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Paper recipricity and the Loch Ness Monster

Discussion in 'Enlarging' started by fhovie, May 13, 2003.

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  1. May 13, 2003 #1
    fhovie

    fhovie Subscriber

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    I tend to gravitate to exposure times of more than 8 seconds and less than 20 seconds and avoid the lowest f stop and f stops over (focal length/4). The first is for control. Timer error and time for manipulation are factors for very short exposure times. Very long times seem less effective as well. As far as f-stop - It is my understanding that the threshold for diffraction in the iris of a lens is about (focal length/4). That would be a good max of f22 for my 150mm lens and f16 for my 50mm lens. I have read posts here that indicate some of you are using very short times. Is there a benefit? Are you just using the "sweet spot" on your lens? What about times over 30 sec. I hate these long ones. My old timer really starts to stick over 30 seconds. What have you observed??
     
  2. May 13, 2003 #2
    Nige

    Nige Subscriber

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    I use f8 with my 80/4 Schneider Componon S (f11 for postcards), and either f5.6 or f8 with my 50mm lenses (EL-Nikkor 50/4 and Schneider Componar 50/3.5) I only justification for this is viewing the grain though the focus thingy (Peak Microsight) where it looks best, and the regular bleatings of people who say "stop down 2 stops from wide open". My exposure times for a 10x8 generally are about 8-10secs which I'm comfortable with in regard to burning and dodging (hardly ever dodge).
     
  3. May 14, 2003 #3
    FrankB

    FrankB Member

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    f8 on an EL-Nikkor 50mm, but for no terribly scientific reason! It gives me useful exposures of between 10 and 20 seconds for most straight 10x8's on Ilford MG WT RC and I have no gripes about sharpness or distortion.

    Allow me to tempt you spend money, however:

    http://www.rhdesigns.co.uk/SCPro.html

    I bought one of these late last year after humming and hawing about it for a longish time because of the undeniably steep price (about 2/3rds what I paid for the rest of my darkroom!). Best money I ever spent. My only regret is that I waited so long.

    I printed a B&W calendar for family and friends last year made up of, 12 5x7's mounted on a pre-printed calendar. I did 9 of the *%$&**$% things and if it hadn't been for this timer I'd be printing them yet!

    Sorry to wax lyrical but really good kit brings out the evangelist in me! ;-)
     
  4. May 14, 2003 #4
    Ole

    Ole Moderator Staff Member Moderator

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    My exposure time (when using the Opemus 6a) is 10 seconds. I use an Ilford print exposure meter, and adjust filtration for contrast, then set aperture and ND filtration to give an exposure of 10 seconds. If the contrast isn't right, I then decide whether to change the filtration or try burning first.
    I have ended up never dodging, but I might well burn in everything but one tiny spot...

    My timer is a metronome - if it was good enough for Saint Ansel in the Dark, it's good enough for me!
     
  5. May 14, 2003 #5
    David Hall

    David Hall Member

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    Ole...

    Interesting comment about never dodging but burning everything but one spot. I find myself doing that too from time to time and always laughed at myself...saying "why not just dodge that spot?".

    What is the Ilford exposure meter you mentioned?

    dgh
     
  6. May 14, 2003 #6
    Nige

    Nige Subscriber

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (OleTj @ May 15 2003, 06:15 AM)</td></tr><tr><td id='QUOTE'> I have ended up never dodging, but I might well burn in everything but one tiny spot...
    </td></tr></table><span class='postcolor'>
    hehe! I've never thought of it like that but I tend to do the same in that situation.

    I'm guessing Ole is talking about a Ilford EM10?
     
  7. May 15, 2003 #7
    Ole

    Ole Moderator Staff Member Moderator

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    Ilford EM10 it is - I didn't know what type it is since it's only ever used in the dark. It's sensitive to safelight, too...

    I've had it for yeard, but nver figured out a good way to use it. Then I got bored one dy, and ran a whole series of tests: One negative, one paper, all grades. I measured key values (black, almost black, midtone, almost white, white) at constant 10 seconds exposure, hten plotted the readings on graph paper. Suddenly it all became clear, so I can now produce a test print right away - and know what I'll get with 10 seconds base exposure.
     
  8. May 15, 2003 #8
    glbeas

    glbeas Member

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    I've got an EM 10 also, I used to use it like that too. Now I use a beseler pm2 analyzer pretty much the same way for B&W printing. I can get twice the range on it as I do the EM 10. Stll takes a while to get things zeroed. Usually when I get a good tonality print I'll do some readings on selected areas and jot down the results along with the time and filtration. Pretty soon I have a list of values for each time and contrast filter setting I use the most and saves time and paper. So if I make a big print and my aperture is nowhere big enough for a 20 second reading I can shift to a 60 second reading for similar tones and get on with business.
    As and alternative you can do your setups for a standard aperture setting and read your values to find differing times for each tonal value. I think this takes longer to establish but can be worthwhile.