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  1. #131
    Scruff McGruff's Avatar
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    Quote Originally Posted by Kirk Keyes View Post
    I was able to follow you until you got to that! Thanks for the reply.

    I do a variety of inorganic and organic analysis. Typically I've done all wet chem stuff, but lately, cyanide, COD, TOC, pesticides/pcbs and a bunch of other chlorinated compounds in water and solids. Recently, I've moved into volatile compounds in air.
    It wasn't a cake walk, but I'm sure it sounds a lot more complicated than it really is, at least as far as my work was concerned. You lost me pretty quickly too-- Cash On Delivery? Table of Contents? I should have paid more attention in my chemistry courses, apparently.

    I'll take another crack at the Vuescan densitometer; I did most of what you described, but I didn't clear my settings so maybe that's the issue (Vuescan is so finicky sometimes). Either that, or maybe it isn't supported by all scanners. Thanks for the tips, though.

  2. #132

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    Quote Originally Posted by Scruff McGruff View Post
    You lost me pretty quickly too-- Cash On Delivery? Table of Contents?
    Sorry - Chemical Oxygen Demand and Total Organic Carbon - both tests used to predict how much oxygen will be consumed by waste water when released into natural waters, i.e. rivers or lakes...
    Kirk

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

  3. #133

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    You're getting real hung up with a difference in base density between 35mm and 120. There is a difference in base density, I'm at work and don't have access to my readings, but 35mm base stock is dyed for anti-halation properties

    Quote Originally Posted by Scruff McGruff View Post
    So I seem to be having some trouble figuring out how to use Vuescan's densitometer function; I have tried googling, but the only tip I could find-- pressing the cntl key-- doesn't seem to work. I've tried all sorts of keys, but all I get is an RGB number b/t 0 and 255.

    When I adjusted exposure, this number would change, so I tried to control for that by including pure white (the opaque negative holder) and pure black (empty space in negative holder) in the crop and locking the exposure. The opaque parts read as 255, and the empty parts read as 0. I have my brightness setting (corresponds to midpoint gamma, AFAIK) at 1, the default setting. I don't know if this is a good enough control, but here are my results. To get these value ranges, I took several readings at random points on the film pieces.

    Cleared film leader of 135 size Tri-X: ~51-54
    Unexposed but developed section of 120 size Tri-X: ~50-53
    Unexposed but developed section of crappy 135 size Tri-X (two samples from two separate rolls): ~63-65, ~68-70

    You'll notice that the cleared film leader had a slightly (perhaps insignificant) higher range of readings than the developed 120 Tri-X. My thoughts are that, if there is a real difference (especially as one would expect the base density+fog of the developed sample to push it higher than the base density alone of the cleared sample), this a result of the 120 size having a different film base than 135 (though you had mentioned you thought 120 had a higher base density... curious) and/or it has something to do with the purple tint that is pretty well removed in the developer step, which is obviously absent on the fixed-only cleared sample.

    Are these numbers significant? In my searching I don't think I saw any methods of inputting these 0-255 numbers into the density equation transmission density=-log(2^(meas/reference)), so I'm really not sure how to interpret my results.

    Regardless of all this work, the fact that 120 film does not suffer the same problems 35mm does is a huge help in narrowing down possible causes. I have since removed my 120 film from the place I normally store my film, just in case. I haven't gotten around to buying a new roll of 35mm Tri-X (hey, it's Sunday, gimme a break!), but I'll do that soon to control for my storage issues.

    If it is a matter of storage, I assume it is my fault. Even after the other unidentified cause, which I highly suspect existed (as my development problems existed long before I started storing film the way I do now) but never really pinned down was eliminated, film purchased at different times and from different vendors has all shown the same behavior. [Sorry for that freakishly ugly sentence.]

    It's not like I store my film in a particularly strange way; I keep it in boxes/canisters in a dark, relatively cool wooden cabinet. Perhaps some other item I have in there is putting out low levels of radiation. It is also possible that something was releasing aromatic compounds (varnish in the wood cabinet, etc.), but I have my doubts that such contaminants could work their way through 35mm containers so easily.

    FYI, I have had similar symptoms on rolls that have been purchased from multiple different vendors and have never gone near that cabinet (different cities), hence why I am so suspicious that I had another source of error and that storage was not always the problem. I admit that it is very ugly science, but I didn't have the sense to write down all these variables at the time.

  4. #134
    Scruff McGruff's Avatar
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    Kirk,

    No problem, I was just joking around a bit. Neat stuff, though!

    Steve,

    Thanks for that bit of info-- I asked in a previous post if there were differences between the 135 and 120 film base/emulsion, so I appreciate you chiming in!

  5. #135

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    Base density

    Just from memory, 120 base density around 0.10. 35mm triX around 0.25, so quite abit of difference. Some 35mm bases are very clear but have problems with light piping-such as the micro films.

  6. #136

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    Same Problem

    Scruff,
    I just ran across this thread. I'm having the same problem. I've been through many, but not all of the checks you have done to eliminate causes. It's not my camera or scanner, I had ruled them out. It looks as if you have done exhaustive testing over a long period of time. In the same period of time I have only shot & developed maybe 5 rolls of B&W but have seen the problem on all. I will be trying some of the suggestions here and continuing to follow the thread. If I run across a solution I will post.

  7. #137

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    Scruff,

    How are you rinsing and drying the film?

    Is it possible there's reticulation from a temperature shock due to running water into the tank as your rinse method? Some of the earlier images looked a bit like reticulation but it's not easy for me to be positive.

    Just to be sure, are you using one of the vacuum column 'archival' film reel washers fed by tap water? Or are you using the Ilford three step wash method, preferably with DW?

    When you dry the film do you hang it at an angle so the water can run down one edge or straight down so it can run down the entire film surface and both edges?

    Either way are you applying a weight at the free end to keep the film straightened out during the process? It can "pool" either way and change the apparent density of the edges, btdt.

    Are you using a squeegee, your fingers, or a sponge to get most of the water off the film after rinsing prior to hanging to dry? I'm assuming you're not using a DSA/Senrac or the like for forced air drying while the film's still on the reel, right?

    Got a ceiling fan running or are you near an air conditioning vent that might be changing the temp of the film while it's still wet? Long shot I know but it's worth asking I think.

    Some emulsions are more prone to reticulation than others and it's not absolutely positive that the Arista is absolutely identical to Kodak Tri-X, at least not to me anyway for what that's worth. Apparent base+fog can increase if the film gets reticulated, maybe you could provide a magnified scan of some of the worse bits of film to see if there's a reticulated pattern present.

    HTH,
    Pete

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