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  1. #1

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    Long lens for Nikon for Picture of Moon

    My 8 year old daugter loves science and things having to do with space. I would like to take a really nice picture of a full moon for her birthday, which is quite a while off. Currently, my longest lens for my Fm2n is 135mm, and I'd like to get a longer lens to get a better shot of the moon. I probably won't use the lens very much for other things, and so I don't want it to be excessively expensive, and I'll have to sell other equipment to finance it. What would be some good options?

  2. #2
    Lee L's Avatar
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    Peter,

    The moon is 0.5 degrees in diameter. You can calculate how much of the frame that will fill if you get the angle of view for the lenses you're interested in. You'll need to be around 1000mm to get close to full frame, but you could also enlarge from a somewhat smaller image. You might want to try a decent refracting or Newtonian telescope and T adapter for a moon shot. A yellow filter and B&W film would be a good choice, as that would decrease apparent chromatic abberation found in less expensive refractors. One of several good places to find a decent small telescope would be Orion Telescopes. This has the advantage of being an instrument your daughter could use to explore the night sky rather than a long lens you'll never use sitting in a closet.

    PM me if you want more specific recommendations for vendors and telescopes.

    Lee

  3. #3
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    See my posts in the Exposure forum recently. The topic is using a f/10 telescope. I talk about the exposure and focal length factors.

    In brief shutter speed must be less then 1/one half the focal length of the lens:
    50mm lens => 1/25 second
    100mm lens => 1/50 second
    ...

    Exposure - the full Moon refects half the light it receives from the sun. Therefore use the Rule of 16 and open one stop.

    Tri-X f/16 @ 1/500 sec => f/11 @ 1/500 sec

    Steve

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    moon project

    I totally agree with the first reply about the value of a decent starter scope. I got an inexpensive 6inch aperature Newtonian reflector when I was 16 (10 yrs ago), and I took care of it so it's still perfectly usable (and used). As far as the Nikon goes, if you're going with an inexpensive lens solution....I've used a fine grained film to enlarge from a 200mm f/4 lens with teleconverter. The incredible brightness makes the small aperature doable. Remember to use cable release or self timer for steadyness.

  5. #5
    Jim Jones's Avatar
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    Decades ago there were several 400mm f/8 and f/5.6 lenses on the market that were decent performers if well made. I tried several before finding one of the good ones. They are now quite inexpensive on the used market. A basic telescope may be better for your daughter, but a camera adaptor and a solid tripod run up the cost. Eyepiece adaptors are another way to enjoy astronomy viewing with telephoto lenses.

  6. #6

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    Use this as a visual guide:

    http://www.sportsshooter.com/contest...ge.html?id=626

    The longer the lens the better you will be. The moon ain't big up there.

  7. #7

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    I appreciate all of the advice. I do have some large and sturdy tripods and tripod heads, and I'll certainly use a cable release and mirror lock-up. I'm leaning towards the spotting scope idea, if a decent one can be had for a reasonable amount.

  8. #8
    Lee L's Avatar
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    Quote Originally Posted by Stever View Post
    Exposure - the full Moon refects half the light it receives from the sun. Therefore use the Rule of 16 and open one stop.

    Steve
    It would be more accurate to say that the moon reflects about half as much light on average as does the earth. Since the moon and earth are roughly the same distance from the sun and so receive essentially the same amount of light from the sun, you'd need to give the moon about a stop more exposure than the sunny f:16 rule to get the moon up the gray scale a bit. We're used to perceiving the moon as bright, so it helps to "overexpose" it a bit.

    (The earth reflects about 12-14% on average, and the photo industry has settled on a standard 18% gray "average" target. On average, the moon reflects about 6% of the light that hits it, or about half what earth does. The term for this reflectance is "albedo".)

    Lee

  9. #9

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    Quote Originally Posted by Lee L View Post
    It would be more accurate to say that the moon reflects about half as much light on average as does the earth. Since the moon and earth are roughly the same distance from the sun and so receive essentially the same amount of light from the sun, you'd need to give the moon about a stop more exposure than the sunny f:16 rule to get the moon up the gray scale a bit. We're used to perceiving the moon as bright, so it helps to "overexpose" it a bit.

    (The earth reflects about 12-14% on average, and the photo industry has settled on a standard 18% gray "average" target. On average, the moon reflects about 6% of the light that hits it, or about half what earth does. The term for this reflectance is "albedo".)

    Lee
    Check out this link:
    http://jeff.medkeff.com/astro/lunar/obs_tech/albedo.htm
    As you can see from this link the 6% number is a bit mis-leading. Reading down you can find that various features have albedo's that vary from 8.6% to 30%. You could simply add 1 stop to the sunny-16 rule, but it might be more interesting to expose using the sunny-16 rule, and then use expanded development to bring up the highlights - the additional contrast might prove visually appealing.

  10. #10

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    Quote Originally Posted by Peter De Smidt View Post
    I appreciate all of the advice. I do have some large and sturdy tripods and tripod heads, and I'll certainly use a cable release and mirror lock-up. I'm leaning towards the spotting scope idea, if a decent one can be had for a reasonable amount.
    I would recommend going with some kind of telescope. This has the added advantage of allowing you to use an eyepiece to look through it and check the moon's image. Once you have eliminated vibration, the next biggest limiting factor for lunar shots is going to be the atmosphere itself. At the kind of magnifications you need for lunar shots, unsteadiness in the air becomes very significant. You will want to try and pick a night when the air is very steady - astronomers refer to it as good seeing. The best nights won't necessarily be cool or cold clear nights - on those nights winds in the upper atmosphere cause unsteadiness. The best nights tend to be hot, humid nights in the summer when the air is completely and a bit hazy.
    Good luck

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