Results 1 to 4 of 4

Hybrid View

  1. #1

    Default HELP...Any idea what is causing this?

    Hello.

    We have a FLI Proline backlit CCD. Tonight, these are the images that I am getting, see attached. Any idea what is causing this? Thx. Grady

    Bad image.jpg

  2. #2
    Join Date
    Oct 2005
    Location
    Mesa, AZ
    Posts
    33,784

    Default

    Someone else with more experience might know, but me? I don't have a clue. It doesn't look good though.
    -- Bob

  3. #3
    Join Date
    Nov 2005
    Location
    Virgil, NY
    Posts
    6,054

    Default

    Hi Grady,

    Well, I can see that there are numerous "stars" (for lack of a better name :-) scattered over the image. A lot of heavy image processing yields up a passible image. But is it real? Does it look familiar? I can't identify the field because I don't know the plate scale. All-Sky yields nothing. Your .jpg image is about 800x800, probably not the original sensor size of the FLI Proline. In any case, recreating the image doesn't answer your question.

    Bad image5.jpg

    There seem to be two different problems - the "shadowed" star images and the grey background. Both can be explained as the result of subtracting (or dividing) one image by another, in which the two images are not precisely aligned (horizontally
    in this image).

    Calibration might be a problem. The usual calibration step is an arithmetic division of the real image by the calibration image, but calibration would not normally generate a grey background. Were new calibration flats taken recently? New calibration masters might have been incorrectly created.

    Were all of the images last night were bad, or just one series, or just one? Can you tell me where you were imaging? Otherwise, a problem in the camera readout?

    A real conundrum right now. I'm sorry, this is not much help, either.
    Dick
    www.VirgilObservatory.us
    Pier-mounted Meade 12-inch SCT "classic"
    Optec TCF-S focuser
    SBIG CFW-8A and ST7-XME
    H-alpha, BVRI, RGB & Clear filters
    FOV ~15’ x 10’



  4. #4
    Join Date
    Nov 2015
    Location
    Christchurch, Dorset, United Kingdom
    Posts
    417

    Default

    I don’t know the model of the camera you are using but vaguely similar images can be created on shutterless cameras when Auto-dark subtraction is accidentally left enabled in MaxIm (see options menu on the Expose tab of MaxIm’s Camera Control window) and an auto-dark is taken with the telescope uncovered but pointing at a target and then a normal image is taken of the target a little later with a small drift in mount pointing, after automatic subtraction of the auto-dark you are left with black shadows around the side of the star(s) corresponding to the opposite direction of drift, and a zero or negative ADU background pedestal.

    If your camera has a shutter and you do use auto-dark subtraction then check that the shutter has not failed in the open position and if the camera doesn’t have a shutter check that auto-dark is not enabled in MaxIm.

    Besides the above, any problem with the camera sensor bias voltages or clock timing for the sensor readout due to a camera electronics fault could produce a similar looking image.

    William.
    Last edited by William Bristow; Nov 20, 2023 at 18:08. Reason: Spelling

 

 

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. You have no idea....
    By Bob Denny in forum Help Using the Comunication Center
    Replies: 0
    Last Post: Jan 19, 2019, 01:18

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •