no AH layer over-exposure is self-defeating. I rate at 400 ASA and shoot through an R25 filter. I also use an incident meter (set at 50 ASA to allow for the R25 filter). I shoot as the meter indicates and I don't bracket. Typically on a bright day (full sun) this gives ne 1/60 at f/11.5. If you intend to use the camera's internal light meter then note that some meters are red-sensitive and cause under-exposure. Check that with the filter in place your meter indicates a three stop reduction in light.

[gerald_widen]

I shot a roll of HIE recently and set the meter to 400 with the red 25 filter. Even without much bracketing the photos were pretty well exposed. I developed in D76 full strength. Be careful of focusing however as a lot of mine were out of focus.

[stephen hazelton]

Chris, I've bracketed two stops over and two stops under. I've gotten overexposed and underexposed shots. But I haven't got dimple patterns!

[ecarter]

I shoot HIE rated at EI-640 in my OM-2 which has a dimpled back plate and I notice occasional faint suggestions in it. It's a matter of experimenting to find out what conditions this occurs in and what can be done to prevent it if necessary. I've seen suggestions that taping something CAREFULLY over the pressure plate in the camera (the back-paper of 120 film or a piece of dark plastic from Ilford B/W paper lightproof plastic bag perhaps) may avoid any pressure-plate patterns ... hopefully without causing scratching or focus problems. I haven't done this myself (yet) but may do it just to see what happens. Otherwise, I love the "HIE look."

[ecarter]

Should note that I shoot metering through a 25 red filter. Sorry.

[chris_waller]

Stephen,

 

That's interesting. A friend of mine some time ago shot IR and got definite reflections off the pressure plate. Mind you, the camera was quite old and the pressure plate well-worn so maybe the black paint had worn off.

[lunarlight]

I haven't used HIE in a while, however fifteen years or so ago I

used it quite a lot. The camera was a Minolta SRT that had a

waffle pattern on the pressure plate that left big square flare

spots on the film. I corrected for the problem by making an

aluminum foil pressure plate cover and then blackening it with a

sharpe marker. The foil was folded so that the ends tucked

under the long ends of the pressure plate, so that it would stay in

place while the film slit over it. I found that care was needed to

ensure the cover was perflectly flat over the pressure plate - no

folds or creases. I used it for many years, took it off and put it

back on repeatedly. Make sure that the blackening is very even

and complete.

 

For a sample image made using this pressure plate cover, see

 

http://home.earthlink.net/~kitathome/LunarLight/landscape_galle

ry/pages/174-08.htm

 

Kit Courter