Imaging the sky with a telescope

February 14th, 2011

The ever-challenging Astronomy hobby has led me to experimenting with taking images through a telescope.
My telescope is a rather large reflector on a Nyx - 22 mount that moves in altitude and azimuth (Dobsonian). These telescopes are not generally suitable for astro-photography because they do not compensate Earth rotation. However having 22″ of aperture allows to image brighter deep-space objects with reasonable results using exposure time under 15 seconds.

Saturday night was half-clear and I put my Sony NEX-5 camera into the telescope and took a few images (it always helps to take a few images and stack them together to minimise noise). It was quite thrilling to take an image of the Orion Nebula and see a lot of colour on the camera screen so I kept going and tried a few more objects. The images below are quite modest in modern astro-photography but I’ve had a lot of fun doing it.

You can view a full size image, a brief description and technical data when you click on a thumbnail below and scroll through the gallery.

Equipment

Tags:

22 Comments for this entry

  1. Tricky:

    Hi
    I’m new to astronomy and would like to take photos I have the nex 5 and an 8″ dob with synscan how do you attach your camera to the scope?

    • terrastro:

      Hi, you need a NEX to T2 adapter. I got mine off ebay.

  2. Tricky:

    Thanks for your reply
    With that adapter on does that mount directly to the scope with the lens removed ie telescope Barlow then camera unit or am I missing something.

    • terrastro:

      The adaptor allows you to attach a camera to a T2 thread (M42x0.75). Some focusers have this thread, for others you can use a T2 threaded nose-piece.
      I use Televue Type 2 Paracorr that goes into the focuser. The Paracorr has a T2 adaptor and the camera adaptor screws on to that:
      http://www.terrastro.com/wp-content/gallery/equipment/sony-nex5.jpg

  3. Nich Potter:

    Hi, I’m another person new to imaging, and thinking of the NEX-5. Two questions. Firstly, do you need a laptop connected to do the focussing, or can you focus just using the camera? Secondly, can you do lunar/planetary shots using the movie mode of the NEX-5 (then stack selected images)? Regards, Nick.

    • terrastro:

      No laptop required – I focus on the rear screen. The movie mode is not really usable because it is not possible to set manual exposure and planets are overexposed.

  4. Del Johnson:

    How are you driving your Dob for the 15 second exposures? I use an equatorial platform for mine:

    http://www.equatorialplatforms.com/del.shtml

    I am about to buy the NEX-5n camera and get back into astrophotography. Do you use a remote control for the camera or jsut the built0in time delay?

    Del Johnson

    • terrastro:

      I use an aluminium bracket to depress the shutter button (two cable ties work as well) and use continuous mode – this uses the least battery possible. My telescope is driven in Alt-Az with ServoCat, but with the EQ platform you should be able to do longer exposures than 15 seconds.

  5. rupam:

    Dear Terrastro.

    I have a sony nex 5 and an orion telescope (Orion Apex 127mm Maksutov-Cassegrain Telescope)- 1.25”

    Do you know what adaptor can I use in this combination?

    Thanks much in advance,

    RS

    • terrastro:

      You need two adapters – 1.25″ barrel to T-Thread and T-Thread to NEX. Please not that the high f/ratio of the Maksutov-Cassegrain Telescope will make focusing and pointing very difficult with NEX-5 and may restrict you to planetary photography only.

  6. John Shutz:

    Fantastic shots and with 15 second exposures makes it more fantastic. I’m new at this and using a pretty good point and shoot to learn with. I know I can’t come up with good images, but again, its for learning the steps. Confirm you went to continuous shooting and using the bracket to depress the shutter for how many 15 second cycles you want while also programming the camera shutter for 15 second exposures? Say if you wanted four 15 second exposures, did you have to manually count out the shooting cycles or can you program that as well into your camera? In other words, can you depress the shutter once and simply walk away for a minute and come back and its done? Lastly, if you have tracking in alt/azi what is the maximum shutter time for that set up and how long can you program your Nex 5 shutter for? I’m limited to 15 seconds with my camera unless I learn to hack it for longer exposures. My alt/azi question I don’t think applies to me since I have a goto equatorial mount, but I was curious about that nonetheless. I’ve heard I would be limited anyway even if my camera could go beyond 15 seconds by a couple factors. One is I don’t have a guider and the other is the mount doesn’t have the PEC feature. I’m just thinking ahead and taking advantage of your generousity in answering these questions. Thank you.

    • terrastro:

      Hi John,

      Having fast f/4 optics with a large mirror helps to get enough photons in 15 seconds. Yes, I now use just a mechanical bracket or a cable tie to lock the shutter in the continuous mode, then leave it for 15-30 minutes and go to another object. In Alt/Az I am limited to about 15 seconds with 2m focal length, if your telescope is shorter than you would be able to go for a minute or even longer exposures on an EQ mount without guiding and PEC. NEX-5 gos up to 30 seconds, then it has a bulb mode where you can use the IR remote to open the shutter and then another press to close it.

      Cheers,
      Alex

  7. Edgar:

    Hi!

    In order to connect a Nex camera to the Orion SkyView Pro 8″ Equatorial Reflector Telescope, do I only need a T-Thread to the Nex or is a 1.25″ barrel to T-Thread also needed?

    Thanks in advance for any help!
    Edgar

    • terrastro:

      I don’t know the focuser of Orion SkyView Pro 8″, but if it is 2″ Crayford like on some Orion reflectors then you may be able to screw the T-Thread2Nex adaptor directly to the focuser. Check if the top-part of the focuser unscrews and exposes the T-Thread.
      Otherwise get 1.25″ barrel to T-Thread as well.

  8. Annette:

    Hey, wonderful pictures! Came across your gallery while searching for info on Nex-5N and telscopes/astrophotography. I found the adapter info in the comments here very, very useful! Thanks a million for being so specific! I have the Nex-5N + 18-200mm lens + (Opteka RC3 Remote) and enjoy star grazing with it for hours on end(in the 15 secs range, but still breathtaking). But I need to look deeper … I want a telescope. I am pretty sure I will go with one just a tad smaller than yours, though ;-)
    Enjoy your time out there! And thanks again for the info! Annette

    • terrastro:

      Thanks!
      If I was to give any advice about the telescope that would work well with NEX (no optical viewfinder), then it would be one with fast f/ratio. F4-5.6 would work ok, anything slower than that will make focusing very difficult because you may not find a bright enough star in the field of view.

      • Annette:

        Uhm, am still very (!) new to all the numbers and letters. But F4-5-6 was not what I seemingly found suitable for deep space objects, my yearning. (planets and moon are just too close and young to be interesting). An 8″ reflector is on my wishlist. But before I can afford that, I am now thinking of getting a motorised mount, first. Only a mount. And then put my camera on it and do long exposures with it’s remote control while the mount tracks the object to keep it in focus. Do you think that will work? Have yet to find out how …
        Someone told me about http://www.vixenoptics.com/mounts/polarie.html – cute thingy! But ultimately, I do want a telescope. And I can’t afford such a gadget, limited in growth, like the Vixen.
        Ah well, the temptations and tribulations of a noobie :-)
        It’s great to see someone like you who is already THERE.

  9. Gernot:

    Do you have a modified (IR filter removed) camera?
    Great pics – you have definitely a better sky than here in Germany :/ (too much light polution)

    Best wishes
    Gernot

    • terrastro:

      Yes – stock filter replaced with Baader UV/IR cutoff filter.

  10. james woo:

    I have a 10 inch zhumell reflector. I bougth an adapter, ultrawide 2 inch for my sony nex5. The problem i have is with the adapter on the camera the camera tells me it-cannot reconize lens. attatch it properly. This happens when i try to snaap a photo. how can i fix this problem?

    • terrastro:

      Go to Menu, then Setup and enable “Release w/o Lens” option

      • james woo:

        Thanks so much for the help! Did not know that option was even on the camera. Thanks again.

Leave a Reply