SC-3 or STXL Self Guiding Cover?

Discussion in 'STX and STXL' started by csauer52, Jan 6, 2020.

  1. csauer52

    csauer52 Standard User

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    Hi,

    A little background prior to my questions:

    Previously I was imaging with a Meade LX-850 mount which has the built-in Starlock system and precluded the need for an autoguider therefore when I purchased my STXL-6303 and CFW I decided not to purchase the guider option.

    I'm now upgrading to a Paramount MX+ and will need to add the guider option and I'm not sure what the best solution would be for my use case (either the SC-3 or the CFW plate with the auto-guider built-in)?

    I'm concerned primarily with 3 items:
    1) backfoccus (will list concerns below)
    2) stability - which is a sturdier mounting, the SC-3 or the CFW plate?
    3) compatibility

    I will be imaging with two scopes but for the purposes of this discussion let's assume the following gear (front to back)

    Takahashi TOA130
    Tak 67 Field Flattener
    Optec TCF-Si
    (STXL-CFW Plate with auto guider or SC-3)
    STXL-CFW
    STXL-6303

    Additionally, with the move to the new mount I plan to adopt The Sky X Pro (TSX) to control the entire system. Previously I've been working with Maxim for well over 15 years but part of the allure with the Bisque mounts is the SW integration (for me anyway) therefore I plan to make the switch.

    Questions:
    1) What's the primary difference between the two available options other than the $100 price differential? I know the sensor on the SC-3 is CMOS but is the FOV similar and do the chips have similar performance characteristics in terms of sensitivity? I don't have the best skies in my backyard and I don't want to have difficulties with picking guide stars. I believe both have shutters correct?

    2) Have the drivers for the SC-3 been tested with TSX? Additionally, will the SC-3 work with the direct guide option on the PM or will I need to use the ST-4 relays? I quite like the idea of sending the commands directly through the USB cable rather than having an additional guider cable to potentially cause drag issues.

    3) Back focus - The Tak flattener requires 106mm and I'm right about there at the moment. What impact would each option have on my current back focus situation?

    4) Eventually I'll be using this setup with a Meade 14" ACF F/8. Once I get to that point I'll likely be considering the STXL AO unit. In terms of future proofing the system - which option would integrate better with the AO unit or would it be unnecessary given how well the PMs are known to track once a PEC curve has been generated/applied?

    If I think of any others I'll be sure to post them here.

    Regards,
    Chris
     
  2. Colin

    Colin Cyanogen Customer

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    Hi Chris,

    I have a couple answers for you, more coming ASAP:

    1) Yes, both units have mechanical shutters.
    The CMOS chip in the SC-3 has 1280 x 1024 active pixels, 4.8um pixel size, 10,000e- Full Well Capacity, and <8e- Read Noise.
    The CCD chip in the Filter Wheel has 648 x 486 active pixels, 7.4um pixel size, 25,000e- Full Well Capacity, and 8.6e- Read Noise.

    2) The drivers are not yet completed, the development is ongoing as Bisque is working on the integration. Guiding can be done via ASCOM PulseGuide, or through the ST-4 guide cable.

    3) The SC-3 adds 22.1mm of back focus. The Guided Filter Wheel cover adds 17.1mm of back focus.

    Kindly,
    Colin W
     
  3. csauer52

    csauer52 Standard User

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    Thanks Colin, this is very helpful. Looking forward to the remainder.
     
  4. Colin Haig

    Colin Haig Staff Member

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    Hi Chris, I'm the "other Colin" and will chime in.
    I recall seeing a version of the Crescent Nebula you did in a modified hubble pallette a few years back with a Meade.

    One clarifcation on point 2)
    ASCOM drivers are available NOW for the SC-3 and SC-2. You can use TSX with those.
    Software Bisque has almost finished DL Imaging native driver work using the DL Imaging drivers for the Aluma series, and that is related to native support for the SC-3 as well.
    AO operation REQUIRES the Bisque software to use DL Imaging, not ASCOM.
    So not quite there yet if you add AO into the mix.
    More below.

    On point 4) :
    The AO-X can be used with either an STXL camera with FW8G-STXL self-guiding filter wheel or a standard FW8S-STXL filter wheel and SC-3 StarChaser.
    This works well either way with MaxIm DL Pro 6.21.

    Software Bisque currently supports the STXL+FW8G+AO-X with TheSkyX 10.5.0 latest daily build.
    SB is catching up on the new hardware - they aren't quite there yet, and I would go ask them on their forum - a little prod from their customers helps.

    About 6 months ago, we shipped them a complete Aluma 814 + FW8G-Aluma + AO-8A adaptive optics unit a little over 6 months ago, so that they can do DL Imaging driver integration of everything.
    DL Imaging also handles the SC-3.
    I think they got a bit swamped with trying to get the new mounts and SkyX Fusion box out for the AIC show in November.

    The SC-3 will work as an ASCOM camera; but control of the AO-X requires the DL Imaging drivers.
    So, Bisque is a wee bit behind where we'd like them to be on this.

    While I agree well-trained Paramounts can do 10+ minute unguided exposures, it may start to show up with the long focal length of the ACF. The AO-X will help a bit here.
    If you have slow-seeing effects, the AO-X will do a beautiful job of tightening up the PSF, giving you tighter stars with up to a 10Hz AO rate.
    This may be an advantage on the 9um pixels of the 6303 - you probably are binning 2x2 now.

    A couple other points:
    A self-guiding filter wheel can be converted into a standard (non-guiding) filter wheel by purchasing a replacement cover. So, if you want maximum software compatibility with TSX, and can't wait on Software Bisque, then go with a self-guided filter wheel. We are running low on stock, and we'd have to check on availability of the self-guiding wheel, as ON Semiconductor has discontinued the chip as of mid-March.

    If you aren't in a big rush, you can go ahead with the SC-3 when ready. They are close to shipping - should be a few more weeks.

    The manual for the SBIG StarChaser SC-3 is available for download on the blue DOWNLOAD tab on the product page.
    https://diffractionlimited.com/product/sc-3/

    I hope that helps.
    Cheers,
    Colin H
     
  5. csauer52

    csauer52 Standard User

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    Thanks Colin. I’m a little confused by the following:

    ========================================
    A couple other points:
    A self-guiding filter wheel can be converted into a standard (non-guiding) filter wheel by purchasing a replacement cover. So, if you want maximum software compatibility with TSX, and can't wait on Software Bisque, then go with a self-guided filter wheel.
    ========================================

    I was hoping this would be the other away around, e.g. convert the standard filter wheel into the guided filter wheel by adding the cover add on SKU: FW8-STXL-GUIDER-COVER? That’s really the crux of my dilemma, should I go with the cover that adds guiding or the SC3 given the former likely already works with TheSkyX or hold off until the SC3 testing completes and/or use it through ASCOM?

    ‘Ideally id like to standardize on the SB suite given the integration therefore I’m leaning towards the filter wheel cover given it will work out of the nix.

    Thoughts?
     
  6. Doug

    Doug Staff Member

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    Yes you can convert the standard wheel to guided with the FW8-STXL-GUIDER-COVER. You can easily switch back and forth.

    At this point in time I would recommend going with the guided cover, as it will work right away with your chosen software.
     
  7. csauer52

    csauer52 Standard User

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    Hi guys,

    As per phone conversation today - just wanted to follow-up with documentation in the event others have a similar issue as I do.

    As noted in my testing this weekend, the SC-3 does not appear to be compatible with 2" camera nose pieces as the pickoff mirror doesn't extend far enough into the lightpath which naturally creates a problem when trying to find a viable guide star. Hoping you may have some sort of solution otherwise will require a return slip and exchange the SC3 for the CFW cover that has the guider built-in.

    Please let me know at your earliest how you'd like to proceed.

    Regards,
    Chris
     
  8. Doug

    Doug Staff Member

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    Yes I think we have a solution. I've come up with an improved version of the mirror holder, which allows greater adjustment range for the mirror position. Would you like to try it? It will take a few weeks to get the part made. It's something that you can easily swap out yourself.
     
  9. csauer52

    csauer52 Standard User

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    Hi Doug - I'd be happy to test it for you, I had the cover off the unit the other night to see if there was any way I could extend the distance so already aware of how easily it can be replaced.

    I'd still like an option to go with the CFW cover option if this doesn't play out in my favor. Provided you will honor that for me I have no issues trying out a different part to see if we can get it working.

    Chris
     
  10. Doug

    Doug Staff Member

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    Yes of course. It will take a few weeks to get the parts made and sent off to you. If successful we'd like to get the original mirror slide back. If not successful we'll arrange a swap.
     
  11. csauer52

    csauer52 Standard User

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    Sure thing - that works for me. Do you have any concerns related to focus with the extended mirror slide?
     
  12. Doug

    Doug Staff Member

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    I think we should be okay. The focus range on the SC-3 is quite large.
     
  13. blackdragon72

    blackdragon72 Standard User

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    For STX16803, is the SC3 the only option?
     
  14. Colin Haig

    Colin Haig Staff Member

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    Yes. The former soolution was the STX-Guider, which used the ON Semiconductor (former Kodak) KAI-0340 CCD sensor. ON Semi discontinued all CCDs September 18, 2019, so we just can't get any now.
     

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