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Thread: Use of X-ray film: technical discussion with example images

  1. #5071

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    Re: Use of X-ray film: technical discussion with example images

    I had similar issues with a batch of Ektascan I bought 3-5 years ago. I think it’s a quality control issue. It’s still a great film to learn with. As a former chemist, Pyrocat HD, uses sodium or potassium carbonate to get pH high enough for development. Acid stop bath would be more likely than plain water stop bath to create issues in terms of converting the carbonate to carbon dioxide gas and little bubbles. But, I really doubt that’s a real issue. And I really doubt that’s at the root of the issue.

    Please post a review of the camera, I saw that and really wanted one! I’m wondering if it’s as nice as the ads.

  2. #5072

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    Re: Use of X-ray film: technical discussion with example images

    Quote Originally Posted by andrewch59 View Post
    Doesn't dust normally show up as white specks?
    On a negative they would do , as no light got past the bits to leave an exposure .

    The sample posted is a scan of the negative then inverted to a positive .
    So the white dots on the negative are now black dots on the scan/print .

    There's a lot of it to be dust though , so possibly a fault in the emulsion .

  3. #5073

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    Re: Use of X-ray film: technical discussion with example images

    I was wondering if it was from the development. I am using a Paterson Orbital unit but Agfa double-sided processed the same, which I thought would be more problematical came out fine and so too sheets of FP4. Here is magnified clip from a different sheet, not just little spots but also broader marks. It does seem to be emulsion related and is not like handling scratches.

    Click image for larger version. 

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  4. #5074

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    Re: Use of X-ray film: technical discussion with example images

    Maybe try pulling a piece and scan it without any processing at all. If there are visible marks, then try washing it and rescan and see if they go away.
    That would help eliminate processing sources. If it's black in scanning, it's got to be there before exposure. If it's black in scan, it's got to be clear on the negative, and the only things I know of that can cause that are either dust and dirt pre-exposure that is then washed away in processing, or missing or scratched emulsion.

  5. #5075

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    Re: Use of X-ray film: technical discussion with example images

    The marks are are not from scanning, I placed a negative on a light table and you can these pin holes with a loupe.

    I took a piece of unexposed film and inspected that on the light table and that was fine, and after washing to remove the anti-halation layer. Then I processed piece of that as before and then cut that into two further pieces, one stopped with water and the other with an additional stop bath. No holes or marks. I then fixed same pieces and no difference. It is a bit of a mystery as other film processed using the same holders and chemicals have come out fine. I shall just have to try another sheet.

  6. #5076

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    Re: Use of X-ray film: technical discussion with example images

    OK, what I have learned is that this film is extremely sensitive to agitation in development. I have been using a Paterson orbital and noticed that there was a circular area in the middle of the negative that was affected most with these black dots (in the positive image). So I observed the movement of the fluid in the processor with the lid off and noticed that there was an area in the middle that was did not experience as much fluid change with the orbital movement.

    So, I change the processing technique to a tilt one which you would do with standard tray development. I must add that I have no dark facilities. Well, this just confirmed the agitation variation theory; I was quite aggressive in the agitation frequency as it seems and now I got those marks in a cross pattern corresponding to the opposite corner tilt technique. How, was I to get more consistent agitation? I then remembered that when I got my Jobo CPE2 it came with a print tank extension 2800 so I dug this out of the garage.

    I have just developed a test sheet rolling the film into the tank and things are starting to look better. I now have streaks, in the rolling plane, so will have to figure out volume of liquids and make sure it is level (I am hand rolling). The sky area is still the most affected but I noticed that some marks were due to handling; I only have a Harrison Pup tent and it's a bit of a squeeze and although I used gloves it is no possible with these to locate the film edge under the holding slides so had to use bare hands. Another observation is that somewhat similar marks, that is to the finger prints, occur where is seems some tiny particle remains stuck on the emulsion and you get kind of micro trail of dark area from that mark, although I did rotate alternately in both directions.

    The other thing that comes to mind is that we are experiencing a heatwave here in the UK and using a changing tent it gets very humid in that enclosed space within the tent so maybe that is factor and development temperatures are up too.

    I've got the best results from the Jobo drum in terms of the black dots, agitation problem, but now have to sort out streaking and the other handing type marks. The tonal results from the film are great but with all the issues maybe I should bear the cost of FP4. The Agfa double sided CPG works nicely so I might try and get the mammography version of that film.

    Richard

  7. #5077

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    Re: Use of X-ray film: technical discussion with example images

    Click image for larger version. 

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    This was taken two days ago, agfa green, lc29 1:100 35mins stand, picture vignetted to isolate subject matter and artistic effect. color tinge is a by product of file reduction I think

  8. #5078
    Les D. Wall DeBone75's Avatar
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    Re: Use of X-ray film: technical discussion with example images

    Ok this is going to be a little long so please excuse. First this is the first Ive posted in several years. Being the frugal type. Meaning I don't have much money to play with. I try to use what I have on hand. I have an abundance of Dektol. I shoot Full blue film. I've spent the last several hours figuring Iso, dev. time and dilutions to use the Dektol as the film developer. I've read that it can be contrasty and grainy. Again trying to be frugal I mixed the 1 gallon bag of Dektol with 1/2 gallon of water to make a concentrate. After the experimenting I came up with an ISO of 150 with a dilution of about 1:17 or 30ml to 500ml of water for 10min. To my feeble eyes the negatives look very good. These where shot in hazy sun down a wooded path. Plenty of shadow detail and high lights very printable. Contrast and grain are not that bad. I have no way of showing these as I do not scan. Not saying this is the definitive for all but this worked for me. Now I have a question. Hypothetical. If you have an ISO of say 200 and you strip the emulsion is that the same as dividing the ISO to 100. For the people that say they get ISOs below 20 are they stripping the emulsion and are they shooting strictly in doors or under very low light. I've tryed using a low ISO and I can't even see thru the negative let alone print thru it. Just some thoughts.

  9. #5079

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    Re: Use of X-ray film: technical discussion with example images

    Concerning stripping: I find it's not the same as halving the iso. The side of the film facing the lens during exposure gets more light than the other side. Hence, you loose less than a stop when stripping the backside.

    As to your iso of 150: that's pretty high, but if it works for you, that's great. I got something like iso 50-80 with double sided green sensitive film. Note that testing with a shaded scene may throw your calibration off, particularly if it's a low contrast scene.

  10. #5080
    Les D. Wall DeBone75's Avatar
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    Re: Use of X-ray film: technical discussion with example images

    I have been shooting at 80 or 100 all along but the negs always looked a little to dense for my taste. They printed ok but just never quite liked the look. My developer of choice was always Beutler High Definition but currently I don't have the bulk chemical to make it. Most of what I shoot is either wooded or full sun land scape. Full blue is faster film than green.

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