Stars with tails even at 30 seconds?

Discussion in 'Beyond the Basics' started by battletone, Oct 10, 2009.

  1. battletone

    battletone TPF Noob!

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    Is this right? I have like 5 photos I took at night with my new tripod, and even with a 30 second exposure the stars are motion blurred.

    I think they are 2x-3x as long as they are wide.

    Really kind of ruins the photos.
     
  2. dmatsui

    dmatsui TPF Noob!

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    I havent been able to try this myself but most people trying to capture the nightsky, or milky way without the sky trails do so with a maximum shutterspeed of 30 seconds. Slight star trails are visible if you zoom in a believe but they should be relatively unnoticable when resized to say 800px for the web. but yes i wouldnt recommend using a shutterspeed of more than 30" if you dont want star trails (as you've noticed)
    I dont know to what extent your stars have traveled or if in certain regions in the world it is more noticeble than others.
     
  3. battletone

    battletone TPF Noob!

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    Here are a couple 100% croppings. Both are at 30 seconds.

    [​IMG]

    [​IMG]
     
  4. chammer

    chammer TPF Noob!

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    i see you shot at iso 800. as you're on a tripod, and shooting a long exposure anyway, you really can back it down to iso 100. would really cut down on the noise in the images.
     
  5. astrostu

    astrostu I shoot for the stars

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    It all depends on the lens (field of view). With a 35 mm lens on a 1.6x crop body (56 mm equiv.), star trails will start to show after about 20 seconds.
     
  6. battletone

    battletone TPF Noob!

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    Well based on looking at the settings, the crop with the roof was 400. But the other was 800 with reduction on.

    I had just bought a remote too, but it wasn't with my gear. The 100 wasn't allowing enough exposure at 30 seconds for what I was trying to do. It was f9 for the roof crop and f11 for the other. I probably could have used a much lower f stop but I was experimenting, so maybe next time. :thumbup: I wanted the forground to be in focus though as there was trees and a grain bin I wanted with the clouds moving. The stars were something I wanted to experiment with too, but these pics I honestly wasn't expecting the tail issues I had read about.

    iso800, f11, 30 seconds
    [​IMG]

    iso400, f9, 30 seconds (this is an edited RAW with exposure and stuff)
    [​IMG]
     
    Last edited: Oct 10, 2009
  7. Josh66

    Josh66 Been spending a lot of time on here!

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    I think that what charmmer was trying to say is that since you're already using a 30 second exposure, why stop there?

    Drop the ISO down to 100 and expose for 240 seconds (4 minutes).
    This would be the exact same exposure as your 800 ISO 30 sec shot.
    [EDIT]Although, since it's a longer exposure - the star trails will be longer and you will capture more movement in the clouds.[/EDIT]

    (You will have to use Bulb to do this.)
     
    Last edited: Oct 10, 2009
  8. astrostu

    astrostu I shoot for the stars

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    Unless your roof was within ~10 meters/yards of the camera, it's doubtful that it would be out of focus even at f/2.0. The image below (not meant to thread-jack, just as an example) was taken for 15 sec, f/1.4 at ISO 200. Camera was on a stationary mount about 10 m from the brown roof, maybe 20 m from the dome, and 20-30 from the trees. They're in focus even when the image is printed as a 12"x18".

    [​IMG]
     
  9. battletone

    battletone TPF Noob!

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    Points taken.

    My remote I bought wasn't with my camera so I was limited to 30 seconds.
     
  10. Garbz

    Garbz No longer a newbie, moving up!

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    As a very rough rule of thumb you can consider the maximum exposure allowable for NO star trails to be 600/EFL. So say you have a 20mm lens on a D200, the equivalent focal length for 35mm becomes 20x1.5 = 30mm. So 600/30 = 20 seconds. Anything beyond 20 seconds on this very wide angle will cause very clear star trails.

    You can adapt this formula so you don't need to remember your EFLs just make it 900/focal length for Nikon non-fullframe cameras, or 960/focal length for Canon non-fullframe cameras.

    As always these rules are based on standard viewing practices. If you zoom in at 100% you'll probably note that there are very slight trails, however at any normal viewing they should not be noticeable.
     
  11. Hellrot

    Hellrot TPF Noob!

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    at least, with nikon, you can use any infrared device as a remote, as well. So you can use the remote shutter function. I use my comcast remote, personally :)
     
  12. Josh66

    Josh66 Been spending a lot of time on here!

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    :lmao:

    Really?

    I'm going to try that (Canon)... Any certain button you have to push, or does any button work?
     

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