infrared rating question..

[toantruong]

I'm retared. I shot a roll of Kodak B&W HIE Infrared today, followed

all the steps, or I thought I did from here..

http://www.cocam.co.uk/CoCamWS/Infrared/INFRARED.HTM It says with a

red filter, the ASA rating should be 50 so I did set it to 50. So now

i'm shooting the roll rated at 50 in camera, i'm letting the camera

meter the scene with my red filter on so the camera is overexposing

about 2-3 stops because of the red filter ontop of my overexposing (or

maybe not?) my roll of infrared.

 

I guess it all boils down to, did I just overexpose my film 3 stops?

Should I have left the ISO setting on my camera at 200 and let it

compensate itself with the red filter on? If I did mess up, how much

am I going to have to pull it? I feel stupid.

[slichtyler]

Probably, yes. With HIE and a Red #25, I often set the ISO on my camera to 400 and let the

camera's TTL metering suggest an exposure with the filter in place. (Kodak's

recommendation of ISO 50 is if you meter *without* the filter.)

[dan_mcclain]

Yes, you probably did overexpose it, but not all is lost. You could just give it very short development, or if you aren't very far into the roll, just shoot the rest at 400 and sacrifice the first frames. I pushed some Konica 750IR to 200 once, and had to give it 30 minutes of development. It was very grainy, but at least I still got some pictures!

 

Infrared is definitely worth the learning curve.

[toantruong]

Unfortunately, I shot the entire roll like this. Any recommendations time wise on pull processing the roll?

[toantruong]

I did shoot everything 2 stops under/over, I could possibly eat it and develop normal and hope the underexposed shots turn out. But knowing what the pull times are would be nice.

[toantruong]

Sorry but another random thought, I usually process film (tmax, tri-x etc) D76 1:1. I know development times under 5mins is generally not recommended, if I use D76 1:1 (assuming developer is at 68 degrees) and from the digitaltruth chart, I could pull development time down to maybe 6min and increase agitation? Thoughts?

[chris_waller]

The film is rated at 400 ASA so if you use a red (R25) filter and you are using an INCIDENT meter, then you set that meter to 50 ASA to allow for the 3 stop loss of the R25. But, if you are using the camera's internal meter then set the film speed on the camera to 400 ASA. Having said that ssome camera meters are red-sensitive so check that you get a 3 stop drop in the reading with the filter on. If it is less than 3 stops then compensate acordingly.

[toantruong]

I understand that, I just wasn't thinking straight. I just really need to know how much I need to pull it in developing time wise. Thanks though.

[ivan_dzo]

I've done a similar thing. I would suggest that you'd do best in a two bath compensating developer. Lots are listed on line but even divided d76 would do well. Then you can cut back a little on the time in the second bath and all should be well. Burnt out highlights are a real problem with HIE anyway, so severe overexposure will make it very very grainy with severe burn out. Not a good combination (unless deliberate). This is what I did, so I hope it helps.

[slichtyler]

For a simple three-stop pull, I'd try giving it half the usual development time.

[rustys pics]

Yes, you overexposed it badly and you need to compensate by develping less.

Try using Rodinal diluted 1:100 for 12 minutes. Agitate the first 30 seconds and then let it

stand for the rest. Next time put your red filter on, and set your meter at ISO 400.

Good luck and let us know how it turns out.

[toantruong]

Temp ended up being 65 degrees so I winged it D-76 1:1 for 8min. Turned out pretty well. Very very grainy, I know grain is really prevalent in infrared but maybe cause I pulled it. Anyways, thanks for your help guys, I definetly won't make the same mistake next time.

[neil_grant]

You need to treat filter factors very carefully in this instance - almost all will be wrt to

normal panchromatic film used in daylight - not infra red film with its extended spectral

sensitivity. One post quotes a factor of 3 stops for an R25 - which will almost certainly be

wrong for an IR film.

[carbon_dragon]

It sounds like you already have some good advice. However normal light meters don't work perfectly for infrared because some things (such as grass) don't reflect infrared light in the same way they reflect visible light. Grass is an intense infrared emitter but a medium grey visible emitter. So, using a normal light meter with infrared film requires some rules of thumb and some intelligent guessing (and maybe some bracketing). Otherwise you can get some real overexposures.

 

Or you can use a light meter modified to be sensitive to light in the infrared spectrum. I bought this one from David Romano.

<http://www.davidromano.com/>

It's a Minolta meter with the sensitivity modified for Kodak HIE (primarily). It seems pretty accurate in the times I've used it. I'm very happy with it.

[john carter]

Develop the film and hope. Next time don't bother with the meter. Shoot HIE at EV 14.5 to 15 in full sun with a lot of green, and EV 13.5 to 14 in half shade, lots of water or a major building in the shot. D-76 @ 68 degrees 11 minutes.