SBR of Perigree Moon

Discussion in 'B&W: Film, Paper, Chemistry' started by Puma, Mar 26, 2011.

  1. Puma

    Puma Member

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    Has anyone tried to develop shots of landscapes with the perigree moon? Due to time limitations I only got a few minutes to shoot it and couldn't measure the SBR highlight of the moon. I'm just looking for a basic guideline of N, N-1, N-2, etcetera? Note that I shot this moon with a wide angle lens so it isn't a closeup, not sure if that matters?

    I realize that I could under develop it (N-2) and squeeze out some detail in printing but I wonder about this because I've heard that a moon like is much brighter than our eyes realize because it's reflecting the sun. Mostly I just don't want to wait another eighteen years for a shot of such a unique moon.

    Thank you in advance for your kind insight,

    Puma
     
  2. 2F/2F

    2F/2F Member

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    Hi,

    The easiest way to do this (although it really isn't all that easy) is with double exposure. There are three ways to do it that I can think of. 1) Expose for the moon. Wait for it to move out of the frame. Then expose for the rest of the shot. 2) Expose for the shot without the moon. Wait for the moon to come into the frame. Then expose for the moon. 3) Expose the moon and the scene onto separate negs, and stack them when printing. You can even change lenses for the moon shots to minimize or increase its size in the print.

    Of the three, option 3 gives you the most options, but it also presents the largest challenge in printing, minimizing dust and scratches, and making sure everything is in focus.

    Putting a piece of tracing paper over your focusing screen and sketching the basics of the composition (in option 2) or the moon's location (in option 1) will help you position the moon or the landscape shot in the second exposure, respectively.

    FWIW, sheet film is ideal for this.

    P.S. If the moon is isolated enough (i.e. free from any other subjects, and just hanging there in a purely black sky), you can drop it on top of your other shots at any time. You need not necessarily follow the exact procedure I wrote in option 2. With sheet film, you can carry on with your shooting, exposing as many landscapes as you want, and making your tracing paper sketches for each shot. Then you can come back later and hit them all with the moon. Again, you can change lenses before you do this.

    Even if the moon is not all that isolated, you can make a dodging tool to use in camera, over your lens, so that only the moon and the sky immediately surrounding it shines through to the film. Bring some black card stock and a pair of scissors and you are set. You can see exactly what it does through the viewfinder in order to make the right size hole and place it in the right spot.

    I am sure it is going to come up about how the hell Ansel Adams did it with one exposure. The answer is that the Hernandez picture was not taken at night, but at sunset.
     
    Last edited by a moderator: Mar 27, 2011
  3. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    The exposure for the moon itself is 1/ISO at f:11, even for the perigee-syzygy of a few days ago so compare that to your actual exposure, and you should be able to figure out the SBR. It's going to be more stops than you can compensate for in development, and the moon moves fast, so even with a wide lens, I doubt you'll have much detail if the exposure was longer than a few seconds.
     
  4. Wade D

    Wade D Member

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    I don't know if this helps with your landscape shots. The shots I took didn't include a foreground other than silhouetted trees. The exposure was for the moon itself through a veil of light clouds. I used Plus-X and the basic exposure was 125 @ f/8 which I bracketed 2 stops either way. It really depends on what your exposure was to find out if any detail in the moon will show up.
     
  5. Rick A

    Rick A Subscriber

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    I did the same thing as Wade. I usually stack negs to include the full moon. Occasionally, I double expose to have the moon unrealistically large in a photo.
     
  6. Lee L

    Lee L Member

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    As the moon moves around the earth from the side toward the sun to the side away from the sun, the variation in the moon's distance from the light source, the sun, is about 0.00269179%. You can run the "square of the distance" calculations and see that there's no way you can even set your camera remotely accurately enough to compensate for such a small difference. The difference between an apogee and perigee full moon (both on the side away from the sun) is much, much smaller. So just use the numbers David mentioned and you'd be fine.

    The difference in angular size between an apogee and perigee moon is about 10%, not very noticeable, and likely impossible to see any difference in a wide angle shot. The actual moon sizes in apparent degrees are perigee 0.567666667 degrees and apogee 0.495666667 degrees.

    For more on the recent full moon see:
    http://blogs.discovermagazine.com/badastronomy/2010/08/26/does-this-perigee-make-my-moon-look-fat/

    There was a lot of hype from scientific illiterates in the press about this one.

    Lee
     
  7. Sirius Glass

    Sirius Glass Subscriber

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    Gee, when I suggested opening one stop from Sunny 16 here a few years ago, I stated that assuming an albedo of about 0.5 was close enough. A bunch of neo-pseudo-nerd-experts jumped all over me pontification that the albedo was much less than that. Guess what?? After all their bull pucky and blither, that exposure works!

    Steve
     
  8. Jim Jones

    Jim Jones Subscriber

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    You might have a dozen times in the next year to shoot a similar moon. If this month's full moon is rare, it's only by a very slight margin.

    As for the sunny 16 or loony 11 rule for photographing the full moon, that applies to the moon fairly high in the sky or in very clear atmospheres. Near the horizon light from the moon must pass through much more air than when higher. This filtering is so strong that we can sometimes look directly at the setting or rising sun. Bracket many stops towards greater exposure. Film is less valuable than good photo ops.

    Steve is right about lunar photography rules sometimes being useless. It is indeed a rare simple rule that applies to all complex situations, Murphy's law being perhaps the best exception.
     
  9. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Close to the horizon at dusk, I would spot meter the moon, but when I photographed it on March 19, I waited until after dark to get a black sky, so it was fairly high up, and loony 11 worked just fine (actually it was more like f:14, since I set the lens on 11 and was using an FD-EOS converter, which acts like a 1.2x extender). It wasn't a photograph appropriate for APUG, but you can find it in my flickr account, if you're curious.
     
  10. Kirk Keyes

    Kirk Keyes Member

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    Well, you will not have to wait another 18 years. You're about 1 week too late - the "super perigee" was on the 19th of March. Now it's pretty much like any other waning moon.

    Now you just have to wait about 17 years and 51 weeks for the next one!