Anyone Ever Experienced With BlackLight & B&W-Film??

Discussion in 'Lighting' started by Contrastique, Mar 16, 2009.

  1. Contrastique

    Contrastique Member

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    I'm trying to make a photo using blacklight, fluorescent make-up and a black-and-white film in studio.
    I first made polaroids with a DSLR to see how the aprox time would be, how the paint (and if) would react to the light and so on.
    I finally got it about right and made the final shot with my Rolleiflex and developed the film. And that's when I got a little surprised...

    The body (naked) came out WAYYYY lighter than on the polaroid and the text appeared to be more black then illuminated....
    It seems to be reacting totally opposite of what I got before and I haven't got a clue of what to try next... maybe I should use an uv-filter or something...?

    Anyone any advice or thoughts you might feel like sharing?
     
  2. AgX

    AgX Member

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    What is a `polaroid with a DSLR┬┤ ??


    Seemingly your DSLR is less sensitive to UV radiation than your Rolleiflex with pan film. And then in the visible range both cameras seem to react different too. But bear in mind that you related both exposures via the result of your metering.
     
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  3. AgX

    AgX Member

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    I just was told that the UV-transmission of modern lenses is much less than that of older lenses. Especially modern optical cement is said to be of influence here.
    Another source says that is modern coating which is optimized to reduce UV-transmission.
     
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  4. Tim Gray

    Tim Gray Member

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    Digital chips have extended sensitivity into the IR and little in the UV. Film usually has sensitivity in the UV but it's a lot harder to get it into the IR. That's why early films were just blue sensitive, then blue+green, and finally pan.

    The lenses could certainly factor in here, but I would imagine film is going to be more UV sensitive than your DSLR.
     
  5. cowanw

    cowanw Member

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    Won't the reflected light off the subject figures that you see be regular film sensitive wavelengths?
     
  6. Contrastique

    Contrastique Member

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    If it were to be normal wavelengths I doubt the differ of the two media would be so big. I've used the DSLR for quite some time for "polaroids-sake" and never had that big of a difference besides the "obvious" ones.

    Think you for your responses. I also think it has to do with the blocking of UV a DSLR has built in and most likely the better coating of the new lenses as well.
    Film is more sensitive to UV as it turns out to be quite a bit lighter when being confronted with it.

    Here are 2 examples of the differ so you have a view on what really went wrong. The light version is a quick scan from a quick testprint from the negative which was even exposed a full stop darker than the digital version, so don't shoot me because of the lousy qual; you'll get my point.

    Kodak Tri-X 320:
    [​IMG]

    Nikon D200:
    [​IMG]

    I will redo the shot tonight with two changes. One film will be taken with a skylight filter which is supposed to reduce UV-haze.
    One will be taken with a green-filter to darken skin tones and lighten up the paint as it's a little yellow-greenish.
    I am not sure if the latter will work but the experiment will be interesting nonetheless. I can find lot's of info using slide film with blacklight but nothing with black & white film.
     
  7. Akki14

    Akki14 Member

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    From the lighter (film) version, I can see shadows above the chains. What other light sources (absolutely anything) in the room was there? Specifically something at your feet pointing up? I suspect the film took longer to expose than the digi shot which means other sources of light besides the black light might be lighting up the subject? unless the blacklight is the light at the bottom.
     
  8. Contrastique

    Contrastique Member

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    The blacklight is the light at the bottom. No other light being used besides the one at the floor behind the tv lighting up the background.
     
  9. ath

    ath Member

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    Looks like you have to get rid of the UV sensitivity of the film. UV filter, yellow filter, orange filter, red filter might help. Depending on the colour of the flourescending letters these are affected too.
     
  10. cowanw

    cowanw Member

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    This is very interesting.
    I am still of the opinion that the lighting of the body in the film image is not only uv lighting. The lighting must emit visible wavelengths. Indeed the image looks distinctly not blacklight and Quite ordinarily lit.
    I will be most interested in your further results
     
  11. Contrastique

    Contrastique Member

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    Thanx for your interest.
    I have tried shooting it differently this time. To get rid of the UV-sensitivity of the film I shot one roll with a uv-filter on it. This helped in a way that the body turned out darker and the text seemed lit this time instead of nearly black/grayish. So that would explain the problem I was having.
    Still the image was way too light and killed the other light which was supposed to bring in some ambience.

    The second roll of film was shot using a green filter to have the red of the body filtered out, i.e. making it appear darker, and emphasizing the green of the lit text.
    This worked very well. All was actually perfect accept for it being to dark overall. I couldn't distinct the body from the background. The ambience was back and it resembled the digital photo much better.

    A day later I redid the shoot with 2 blacklights instead of 1 and again the green filter. I have to make contact sheets tomorrow but it's actually looking as I had it in mind so I'm fairly happy so far :smile:

    As soon as I have finished the contacts I'll post some examples in here for the ones interested.
     
  12. Contrastique

    Contrastique Member

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    I have scanned the contact sheets and they suck (the scans I mean). I will place them anyway to show what the difference in lighting does but it's by no means HQ huhum... Here we go:
    With UV-filter & 1 Blacklight:
    [​IMG]

    With Green-filter & 1 Blacklight:
    [​IMG]

    The testprint of the new version with greenfilter and 2 blacklight lights will be dry by tomorrow. I'll scan that one as well, which is going to give somewhat better qual than these scans and you'll see the effect even better. The green filter worked really great though I needed to shoot it with 2 blacklights as it took away a lot of the light.
     
  13. cowanw

    cowanw Member

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    Good problem solving.
    Am I right in presuming that, even thought you are illuminating the subject with UV light, what is being reflected off the subjects is always visible light? and the green filter has filtered out the skin tones and allowed the green of the paint to pass.
    The moniter in the back is a good measure of the consistency of your exposures.
    I still do not under stand the digital picture: it behaves as if it has the green filter on?
    Peculiar!
     
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  15. AgX

    AgX Member

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    Bill,

    White skin reflects all wavelenghts from UV to IR. Though IR penetrates skin a bit and thus gives an image of deeper layers.
     
  16. cowanw

    cowanw Member

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    Yes, but the wavelengths passed by the green filter can only be that (visible) green wavelength. and the reflected illumination we see from a blacklight can only be visible wavelenths since we can not see UV.
    I am just having a difficulty putting together a general theory of illumination to explain all the OP's images.
    Can you help explain the 4 images?
     
  17. Tim Gray

    Tim Gray Member

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    Not true. The green filter can be passing UV and IR, though from the images (and plots of filter transmissions) UV isn't being transmitted and it doesn't matter if IR is. And even though we can't see UV, film can. And just because film is sensitive to UV, doesn't mean a digital sensor is.

    For reference, here's the spectrum from a blacklight from wiki: spectrum.
     
  18. ath

    ath Member

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    That's wrong. In these pictures you don't see the reflected light, you see what the film recorded from the reflected light. And film is UV sensitive.
     
  19. AgX

    AgX Member

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    Bill,

    I admit I did not quite follow the discussio for a while, so I overlooked that green filter.

    Tim,

    That was my idea too, but I checked some charts and I did not find a green camera filter with UV transmission (though IR transmission).

    However, looking at some charts of green lighting filters, there are some with seemingly UV transmission.
     
  20. Contrastique

    Contrastique Member

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    So, here's an image from the second exposure with the green filter:
    [​IMG]

    From all I have seen now is that film is way more sensitive to UV than digital is. How to explain the text being close to black/grayish on the non-UV-filter photo stays kind of a riddle to me, maybe also because I'm just too tired to think about it now, I can merely take a guess.
    Anyway, the green filter did have the effect I had in mind.
    Thanx for all of your input :smile:

    Ow and this scan sucks as well as there's much more delicate detail in the shoulders and top of the body....sorry again for the lousy Q...
     
  21. cowanw

    cowanw Member

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    Tim can you show why the green flter can be passing UV?
    I aways thought that the reason a filter was the colour it was, was that it passed only that wavelength. (of course nothing is perfect, not even B+W filters:smile:). Nevertheless, if a green filter passes UV and IR then it might reasonably pass deep red and deep blue, in which case it would not be a green filter.
    As to what the eyes see, I was kind of wondering which image most closely approximated the OP's actual eyeball view.
    Here is an interesting site concerning UV imaging, both film and digi. Note how the L37C uv filter completely removed the UV image on XP2 and the UV pass filter U360 allowed imaging on XP2.
    I am beginning to think the fist image in the thread is the only true UV image.
    see this page
    http://www.naturfotograf.com/spectral.html
    Any ways congratulations on achieving what you wanted, Contratique.
    Regards
    Bill
     
  22. Tim Gray

    Tim Gray Member

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    I didn't say the green filter was passing UV and IR. I just said it could be. It is passing green, and presumably blocking the rest of the visible spectrum, but UV and IR aren't visible, so you'd never know by looking at it if it was blocking or transmitting those frequencies.

    From my experience, most visible light filters pass IR. They probably don't pass UV, but they could - you don't know unless you test it yourself or find a spec sheet on it. I've attached an image of B+W transmission curves. The 'green' filters are the 060 and 061. Notice how much IR they pass, especially the lighter green one. It looks like neither pass UV, at least as far as the graph it up to 300 nm. Presumably they don't pass much above that. Transmission of UV in the atmosphere stops around 200 nm.

    If you look through the B+W filter guide, they have numbers in square brackets after some of their names. For example, the B+W IR filter 092 has a [RG695] after it. That's the type of Schott glass used for the filter. You can look up the transmission curves somewhere on the Schott website - I found them once but couldn't find them just now. Or you can just look in the B+W transmission curve PDF.

    I also wanted to stress again that the 'native' sensitivity of film is UV/blue. That's why the alt processes use UV (UV photons have more energy than visible light, i.e. photoelectric effect) and why early films were ortho. The technology progression of film has been to extend sensitivity in the red direction. Digital sensors are the other way around. They all have hot mirrors to block IR, because they have huge sensitivity in the IR. I don't know what their UV sensitivity is. And also, just because the IR is below red, doesn't mean that the digital sensor is going to interpret IR as red - the green and blue channel filters could also transmit IR too. Same goes for UV on a digital camera - the RGB filters are designed for performance in visible light. The hot mirror takes care of the IR sensitivity and presumably the optics take care of the UV (most optics don't pass UV that well, and optical cements also filter UV).
     

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  23. Contrastique

    Contrastique Member

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    Actually the first digital shot resembled what I saw with my own eyes best.
    The final shot when using the green filter "ate" some of the reddish light caused by the light on the floor aimed at the background which I expected anyway.
    Thank you for all the interesting comments in this thread. I realize I have to specialize a little in reading graphs (all kinds of graphs) as that knowledge does come in handy.
     
  24. Ole

    Ole Moderator Staff Member Moderator

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    There is a special gel filter which absorbs all UV, I have one from when I was photographing fluorescenct mineral many years ago. Even with colour film the UV light is very bright blue without a filter, with this filter everything except the fluorescence was totally black.
     
  25. wally

    wally Member

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    UV filters vs. black light filters

    I have a rockhound's fluorescent black light unit. It's got a very dark plastic filter over the tube. It's so dark that no visible light can be seen. But the UV gets through well enough to illuminate flourescent material within about eight inches from the bezel. I'd like very much to find a source for that black light filter.

    Something I discovered early on in my search for UV light sources and filters is that if you're interested in filters that pass UV, you need to use "black light" in your search instead of "ultraviolet" or "UV".
     
  26. Ole

    Ole Moderator Staff Member Moderator

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    Found it - it's a Wratten 2E. It's very pale yellow and cuts all UV light and a little of the shortest blue, but not enough to make a difference on photos. The UV is completely absorbed.