Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,481   Posts: 1,542,704   Online: 931
      
Page 2 of 8 FirstFirst 12345678 LastLast
Results 11 to 20 of 72
  1. #11

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,712
    For whatever it's worth, since the test appears to be pretty simple to perform, I'm going to try it just out of curiosity.

    My prints look pretty sharp to me. But I never need high contrast filtration (I'm usually around grade 2) so the effect might be negligable at those settings. Who knows. So I'd be curious to see if there is a noticeable effect when dialing in higher contrast on my setup with my usual paper.

    The figures thrown out by Ctein are still somewhat shocking to me. I mean, if you're making an 8x10 print from a 35mm negative (as in his example) and your focus is off by a whopping 15mm, wouldn't the print be grossly unsharp using a reasonable aperture?
    Last edited by Michael R 1974; 08-01-2011 at 12:55 PM. Click to view previous post history.

  2. #12
    Greg Davis's Avatar
    Join Date
    Feb 2004
    Location
    Crestview Hills, KY
    Shooter
    8x10 Format
    Posts
    1,913
    You are referring to the section in the lens testing on page 82 titles "An Unfortunate Omission". I suppose you could test for this by checking for correct focus in the extreme corners vs. the center at the extreme ends of the contrast scale. If you have a UV filter of the proper size, try running the test both with and without the filter in place and see if there is any perceptible difference. Ask other people if they can pick out a sharper print to eliminate bias.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  3. #13
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,213
    Oh no, not this again...

  4. #14
    Greg Davis's Avatar
    Join Date
    Feb 2004
    Location
    Crestview Hills, KY
    Shooter
    8x10 Format
    Posts
    1,913
    Quote Originally Posted by ic-racer View Post
    Oh no, not this again...
    I know, right?
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  5. #15

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,712
    Sorry about that. I guess this has been hashed and rehashed to death.

    Greg, in the detailed description he gives beginning on page 131, he suggests a simple test raising and lowering the easel from the point of visual focus and seeing if either of the "out of focus" prints are sharper than the one that appeared to be best in focus visually.

  6. #16

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,712
    Sorry I meant the discussion beginning on page 145, not 131.

  7. #17

    Join Date
    Mar 2007
    Location
    Cardigan, West Wales
    Shooter
    Multi Format
    Posts
    90
    Hello, again, Michael, (just read the previous comments). I don't think the effect can be practically solved with a UV filter because of the various conditions under which you would want to enlarge. The focus effect will shift dependent upon the filtration used, the amount of enlargement and the aperture. Also, Ctein was using specialist UV filters which only reduced the problem and cut down light by half and made grades 4 and 5 fall outside the parameters. The only real compromise, he suggests, is to make fixed focus tests with shims at 5mm and 10mm and none, under the easel to: 1) determine if you have a shift, and 2) to approximate its compensation. This being for one paper, lens, filtration, enlargement size only.
    This is how I interpret his findings, anyway. (It appears that the theory of focusing through a blue filter - which I have never done- is not a reliable method).
    Regards, Mark Walker.

  8. #18

    Join Date
    Mar 2007
    Location
    Cardigan, West Wales
    Shooter
    Multi Format
    Posts
    90
    The point of bringing this up 'again', is that for many people it will be the first time. Not all posts can be original.

  9. #19

    Join Date
    May 2011
    Location
    Nova Scotia, Canada. Ex-California
    Shooter
    Multi Format
    Posts
    346
    Oh no, not this again...
    Perhaps such experienced forum readers (and writers) can go beyond simple expressions of dismay and provide links to the relevant threads which in the past have resolved this issue (these issues), at least to the extent they can be resolved in this Enlarging forum. Failing that, at least they could point out the relevant thread titles or keywords for searches (though if they can do that then they can probably provide links to the best threads).

    How about it? A helping hand rather than a superior statement?

  10. #20
    Mainecoonmaniac's Avatar
    Join Date
    Dec 2009
    Shooter
    Multi Format
    Posts
    2,993
    Images
    6
    Are we not seeing the forest for the trees? I mean not seeing the print for the grains?

Page 2 of 8 FirstFirst 12345678 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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