16200 backfocus question

Discussion in 'STX and STXL' started by Dave, Oct 15, 2019.

  1. Dave

    Dave Standard User

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    I'm considering this camera for a Tak epsilon 180 but unfortunately I think the backfocus is slightly too much for this system. Perhaps someone is using this scope with an SBIG camera and would certainly be interested in your set up but for this system what I have determined is the best I could do would be a backfocus of 59mm or so with a standard filter wheel and 3" accessory ring. The optical plane of the Tak 180 is only 56mm from the corrector lens so my conclusion is that it's slightly too long for it?
    Thanks
    Dave
     
  2. Colin Haig

    Colin Haig Staff Member

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    Hi Dave,

    The standard filter wheel will leave PLENTY of back focus.

    There's a back focus table on the DOWNLOAD tab of the camera.
    https://diffractionlimited.com/product/stxl-16200/

    The STXL-16200 camera is 24.1 from the top of the sensor to the front of the camera including optical effects.
    The FW8G-STXL Self-Guiding filter wheel is 36.50mm thick.
    The FW8S-STXL Standard filter wheel is 19.40mm thick.
    Subtract 1mm for 3.0mm thick filters.
    So I get 42.5mm with the standard wheel, and 59.6 with the self-guiding wheel.

    42.5mm gives you room for adapters and so on. Should work fine.

    We also have a new accessory nose piece that might work to get you up and running more quickly:
    https://diffractionlimited.com/product/stxl-acc06/
    It does consume a bit of backfocus, but may make adapting things easier, as an alternative to the 3" dovetail adapter.
     
  3. Dave

    Dave Standard User

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    Thanks Colin! I do have that backfocus info. I forgot I included the 3" accessory plate which adds another 17mm. It appears I won't need this . So I have a couple more questions then:
    1) The output threads on the Tak are 2" T threads so I don't think the new nosepiece can be used. Any suggestions on that?
    2) I already have a self guiding wheel I can use but need to convert it to a standard wheel. Can I just get a replacement cover from you guys?
    Thanks again.
    Dave
     
  4. Doug

    Doug Staff Member

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    The standard cover is available for purchase on our web store.
     
  5. Colin Haig

    Colin Haig Staff Member

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    You need to think differently about the 3" dovetail plate.
    If you are threading into it, it adds 0mm ZERO.
    If you are using the dovetail, then it only adds about 5mm for the base flange, as that is where your attachment point ends.


    1) Not sure exactly what you mean by 2" T-threads? Never heard of it... but maybe you mean a 48mm x 0.75 thread ?
    An actual T-thread is 42mm x 0.75.

    2) Yes, you can convert a FW8G-STXL self-guiding filter wheel to s Standard one with a cover swap. Here's the part you need:
    https://diffractionlimited.com/product/ms-standard-cover-stxl/

    Do you already have the camera? or are you planning to order it soon?
     
  6. Dave

    Dave Standard User

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    Ok thanks guys. Good question. It's probably 42mm but I will check on it. Looking at my options for possible purchase by end of year or so
    Dave
     
  7. Colin Haig

    Colin Haig Staff Member

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    Hi Dave, if you're going buy, before year end is best - On Semiconductor has advised us that the sensor prices are going up Jan 1 2020, and they are winding down production next year of all CCDs.
    So get it before if you can.
     
  8. Dave

    Dave Standard User

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    Alright sounds good. That's what I figured!
    Dave
     
  9. Dave

    Dave Standard User

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    Ok so you mentioned prices going up Jan 1. I already have seen one vendor say the prices went up 11/1?? Just confirming the status at this point.
    Thanks
    Dave
     
  10. Colin Haig

    Colin Haig Staff Member

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    Hi Dave,
    ON Semiconductor hiked pricing on September 18, 2019. A further increase was announced effective January 1, 2020.
    We've had to put our prices up in response. I wish we didnt have to, but we just don't have the margin.
     
  11. Mike Hambrick

    Mike Hambrick Cyanogen Customer

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    I hope you don't mind my chiming in here. Do I understand correctly that I can switch out the cover on my FW8G-STXL with a standard cover ? I purchased my camera with the self guiding filter wheel, but to date, all of my images have been guided using my STi on a separate guide scope. The extra 17.1 mm of backfocus would come in handy for some of my imaging trains.
     
  12. Doug

    Doug Staff Member

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