OAG

We have very good feedback on OAG 5 as reliable tool and flexible design concept from all of users. All say guiding have got obviously improved.  I tested how OAG5 worked with 7887(0.85x reducer) based on the inquiry from 7887 user. My biggest concern was how it can be par-focal for both guiding and imaging ports since 7887 must be set behind OAG5. See the following setup.

Fortunately and surprisingly, the light path difference was only 13mm.  This is fully within guide port adjustment range with 4604(28mm long extension tube). Usually I didn’t recommend setting the reducer behind OAG since it makes the configuration more complicated. But as long as 7887 is used,  now I highly recommend this way.  This setup covers 35mm full format sensor through OAG. Also 7887 is well known as widely compatible with non-BORG refractors. So if your refractors have the flexture issue and are looking for OAG solution, this is the one covering up to 35mm format sensors. The above configuration is OAG5 – 7352 – 7887 – 5005 – Canon 5D Mark II. 7352(camera rotator) allows to independently orient a camera itself without rotating OAG unit. Meanwhile OAG’s front adapter allows to rotate OAG only to locate a proper guide star as well. So this is double rotating system.

 

 

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~ by tedishikawa on February 8, 2011.

2 Responses to “OAG”

  1. Thanks for this update Ted. Interesting to see how you set this up. Might the same apply to SBIG CCD setup?

    • Thanks for your response, Morgan. I believe you have most of parts already.
      Basic configuration for SBIG ST cameras is
      OAG5 – 7352 – 7887 – M49.8-ST – SBIG CFW/ST

      In this setup, the guide port should be still too short. So 4604 should be solution. If you wish to use 7315, I need
      to calculate though.
      Do you have the par-focal eyepiece for your guide camera. That should reduce the time for par-focal work for both
      guide and imaging ports.

      Next what I want to describe here is to use 7528 at the guide port. OAG5 and 7315 has T-thread male for guide camera.
      So technically these allows to connect camera via t-thread without nosepiece. But the problem is to align the camera orientation.
      7528 works as a locking ring when guider camera is attached via t-thread and align its orientation. Unfortunately, I don’t have
      7528 in stock right now. Once it comes in stock, I will describe here.

      Also Scopestuff has several T-to-T extension tubes. This must be useful if the camera is attached via t-thread.
      http://scopestuff.com/ss_ttet.htm

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