Residual signal issue

Discussion in 'Image Capture' started by Matt, Aug 4, 2015.

  1. Matt

    Matt Standard User

    Joined:
    Aug 4, 2015
    Messages:
    3
    I have an STF8300M and am struggling to understand what appears to be a critical issue.

    When I expose an image of a lit object for a couple minutes and then expose another image for a few minutes, in a 100% dark environment, I see a 'ghost' of residual signal from the previous exposure. For my application, it is critical that there is no residual signal for subsequent frames. From digging through the SDK, it appears that residual signal should be handled automatically (I call csbigcam.GrabImage()). The signal appears to dissipate over time but is still present even after a full minute.

    Is there a way to force the sensor to 'reset' such that there is no signal carry over in subsequent exposures? Any input is very appreciated.
     
  2. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    5,603
    Sounds like you are experiencing Residual Bulk Image. All front-illuminated CCD sensors are susceptible to this to some degree or another. Google it for an explanation.

    The usual solution is IR preflash, although that does add additional noise into the images. The higher-end STX / STXL series has preflash capability.

    In most operational situations the RBI for KAF-8300 sensors is not bad enough to require preflash, especially when shooting astronomical targets.
     
  3. Matt

    Matt Standard User

    Joined:
    Aug 4, 2015
    Messages:
    3
    I hadn't heard of residual bulk image but that is exactly what I'm seeing. Thank you for you help!
     

Share This Page