First quick attempt of astrophotography

Discussion in 'Landscape & Cityscape' started by toruonu, Oct 11, 2005.

  1. toruonu

    toruonu TPF Noob!

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    with 20D :) I have dealt with astrophotography with professional equipment (nice telescopes with CCD cameras etc), but this is a first try with my own technology :) So what I used was a tripod + 20D + Canon 300mm f/4L IS USM + Canon 1.4 EX II which gives a full frame for pleiades. Below you'll find the shot itself. I will try today or in the near days also to take a shot at Andromeda galaxy which should be exactly full frame for this configuration.

    [​IMG]
    it's 6 second exposure which already gets the dots to arcs so I have to experiment with higher iso levels and maybe removing the converter to get shutter speeds down :)

    Technical parameters: 6s, f/5.6, ISO 100
     
  2. PlasticSpanner

    PlasticSpanner TPF Noob!

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    Are you using a remote cable and the "Hat Trick" method? There's some movement in the camera which may be causing that curved effect.

    Also try taking several shorter exposures and stack them (or merge in PS) to increase exposure i.e 5-3 second exposures to get 1-15 second exposure!

    It's quite clear considering you're using am F4 300mm and 1.5X (?) extender! :thumbup:

    A very good start & I can't wait to see your next ones!:)
     
  3. doenoe

    doenoe TPF Noob!

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    also make sure your tripod is on a steady underground. I noticed that when i walk around next to one of the legs, i get camera shake. My floor in my room is "floating" so when i walk, the floor moves abit and so the camera moves too.
    Good luck with the next shots :)
     
  4. toruonu

    toruonu TPF Noob!

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    Alright, now tell me what's the hat trick :) I do use mirror lockup and remote control for the shots. And I'm shooting outdoors so it should mostly be steady ground :D
     
  5. PlasticSpanner

    PlasticSpanner TPF Noob!

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    The "Hat Trick" goes back to the beginnings of photography and is possibly the most reliable method of avoiding camera shake for astrophotgraphy.


    Basicly you hold a matt black peice of card over the lens (but not touching it) and operate the remote release on Bulb setting. After waiting for a few seconds for any movement in the camera to cease you quickly lift up the card and expose for however long you wish. At the end of the exposure time you drop the card back in front of the lens and close the shutter. This used to be done with the photgraphers hat before the advent of mechanical shutters (hence the name "Hat Trick") and is still used today with pinhole cameras! :)

    You need to practice counting the exposure time in your head with a stop watch and with each stop of exposure being twice as long as the last there is little difference between 4, 8 and 16 seconds except for the motion of the Earth!
     
  6. PlasticSpanner

    PlasticSpanner TPF Noob!

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    If you're using the mirror lock up then the shake is probably caused by the remote moving the camera when you start/end the exposure!


    Also even when outside I tend to "creep" away from the camera whilst it's running to avoid vibrations. If you use a telescope you'll see how sensitive these things can be to footsteps!:lol:
     
  7. pursuer

    pursuer TPF Noob!

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    Good first try, that is definatly a mechanical vibration. there wouldn't be any perceivable curve in a star trail that short. Using the hat trick is good advice. Try jacking the ISO up, 800 is a safe bet for astrophotography. Keep the images coming :)
     
  8. Mike Jordan

    Mike Jordan TPF Noob!

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    You are using to much lens. The longer the lens, the shorter period of time you can take shots before you see movement without a tracking mount. Plus the longer the camera will viborate after you click the shutter. You really aren't going to gain that much with a teleconverter on a 300mm lens. If you have one, go with 50mm or so. You can get around 30 second shots at 50mm without movement showing in the stars. And make sure you have your lens set on infinity. I had to focus on distanct things with my camera and see where the lens ended to make sure that I could manually focus it in the dark. I used a small flashlight to set the lens on the mark as the auto focus just doesn't work very well on stars.

    Mike
     
  9. PlasticSpanner

    PlasticSpanner TPF Noob!

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    When setting the focus on my astrophotography camera I tape it down with insulation tape to prevent it from moving (or myself instictively trying to focus!)


    You can also do the same with the aperture ring if you think you might accidently try to adjust it!
     

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