Rollei 400 infrared - some odd questions

Discussion in 'Film Discussion and Q & A' started by Kramertron2000, Sep 13, 2018.

  1. Kramertron2000

    Kramertron2000 TPF Noob!

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    So Im thinking of getting a few rolls of rollei 400 infrared to both use as a normal black and white film and with a 720nm filter for surreal near-Ir shots (such a shame there are pretty much no other options at all let alone colour Ir film). The odd question comes in because of the camera Id like to use it with.

    Im thinking Id like to use it with an Olympus Trip 35 (rather than my Nikkormat FTn), for a couple of reasons, but Im not sure itll even be possible let alone practical. I know it will be fine for straight up B&W - just meter for ASA 400 or maybe lower to get more highlights and shoot away.

    The problem with using it with an almost completely opaque filter is that the meter on the trip, which basically dictates entirely what the camera will do in auto is around the lens, and being a selenium meter, it probably wont pick up much, if any near-Ir light, so will lock the shutter completely.

    I can still use it in "manual" though. Manual mode locks the shutter speed to 1/40s, and I believe will allow the aperture to be set manually. Iv read the effective film speed for this film with a 720nm filter is somewhere between ASA 3-12, with about 6 being best (the camera's meter doesnt even go down to 12 let alone 3). Would I be right in saying that with Sunny 16 to approximate the aperture for 1/40s shutter speed and ASA 6 Id have to stop the lens down to somewhere around f/5.6-4 to achieve "correct" exposure?

    Im not even going to go into the fact actual Ir levels depend on more than if it's sunny or overcast, but I will assume given Im in the tropics, coming up to summer at close to sea level Ir will pretty much always be off the chart anyway.

    The main reasons for wanting to use the Trip instead of an SLR, are that:
    1. I intend to use it mainly for B&W and other film Ill be using for more candid shots anyway, leaving the SLR for colour and more carefully considered shots.
    And 2. The zone focus (as opposed to TTL) means I can still focus without having to take the filter off before every shot to focus, then potentially move it in the process of putting the filter on to shoot.

    Anyway, do my calculations sound right? Am I crazy? Does anyone else like this film (either as a conventional B&W film or for whacky near-Ir madness)?


     
  2. jcdeboever

    jcdeboever TPF Supporters Supporting Member

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    sunny 16 for ISO 400 film is f/16 @1/400s. count down from there. 6 to 7 stop difference with filter. Keep in mind that is full sun, no clouds. Get yourself a light meter, set the light meter at the recommended ISO. Have a tri-pod and shutter release (or use self timer) with you. There are phone light meter apps but not sure how accurate they are.

    3,6,12, 25, 50, 100, 200, 400
     
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  3. Kramertron2000

    Kramertron2000 TPF Noob!

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    Thanks, yea I was kind of extrapolating because the Trip 35 when in "manual" is locked to 1/40s shutter speed (and its only other speed when its in auto is 1/200), so in auto the camera auto exposes the best it can or locks the shutter and pops up a red flag to say you cant shoot, and in manual all you can do is change the aperture to expose correctly.

    With Ir film you pretty much have to shoot in full sun to get a good effect, and I think with 1/40s as my only speed Id probably run out of stops trying to use it in much lower light.
     
  4. Kramertron2000

    Kramertron2000 TPF Noob!

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    Also the metering app on my phone seems to work alright so far, but it only goes down to asa 50. The app is just called "Lightmeter" and the GUI looks like an old fashioned light meter.
     
  5. webestang64

    webestang64 Been spending a lot of time on here!

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  6. petrochemist

    petrochemist TPF junkie!

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    With the sunny 16 rule ISO 40 would give you 1/40s, three stops less than this ISO 5 is pretty close to the optimum IR sensitivity of the film so f/5.6 should be about right.

    However shooting IR film is very tricky (must be loaded in complete darkness, films go off easily etc) so would it not be more practical to use a converted compact digital camera for your quirky IR candids? I've often seen pre-converted models listed on e-bay for ~$30 - mainly sold for ghosthunting.

    The IR recorded by film would be near infra red which is not really heat any more than visual light is heat (an incandesant bulb gives of light by being very hot) Both visual light & infra red in all it's forms are electromagnetic radiation the sub categories of which are all a little bit woolly.
    IIRC IR film typically maxes out around 900nm, 'Thermal Infra Red' (as used by thermal imaging cameras) is typically quoted as 8000-15000nm the difference between the two is many times more than the range covered by visual light (~400-700nm)

    The human eye CAN see these wavelengths at very low sensitivity, holding an IR filter to my eye outdoors I've found I can see through a 720nm filter and even a 950nm one. I've even found scientific papers suggesting the mechanism for this - The trigger energy being supplied by 2 photons, a second photon must arrive at the cell while it's in a metastable state following the first photon...

    Film's sensitivity above 900nm is also considerably less than at 750nm - digital sensors are not quite so bad they can reach ~1100nm (where silicon becomes transparent to IR).

    While I like to think I'm superhuman, I could see through this filter this before the upgrade to my visual systems :)
     
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  7. Kramertron2000

    Kramertron2000 TPF Noob!

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    Awesome article Webestang! As a scientist I like the way its written too - kind of like an article in Nature (like a scientific paper made into an article).

    Petrochemist, thanks for confirming my maths. Ill probably bracket 1 stop either side when I get around to actually doing it (I have to learn to develop my own film because there isnt anywhere around here that will do black and white). I figured rollei infrared 400 is a good choice rather than a single purpose digital camera, because from what Iv seen it produces very good results when used as a normal black and white film too. Very sharp, contrasty and low grain, which gives it a modern look and it doesnt cost any more than any other B&W film. Iv also heard its hard to get good results with converted digital too, so it may not actually make it much easier.

    Thanks guys. Anyone have any experience using this film either for Ir or as a regular film?
     
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  8. petrochemist

    petrochemist TPF junkie!

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    I've not found it hard at all to get reasonable results from digital. My 'full spectrum' converted model is a mirrorless, so I can see through any filter I put on the lens, focus is done by what the main sensor sees (no need for any shift), and shutter speeds in sunlight are similar to visual shots (metering is pretty much correct automatically).
    Really good results are hard with any camera (visual or IR), I know a few experienced photographers who IMO never quite manage it!
     
  9. Kramertron2000

    Kramertron2000 TPF Noob!

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    Yea it sounds challenging no matter what route you go when it comes to near infrared. Probably because it doesn't really behave quite like normal visible light.

    Im probably going to go ahead and order a couple of rolls anyway (I have the camera - well I will before the film arrives anyway - and I can get a conversion ring and filter easy enough). I have a roll of TriX I want to use before any other B&W film to get my eye in and get an idea of how the zone focus on the camera works, and to practice developing the film once I get the gear for that. After that I can play around with the Ir stuff or just shoot it straight B&W if I cant get it right. Not sure what the zone focus results will be like either because for anything other than infinite focus itll be a case of the focus shift from the Ir vs. the depth of field my narrow range of possible apertures will allow as to how well it will work. Basically because of the fixed shutter speed Im limited to only 3 or maybe 4 stops of aperture size with a 720nm filter.

    Obviously I can still use the film in my Nikkormat, but that also has its issues (mainly having to take the filter off to focus every time unless I can judge the distance well enough or have a small enough aperture for a wide D.O.F).
     
  10. petrochemist

    petrochemist TPF junkie!

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    Focus shift applies equally at infinity. Many old SLR lenses have a small mark for IR focusing - The idea being focus using visual, then nudge the focus ring till the distance against the visual mark lines up with the IR one instead. I used this approach when first playing with IR with a DSLR.

    Good luck with the TriX & remember to take COPIOUS notes of all settings etc.
     
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  11. Kramertron2000

    Kramertron2000 TPF Noob!

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    Interesting. My nikkor lenses also have the Ir focus mark. I dont think Olympus ever imagined someone would try shoot Ir with the Trip 35 though :bouncingsmileys: It only has 3 focus settings - one person (~1m/3'), two people (~2m/6' - I think) and mountain (infinite), so to use it for that it will pretty much just be trial and lots of error. Itll be an interesting experiment, but I may end up having to use the Nikkormat for Ir and just stick to straight black and white with the Trip.

    One thing jumping into film has taught me is that you can never take too many notes. Im sure with black and white that's even more the case. The TriX is literally the only B&W film I can get locally (and in colour I can only get Fuji superia 400 or Kodak UltraMax - I just got some Portra 400 I ordered from Melbourne, which took a week to get here, and the same store has the Rollei for about the same price I can get anything locally), so its just one I grabbed and have kept in the fridge to try out when I get a chance.
     
  12. jcdeboever

    jcdeboever TPF Supporters Supporting Member

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    Do you think a light meter would be helpful with this type of photography?
     

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