When is IR most powerful?

[eugen_mezei]

<p>Hello all!<br>

<br /> I got me a roll of 35 mm Efke IR820 with antihalation, know which camera I would use, got 2 filters, a Hoya R72 and an old ORWO that I don't know exactly what an extinction curve it has but it is darker than the Hoya, hopefully not beyond the spectrum of the Efke but I think not, as I can see the halogen bulb of a desklamp through it when putting it near. (I suspect it cames near the RG780 or maybe 715.)<br />Unfortunately opened the black plastic canister where the filmroll is in, just to read later that this will fog half of the roll. Too bad Efke was to cheap sticking a warning to the canister.</p>

<p>Also grabbed all the information about IR photography I could. (Exposure TTL, with lightmeter, ISO settings, Schwarzschild, etc.) Unfortunately 3 questions remain:</p>

<p>1. Literature often says IR radiadion is very variable. But not how it varies. I am interested about how it varies in the landscape. Ok, clouds absorb IR. But I read different infromation about when during the day I have more IR. Some sources states maximum IR would be at sunrise and sunset. That sounds logic to me. (Light traveling trough more atmosphere and blue radiation beeing absorbed.) But other state IR radiation will be most powerfull at noon.<br />Am I mixing up different things, perhaps when IR is more powerfull and when the Wood effect is more pronounced?</p>

<p>2. Again about how the percentage of IR in the light varies. When do I have more IR, when the sun is in front of me, at my back, above me or in a right angle to the direction my lens is oriented?</p>

<p>3. Same question as 2 but not about when I have the most IR but when I have the most pronounced Wood effect.</p>

<p>And a final question: I intend to develop in Xtol, is this a viable (or even ideal) solution?</p>

<p>Thank you,<br /> Eugen</p>

<p> </p>

[Fotohuis RoVo]

<p>April - June late afternoon, 3:00 - 5:00 PM.</p>

<p>You have to test, IR curcumstances in the atmosphere can vary very much on time and location.<br>

Make a bracketing -1 F - 2 F stops.<br>

And do not forget to compensate for the focus distance (different breaking index of IR light)</p>

<p>The most pronounced wood effect you will have with plants with a lot of chlorofil.<br>

Efke 820 IR is based on Efke 100 film. So the best type of developer will be Beutler A+B (divided) or Rodinal. But Xtol is also possible however less acutance and sharpness however if you go to 1+1 or 1+3 sharpness with Xtol will increase.<br>

Best regards,</p>

<p>Robert</p>

 

[Fotohuis RoVo]

<p>About loading and unloading in the camera: Efke IR 820C with A.H. you can load and unload in subdue light. Efke IR820C without A.H. can be a problem due to the light pipe effect. But the problem will not be as strong as with Kodak HIE IR film where you will loose 1/2 film.<br>

Hoya 72R will be the best filter for most IR films (Efke IR820C - Rollei 820-400 IR - Rollei Super Pan 200).</p>

[larrydressler]

<p>With the Volcano in Iceland the IR effect may be a little different this year in Europe.</p>

[stp]

<p>IR is best when there is lots of sun. It's nice to be able to shoot film/digital in the early morning, IR during the middle of the day, then back to film/digital in the early evening hours. Then hook up your tracking telescope to to astrophotography all night long, and start the process all over the next morning. RIP.</p>

[wolf_rainer_schmalfuss]

<p>The IR effect is not everywhere the same! For Europe it can be figured, in the morning until 10:00 o'clock, and in the afternoon, starting around 15:00 o'clock, is the best time for IR photography. Good luck, the photographers in the South Sea theater, does'nt have these problems!</p>

<p>Cheers</p>

[carbon_dragon]

With an anti-halation layer, you won't lose large parts of the roll, at least I don't think so. Most vegetation emits brightly in

infrared so that tends to bias the exposure. Water and sky tends to be black. Clouds reflect well and are white. If you buy a

book on infrared (will probably be biased to Kodak HIE) it will give you lots of rules of thumb to use as well as advice to

bracket. It is possible to build a light meter which is sensitive to the right frequencies (I have one) which saves on film.

[racerxphoto]

<p>I just shot my 1st roll of Efke in 120 and got very strong wood effect using a Lee 87 gel filter<br>

I was only able to make one crappy test before my scanner went belly up<br>

http://imagegods.com/?op=pic&id=136&photonum=797bb2c7404f95c63e327d503b0e9036fabd3331<br>

ISO 1-3 seems best starting point with that filter<br>

Here is a pdf data sheet on EfkeIR 820<br>

http://www.freestylephoto.biz/pdf/MACO_IR820c_AURA.pdf</p>