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  1. #1
    Ian Grant's Avatar
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    Modern Rodinal Substitutes Part II

    Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

    So with a bit of telepathy

    Quote Originally Posted by Kirk Keyes View Post
    Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

    But for MSDS work, it doesn't have to be too precise.
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    Kirk

    A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

    The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

    Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

    Can someone please post a link to this continuation on the original post.

    Ian

  2. #231
    gainer's Avatar
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    Here is an example of two different ways of showing the same negative. One is a scan directly from the negative at 2400 dpi. The other is scanned at 2400 dpi from a portion of an analog 8x10 print. Finally, I resampled each one to have the same height in pixels.
    As you may see, the scan from the print has much higher resolution and very much finer apparent grain than the scan directly from the negative. It is not going to be easy to compare grain and resolution in digitized photos.
    There will be those among you who will not believe what I just showed. You will have to repeat the process with a negative of your own.
    Attached Thumbnails Attached Thumbnails Print from film-2400 dpi.jpg   film-2400 dpi.jpg  
    Gadget Gainer

  3. #232
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    I completely believe that (apparent) sharpness and grain are totally different for a scanned negative and a scanned print of the same negative.
    Maybe it may be more fair that you reduce the scan resolution from the print with the enlargement factor used for making the print from the negative: you then have at least a comparable pixel density to start from. But off course this is only ignoring the real problem, that a digitized version of reality will have a difficult time competing with the real thing

  4. #233
    gainer's Avatar
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    Quote Originally Posted by DutchShooter View Post
    I completely believe that (apparent) sharpness and grain are totally different for a scanned negative and a scanned print of the same negative.
    Maybe it may be more fair that you reduce the scan resolution from the print with the enlargement factor used for making the print from the negative: you then have at least a comparable pixel density to start from. But off course this is only ignoring the real problem, that a digitized version of reality will have a difficult time competing with the real thing
    Perhaps you noted that although each image is the same size on screen as the other, the sizes of the .jpg files are 140.4 for the scan from print and 77.0 for the scan directly from the negative. No matter how I go about it, I will either not get a fair comparison of two negatives or a fair assessment of grain and resolution of a single negative that I can transmit over the Internet.

    One would think that a direct scan from the negative would eliminate the losses due to enlarger lens and paper. The film grain was enlarged in the print as well as the other characteristics of the film image, and then scanned at 2400 dpi. In my opinion, it would be better to judge the qualities of film and development on the enlargement of the paper print rather than to reduce its quality to match the direct scan. Either that, or find a way to scan at 19200 dpi from the neg.
    Gadget Gainer

  5. #234

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    Posting scans of prints every time a formula is tested seems a bit like hard work for you to have to do and slows the whole process down.
    In my case I would be happy to rely on your Mk 1 calibrated eyeball to assess grain unless a formula you consider of special interest is found.

  6. #235
    gainer's Avatar
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    I do have 19200 dpi on my scanner, but my system memory will not handle the resulting file when I try to scan only the area I showed above. I got up to 7200 dpi, but found that the resolution was worse than at 2400. I'm beginning to think that the resolution of my scanner's optical system is not as good as that of my enlarger, There is a point at which the scanner shows very clearly the lack of clarity of its own optical system.
    Gadget Gainer

  7. #236

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    Quote Originally Posted by gainer View Post
    There will be those among you who will not believe what I just showed. You will have to repeat the process with a negative of your own.
    I'm not surprised the print looks better than the neg. It's hard to get that much magnification with the scanner alone as you can with an enlarger in the middle of the process.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  8. #237

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    Quote Originally Posted by gainer View Post
    I do have 19200 dpi on my scanner,...I got up to 7200 dpi, but found that the resolution was worse than at 2400...
    Which is interpolated, not real, hence the better resolution at 2400 vs 7200. Your enlarger's resolution is much better.

  9. #238
    Photo Engineer's Avatar
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    I have to say that I can get far better resolution from direct scans of negatives and transparencies than I can get from prints and I make prints up to 16x20 regularly, both B&W and color.

    PE

  10. #239
    gainer's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    I have to say that I can get far better resolution from direct scans of negatives and transparencies than I can get from prints and I make prints up to 16x20 regularly, both B&W and color.

    PE
    But can I afford the scanner you have?
    I don't remember seeing anything in the instructions about interpolating, and HP is usually pretty good about such things.
    I have 6 Super B sized prints scanned from 35 mm negatives hanging on my wall, and they look pretty good to me and all others who have seen them. Of course, I have them arranged so that grain-sniffers can't get close enough to comment on that. They can, however, get close enough to see the proper perspective.
    The only reason I went to such high dpi was to see what would happen. Now I know.
    Gadget Gainer

  11. #240

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    Quote Originally Posted by gainer View Post
    I have them arranged so that grain-sniffers can't get close enough to comment on that.
    grain-sniffers ?




 

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