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  1. #91
    holmburgers's Avatar
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    The Proof is in the Pudding

    At long last!

    Proof of concept, results, tangible evidence!

    It's far from perfect, but the verdict is in, the judge has ruled and a sentence dealt... Louis Ducos du Hauron was right, the Lumiere brothers were not total crack pots, and Dufay has rotated 360° in his grave!



    I kid, I kid... but I am excited to finally have something to show for my efforts. And although there is room for improvement, a color image has been formed!

    I've posted two pictures. The black & white positive and the composite screen-plate photograph (b&w slide + TV-screen-plate).

    As you can tell, the positive is underexposed. There is definitely more detail to be seen in person, but my scanner isn't quite able to peer through it. Add that density to the screen plate and you've got a really dark image; hence the nasty looking scan that has been boosted beyond reason. In real life the colors are much richer.

    Now, I've learned quite a few things. For one, the color balance of the screen is the least of my worries at the moment, as registration is more difficult than expected. The pin-registers only get you in the ballpark, and the real aligning has to be done visually. This in itself is difficult because the two films don't lie flush. I overcame this by taping the positive to my light table and then taping the screen plate to a piece of glass. Pressed emulsion to emulsion, I could then line them up visually and maintain good contact. With part of the screen lying off the edge of the glass, I was able to tape the two together with painter's tape once I achieved "good-enough" registration.

    Moving the screen in relation to the positive causes all sorts of rainbow-colored moiré patterns to dash across the image. It's very strange and beautiful! But as it is, it's impossible for me to get the whole image to look color-correct in one position. However, I can get each individual part to look right at the expense of another; i.e. the banana will look yellow but the Budweiser logo will be purple instead of red, the white apple will be tinged green, and so on.

    I think the problem lies in the fact that there was space between the screen & the film during the exposure. Getting the two taped-together films to slide under the grooves of a 4x5" film holder was no easy task and undoubtedly the crude registration (by means of a strip of masking tape) was not sufficient to hold them perfectly together. This needs improving, because without good contact, registration of the two films is a complete crap shoot.

    Secondly, the color balance really doesn't look too bad, and the example here is utilizing the screen-plate (réseau) derived from a flat-screen CRT television; a.k.a. the one that I posted above and that appeared quite blue. I illuminated the subject with an ordinary tungsten light bulb, and I think the bluishness of the screen actually balanced it quite nicely to white.

    Considering how finicky the registration is, I can't imagine working with anything higher resolution than SDTV at this point. I think I'm going to stick with TV (in lieu of LCD computer monitors) for now. Plus, I think it looks pretty cool!

    So for next time, I need to produce a much brighter black & white positive, and process it myself (*cough *cough, dr5 took over a month) while figuring out some solution for maintaining better registration. Ultimately I'll mount the two together permanently with Canada balsam or the like and build some kind of opal glass viewing frame, but something temporary must be done for the exposure registration.

    Cheers!
    Attached Thumbnails Attached Thumbnails screen-plate photograph ceholmquist2010.jpg   screen-plate b&w poz ceholmquist2010.jpg  
    If you are the big tree, we are the small axe

  2. #92
    Photo Engineer's Avatar
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    Congratulations!

    You may be having a problem with the swell of the support. Estar support was used to remove this problem in Dye Transfer, otherwise you would get color fringing. On acetate support the change in dimension with processing can cause such a problem with screen materials. Back in the early days, the integral screens were used to avoid such problems.

    PE

  3. #93
    holmburgers's Avatar
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    How much of a dimensional change can occur on acetate supports and what can be done, if anything, to mitigate it? Where is the estar used in the DT process; on the matrix films?, or the separation negatives? Are there any films still coated on estar these days that I could use, either for the screen or b&w positive?

    I'd like to think that in the present example this is not my problem, considering the resolution of the screen being fairly coarse and also the aforementioned problems with jamming the film into the holder. Plus, this is something I have no ability to remedy, so thinking about it is depressing!

    But, only further testing and refinement will tell.

  4. #94

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    Right On Chris!

    I'll keep watching to see how far you can take it. Looks like you should be able to get some rather unique images with a character all their own.

  5. #95
    Photo Engineer's Avatar
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    Quote Originally Posted by holmburgers View Post
    How much of a dimensional change can occur on acetate supports and what can be done, if anything, to mitigate it? Where is the estar used in the DT process; on the matrix films?, or the separation negatives? Are there any films still coated on estar these days that I could use, either for the screen or b&w positive?

    I'd like to think that in the present example this is not my problem, considering the resolution of the screen being fairly coarse and also the aforementioned problems with jamming the film into the holder. Plus, this is something I have no ability to remedy, so thinking about it is depressing!

    But, only further testing and refinement will tell.
    Estar or Melenex or this material under a number of names is used on all films in the Dye Transfer production sequence to minimize size changes. The change is enough to cause a "moire" or "rainbow" pattern on photos which experience such changes.

    All sheet films from Kodak are on Estar IIRC.

    PE

  6. #96
    holmburgers's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    All sheet films from Kodak are on Estar IIRC.
    Oh, well that's reassuring. So then, no more Ilford Delta 100 perhaps...

    R Shaffer; thanks! That's what I'm hoping for and I appreciate the encouragement, it makes it all the more worthwhile.

    If you are the big tree, we are the small axe

  7. #97
    Stephen Frizza's Avatar
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    if its of any interest i have been playing around with screens and films and so far this is as good as I have been able to come up with. do you find too that your screen causes a degradation in fine detail?
    Attached Thumbnails Attached Thumbnails B&WposviaRGBscreen.jpg  
    "Its my profession to hijack time" ~ Stephen Frizza.

  8. #98
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    Quote Originally Posted by holmburgers View Post
    Ok, so I got back my latest screen-plates. These I made by photographing a flat-screen CPU monitor. Both good news and bad.

    Since my earlier tests turned out blue, I made a custom color that was a light yellow. What I got back were distinctly green slides. At first I couldn't wrap my head around it; I thought maybe it was a processing error, I thought maybe the film was too old, maybe the heat encountered in mail-order shifted the color.... etc.

    HOWEVER, the lightbulb over my head lit up and I realized that this color shift is due to the fluorescent illumination used in flat-screen monitors. Duh!

    The good news is that under the loupe I can see definition to the RGB elements, however I can't make out the colors. But the lens can render this fine detail and the resolution promises to be excellent with CPU monitors.

    Meanwhile I've taken a picture with my first bluish screen-plate under tungsten light (to hopefully balance it out). That film will be going to dr5 soon.

    So any suggestions on dialing in this color? I've decided that I can't continue using/wasting 4x5" film until I have the right color balance, so I think I'll be running a roll of 35mm with many different source colors to see what comes out the most neutral on the slides. But since I'm dealing with fluorescent illumination, aren't I kind of shooting in the dark? If I add magenta to my source, can I expect that to eliminate the green, or is it going to be more complicated than that?
    If you wanted to spend the money there's a new breed of LCD moniter out that uses white LEDs as a light source, and are brighter with a higher contrast ratio.
    Either way you should be able to color balance the monitor screen to any color you want in spite of the light source.
    Gary Beasley

  9. #99
    holmburgers's Avatar
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    Stephen, that result is stunning. What are you using for the screen? Is that 4x5"? Definitely of interest to me and others I'm sure! I'd love to hear your method.

    As for fine-detail, I can't speak authoritatively as I've still only got one example under my belt. It does stand to reason that there will be a loss of fine detail, due to the fact that a pure green object (for instance) would only be using 1/3 or less of the screen in that area.

    glbeas, that monitor sounds awesome, but I'm in no position to buy one at the moment. At some point I am going to shoot a roll of 36 with different filtration to see what comes out the most grey, and then use the best for my 4x5" screens.

  10. #100
    Athiril's Avatar
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    I'm going to try dye some starch and mix it into a gelatin emulsion and paint it on top of some foma, I dont think it'll hold during processing, but I can re-apply a screen after scanning (or painstakingly on some RA-4 when I get an enlarger).



 

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