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  1. #1

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    Infrared Excursion...

    I'm heading out to the Messum Crater (S21˚25' E014˚ 12') in the next few days, and I'm planning to take my Fotoman PS45, which is fitted with a Rodenstock Grandagon-N 90mm f/6.8. Yipee for me.

    I have an appointment with a Welwitschia Mirabilis the age of which I estimate to be around 2500 years. (Ignore the claim in the article that the biggest Welwitschia is only 1.4 metres high; this is nonsense; I know of a few much larger ones...)

    I'm planning to take a few infrared photographs with that camera.

    While I've shot quite a bit of IR with my Rolleiflex, I've never shot 4x5 sheet film, which in this case is Rollei IR400. So I have a few questions.

    1. Shooting through a Hoya R72 filter. I'm assuming that's going to be OK...

    2. IR focus correction: There aren't any IR focal correction marks on the lens or the helicoid. Any pointers? I'm anticipating shooting stopped well down (f/32 or so); should I just let depth of field handle it?

    3. I have Fidelity film holders. The darkslides are plastic. Should I be worried about IR leakage? I loaded them in a dark bad (duh), in very subdued lighting in a bathroom with no exterior windows (aka my darkroom), immediately transferring the holders to a leather satchel that I normally use to transport my holders to the site. I'm planning to leave the holders in said bag until the last minute, after putting the IR filter on the lens. Should I take any more precautions, or am I already sufficiently paranoid?

    General suggestions on shooting IR in the desert? I'm not expecting the 'shiny trees' effect (um, no trees, duh...), but I'd love to hear any other suggestions.

    Thanks in advance for any/all pointers!

  2. #2
    keithwms's Avatar
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    1. Yes it's okay, and with that film and a 72 I typically do EV+ 8 stops or so. In a desert I think I'd go for EV+6 or so, depending. I'd do a test sheet (see #4 below).

    2. f/32 is going to get you into some really long exposures with that film, and pretty soon you're off into reciprocity issue. If that's okay then fine, but it isn't necessary. Just review your hyperfocal technique and recall that the distance to which you focus plays a very big role in DOF. I.e., above all, know the hyperfocal distance for your setup. Now, with IR, you want to focus a bit (few percent) closer than what your eyes instruct you to do. But with this particular film and the 72 filter, you're actually not getting that much light beyond ~700nm, not nearly as much as you'd get with HIE or such. So the refocus will be relatively minor, and yes it can usually be taken care of by stopping down one stop or so. By the way, I have used various inexpensive apo process lenses and find no need for refocus from the UV (403 filter) through the IR (#87 filter). Especially if the subject is a good distance away. Anyway you're shooting quite wide, I don't think you'll need to stop down to f/32 unless you're doing closeups. Maybe for your Welwitschia you will indeed want to stop down a good deal. Just don't focus too far in; good hyperfocal technique goes a long way with these near-IR films.

    3. Keep all film in a dark bag as much as possible. When you withdraw the darkslide: don't pull it out all the way, or if you do, make sure the opening is facing downward. Use a dark cloth to cover the camera and darkslide as much as possible.

    4. desert shooting or at altitude: the air will probably be much drier than you're used to, so don't be surprised if you exposure compensations for the filter are much less than you might need at home. Here's what you can do: take a test frame each day and develop that first when you get home. You can use that to optimize your development for the other frames. Don't be shocked if you need a 2 stop adjustment in development!

    P.S. Oh and don't forget to put the filter on after you compose I've got a whole lot black frames after a scene got me excited...

    P.P.S. Welwitschia looks like an awesome subject for IR! Enjoy!
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  3. #3

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    Thanks!

    1. So with EV +6 I'd be looking at exposing as though the film were rated at ~12ASA? So assuming 'sunny 16' applies, I'm looking at ~ 1/10 @ f/16?

    2. With the Fotoman, I'm anticipating shooting landscapes (The Messum is a big "sweepy" place), perhaps with a subject (e.g., a 2-metre high Welwitschia) in the middle foreground, obviously depending what I find. I've shot ASA25 film at f/32 before without too much difficulty, so if I reckon it's do-able, and you reckon that DOF will handle minor errors, I'll bear hyperfocal distance in mind and compose accordingly. Cool.

    3. OK, that's more or less what I thought. Since I'm too cheap to use a darkcloth (I generally wear a fleece out there, which then does double duty as a dark cloth for me when I'm shooting), I'll just go 'common sense applies'.

    4. I *am* accustomed to bone-dry air; I live in what's considered hyper-arid highland -- 1650m amsl, ~400mm rainfall per annum... By contrast, the floor of the Messum Crater is generally around 360 metres, and about 3mm/year precipitation, but with occasional fog).

    OK, hypothetical: Big landscape, early morning just after sunrise, no clouds, facing west into valley, light fog covering the floor. Tentative guess at exposure?

    I'm processing in a CombiPlan (v. rudimentary lab), so unless I bracket, I'm going to have to resort to 'best guess' in terms of exposure. It's worked for me in the past (Baobabs are pretty funky in IR too...), so exposure-wise I'm feeling as though I can probably handle it... I was more concerned about the 'ground handling' of the film in this particular format.

    I suppose I should take the rest of my film with me, and not just the film in the holders...

    For what it's worth, I'm also taking my Hasselblad (Packing Kodak Tri-X and Fuji Superia 100) and my Nikon D700, so equipment-wise I'll be pretty busy...

    Thanks for pointers so far!!

  4. #4
    keithwms's Avatar
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    Quote Originally Posted by kavandje View Post
    OK, hypothetical: Big landscape, early morning just after sunrise, no clouds, facing west into valley, light fog covering the floor. Tentative guess at exposure?
    IR at sunrise? Yikes, that's a hard call, especially if there is ground fog. I'd go with EV+8 or so at least, but I'd also definitely expose two sheets and keep one in reserve should major processing adjustments be necessary.

    At sunrise I think you might do better with a deep red filter and EV+2 or 3. There probably won't be much IR component at all until mid morning. The optimal IR hours (i.e. when exposures are shortest and the Wood effect is at its strongest) are typically from about 11 am to 3 pm in most places; maybe in dry desert you might extend that by a couple of hours, but even in the desert, when the sun is low it scatters through all kinds of moisture on the horizon.

    P.S. Yes, by "EV+8," I mean an 8 stop filter factor. So in sunny 16 light, rating the film at 400 and shooting at f/16, the normal exposure would be 1/400 and the exposure with the IR filter would be ~1 sec. With exposures longer than that, you are quickly getting into reciprocity issues and will find yourself doing exposures of 30 sec or more!

    P.P.S. I miss the baobabs! I grew up around them. Thanks for that link!
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  5. #5
    keithwms's Avatar
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    P.S. Do you have a rollfilm back for that rig? I have a 612 back for 4x5 that I could theoretically part with, I am not using it much anymore since I got intrigued by 5x7 and 5x8. Rollfilm certainly lifts some of the burdens of bracketing when doing IR!
    "Only dead fish follow the stream"

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  6. #6

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    I don't have a rollfilm back for the Fotoman, and I don't think it's possible to fit one. I'll one day own a 'proper' 4x5 field camera, at which time I'll consider going that route. But if I'm shooting IR on rollfilm, my old (and rather splendid) Rolleiflex Automat from 1951 does the trick rather well...

    Where did you grow up around baobabs?

    My difficulty with keeping unprocessed film in reserve is a function of not quite knowing how to identify film once it's out of the holder; I've only got five (they are seriously hard to get hold of around these parts), so once I shoot, they have to come out and into the "buffer box".

    I'm not too worried this time round about keeping the IR film separate from the conventional film I'm taking (Adox 25ASA) as the IR film is a lot thinner, and I'll be able to identify it by feel, but I don't currently have a usable 'filing' system for reliably identifying exposed film once it's out of the holder.

  7. #7
    keithwms's Avatar
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    Quote Originally Posted by kavandje View Post
    Where did you grow up around baobabs?
    Rhodesia/Zimbabwe. Most of my childhood was in Bulawayo and we'd often go south through the baobabs en route to S. Africa.
    "Only dead fish follow the stream"

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