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Old 29th January 2021, 10:39 AM
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Default Infrared film filter use

I have used this film with a red filter and was please with the results but they were not the proper white foliage results you would expect.

I have now obtained an infrared filter. My question is there a simple rule of thumb in gauging exposure?

I have done some research on the net but the answers are vague. I know that it can be a bit hit and miss to start with but need a point to start from any suggestion would be helpful thanks.
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Old 29th January 2021, 11:10 AM
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Sorry Mitch,
Which film did you mean?
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Old 29th January 2021, 11:49 AM
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I have only used a couple of B/W Infrared films in years gone by.

Unsure of how it would meter, I always took pictures on a sunny day.

Remember, even in brightest light, you are more likely going to have to compose, with the camera on a tripod, then attach the filter and then expose the film.

Even in bright light, I gave up to 4 stops OVER exposure, in 1 f-stops, to balance the VERY dark filter. (I can't remember how accurate the camera meter was with the filter on the lens.) I then developed them in my developer at the time, Ilford Ilfosol S. As far as I remember, all the negs were usable, depending upon how much detail you wanted in the negatives.

So, give it a try and see how your combination of film and developer works out. It's always fun to experiment.

Terry S
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Old 29th January 2021, 11:52 AM
mpirie mpirie is offline
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If memory serves, an R72 IR filter drops about 6 stops with Rollei 400.

Mike
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Old 29th January 2021, 12:03 PM
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Quote:
Originally Posted by mpirie View Post
If memory serves, an R72 IR filter drops about 6 stops with Rollei 400.

Mike
Same here, 6 stops.
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Old 29th January 2021, 12:26 PM
Terry S Terry S is offline
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Quote:
Originally Posted by mpirie View Post
If memory serves, an R72 IR filter drops about 6 stops with Rollei 400.

Mike
Quote:
Originally Posted by MartyNL View Post
Same here, 6 stops.
You guys could be right - it was a long time ago now. I think I used Kodak IR film.

I would use the first film as a tester film, giving a wide range of overexposure and then you will know how close you can be exposure wise on the next film.

Terry S
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Old 29th January 2021, 12:42 PM
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I have used ISO 3 to 6 as my base (bracketing recommended) with Ilford SFX so I agree with 6 stops with a 720nm (or thereabouts) cut-off filter. Don't forget reciprocity.

Other point - as far as I am aware (someone please correct me if not) all the available "IR" films now are not real IR - they are extended red sensitive. This will only really give the classic IR foliage effect with the IR72 filter in sunlight. If it is overcast, you may as well treat the filter as a 6-stop ND filter...

Last edited by Bob; 29th January 2021 at 12:48 PM.
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Old 29th January 2021, 02:22 PM
Nat Polton Nat Polton is offline
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I experimented a bit with infrared during the first UK lockdown.


Rollei IR in cut film holders, as I wanted a bit of flexibility with my developing times.
Using a tripod I focussed then metered through the filter. Then put the filter in place on the camera.
Meter set on the 25asa as recommended on the film carton.
Hoya R72 filter.
Using the exposures given by the meter I achieved good results.


The photo here, taken on a bright sunny day was exposed for 1/8 Second at f8. Developed in Rodinal 1+25 for 10 1/2 Minutes at 20 C. Metered through the filter.
The other exposures up and down an f stop worked ok as well.
The plants are dahlias and geraniums with a mixture of dark green leaves and variegated leaves. Red flowers on the geraniums.
I hope the figures give you a starting point.
Cheers.

I shall put the photo on another post. I think it may be to large at the moment.
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Old 29th January 2021, 02:37 PM
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The photograph as promised.



Cheers.
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Old 29th January 2021, 02:53 PM
Nat Polton Nat Polton is offline
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Default Pressure Plate Dimples.

Not sure if the following is valid with todays IR films.
I did read that if you use a camera that has a finely dimpled film pressure plate, the dimples may show up slightly in the exposed IR negatives.
The theory is the IR light passes through some film bases and is scattered and reflected back into the film by the dimples.
I have never had this happen to me, but I have only ever used about ten rolls of IR since the 1970s.
Something to watch out for.
Cheers.
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