Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,701   Posts: 1,482,635   Online: 784
      
Page 5 of 10 FirstFirst 12345678910 LastLast
Results 41 to 50 of 95
  1. #41

    Join Date
    Jul 2011
    Shooter
    8x10 Format
    Posts
    2,288
    It's still a curve. Such things differ from one film to the next, and relative to the development regimen.
    I've done analogous shots with 8X10 TMY looking out from very dark tunnels, with detail reproduced over a very long range indeed (and I'm not referring to minus or compensating development, where the
    midtone tonality gets compressed). But one still has to understand at what threshold value the shadows will indeed be decently differentiated, and at what point the highlights will simply blow out relative to the given print media (which can be employed creatively, of course). But if one does plot such things on a densitometer, TMY does have a lot of range for the sake of practical photography, but not quite as much as a few other films I've tested, which aren't commercially available anymore. The
    verstility and quality of TMY makes it my favorite "go to" 8x10 film, yet also my favorite 35mm snapshot product.

  2. #42
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,712
    Images
    65
    Virtually every film has a UV absorber. It is either an incorporated dye (yellow) or in an overcoat.

    As for the curve, my boss used to say "we don't sell curves, show me a picture". So, all of the comments above are useless if that film makes a good picture and the release curve is within specs.

    That is why I suggested that you call EK.

    PE

  3. #43

    Join Date
    Apr 2008
    Location
    Escondido, California, USA
    Shooter
    35mm RF
    Posts
    646
    Quote Originally Posted by Photo Engineer View Post
    That is why I suggested that you call EK. PE
    I just sent EK a description of the issue. We'll see what they say...

    Mark Overton

  4. #44

    Join Date
    Jul 2011
    Shooter
    8x10 Format
    Posts
    2,288
    Curves mean a helluva lot once you start doing something outside the routine - color separations for
    example, where you need to know not only where the linearity begins and ends, but how consistent it
    is between radically different color filters, along with potentially differing exposures and their kind of
    recip failure effect. I how know idea how they figured it out, but if you understand how the film works,
    both speeds of TMax are remarkably consistent in this respect too. In the more ordinary world, just head over to our coastal redwoods - a film which might give wonderful results in a morning fog will be
    just about useless once the sun breaks out and you end up with maybe fourteen stops of range, a task
    just about impossible for any film without a steep toe unless you turn the whole thing into mushy
    compensating dev. Even with TMY under such circumstances, I sometimes have to resort to supplemental unsharp masking, even with the finest VC papers. Curves mean a helluva lot in my world.

  5. #45

    Join Date
    Jul 2011
    Shooter
    8x10 Format
    Posts
    2,288
    Sorry to sound like a wiseguy, Ron ... but I'm really trying to relate the wonderful versatility of TMax if
    one understands the curve characteristics. Right now (besides general shooting) I'm applying TMax to
    color neg masking. This is radically different than good ole Ciba masking ala battleaxe and spike ball
    sheer force, and way more fussy than garden-variety masking for black and white printing. It's like power steering - very delicate, and ideally requiring a straight line way to the bottom of the relevant
    curve even under extremely low-contrast development. This characteristic becomes critical with multiple
    generation masking work - and by golly, TMax can do the job a helluva lot better than the oft-lamented
    long-lost late Pan Masking film ever could. And if it can do that, as well as provide very long scale
    relatively high-contrast predictable separation negatives, for example, that's a remarkably versatile
    product!

  6. #46
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    2,910
    Images
    46
    Quote Originally Posted by noacronym View Post
    Since none of us here knows one another, there is not much basis for definitive laboratory testing. Now if the original poster had also posted the technical receipt from the company where he sent his densitometer to be calibrated then I'd take notice. Calibration of instruments is a daily routine for companies that use these kinds of devices. If a record studio using tape recorders is in the business of quality records and tapes, it would be the engineers job to check tape head alignment, azimuth, and do tests on frequency response, probably before each studio session. A densitometer needs the same attention. When you send your oscilloscope off to Tektronics to be calibrated, you undoubtedly receive a printed report back with your scope. Densitometers can go out of calibration in one day, if you don't keep on top of them every minute. Anything less is just sloppy procedure, and the results are worse than worthless.
    I wouldn't go so far as that. I called up a radio station a while back because my oscilloscope was showing a 45-degree line where the stereo scatter fuzzy oval should be. They thought I was a lunatic until I double checked by listening in my car. No it wasn't my equipment. And my scope is nowhere near calibrated. All their lab equipment was switched on the digital signal so they didn't notice the board on the analog side was switched to mono.

    Meanwhile to add a possibly useful question to the thread. Is this the kind of step wedge layout used for testing?

    http://www.apug.org/forums/viewpost.php?p=1480607

    If so, can you test with an offset, or 90-degree angles to your usual. Maybe you are seeing an effect where the outside edge of the film receives greater development than the center.

    p.s. I work for Kodak, but not in film - here I am a hobbyist. The opinions and positions I take are my own and not necessarily those of EKC.

  7. #47

    Join Date
    Jul 2011
    Shooter
    8x10 Format
    Posts
    2,288
    A lot does have to do with the nature of your step tablet or wedge, esp if they are old and discolored.

  8. #48

    Join Date
    Jul 2011
    Shooter
    8x10 Format
    Posts
    2,288
    Modern densitometers often have a "null" mode relative to the light source, so if a little dust gets on
    the receptor, it is ignored. Actual calibration requires an expensive reference standard - a very expensive kind of step wedge - and not just an ordinary one on film. But you can use your ordinary step wedge to check for any drift. I once worked quite a bit with spectrophotometers, and these had to be routinely recalibrated to a fade-proof standard, typically a white ceramic tile. I've been working with
    the same pair of densitometers for several decades, and they are still within .01 measured density -
    below the advertised plus/minus accuracy factor!

  9. #49
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    2,910
    Images
    46
    Quote Originally Posted by noacronym View Post
    Pardon me for that, Mr Burk. I'm mostly a hobbiest, but also something of a calibration nut. If you put an instrument into my hands, by nature the first thing I'll invariably do is open it up and calibrate it. Frequency generators, scopes, tape recorders, camera, light meters... If it is something that can be calibrated, I'm bound to calibrate it. Can't help myself.
    Ah, and pardon me too noacronym. I know that calibration is good and helps to establish credibility.

  10. #50
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,712
    Images
    65
    I am not criticizing Tmax nor am I extolling its virtues. I am merely pointing out what was brought forward in this thread. Several batches of the same film seem to have different curves. These curves may be indicative of a problem or they may be at the extremes of the nor for released product. But, there have been samples run through the same process taken from different batches of film, and they differ. This is not a problem with a densitometer nor is it a problem with a process as these two results seem to be possible from the same exposure and process.

    So let us avoid the side non-issue of calibration and etc. and look at the results which are odd to say the least. And therefore, contacting EK may help, as Bill Burk has pointed out in his story!

    And remember, some of us do know one another either in extensive exchanges of private mail, or in person!

    PE



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin