Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 75,729   Posts: 1,670,231   Online: 926
      
Results 1 to 6 of 6
  1. #1

    Join Date
    Jan 2007
    Shooter
    Medium Format
    Posts
    905
    Images
    144

    Changes in latitudes, changes in IR exposure?

    Been shooting some Maco 820, and now Kodak HIE, so I have these (sorta) figured out as far as metering and development. But I'm up here in the Great Northwest, and I'm going to Tampa FL next week with some HIE. I assume being more equatorial means more IR, but about how much? Half stop? Full stop? Is this even something to worry about? Thanks, ya'll.

  2. #2
    Robert Hall's Avatar
    Join Date
    Aug 2004
    Location
    Lehi, Utah
    Shooter
    ULarge Format
    Posts
    2,039
    Images
    28
    The sun is the sun. I wouldn't worry about it too much. The thing that changes, and perhaps more so throughout the day, is of the light measured, how much of it is IR. As the sun rises and sets, the amount of IR that makes up the total light can change due to the atmosphere.

    As you change latitude, I wouldn't think that it changes all that much.
    Robert Hall
    www.RobertHall.com
    www.RobertHall.com/mobile
    Apug Portfolio
    Facebook Profile


    Technology is not a panacea. It alone will not move your art forward. Only through developing your own aesthetic - free from the tools that create it - can you find new dimension to your work.

  3. #3
    Mick Fagan's Avatar
    Join Date
    Sep 2005
    Location
    Melbourne Australia
    Shooter
    Multi Format
    Posts
    2,971
    Images
    29
    I live at 38 degrees latitude and what works for me here with Kodak high Speed IR film, is different when I head closer to, or further away from the equator.

    Using a black infrared filter

    Clear sun summer 1/125 f16

    Clear sun winter 1/125 f11

    Cloudy bright 1/60 f11

    Overcast 1/30 f11

    I don't meter at all, I use these figures and I get very, very good negatives.

    D76 neat 11 minutes @ 20C

    If you are using a red filter the film is getting about a stop more light, so you need to change the settings to:-

    Clear sun summer 1/250 f16

    Clear sun winter 1/125 f11

    Cloudy bright 1/125 f11

    Overcast 1/60 f11

    Keeping the aperture smaller than f8 is a great help in obtaining reasonably good focus.

    I use mainly my 35, 28 and 24mm lenses with IR film.

    When I visited Germany and used this film at 48 degrees latitude in Stuttgart I gave the film about 1/2 a stop more as a test, developed the film and this was about right.

    In my own country I have been as close as 20 degrees from the equator and I gave the film 1/2 a stop less which is close to what is required.

    I assume that whatever the latitude of Rochester is would be the latitude that most tests of this film has been done at and which most recommendations would be based on.

    One interesting thing that you can do if you have a genuine IR filter is this. Take the filter off the camera, hold it between your thumb and forefinger, then using both hands and one eye, hold the filter so you block out all light except that coming through the IR filter. You will be able to see what IR rays are around. You'll be amazed at some of the scenes that have virtually no IR rays whilst others are overloaded with IR rays.

    Shooting with IR film is terrific because you don't have to carry a meter, just pull out the chart and set your camera then fire away. The downside is that you have to have a black room or cavity, to change film.

    Mick.

  4. #4

    Join Date
    Jan 2007
    Shooter
    Medium Format
    Posts
    905
    Images
    144
    Hey Mick, that's good stuff. Thank you. Going by the Kodak manual, I'm metering about 1/125 at f16 in bright sun here near the Canadian border. That's with a red 29. Robert, is IR transmission higher at low sun angles?

    Ah, I'm asking q's about light that I cannot see, while I don't fully understand that light that I can!

  5. #5
    Mick Fagan's Avatar
    Join Date
    Sep 2005
    Location
    Melbourne Australia
    Shooter
    Multi Format
    Posts
    2,971
    Images
    29
    Ritch, my experience is that the amount of IR light is dependent pretty much, on the clarity of the atmosphere.

    If you are closer to the equator the sunlight is coming in slightly straighter, therefore stronger.

    If there are clouds or dirty atmosphere, then less IR light gets through.

    You will have a far better idea of how much IR light is around if you have an IR filter and use it to look through.

    You could also do a search on this forum for the subject, there have been previous discussions regarding IR film.

    Mick.

  6. #6
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,283
    Blog Entries
    1
    Images
    31
    Infrared doesn't change much with latitude or time of day. Nowhere near as much as UV, at least!

    It's easy to get overexposed IR film when sunset is coming up if you meter without the filter and compensate, since visible light changes a lot more than IR.
    -- Ole Tjugen, Luddite Elitist
    Norway



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin