Another clear night. They take me by surprise. You think it is going to be cloudy and it turns out clear. Rasa, zwo 290, all 3 minute total exposure , 15s x12 stack and that damn dust is still there. Gave everything another good clean this afternoon, too
ngc 3511 40 mlya and mag 10 in crater . I think the other is ngc 3672 but am not certain
Were those images cropped at all ... or full size?
I ask as I scaled the size of the dust mote off those images, converted that to pixels and stuck the numbers into that website link I sent you in that other email ... the link which calculates how far away from the sensor the dust mote is.
The answer was 0.5mm .... IE less than half a mm away from your sensor itself ... ie That is an extremely small distance! As there is a gap between the surface of the sensor itself and the backside of the protective glass over the sensor, and if that website CCD dust mote calculator thing is correct - it looks like the dust is on the back surface of the glass protective lens. IE. Not on the front of the protective glass over the sensor but on the back side. Maybe you should post some stuff on forums or ask ZWO or ... ?
Perhaps first check my calcs and plug them into that link to calc the distance.
Thanks Howie. I havent got around to looking at the site yet,but I will. I am impressed with your calculation. The images are full size, just stretched on sharpcap. I cleaned the front side only. I dont think I can remove the protective glass. I wont risk damaging it.I will talk to ZWO. Thanks again cheers Paul
do you use RGB or a Raw16 mode for these Paul? I've been trying Raw16 but even with the gain cranked at 10s nothing is vastly obvious and with few stars too. I think I'm pointed in the right direction....
Ian,for the zwo 290 I use mono 16 which is what sharpcap defaults to. The stacked images are saved as FITS files, but I might change that back to Tiff . All I do is a bit of a histogram alteration in either Fitswork or FitsLiberator and save in jpeg and then post. For the colour cameras,it is Raw16 but still saved in FITS.I dont think I ever selected Raw16. Pretty sure sharpcap defauted to it cheers Paul
thanks Paul if I use RGB and longish (~8-10+s) captures, Sharpcap pops a msg asking if I wouldn't like to switch to another setting as I appear to be using 8bit. so I do and then piss about with Raw16 for no success yet. OK to the rest.... I'll check at the Sharpcap forum. cheers
Ian , with a QHY-163 and 8" sct you need longer exposures than 8-10 secs with a 6.3 fr. You will need 30 secs or more . Your CGEM should handle that. I get away with 10 secs with the RASA f2 and the zwo290 which is very sensitive. cheers Paul