Having issues with master bias

[trev27]

Hi all,

New member here. I finished my trial and purchased the full version. Only had one clear night during the trial though 

Have worked through quite a few Harry's and Kayron's tutorials and can get decent (for me!) images. However I've been integrating without BIAS since when I calibrate my lights with a master dark and superbias (or plain master bias) I get very little signal in the resultant images. Just wondering if I have done something wrong during capture.

The camera is an ASI1600mm with BIAS frames captured in APT @ .001 seconds. Would be great if someone could let me know if this master BIAS looks OK. Coming from a DSLR I have no idea. Just a screenshot, but I have linked the Master BIAS, Master Dark, Superbias and a sample light frame from NGC6960 (180 seconds, 7nm HA filter, F6.9 on my 90mm frac). 200 bias frames taken and 40 darks.



The image on the far right is the light frame after integration with Master Dark and Superbias and is already autostretched with STF, as is it's corresponding raw file bottom right. Histogram stretch shows hardly any information in the calibrated light frame.

Any help appreciated 

Update: have added a zip of the master bias, superbias, master dark and a light from to dropbox in case it's of help. https://www.dropbox.com/s/qmz9ni888qus57r/Masters20160901.zip?dl=0

Trev
 

[oldwexi]

Hi Trev!
The most important process in ImageProcessing is the Histogramm Process and Statistic Process.
You should have them always openend.  To see immediately the median brightness etc from the image.
Loading the Bias and the Light and checking the Histogramm and/or Statistic clearly shows
that the MasterBias is BRIGTHER than the Light!!!!
So, during calibration the brigt bias is subtracted from the darker Light, which
removes everything except the bright stars from the Light!!

So something happened with the capturing or saving of the bias.

The histogramm of the Dark looks as it should - darker as the light.

Hope this helps

Gerald

[trev27]

Gadzooks, you're right Gerard. Many thanks. That clears it up. I usually have the histogram open but closed it for the screenshot but hadn't even thought of looking at the bias signal with it. D'oh!

I'll try BIAS with another capture program as this was 4th set of shots I took with the same result.

Thanks again

Trev

[ChoJin]

it's probably a stupid question, but just in case you were tired
are you sure you put the camera's cap back on before taking the bias?