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  1. #11
    holmburgers's Avatar
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    "Every party needs a pooper, that's why we invited you...."

    JUST KIDDING. You raise a good point. It definitely depends on what your end goal is though. Personal enjoyment in my case.

  2. #12
    DWThomas's Avatar
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    I imagine the only way to know is try it, but I would be concerned that the glass face plate on a traditional CRT is quite thick -- approaching a half inch on the larger ones, and the phosphors are essentially point source emitters on the inner surface. This suggests to me there will be a lot of light dispersion and the print will be very low in detail -- but after all those words -- I could be wrong!

    Have access to a Polaroid back? You could experiment by holding it against your TV (assuming you can come up with the film).

    DaveT

  3. #13

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    Hi Chris (holmburgers), it looks like quite a bit of interest in your idea, so sorry I'm going to be another party pooper.

    I sort of chased down a similar idea long time ago, so maybe I can save you some time.

    First, you won't be able to make an actual contact print of the CRT screen, because the glass faceplate keeps you too far away from the image. (You would end up with the equivalent of an unsharp mask.) One way around this is to use a CRT with a fiber optic faceplate, as some commercial printers once did (search for things like Sienna Mileca, or Gretag Netprinter, etc.)

    So once you convince yourself that contact printing won't work, you can move on to the next step, using a lens system to project an image. In essence, you would build an enlarger, using the CRT in place of the negative.

    What I did, rather than build an enlarger, was to simply cut down some color paper to the size of a piece of film, then, in the dark, lay it in the back of a camera. Then, took photos of the CRT screen. You'll have to go back in the dark to remove your paper, then develop it, etc. But you'll be able to see the effect of an enlarger without actually building one.

    The next thing you'll discover is that any color CRT made in modern times has a really difficult time making a red exposure. What you see on the monitor, visually, looks great, partially because of a specific red phosphor (invented in the 1960s, I think), which is really good at stimulating human vision, but otherwise is spectrally lousy. You'll have to drastically hold back exposure on the green and blue. I would guess somewhere around 150 to 200 cc units each, of magenta and yellow printing filtration. My memory is really fuzzy here, but a camera exposure of around 10 seconds at f/4 is probably getting into ballpark range.

    If you have a CRT monitor on your computer, you probably have software to invert an image (that is, it looks like a negative), then lower the conrast, you can probably get a decent image onto your color paper. Then, decide if building the "enlarger" (or use large format camera ala keithwms) is worth it. HAve fun!

  4. #14
    holmburgers's Avatar
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    Hmm, that's fascinating about the red phosphors. My TV has the ability to change tint w/ quite a bit of latitude. Maybe by experimenting with that I can get the color balance right.

    I think to test what you're all saying (that the glass is too thick for a tight image) I'll cut off a short strip of 35mm and tape it to the screen. Then I'll hang my head and admit defeat.... or not!

    Isn't there an Adam and the Ants album with a picture from a TV on the cover. I love that look.

    Thanks again for all the input!

  5. #15
    Joe VanCleave's Avatar
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    I will again repeat my actual experience with doing this, that a simple pinhole box camera, positioned on a tripod in front of the screen at the approriate distance as per the formula I posted previously, is the simplest, most effective way to do this.

    A glass lens capable of imaging the screen with little or no geometric distortion, and able to cover a large format, will be expensive and problematic.

    Regarding the use of color film, you have, with a video image, the ability to alter its hue (i.e. color balance), instead of using filters over the lens/pinhole, so as to compensate for reciprocity failure of the color film that would otherwise throw off the colors in the resulting film image.

    ~Joe

  6. #16
    eddym's Avatar
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    Since all TV is now digital, shouldn't this be under the Hybrid site?
    Eddy McDonald
    www.fotoartes.com
    Eschew defenestration!

  7. #17
    Joe VanCleave's Avatar
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    Digital TV rant warning:

    Not all TVs are digital; I'm still using an old 27" Sony analog CRT set, with a DTV converter box. I detest 16:9 screens, especially considering, after we've supposedly passed the cutoff date for NTSC broadcast, most program material is still originated in 4:3, even many live sporting events that should be broadcasting 16:9. Only prime-time material is originated in 16:9; and your local news broadcast is almost certainly still 4:3, as are most all commercials that originate locally. The result, when viewing 4:3 material on 16:9 screens, are fat-heads, where the images are stretched out horizontally to fit the full width of the high-dollar screen.

    I'd prefer, when "upgrading" my old TV set, to get a large flat panel display in 4:3 aspect ratio, that way I can watch the majority of program material in its original aspect ratio using the full area of the screen, and still enjoy the full width of a 16:9 DVD program. But, alas, 4:3 flat panel screens can only found in sizes under 20" wide. All you people who plunked down your hard earned cash for 16:9 flat panel displays were cheated; they cut off the top and bottom of your picture, so you're forced to watch the fat-heads.

    End of rant.

    But still, taking analog photographs of TV screens, digital or otherwise, is a neat idea, considering how much of our lives the TV occupies, it should be included in central prominence in any kind of documentary of domestic western culture.

    ~Joe

    PS: I was just kidding about the 16:9 TV thing. Y'all can go back to watching your stories.

  8. #18

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    Joe, you indicated that your exposures were onto B&W paper, right? Do you recall exposure times?

    My post was speaking to color paper, from probably a 1990s time frame. The yellow and magenta filtration I alluded to will essentially allow red light to come through unrestricted, but cut down the green and blue by factors of ROUGHLY 30 to 100 times. Thus, overall exposure has to increase by the same factor. So, IF my fuzzy memory is halfway close, and IF today's paper has similar characteristics, exposure times for a pinhole may be unreasonable. That is, possibly 5 or 10 hours for COLOR PAPER, using pinhole, when color balanced to a CRT. Remember, also, this is not just a single exposure and it's done; this is the exposure needed for every test strip while color balancing.

    Clearly, I think some sensible f-number (f/2.8 to f/5.6 or so) is needed if one desires to use color paper, for a color corrected CRT image.

  9. #19
    Joe VanCleave's Avatar
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    I first tried this using a refractive lens, rather than pinhole; this was a single-element adapted lens, so it wasn't anywhere near as sharp as a "real" camera lens; but it only needed to resolve down to the pixel level of the video screen. Rating my paper negatives at an Exposure Index of "2", and using a Gossen Luna Pro F light meter with which to meter the scene, I measured various video frames with readings of from EV3 to EV6. With the lens set to around f/4.8, the exposure times were around 4-8 seconds. The results came out good, exposure-wise, albeit with a bit excessive contrast, which should be adjustable by tweaking the contrast of the display monitor down somewhat.

    BTW, that's what I love about this process, you have the option of tweaking the image prior to exposure. In the case of using color film, you can tweak the tint (i.e. the color balance) of the display to compensate for reciprocity effects, which effects the various color layers in the film differently, throwing off the color balance.

    Then I tried this using an F350, 8"x10" format pinhole camera, using the same paper negatives rated at an Exposure Index of "2". I did three exposures using this method; the first used my camcorder as a video source, with a freeze-framed image as the subject. With the TV set to normal brightness and contrast it required a 40 minute exposure. The remainder of the shooting I did on a playback of a recording from election night 2008, using my old VCR (yes, I still have several); I was ultimately able to get a good exposure at 17 minutes by running the brightness all the way up on the TV. FYI this was a 27" Sony CRT display.

    I'm not familiar with the reciprocity characteristics of color papers, but I'm assuming that their paper exposure index is similar to B/W papers. I also understand that during extended exposures some of the emulsion layers end up with different reciprocity characteristics than others, throwing off the color balance wildly, requiring special filtration; or living with the wild colors.

    Yep, sound like a good flat-field copy lens on a large format camera would be required for your needs. Keep us informed as to the progress of your project, it sounds interesting.

    ~Joe

  10. #20
    holmburgers's Avatar
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    I'll keep you posted, though it might be a bit down the road.

    Thanks for everyone's interest, this is a really great community!

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