Strange Landscapes: UV and IR Comparison Shot

Discussion in 'Night, InfraRed, and UltraViolet Photography' started by nfoto, Dec 11, 2005.

  1. nfoto

    nfoto Guest

    For the novice in the field of "invisible" photography, it can be illuminating to see the huge differences you get in image rendition off either side of the visible range of the spectrum.

    First, the stark clarity of IR,

    12013.

    (Nikon D1, UV-Nikkor 105 mm f/4.5, Wratten 87C filter)

    in contrast to the haziness of UV,

    12014.

    (Nikon D1, UV-Nikkor 105 mm f/4.5, Nikon FF filter which is quite similar to Hoya U-330, plus Tiffen Hot Mirror)

    These shots were taken just a few minutes apart, but since I had to move my tripod a trifle between them, the framing isn't 100% identical. But the message should get through.
     
  2. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
    Last edited by a moderator: Dec 12, 2005
  3. The IR is definately more pleasing to ME. It is interesting to see the light at those extremes.
    Dave
     
  4. We got the message Bjørn...!!!

    Terrific shots.
     
  5. Thanks for the enlightening images. I always enjoy your posts.
     
  6. Nice work.

    Now, how does an ordinary fellow such as myself find a UV lens? Or does it also require a certain camera model?
     
  7. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    I like all photons between 220nm and 950nm the same. These photos show the individuality of those on the edges in a wonderful way Bjørn. The sharpness of IR makes for a visually interesting photo, full of detail right to the most distant part. The veil imposed by UV makes for mystery and unknown, hiding everything far from the camera, but showing details that are otherwise unseen closeup. Thanks for the comparison!

    Beezle brings up an interesting question, that I'd like to rephrase: how far into the uv do our ccd or cmos sensors reach?

    (By the way Ed, in addition to Nikkor's UV lens, you can get transmission down to 350nm or so - that's 50nm into the UV - with an old lens with no coating and few elements. Look for cheap, old view camera lenses.)
     
  8. nfoto

    nfoto Guest

    There are several considerations needed. First of all, how much UV is there really to do the photography with? As my spectral measurements (see below) indicate, on a sunny day you have useful UV amounts between 360 and 400 nm, but below 350 nm or so the UV rays are rapidly attenuated by the atmosphere. Since the radiation concurrently becomes more and more dangerous to our health we should appreciate this more than lament about photographic opportunities lost :smile: The graph portrays incident irradiance for a sunny day, with about the maximum UV you can have at my home latitude (60 N). On dull days, UV levels will be much lower.[​IMG]
    For pictorial UV, we should focus mainly on the range to sub 350 nm, that is, the UV-A range (UV-B commences at 320 nm and goes to 280 nm, from where UV-C begins). Just covering 50 nanometers of the UV band may not sound too impressive, but most things of pictorial value happen to occur here as well. For example, the strange UV nectar guides of flowers begin appear already at 370-380 nm.

    Now, how is the camera response to below 350 nm? Seems there is significant difference between CMOS and CCD designs, with the latter far more responsive. D2X (CMOS) just barely scrapes by with a Hoya U-360 filter (peak at 360 nm), but exposures are long and contrast of the images are really poor, so it is a toss whether or not you get a good UV landscape shot with it. My guess is that D2X responds just to 380 nm so what we get is the falling lower limb of the response curve. On the other hand, my D70 (CCD) gives excellent response with the U-360 filter and even with the U-340 and U-330 variants it still behaves quite obligingly. Same holds for D1H, which also is a CCD model.

    So given that your lens can transmit UV to at least 350 nm, and you mount the lens on a CCD-based camera, then suitable UV filtration is all you need. Take into consideration that all UV-transmitting filters,(which appear black to our eyes) also have a secondary transmission lobe in the near-IR region, where the camera is much more sensitive to IR than to UV. So some IR contamination is hard to avoid, unless you add a IR-screening filter to the setup.

    Chris has provided transmittance charts which indicate that older lenses with simple coating can give response to at least 370 nm, some even lower. Still not optimal for UV, where you should reach 340 nm at least, but that'll have to do if there are no alternatives. Old enlarger or copy-machine lenses can be an exciting starting-point for an encounter with invisible light.
     
  9. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    Thanks Bjørn! Looks like that old Xenatar from a broken Rolleicord may get to see some light again afterall!
     
  10. Thanks for the info. And that handy analyzer of yours, Chris.
     
  11. Joseph S. Wisniewski

    Joseph S. Wisniewski

    100
    Aug 11, 2005
    I missed it when Chris posted the charts. Anyone got the link?
     
  12. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  13. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    Sorry - my department went out for a 3 hour end of semester celebratory lunch and I just got back.

    Joe: I've got a really nice spectrophotometer now. If there is anything transparent you'd like to see the spectrum of, ask and I'll do what I can. I intend to spec all my lenses and filters over the holidays.
     
  14. Bjorn I think you have more photographic skill and knowledge in your pinky than most would ever hope to!

    Great photos and thanks for the in depth analysis and explanation...
     
  15. Really interesting comparison Bjorn.
     
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