SharpCap Forums

Hi! I am now trying for the 3rd time to carry out a sensor analysis for my CCD Atik 16200 Mono, but I always fail towards the end of the procedure when creating the analysis - I get the error message that no analysis can be made...

I used a Lacerta flat box for this, with a dimmer, and also placed ND film on the flat box to darken it. This is how I manage to reach the target of 0.05s - 1s with 65% saturation in the histogram. The analysis then runs without error until the telescope is covered. Here I have to switch to 1000ms manually, since Sharpcap would choose a BLZ of 10ms. Then this procedure runs through until I have to remove the cover again. Now the gain is started to be measured, which still works without an error message. Only at the very end, after I got a lot of green crosses, does the error message mentioned above come up, saying that the analysis could not be completed and I should repeat the analysis with a darker light source set... So close to the end of the error!

But I can't darken any more, otherwise I would exceed the specified exposure time of 0.05s - 1s and therefore cannot start the analysis.
It should be noted that my CCD camera, according to the manufacturer, has a shortest exposure time of 0.2s from the factory... In the analysis, however, the measurement goes down to 1ms, and the CCD goes along with it, also evaluates with a green cross - however at the end, as said, an error comes up and no data is saved as usual.

I could sit next to it and move the mouse to each green cross and write down the values ​​on a piece of paper, but isn't there a less cumbersome way? Are the values ​​vl cached somewhere where I could read them from a temp or log directory, for example, for reuse?
It's a pity that I got this far with the analysis, and then shortly before the end of the evaluation of the recorded data, an error occurs and is aborted...

Sorry for my bad English - translated with Google Translate!

Best regards,
Thomas Grossschmidt

Hi Thomas,

could you please try to send me the SharpCap log created from one of the failed measurement attempts - that will contain the exact wording of the error (which will help me work out what has gone wrong) as well as a lot of detail about what analysis steps were performed and possibly even some of the results.

thanks,

Robin

Hello Robin!
Gladly, I have attached the last two generated LOGs - here, please

Hi,

it looks like it is falling down in the binning measurement - nearly the final step - because it can't get the image brightness low enough. I would suggest just unticking the box at the beginning of the analysis to disable the binning measurement step, which should then allow the analysis to complete.

Another possibility would be if the camera has an offset/black level control then turn that down. I expect that the sensor analysis will try to turn it back up again though, so it might not help.

cheers,

Robin

That sounds good! But, where exactly would be the tick for binning that I should disable?

Hi,

right at the beginning of the sensor analysis - underneath the text explaining what you are about to do - there is a check box 'Skip Binning Measurements'. Just tick that before pressing the Start button to start the analysis.

cheers,

Robin

That worked halfway - but unfortunately the analysis is probably not enough for the Smart Histogram, which I was hoping for ^^

Hi,

since you have a CCD sensor, which doesn't have a variable gain adjustment, you will only get one row in the data table. Nothing looks out of place there except the read noise, which - at 27 - looks rather high. Worryingly high in fact. How do the figures line up with the manufacturers data for the camera?

cheers,

Robin

9e-

https://www.atik-cameras.com/wp-content ... Page_2.png

Hi,

Ah, ok, now I see what might be going on - SharpCap has estimated the sensor to be 15 bit, not 16 bit, which is incorrect. The reason for the 15 bit sensor depth is going to be that all the pixel values were either even (multiple of 2) or odd in the tested area. The only thing I can think of that is even likely to cause that is having the digital gain control turned up when doing the analysis. I'm not sure what the knock-on effects on the read noise etc would be from that.

I would suggest setting the digital gain back to minimum and making sure all other controls that might affect the image are off in SharpCap. Then capture a well exposed frame and look at the pixel values to make sure there are a full range of continuous values rather than all even or all odd. FITSLiberator will do the job for peeking at pixel values.

cheers,

Robin