Just picked up a used STL 11000 and noted long exposures cooled down to -18 have exceptionally clean images. bias and flat frames on the other hand have column defects...great for light frames ...a little harder for flats and bias just the age of the camera or maybe power ?? did notice at 70 deg F ambient cooling is maxed out 100% and limited to about -18 I'm sure I can live with it , just curious whether or not it's worth sending it in or remedying it with a new power supply. Ken
Hi Doug I uploaded 3 fits files for now will get flats ,and lights tomorrow if the mount gets back together....trying to make the G11 guide out until the Titan axis gets here from Losmandy...they got hit with Covid. The 5 second shows the column defects and the 600 sec virtually gone . bare with me ,my mounts misbehaving (24 years old) Ken
Hey Ken, looking at these images, the "hot columns" would be lost in the noise in the longer exposures. Compare the actual pixel values of your "hot columns" - they are quite low. They are drowned out in the rest of the noise in the long exposures. These are warm pixels, and the overall background level of the longer exposures is much higher in the longer exposures, so they're lost. A quick way to satisfy yourself is to use the information window, and check the pixel values. eg at around the line X=366, Y=2620 in the 5 second image, the maximum pixel value is something like 89. Then check the noise at the edge in the corner, and it's higher. Nothing wrong with the camera.
Thanks Colin I stretched the Fits in PixInsight and I can see what your referring to didn't think there was too much to worry about. it's my first time with a decent chip and the columns usually appeared in the long exposures if at all in my stf8300 and definitely my old failed apogee U8300,but not at all in the bias and flat frames. as for the cooling.....should I expect more than -19.5 max without water in summer months?
The STL will only get to about -20C at best, unlike the STXL and STX cameras which are much better cooled, they'll go down to -30 or -35C, about 50-60C below ambient.
Thanks Colin At 6000 ft above sea level in New Mexico I should not need much below -20,...IF needed I can water cool. one last question I have an empty hole in the filter wheel that needs my Ha filter...I'm missing 3 screws and the shoulder washers..is that something readily available or should I search on astromart ? Thanks for your patience.. Ken
