Basic IR Photography

Discussion in 'Mirrorless Digital Cameras' started by sandyv, May 5, 2016.

  1. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    I've been having fun playing around with a GXR and a variety of modules, including the A 12 that will take my old Leica and Nikon glass. Latest in a trail of several actual bargains, an IR modified 24-70 module with 4 varying strength IR filters, filter adapter and lens hood, etc. which I just got today. Have been snapping a bit with it, focus adjusted to infinity on full press. Results are dramatic, but unpredictable. If anyone can suggest a source for quick tips / IR for dummies, or a shortcut or two, I'd much appreciate it.
    I will attach one or two from the first dozen shots I took.
    Apparently the attachments didn't work.
     
  2. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    Same again.
     
  3. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    Samples posted in a GXR IR Gallery.
     
  4. Results are dramatic, but unpredictable.​
    Sandy, can you elaborate. "Unpredictable", in what sense?
    Different subjects (vegetation versus architecture each reflect IR differently) react differently;
    Also, different lighting (subjects in full sun or shaded areas react differently in regard to IR reflection and capture);
    Note that smaller f stop openings (f8, f11, f16) are best to use in order to avoid focus offset error as IR rays are not bent the same way as visible light rays, causing the lens to require different distance of focus (It's not much, which is why using a smaller f stop usually works best, provided you focus on the subject and not just infinity);
    Not sure about your four IR filters; what is marked on them?
    If they are cut filters they may simply allow different proportions of IR rays to be recorded, giving different proportions of IR radiation compared to visible radiation.
    Whatever, an IR filter is needed to allow only so much visible radiation or light to appear together with the IR radiation. If the different filters you have do that to varying degrees then by changing them you should see differing degrees of IR effect imaging.
    Does any of this relate to your "unpredictable" results? You might Google IR photography and get a more complete description of the process of photography. Worthwhile, as it is different than normal photography and knowing a bit about it will allow you to much better profit from it.
     
  5. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    Arthur, Thanks. Went the Google route at some length prior to posting, and didn't get much of use.
    Thanks for the F stop hint.
    I have 4 filters R 590, R650, R850, and R950. The module has been converted. I shot about 45 exposures yesterday, late morning to evening, seven posted in rough order are reasonable all using the 950 filter. Have not shot deciduous trees as yet, or water beyond the koi pond.
    Variations in exposure, in focus, rendition of value, grain (so far shooting B&W only) are puzzling at times.
    Quite interesting -- I played with infrared 35mm back in the '70's, but even early results with digital are more interesting.
    Much appreciate your reply, Best Sandy
     
  6. Metering through an IR pass filter is going to be guesswork. It helps, with a DSLR, to put the filter on the sensor, where it doesn't affect metering through the finder, assuming IR is proportional to visible daylight (it's not). What's left? Trial and error. It helps to take notes on exposure which can be used in similar situations. The effective focal length for IR is about 2% longer than for visible light, which means you can turn the focusing ring about the same amount to compensate, regardless of distance. If you have DOF markings, it is roughly the outer f/8 line.
     
  7. I've shot some film IR within the last few years and I generally consider unpredictability as "part of its charm!" As I see it, our eyes are not sensitive to the spectrum the film/sensor is seeing so some of what would be intuitive with visible light goes out the window. My usual advice is "bracket, bracket, bracket." At least with digital you can see immediate results to confirm whether you're in the ballpark.
    Another problem is that the IR portion of daylight varies, perhaps significantly, during the course of the day, and even depending on the season of the year. I have no idea what the IR spectral sensitivity of a modified DSLR may be. With any of the remaining films that have extended red or IR sensitivity, a 950 filter is about like a steel plate. Even the 850 would be tedious, a common one to use is a 720.
     
  8. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    Edward, thanks. My entire IR effort will be through my GXR with an IR modified 24-70 module. Surprisingly enough, shots can seen to be framed with the evf. Per Arthur's and your suggestion, moving to smaller aperture has improved the DOF situation. The camera has the capability to set a snap focus distance, so a quick shutter press sets to predetermined distance. Using infinity has worked for landscape, I will be working to get a system that yields some consistently.
    Thanks for your input, Sandy
     
  9. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    Dave, thanks! The specifics of the conversion are lost somewhere in China. First day and a bit into it, I am getting some reasonably decent,interesting results. Effectively I am bracketing, but manually so far. Since I can set the camera to auto bracket, which I hadn't thought of (I don't use it on my other cameras) I will try that. Thanks for the idea!
    As previously mentioned, even with the 950, I can see enough through the evf to compose. I have yet to try the other filters. Later, will have to try color, which apparently requires post processing gymnastics that are likely above my current skill set.
    Toys for boys, regardless of age.
    Appreciate your ideas, Best, Sandy
     
  10. Good info here: www.lifepixel.com
     

Share This Page