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Telescope Adapter Help

Discussion in 'Accessories' started by Marine Paethor, Mar 14, 2013.

  1. Marine Paethor

    Marine Paethor Mu-43 Regular

    26
    Feb 17, 2013
    Oregon
    Donny
    I was looking at the new 72 Hour Challenge, Celestial Bodies, a bit ago. I remembered that I have a telescope my mother in law gave me that I've been hauling around for years. The telescope is a Nexstar 80 GPL. I was trying to figure out if I could attach my G5 to it for some lunar photography. I was hoping someone with a little experience in these matter could let me know if I'm headed in the right direction.

    I think I need this:
    Celestron SLR Camera Adapter with Integral 2x Barlow Lens 93640

    And then I would need a T-Ring, followed by a T-ring to m4/3 adapter. The Universal Celestron adapter would drop into the spot where the eyepiece goes, (#2 on picture below), then the T-ring on that, then the T-ring to 4/3, then my G5. Am I correct in thinking this is the proper set up? Is there a better way to do this, or another way to attach the camera to spot #1 in the picture below?

    Thank you very much for any help or advice you can offer with this.


    [​IMG]

    [​IMG]
     
  2. dwig

    dwig Mu-43 Top Veteran

    621
    Jun 26, 2010
    Key West FL
    The instruction manual says the #93625 is the proper adapter. You would then need to add the proper T>m43 mount to connect an m43 body.

    The adapter you list should also work but it adds a 2x Barlow ("Barlow" is astronomer-eze for "tele-extender", actually "Barlow" is the proper original term). The resulting field of view may be rather narrow. The scope is a 900mm f/11 lens as is and the 2x Barlow would make it a 1800mm f/22.

    With either adapter, you would likely find that mounting it a "position #1" to be the preferred position.
     
  3. Djarum

    Djarum Super Moderator

    Dec 15, 2009
    Huntsville, AL, USA
    Jason
    I wouldn't use a barlow lens if I didn't have to. It really depends on how much in focus range you need.

    I've tried two different setups with my refractor. The first one was using this:

    Adorama 07TM0M43 T-Mount for Micro 4/3 System Cameras 07TM0M43

    With this:

    Celestron 93625 Universal 1.25in T-Adapter f/ Telescope 93625.

    Basically, T adapter to m43, then T to 1.25" eyepiece/nosepice.

    When I tried to drop this in to the eyepiece holder (after the 90 degree prism/mirror, or number 2 in the image), I could not get it to focus. The problem is that using this setup requires more in focus than my refractor was designed for. You may run into the same problem. If I removed the 90 degree prism and hooked it straight to the scope, I then ran out of back focus(couldn't rack the focuser back enough). However, I could put a barlow in between the focuser and could get the camera to focus(number 1 in your image)



    The other option which works better for my scope is this:

    Adorama VDCM43 Video C Mount for Mounting C Lenses VDCM43


    with this:

    Baader C-Mount Adapter with 1.25" Nosepiece # C-NOSE 2958515

    This gets me there with my refractor with a little in focus to spare when using the 90 degree prism/mirror(nosepiece in number 2).
     
  4. RobWatson

    RobWatson Mu-43 Hall of Famer

    Yes, back focus range is a significant problem. Generally refractors and catadioptrics are pretty forgiving but low end models are not.

    A way around that issue is to use eyepiece projection methods. Google turns up quite a bit .... almost certainly the M43 to T adapter will be required and it is a good thing to have generally if intending to do other work with telescopes. There are lots of T to whatever for linking all manner of things to a telescope.

    For really good eye piece projection quality eyepieces are a requirement and ones specifically designed with large exit pupils so you can cover the sensor more fully - be prepared for some vignetting. If you can use 2" eyepieces instead of 1.25" ones (not an option with the scope you showed). Longer focal length eyepieces will be easier to work with (25mm is decent but do not bother with less than 9mm - even 12mm will be tough).

    Take heart - even with no adapters one can practice eyepiece projection by simply using a zoom lens with close focusing abilities and just point it into the eyepiece and snap away. Practice during the daylight and find the lens that gives decent results. Just use the telescope to locate and object and focus as best you can the use you camera and fiddle a bit.

    The same tricks that work with a telescope used with eyepiece projection will also work with a microscope if one is so inclined so consider the effort as a multitask with cross platform payback.


    Forgot to mention - skip the 90 degree prism and you will gain some more back focus distance.
     
  5. RobWatson

    RobWatson Mu-43 Hall of Famer

  6. Djarum

    Djarum Super Moderator

    Dec 15, 2009
    Huntsville, AL, USA
    Jason
    I ran into problems with my refractor both ways when using the standard m42 to t adapter. If I used the prism/dielectric, I couldn't get enough in focus. If I pulled it out, I ended up needing some extension tubes.

    Using a cmount adapter allowed me to use the dielectric. The other nice thing about using the Cmount is that it work for reflectors that don't have a ton of focus tube either.
     
  7. RobWatson

    RobWatson Mu-43 Hall of Famer

    Yeah, my MFT-T adapter + T-1.25" takes a lot of back focus (maybe 2"). Lucky me my telescopes all have lots of back focus room (well, now that I modified them)!

    C-mount is nice but c-mount to 1.25" eyepiece adapters are crazy expensive for what they are. Even this one is $15

    I like eyepiece projection in this case as it can be tried right away without $ and waiting for parts to arrive. The OP did mention the current 72hr challenge to time is a factor (for now).



    And some telescope manf are kind enough not to make the telescope actually have 1.25" eyepiece tube so you have to use their prism (or 90 mirror) or get their adapters.
     
  8. RobWatson

    RobWatson Mu-43 Hall of Famer