Page 1 of 3 123 LastLast
Results 1 to 10 of 25

Thread: Infrared Exposure Meter?

  1. #1

    Join Date
    Feb 2012
    Location
    South Texas
    Posts
    820

    Infrared Exposure Meter?

    Is there such a thing as an infrared exposure meter? A narrow-field one would be optimal.

    I'm interested in trying some near-IR film like SFX 200 but want to be able to meter reasonably accurately how much IR of the appropriate wavelength is reflecting off the foliage so I can more accurately expose and develop the film without having to bracket several frames on a minimum of two rolls... this allows me to adjust development on the second roll.

    Hmm... now that I think about it burning extra film is probably more cost-effective than a dedicated IR meter because I won't be shooting that much. None-the-less... my curiosity is up now!!

  2. #2

    Join Date
    May 2006
    Location
    grand rapids
    Posts
    3,149

    Re: Infrared Exposure Meter?

    Yes
    Here's one:
    http://www.davidromano.com/TrueIRMeter.html

    Bracketing is for sissies.

  3. #3

    Join Date
    Aug 2008
    Location
    Germany
    Posts
    1,330

    Re: Infrared Exposure Meter?

    Quote Originally Posted by Old-N-Feeble View Post
    Is there such a thing as an infrared exposure meter?
    Not that I am aware of. Given that IR film does not have a standard spectral sensitivity and the IR spectrum it sees is generally still quite close (and proportional) to the visible, a generic IR exposure meter might have disappointingly little advantages over a visible light exposure meter, and fail to pay for itself.

    It should be possible to convert some common pyrometer to such a task by applying a suitable filter set and substituting a firmware that can input sensitivity and display the inverse of intensity as EV or time/aperture. But hardware hacking aside, the cost of working out the calibration for one film would probably exceed any amateurs lifetime consumption of film, even if he'd use his film's IR equivalent to sunny sixteen plus bracketing like mad...

  4. #4

    Join Date
    Aug 2008
    Location
    Germany
    Posts
    1,330

    Re: Infrared Exposure Meter?

    Quote Originally Posted by vinny View Post
    Autometer V, with blue filter removed/substituted by a Wratten IR filter. The same stunt can be pulled off with any meter without a IR blocking filter (or with the filter removed) - the real value (above the hardware components) of that kit would be in the accompanying user manual with sensitivity tables, as you'll go through insane amounts of film working out the latter.

    The real issue is that the said IR filters only model the visible/IR transition, and cannot model the spectral response of the film within IR - where the currently available films are distinctly odd and difficult.

  5. #5

    Join Date
    Feb 2012
    Location
    South Texas
    Posts
    820

    Re: Infrared Exposure Meter?

    That's pricey but not as bad as I expected. Maybe I can find a used one?

    I'd most likely be using #25 and #29 filters since I'm not looking for "pure" IR but rather extended red... like SFX200... because I want light but not white foliage and I don't want significant halation effects. I'm looking for subtle tonal enhancement rather than dramatic effects. The reason for the IR meter is to provide more predictability.

    I guess the only concern, as mentioned above, is unpredictable exposure readings due to the meter seeing different IR wavelengths than my film and filter. Is there an affordable/predictable way around this if I stick to one film such as SFX200?

    RE modifying a meter myself: Any link(s) to basic instructions?

    Quote Originally Posted by vinny View Post
    Yes
    Here's one:
    http://www.davidromano.com/TrueIRMeter.html

    Bracketing is for sissies.

  6. #6

    Join Date
    Aug 2008
    Location
    Germany
    Posts
    1,330

    Re: Infrared Exposure Meter?

    Quote Originally Posted by Old-N-Feeble View Post
    That's pricey but not as bad as I expected.
    Well, if that offer still exists and the meter is new (Minolta quit making meters many years ago), that would be less than a hundred above the retail price. The same goes if he now ships the Kenko relabelled current version of the meter (KFM-1100). Not that much, if there are good tables along with it. But apart from these, any meter with a removable (or never installed) blue filter would do just as well for a DIY conversion.

  7. #7

    Re: Infrared Exposure Meter?

    This site's bandwidth has been exceeded.

    http://www.999-wed.com/pg/pg9-infrared-allenmeter.htm

    But he takes a $20 lux meter and converts it to IR, and shows you how. I would try that before messing up a perfectly good Minolta.

  8. #8

    Join Date
    Aug 2008
    Location
    Germany
    Posts
    1,330

    Re: Infrared Exposure Meter?

    Quote Originally Posted by Old-N-Feeble View Post
    RE modifying a meter myself: Any link(s) to basic instructions?
    None that I know of - the process itself probably is too trivial, and the more complex calibration issues are exactly the same as for meters without filter modification.

    Given the low IR sensitivity and limited spectral range of the remaining IR films, attaching a deep red or IR filter to a unmodified meter might already be good enough. For EIR or HIE you had to remove the (IR cut-off) blue filter from meters with silicone blue cells (and ideally substitute it with a deeper IR filter), and then could meter through the same filter you'd use for exposure. Mind, these films had a wide IR response and good visible/IR relation. With all current films it never is a 1:1 process, you still have to compensate considerably to match film to meter readings, as their IR sensitivity is odd, short-range, wobbly and disproportionally lower than the visible one - hence it might even be advisable to leave the blue filter on.

  9. #9

    Join Date
    Feb 2012
    Location
    South Texas
    Posts
    820

    Re: Infrared Exposure Meter?

    Thank you... I'll keep trying that website until I get through.

    Quote Originally Posted by RichardSperry View Post
    This site's bandwidth has been exceeded.

    http://www.999-wed.com/pg/pg9-infrared-allenmeter.htm

    But he takes a $20 lux meter and converts it to IR, and shows you how. I would try that before messing up a perfectly good Minolta.

  10. #10

    Join Date
    Feb 2012
    Location
    South Texas
    Posts
    820

    Re: Infrared Exposure Meter?

    Basically, what you're conveying is, particularly with films with spectral response similar to SFX200, I'm just as well off metering through a #29 filter with a non-SBC meter? There's not much I can do to more accurately read the IR reflected from foliage? If that's true then I'm back to bracketing and shooting a roll of film as a back-up to development time.

    Quote Originally Posted by Sevo View Post
    None that I know of - the process itself probably is too trivial, and the more complex calibration issues are exactly the same as for meters without filter modification.

    Given the low IR sensitivity and limited spectral range of the remaining IR films, attaching a deep red or IR filter to a unmodified meter might already be good enough. For EIR or HIE you had to remove the (IR cut-off) blue filter from meters with silicone blue cells (and ideally substitute it with a deeper IR filter), and then could meter through the same filter you'd use for exposure. Mind, these films had a wide IR response and good visible/IR relation. With all current films it never is a 1:1 process, you still have to compensate considerably to match film to meter readings, as their IR sensitivity is odd, short-range, wobbly and disproportionally lower than the visible one - hence it might even be advisable to leave the blue filter on.

Similar Threads

  1. "FSV" - Horseman Exposure Meter
    By Matt Chroust in forum Style & Technique
    Replies: 4
    Last Post: 28-May-2011, 13:33
  2. Efke IR 820 Infrared Exposure Suggestions
    By rguinter in forum Darkroom: Film, Processing & Printing
    Replies: 10
    Last Post: 29-Sep-2009, 10:05
  3. Darkroom Exposure Meter
    By John Cooley in forum Darkroom: Film, Processing & Printing
    Replies: 5
    Last Post: 9-May-2005, 13:13
  4. Horseman Exposure Meter 69
    By Jan_5456 in forum Cameras & Camera Accessories
    Replies: 2
    Last Post: 27-Apr-2005, 16:35
  5. Using Horseman Exposure Meter
    By David Carney in forum Style & Technique
    Replies: 1
    Last Post: 9-Feb-2001, 20:16

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •