I've searched threads but can't find much info on actual exposure times. I typically don't meter with konica 750 and get good results. My results with maco/efke aren't as good so i'm trying the 87 filter. I've been working so much i haven't had the chance to test a roll of 120.
I've been shooting Maco ir 820/Efke 820 with an 89b and i've made the switch to a #87 filter. I can't find info on exposure times. I'll be shooting 4x5 and 8x10 so longer exposures are the norm for me. How about spot metering w/o filter at iso 3 or 6?
The level of IR is affected by season, latitude and time of day - essentially how much IR-absorbing atmosphere the light path passes through. So, metering the visible-spectrum light (what we regularly read with the meter) won't necessarily tell you much about how much IR you have. (Although it's better than nothing.) That's why personal testing is so often recommended for IR, along with broad bracketing.
Note, too, that the cut-off point for the Wratten 87 is 800nm, meaning that it is cutting off a fair portion of the IR sensitivity of the Efke 820 film, which is sensitive up to 820nm, but little beyond that.
I was pleased with the results I got using an 89b (720nm) filter with Maco 820, which the Efke film is supposed to mimic.
I don't recall the exact exposure, Vinny, but I think it was around 8 stops down from the metered exposure, September time frame for a San Jose, CA latitude. I used a 100mm polyester filter in a holder adapted down to the filter size of the lens.
I'd suggest testing for your area on 35mm film, bracketing widely, so when you use an LF film size you can bracket less.
Be careful moving from 35mm to 4x5/8x10, as the results aren't always the same between formats. What I would suggest is setting your light meter for iso 100 (normalish for IR820) then hold the filter in front of the meter and record how many stops down to go. Put the filter back on the camera and meter as usual, then applying the correct number of stops to compensate for the filter. I used this method for a 120 roll of efke IR820 and a Hoya R72 filter with very good results. Freestyle recommends exposing it at iso 25 with an R72, tiffen 87 or B&W 092. Find notes and technical data sheet here:
I recently did some experimenting with 120 Efke IR and a #87 filter. I eventually ended up between ISO 1 and 3. Some great IR effects, but all 5 rolls I shot had weird emulsion issues - loads of light blocking spots like fine dust in patches. It ruined some worthwhile shots so I gave up on it.
Don,
I noticed the same thing on some of my negatives. I did not see them until I had scanned the negatives and zoomed in a lot. Doesn't seem to affect traditional enlargements however... Does anyone know how/why this happens?
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