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  1. #11

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    Roger, I'd be the last to defend the academic rigour of Wikipedia, but in this case I vaguely remembered Zeiss themselves making this claim. So I went and Googled it, and lo and behold, Zeiss actually have the audacity to claim they captured 400 lp/mm on film! Here you go. Apparently achieved with some kind of copy film processed in an unusual manner, a combination which allegedly delivers 800 lp/mm at a subject contrast ratio of 1000:1 (see PDF datasheet on this page). Never mind that the characteristic curves of that lot would probably give one vertigo!

    Still quite irrelevant in the real world, if true at all.

    PS. Loved Perfect Exposure. Actually have a signed hardback among the handful of photography books I own. It must be as strange for you to know your signature is in loads of strangers' bookshelves as it is for me to bump into the author on a forum... Assuming you're not another Roger Hicks, that is!

  2. #12
    jd callow's Avatar
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    kind of like the 'wind chill factor.'

    *

  3. #13
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    I have an enlarging lens which resolves over 400 lp/mm according to my microscope and allowances for not using a proper resolution test target. I have a Kodak film which resolves 800 lp/mm. In theory I should be able to resolve 300+ lp/mm on film. Hopefully I can do my tests in the next couple of weeks and post the results when I am done.
    Last edited by richard ide; 01-29-2007 at 11:42 PM. Click to view previous post history. Reason: seplling

  4. #14

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    Quote Originally Posted by Dorian Gray View Post
    , Zeiss actually have the audacity to claim they captured 400 lp/mm on film! Here you go. Apparently achieved with some kind of copy film processed in an unusual manner...
    I stand corrected. I'd quite forgotten the claim until you reminded me, because it was so useless. I did cover my arse by saying 'no useful film' and 'no camera could hold it flat enough'; the 'float' in a 35mm camera film gate is what limits sharpness. But no doubt Zeiss built a test rig...

    I did remember their claim to get 200 lp/mm in camera, but they admitted you had to use 'focus bracketing' to get it, i.e. refocusing slightly for several shots. Apparently for a given film and camera this will allow you to see 200 lp/mm sometimes -- but again, you have to ask why, and what it means.

    Thanks for the kind words about the book; if you take a look at www.rogerandfrances.com you'll see what I'm increasingly doing nowadays instead of books.

    Cheers,

    R.

  5. #15
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    Quote Originally Posted by Rob Skeoch View Post
    What does this actually mean?
    That someone has forgotten waht it means to make pictures.

    Isn't the limit for handheld typically around 30-40l/mm?


    BTW, some compact digis are probably pushing 300 lines/mm

    ~12mm/~3000 sites/12mm sensor = 250l/mm and I recall that some sensors are smaller and higher-res

    They are NOT, however, large lenses -- holding a level of sharpness at sizes appropriate for 35mm or larger would be a far more difficult lensmaking task.

    If rumours about the new high-end Canon SLR are correct, it will be a bit less than 6K*4K pixels or for 24x36 framing, ~175l/mm

    This is WAY high for an SLR and I expect that few SLR lenses can approach that. Seems kind of pointless beyond that point to talk about greater precision give the limitations of the 35mm-style format.

    "What Would Zeus Do?"
    KBPhotoRantPhotoPermitAPUG flickr Robot

  6. #16
    jd callow's Avatar
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    Kevin,
    I believe that l/mm requires at least 2 samples to create the line so a (6k/36mm)/2 or 166.7/2 = ~83 lines per mm. If I'm wrong I'm sure someone will correct me.

    I do agree wholeheartedly that the practical use of the information is pretty minimal.

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  7. #17

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    The lines/mm came from video usage of lines/height, and is often used on newer D-SLRs. What is missed is that actual resolution capability has nothing to do with photosites nor file sizes. There are dead areas on imaging chips, unlike film which does not have dead areas.

    On the subject of handheld photography, it is rare to do much better than 40 lp/mm (line pairs/mm) regardless of technique or camera gear. While there are some things that can help that out a bit, a tripod is the only consistantly useful way towards higher resolution. There is nothing magical about image stabilization nor imaging chip that suddenly changes that; handheld photography means accepting lower resolution. Of course, the reason to use smaller cameras is that we like shooting handheld with them.

    With Zeiss, and the high capability of their lenses, even they point out that the reason to even state this is to point out that their lenses will not be the greatest limiting factor in your photography when you want high resolution. Unfortunately, many on internet forums and in publications jumped all over part of the Zeiss statement, without understanding the context and implication (my opinion). It would not be surprising if other lenses showed a great capability too (from other companies), yet our practical limit should be near 40 lp/mm.

    Ciao!

    Gordon Moat
    A G Studio

  8. #18
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    Quote Originally Posted by HerrBremerhaven View Post
    T, yet our practical limit should be near 40 lp/mm.
    Ciao!
    Gordon Moat
    A G Studio
    This was what an old master answered to me decades ago when I asked him, why in his opinion tripods should be welded to camera bottom plates

    A truth not very popular tho and therefore seldom mentioned, spoils all the party for the many gear heads among the "serious " amateurs.

    Regards
    bertram
    A la recherche du temps perdu: www. bersac.de

  9. #19

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    Quote Originally Posted by HerrBremerhaven View Post
    <snip>
    With Zeiss, and the high capability of their lenses, even they point out that the reason to even state this is to point out that their lenses will not be the greatest limiting factor in your photography when you want high resolution. Unfortunately, many on internet forums and in publications jumped all over part of the Zeiss statement, without understanding the context and implication (my opinion). It would not be surprising if other lenses showed a great capability too (from other companies), yet our practical limit should be near 40 lp/mm.
    A G Studio
    Y'know, Gordon, I usually shoot at effective apertures of f/11 and smaller. At effective f/11, its possible that the film, given that my technique is meticulous, limits the negative's enlargeability. Possible at effetive f/16 too. But from effective f/22 down, diffraction kills all lenses equally and sets the limits.

    I mention effective aperture, not aperture set, because I do a fair amount of closeup photography.

    All of this assumes good technique. The big idea that leaps out of the Modern Photography article I mentioned earlier in this thread is that small format shooters are usually pretty casual about focusing perfectly and are absolutely sloppy about motion control. MP had to bracket focus to get really good resolution and went to considerable effort to control motion. Camera motion at high frequency (mirror locked up) and low (on a very sturdy tripod) and subject motion.

    Shooting handheld is a recipe for low resolution. Most of us trade off resolution in the plane of best focus, wherever it might be, for depth of field. And many of us shoot low resolution emulsions and so can't get the best our lenses can give. And, as LF shooters like you never fail to remind the world, what matters is resolution in the final print, not resolution on film.

    All of which are reasons to pay more attention to technique and to the desired result than to lens tests.

    Cheers,

    Dan

  10. #20

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    Hello Dan,

    Definitely agree on many points. As a large format shooter, I would hesitate to claim more than 60 lp/mm from any shots, though I feel that is a good working target. Based on the average viewer eyesight being able to resolve maybe 5 lp/mm (some better, some worse), that would give a 12x enlargement capability. It might be of interest that commercial printing has long stated a preference for 300 ppi image files, which oddly enough equate to near 5 lp/mm.

    I do shoot quite a bit of 35mm images. It is rare that I would have any of those printed larger than 10" by 15", and I think smaller prints have a better chance of avoiding softness. I do have hanging two large 24" by 36" B/W (silver) prints done from 35mm Kodak TriX. Both of those look quite good at that size, and get lots of compliments, but I feel those are the exceptions. It is possible to achieve high resolution images, but not practical to consider it easy.

    Ciao!

    Gordon Moat
    A G Studio

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