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  1. #21
    Athiril's Avatar
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    Quote Originally Posted by Tim Gray View Post
    Why is it not accurate at all? Both numbers are in Kodak's documents...

    TMX - 63 lines/mm for 1.6:1 and 200 lines/mm for 1000:1
    TMY - 50 lines/mm for 1.6:1 and 125 lines/mm for 1000:1

    Unfortunately, unless I missed something, not all of their film docs have these figures, notably Tri-X. So if the film data guide decides to quote the 1000:1 figures as a metric for comparison, then that's all we have to go with for some of these films. It should give a good sense of relative resolution between the films.

    For example, Plus-X was rated exactly the same as TMY, for both numbers. Which is exactly what pstake wrote.

    Sure, it's worth clarifying that these numbers are for higher contrasts (1000:1), but to call them 'not accurate' and then come up with a comparison chart that is pretty much exactly the same as what pstake posted seems a bit pedantic.
    It's neither pedantic nor 'pretty much the same', it is very very different.


    It's not accurate, because you are comparing films resolving power by their 1000:1 reported figures. The low contrast resolving power, as well as the MTF50 simply doesn't scale with the 1000:1 figure against different films, so while you may say film X = 100, and film Y = 50, but when it comes to normal usage, film X isn't four times as detailed (double resolving power) as film Y.


    Given only 1000:1 figures, you could say film X is probably sharper than film Y, but not necessarily.

    Eg, another different film X and Y. Add a film Z, and also another W

    Given their 1000:1 figures only
    W = 180
    X = 200
    Y = 125
    Z = 125

    So you assume X is the sharpest, followed by W, then Y and Z in last place, and they are the same, given your logic it'll give a relative difference of resolution, but it doesn't, not even close, it's incorrect and flawed logic.

    Because the low contrast figures for these four (real films) are:

    W = 80
    X = 63
    Y = 63
    Z = 50

    Unless all your continuous high spatial frequencies are 1000:1 (ie: not a pictorial or normal scene), then W is always going to be the sharpest, followed by X and Y giving equal detail at the lowest contrast, with X having a small edge of Y for anything that has a slightly higher elevanted contrast in high spatial frequencies (but nowhere near 1000:1) as it's resolution will rise faster over contrast.

    And Z coming last in all situations.

    At least by using correct logic by using the reported resolution figures, not simply using one end of them. I cannot imagine any single worse and inaccurate way to compare film sharpness by using the reported 1000:1 figures.


    As for MTF @ 50%?

    W = 48
    X = 125
    Y = 70
    Z = ~70-75


    Using 1000:1 figures as a relative comparison basis is flawed.

    I would even go to say that 1000:1 is the wrong figure for even test charts, if you spot meter the difference between the black and white, at maximum it is probably going to be 5 stops (32:1 contrast)
    Last edited by Athiril; 04-04-2012 at 12:15 PM. Click to view previous post history.

  2. #22
    Thomas Bertilsson's Avatar
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    The only way the original poster is going to properly make up his/her mind is by purchasing a brick of each and get down to business of practicing with them.

    That's what it'll end up being anyway. The films are different in their specifications, but in something as subjective as art, it doesn't really say much until you start using them.

    Tri-X is hardly a high resolution or fine grained film. 75% of major brand films have better specifications, but I use it because I love what my prints look like. None of the numbers mean anything to me.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  3. #23
    Athiril's Avatar
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    I agree. Plus I don't find Tri-X lacking in resolution or too rough in grain. It's one of my main films.

    A better comparison of which film to choose would be by spectral range sensitivity, I like the look of films with longer blue end sensitivity for portraits, and shorter blue and longer red (like Delta 400) for landscape work.

    Quote Originally Posted by Brian C. Miller View Post
    Athiril, you are mixing up "lines/mm" and "line pairs/mm." Those are different.


    As far as I know they are written as lines/mm in the manual but are lp/mm, as you need an opposing line to see that line, otherwise no contrast = no visible line. As they do not count the 'empty space' (opposing line) when quoting lines. So they count every second line, where lp/mm counts them together as 1 unit. They have the same numerical result.

    Eg; the MTF is obviously in the same format, it is cycles/mm which is lp/mm, eg: T-Max 100 MTF 50% is 125 lp/mm, if they were counting the opposing line in the figure, then lines/mm in their docs would be 2x the value of lp/mm, and that would mean the MTF 50% value exceeds the 1000:1 quoted figure of 200. 1 cycle = 1 pair of lines, as 1 cycle of a transverse wave contains both the crest (rise) and trough (fall) - which these are commonly expressed in as well.
    Last edited by Athiril; 04-04-2012 at 12:47 PM. Click to view previous post history.

  4. #24
    Ken N's Avatar
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    I love shooting portraits and events with Delta 400 processed in DD-X. The extended IR response is wonderful for skin. This film-chemistry combination is outstanding when pushed one stop to 800. Event shoots are almost exclusively done at 800. I've also shot tons of this film at 1600. It just keeps hanging in there. An amazing film and it scans very well.
    http://www.zone-10.com

    When you turn your camera on, does it return the favor?

  5. #25
    Athiril's Avatar
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    Quote Originally Posted by Ken N View Post
    I love shooting portraits and events with Delta 400 processed in DD-X. The extended IR response is wonderful for skin. This film-chemistry combination is outstanding when pushed one stop to 800. Event shoots are almost exclusively done at 800. I've also shot tons of this film at 1600. It just keeps hanging in there. An amazing film and it scans very well.
    I haven't used it that extensively for portraiture, can you post some examples or a link?

  6. #26

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    Quote Originally Posted by Athiril View Post
    Using 1000:1 figures as a relative comparison basis is flawed.
    And as you showed, using the MTF 50% figures, or the 1.6:1 figures as a relative comparison basis can be flawed too.

    Like I said in my first reply, unless I missed something, for some of the films mentioned, we don't have any other numbers to go on. Yes, the 1000:1 figures aren't necessarily appropriate for everything, or even much of anything for pictorial. That should be stated. But it IS a point of comparison. Just not a comparison of something YOU might find useful. Then again, it might - that ordering of films by resolution in that chart pretty much matches my experiences with the films that I've shot with. And even then, while there might be some films whose resolution doesn't scale to lower contrasts, it IS information and it IS a valid comparison.

    And by the way, all of your faulty and flawed logic you are attributing to me, I quote myself, "It should give a good sense of relative resolution between the films." Let me break that down for you:

    'Good sense' - an estimate. Maybe not totally correct in every case, but a guide from to work from.
    'relative resolution' - not that film A has 4 times the resolution than B at all contrasts, just that film A is 'higher resolution' than B.

    It's an estimate based on easily available published data from the manufacturer. I wouldn't bet my life on it. But if all I had to go on was that chart to pick a highly resolving film, I think I'd do alright if I realized that HIE can't revolve shit compared a number of other films.

    And please, where are the 1.6:1 numbers for some of these films?

  7. #27
    MaximusM3's Avatar
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    Quote Originally Posted by Thomas Bertilsson View Post
    The only way the original poster is going to properly make up his/her mind is by purchasing a brick of each and get down to business of practicing with them.

    That's what it'll end up being anyway. The films are different in their specifications, but in something as subjective as art, it doesn't really say much until you start using them.

    Tri-X is hardly a high resolution or fine grained film. 75% of major brand films have better specifications, but I use it because I love what my prints look like. None of the numbers mean anything to me.
    No way! Why do that when one can go the easy way and come in here and get 2000 different opinions and miss the entertainment of people throwing crap at each other? At the end of the day, there is probably less time involved in shooting two rolls and process them than to read everyone's answers, but what do I know..
    Sometimes I really wonder how photographers survived and made good art before the internet.

  8. #28
    Athiril's Avatar
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    Tim Gray, the 1000:1 figures are not a point of comparison unless you are photographing a subject with high spatial frequencies at 1000:1 contrast ratio. Almost no one is. Therefore it is completely unusable (unless you are photographing 1000:1) as a point of comparison between, because it does not in any way shape or form scale to pictorial resolution. It isn't a valid comparison.

    It doesn't give an estimate between the films.

    "'relative resolution' - not that film A has 4 times the resolution than B at all contrasts, just that film A is 'higher resolution' than B."

    I already demonstrated that film A is lower resolution than film B, despite having a high resolution for higher contrast. I already deomonstrated a difference between 2 films with the same 1000:1 contrast level.


    I don't think you have actually looked for the information, because they are in manufacturer data sheets for many films, if they give out 1000:1 they also give out 1.6:1 and usually (though not always) the MTF chart too. Eg: http://wwwau.kodak.com/global/en/pro...4043/f4043.pdf I'm sure you are more than capable of looking up films on the manufacturer website and clicking on the PDF links for the rest of them.

    If you got your data from a book that listed only 1000:1, and compared resolution to films like that when that book is not about scientific high contrast applications, I would probably throw that book in the bin because they neglected the rest of the data. It is misleading, especially for document contrast films as these figures come straight from the manufacturer for standard developing. T-Max 100 has a better MTF 50% than Technical Pan does.

    Tech Pan 100 lp/mm @ 50%, T-Max 100 125.

    Yet T-Max 100 is listed at 63 lp/mm for 1.6:1 and Tech Pan 125 lp/mm @ 1.6:1 (in HC-110) and 100 lp/mm in Technidol (only MTF is in Tech Pan PDF, stated resolution at contrasts is in the glass plate tech pan PDF).

    That HC-110 is dilution D, which for the given times has a contrast index of 1.35 to 2 @ ISO 80 to 125. With Technidol being more normal from 0.48 to 0.70 (ISO 16 to 25) (also the dMaxis 1.2 @ CI 0.48). The suggested time is 9 minutes at ISO 25, so that is their basis for the technidol resolution figures (they state so), that has a contrast index of 0.64.

    The HC-110 Dil B basis (for 125 lp/mm) is 8 minutes with a contrast index of 2. The grain is also significantly finer, listed at RMS 5 vs RMS 8 for the Technidol basis (vs T-Max value of 8 on their standard basis for their figures which is D-76).


    These books are usually about photography not high contrast scientific applications. Generally you want to use those films at pictoial contrast levels for pictorial photography. You may see a correlation there between contrast and resolution, as being able to resolve something is being able to detect contrast between something. Less contrast, less resolution.
    Last edited by Athiril; 04-04-2012 at 01:41 PM. Click to view previous post history.

  9. #29
    Thomas Bertilsson's Avatar
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    Quote Originally Posted by MaximusM3 View Post
    Sometimes I really wonder how photographers survived and made good art before the internet.
    It is a question well worth examining and pondering.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  10. #30

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    Quote Originally Posted by Athiril View Post
    I don't think you have actually looked for the information, because they are in manufacturer data sheets for many films, if they give out 1000:1 they also give out 1.6:1 and usually (though not always) the MTF chart too. Eg: http://wwwau.kodak.com/global/en/pro...4043/f4043.pdf I'm sure you are more than capable of looking up films on the manufacturer website and clicking on the PDF links for the rest of them.
    So now we are patronizing too.

    Yup, I had already looked. And if you had have looked, you'd have seen that Tri-X and several other films don't give any of these numbers, just the MTF charts (unless of course I'm mistaken, which I've said three times now). Which are useful, but again, not that same. I found numbers for TMY, TMX, TMZ, Plus-X, but not for Techpan, HIE, or Tri-X. I stopped looking after that. The only place I've seen numbers for some of these films is in the Kodak B&W Dataguide, and they apparently only quote the 1000:1 number. WHICH WAS MY F****** POINT.

    Again, also stated for the third time, that the chart pretty much matches up with my experiences, and I bet it matches up with most others' experiences as well, and isn't totally invalid. But here, just for you: YES, YOU ARE RIGHT.

    So to recap, the next time any one asks me if Tri-X is sharper than Techpan, I'll say I don't know. Athiril told me that I should only use the 1.6:1 numbers for comparison, and I can't find that for Tri-X. Also, too, you should throw your Kodak B&W Dataguide in the garbage, because it quoted 1000:1 numbers.

    Sorry for the digressions. I won't bother this thread anymore.

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