M101 as seen by STC-7

Discussion in 'My Astrophotos' started by Tim Povlick, Jan 17, 2021.

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  1. Tim Povlick

    Tim Povlick Cyanogen Customer

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    Here is M101 taken with s short session (9 exp of 5 min each) using Maxim DL to capture.

    Scope: 305mm @ f/3.7
    CCD: STC-7 @ -25°C
    AutoGuide: ST-402m
    Mount: AP 900
    Skies: SQM 21.29
    Temp: -10°C
    Transparency : suspect a light haze (thin clouds)

    _..--
    Tim
     

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  2. Tim Povlick

    Tim Povlick Cyanogen Customer

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    Another day - another galaxy to image:

    From last night, m101 with four images / RGB channel at 4:00 minutes each.
    Not what I'd hoped as a thin cloud layer developed as the imaging progressed
    so pulled the plug.

    _..--
    TiM
     

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  3. Doug

    Doug Staff Member

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    You're making great use of the camera!
     
  4. Tim Povlick

    Tim Povlick Cyanogen Customer

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    It's a great camera!

    Tim
     
  5. Ross Ferguson

    Ross Ferguson Standard User

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    Hey Tim, I am considering this camera, but some other options have made it hard to pull the trigger. Does the in camers stacking produce a noticeable improvement, and how often do you use this feature for DSO's?
     
  6. Tim Povlick

    Tim Povlick Cyanogen Customer

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    Hi Ross

    Interesting question and good timing. I had not used the feature as downloads are quick but there is a lot of raw data to deal with if not stacked in camera. Last night I decided to tried M42 in h-alpha using StackPro™ feature. Exposure was 960 seconds with a sub exposure of 60 seconds. So the camera auto stacked 16 images of 60 seconds each. The exposure resulted in the Trap being barely saturated (as desired). The final image was perfectly stacked and (Trap) saturated at 65536 (as expected). Three images of the 960-second "bundles" were processed in Maxim and posted here. Note this is in the high gain mode.
    Normally, if I had 48 images to stack, 6 or 10 would be rejects (due to out of round stars). The guider continues unstopped as the camera is stacking. If individual images are downloaded, the guiding stops, for the download and then a new star acquisition has to happen along with guider settling down. In the setup here, StackPro™ is looking like the preferred method as the overall "system" acquisition results in a smoother operation.

    The dark frames have to match the gain mode and StackPro™ settings.

    Feature request
    : User can upload a master dark to be processed with each stacked frame. This would allow a more dynamic range and be more convenient wrt dark frames.

    There is a nice write up about the IMX 428 gain modes and it's QE graph over at the Flir site:

    https://www.flir.com/discover/iis/machine-vision/sony-pregius-imx428/

    I recall the QE of imx 428 and IMX 455 (at h-alpha) were very close. Can't locate the imx 455 datasheet that I referenced so that that with a grain of salt.

    Hope this helps...

    Tim
     

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  7. Doug

    Doug Staff Member

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    Spectacular shot!

    I would not go by SONY datasheet QE curves. First of all SONY only publishes relative QE curves, with the peak sensitivity arbitrarily set to 1. So you really can't compare one to another. Secondly, in my experience the curves aren't even accurate! SONY is strangely very secretive about their absolute QE performance, which is weird because theirs are among the best in the industry so you think they'd want to show it off.
     
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  8. Ross Ferguson

    Ross Ferguson Standard User

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    Wonderful response Tim, thank you. I really don't want to buy from that one country if I don't have to, this hobby is more than just about the images to me... Whether I can afford this, and 3nm filters without the wife killing me is a definite risk. the pricing on the camera without filters and filter wheel is a little confusing to me. Thanks again, I will continue to check out your photos.

    Ross
    Astrobin@ ferginfay
     
  9. Colin Haig

    Colin Haig Staff Member

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    Hi Ross - if you have questions on pricing etc, you can send me a Private Message or contact me via the contact form on our website.

    The STC-7, STC-428-EVAL, and STC-428-P all share the same camera electronics; same sensor.
    The difference is the STC-7 includes a slightly smaller filter wheel that is integrated and controlled by the camera, and the motor is in the camera body. This lets us get the cost down, and we were able to have filters made for it that are a bit smaller and thus less costly. Overall, it's the best bang for the buck.
    The STC-428-P is for people that do photometry and/or use specialized pre-mounted or unmounted filters in certain sizes - eg unmounted glass at 36mm or mounted 1.25" threaded filters like Methane, Johnson Cousins Bessel UBVRI / Sloan, Biological Fluorescence etc
    These filters require a substantially larger filter wheel carousel to mount them, and the supporting stuff that goes with it all, so it ends up costing more.
     
  10. Ross Ferguson

    Ross Ferguson Standard User

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    Thanks Colin, this is the camera I want, I just ordered the filter slider from Starizona and invested a little too much to put that back in a box. The Optec Focuser got used for the first time last night, and I really want to do an OAG, so I can double my imagine time with the Losmandy. I really want to stay on this side of the pond with my purchases and I know y'all have the best support in the industry, and that is clear from this message board.
     
    Last edited: Feb 25, 2021

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