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  1. #11

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    Quote Originally Posted by Nicholas Lindan View Post
    I don't have many pictures where I look at it and wince, thinking the lens really screwed that one up.
    Ditto here.

    Though i have some. But it isn't resolution or lack thereof that screwed those up.

  2. #12
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    Quote Originally Posted by Q.G. View Post
    Bloom and fill in are the same thing: spread.
    So a negative version will not be able to reveal anything a positive version would not show already.

    Charts like this are indeed intended to be photographed using a lens. You already have a comparison for your lens test in the chart itself.
    But unless you are examining the aerial image produced by the lens, you will indeed be testing the emulsion of the film too. If you print the negative before examining, you'll be testing the emulsion of the print as well. Plus the loss created in the transferral from negative to print (whether it be by contact or projection).

    These charts therefore are of very limited practical use, unless you put the microsope on the optical bench to examine the aerial image produced by the lens.
    Blooom and fill are not the same. I won't relate the details of this, but it is related to the mass of the dark (or light) surround that creates edge effects or overwhelms them, particularly as the subject matter becomes smaller. This is, in some ways, related to macro and micro contrast.

    As for making prints directly from the charts, well, you measure the response of the printing process alone (enlarger or contact - and the paper). If you photograph a chart and then print it, you measure the camera lens, flare and film. That print will be the overall system response.

    PE

  3. #13

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    When I need to do some comparison testing, I just use some fresh and crisp dollar bills. Take out a form core board, tape one dollar bill in the center, one at each corner. It has enough font sizes for good reference, prints are crisp and size and quality are very uniform. Enough for my purpose....
    Develop, stop, fix.... wait.... where's my film?

  4. #14
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    Quote Originally Posted by ic-racer View Post
    I think there are some on the internet you can download and print out. Search for USAF test chart. http://medfmt.8k.com/mf/USAF.pdf
    The link did not work for me either, but here is another alternative:

    http://www.darkroomagic.com/DarkroomMagic/Camera.html

    You can print these yourself, but depending on your print quality, you may want to use a distance, which makes you independent of the smallest bars. High-resolution alternatives can be purchased for little money from Edmund Scientific.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  5. #15

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    All the sites worked fine for me, I really appreciate the efforts. I'm using box stock IE 8 and xp fully patched BTW, and did not need to do a refresh or anything. Your mileages obviously varied ;-)

    Boy,,, I was on the Edmond Sci site,,, inexpensive is something I didn't even think about when looking at most of their prices. I'll go check again.


    quote: "Shooting hand held, wide open, at medium/low shutter speeds, on high speed film or using an 'acutance developer' degrades the system performance to such an extent that lens performance is largely irrelevant. Which is as it should be"

    A little out of context for sure,,, but I think I'd add,,, "for me" (actually for you), at the end of your sentence. Different folks, different directions in the hobby. I enjoy the technical side of the hobby, and have just begun (like since I joined apug), to appreciate a little grain visible in the final print. My usual combination in the 70's was Pan X and microdol x 1:3 with an ASA of less than 25. For some folks, being able to previsualize perspective and a particular lens barrel distortion or bow is totally irrelivent to the picture. For me,,, its an important (and fun) part of the process,,, unless I'm just snapshotting the 6 year old "alternative process" pocket thing which does any number of bad things in the corners. (and in the middle for that matter).

  6. #16

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    snip: "A little out of context for sure,,, but I think I'd add..."

    Sorry about that,,, not your comment out of context,,, it was out of context after I snipped it. I think I understood what I tried to write, but when I read what I wrote wasn't what I meant to write???

  7. #17

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    Quote Originally Posted by Photo Engineer View Post
    Blooom and fill are not the same. I won't relate the details of this, but it is related to the mass of the dark (or light) surround that creates edge effects or overwhelms them, particularly as the subject matter becomes smaller. This is, in some ways, related to macro and micro contrast.
    Both however are the result of one and the same thing.
    If you have a measure of that (spread), you'll know about both bloom and fill.

    Quote Originally Posted by Photo Engineer View Post
    As for making prints directly from the charts, well, you measure the response of the printing process alone (enlarger or contact - and the paper). If you photograph a chart and then print it, you measure the camera lens, flare and film. That print will be the overall system response.
    The OP asked about a way to test a lens.

  8. #18
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    Quote Originally Posted by Grif View Post
    ... Boy,,, I was on the Edmond Sci site,,, inexpensive is something I didn't even think about when looking at most of their prices. I'll go check again. ...
    I have used these, and at $3 a piece, you don't need to re-mortgage the house.

    http://www.edmundoptics.com/onlineca...productID=1852
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  9. #19

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    Hey,,, good job. I finally went thru most of them,
    http://www.edmundoptics.com/onlineca...productID=1665

    Is also an affordable item I'll likely add to the order with the small resoulution target.

  10. #20

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    Resolution represented by the lines on the target is a function of distance and focal length (i.e. scale).
    So one target can serve for both low and high resolution tests, just by altering distance.

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