STL & internal STL FW8 Filters for clear guide chip ?

Discussion in 'STF Series CCD Cameras' started by Greyandbrown, Oct 10, 2016.

  1. Greyandbrown

    Greyandbrown Standard User

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    Now here is a stupid question - would it be possible to modify the 50 mm filters so that they do not cover the internal guide chip ? and how would one go about that ... modify or buy specials ?
    What would be the pro's and cons ?
    I have an STL11000M & the large format FW8-STL.
    Or are there other options to get good guide stars with narrow band filters ?

    Many thanks in advance.
     
  2. Doug

    Doug Staff Member

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    I really don't think that's feasible. The light enters the camera as a cone, so if you were to somehow cut away part of the filter (which would be exceedingly difficult to do without destroying it), you would have a region of the main chip that was getting unfiltered light as well as filtered light.

    You would need to put an off-axis guider in front of the camera and use a separate guide camera (or the STL remote guide head if you have one).
     
  3. NoiseJammer

    NoiseJammer Standard User

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    If you're using a SCT or similar, you will probably need an off axis guider. I've used one (Van Slyke Versaport II) on my M12 but it's challenging. If you have a refractor or a scope with fixed mirrors, a separate guide scope is the way to go. I've found the ST-i + the standard kit works fine for my TOA150. A Lodestar may offer you slightly better performance because the Sony chips have less noise.
     
  4. Doug

    Doug Staff Member

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    I should point out that the ST-I has a built-in shutter for dark frames, so there's far less problems with hot pixels. (Yes the Sony chips are low noise, but especially when uncooled they still have hot pixels.)
     

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