SharpCap Forums

I have been using a ZWO ASI294MC Pro camera with SharpCap for some months now and thought it time to get to grips with the Sensor Analysis feature. However I have hit a problem at the very start. I would be grateful to get the answer to the problem.

Having :

• arranged the camera to view an evenly illuminated “flat” white area (using at different times a white tee shirt over the front of the telescope and an illuminated panel)
  selected bin 1 mode
  selected 0 gain
  adjusted the camera control settings so as to get the luminance (i.e. white) histogram peak at about 65%
  opened the sensor analysis tool
  clicked the Start button in the first of its instruction displays

the next instruction display shows (see screenshot attached) :

• an instruction to “Select an area of the image ...”
  an instruction to “Adjust illumination ...”
  a message saying “Selected area is too small. Please select a larger area.”

On consulting the Help file (see second screenshot attached) I see that it says “Once the Start button is pressed, SharpCap will automatically select the highest gain level ...” but as is evident in the first attached screenshot the gain setting remained at 0.

The Help file also says “At this point you should adjust the move and/or resize the Selection Rectangle to select a region of the image ...” But I cannot find the mentioned selection rectangle – it is not displayed. Adjusting the zoom level all the way from auto (i.e. full frame) to 300% makes no difference to the message saying that the selected area is too small. Also, with bin 1 mode selected (and that seems to be necessary as per the first instruction display) the camera control panel does not show a region of interest section like it does with bin 2, bin 3, etc.

So I don't seem to be able to get any further.

Hi,

firstly, the documentation in this area is out of date - once the sensor analysis did start at the highest gain, but this tended to lead to problems as the highest gain goes with the shortest exposure (and the lowest gain with the longest exposure). If someone started at high gain and >10ms exposures, they might end up with the measurement trying to use 5-10s exposures or even longer at the low gain end and the whole process would take for ever.

The new code starts at low gain because this means setting the illumination up at the longest exposure that will be needed during the measurement (typically in the 0.5s to 2s range).

Now, the selection area. Sometimes it seems to get set down to a tiny size that is hard to find. In SharpCap 4.0 I've added code so you can double click anywhere on the image and it resets the selection area around the place that you have double clicked (which makes fixing this easy).

In SharpCap 3.2, you have to look for the double red arrows that point to the selection area when it is too small - zoom out to see the whole image and somewhere there will be the arrows - like this
Hold the mouse over this area of the image, hold down CTRL and use the mouse wheel to zoom in - as you zoom in, keep the arrows in the center. Eventually you will zoom far enough to see the selection area box, at which point you can drag the edges to enlarge it
cheers,

Robin

Thank you Robin for your prompt response and comprehensive information. I have now successfully found the selection area rectangle and I have therefore been able to progress with, and complete, the sensor analysis routine.