andrew s

Given the number of questions on calibration related issues, poor flats, bais or not with CMOS. Maybe a session on the basics would be good. Regards

Somethings for a miserable day Regards Andrew

Stop the Newtionian down with a mask to say f10. If it's still an issue I would suspect the eye piece. Regards Andrew

I see no vampires. Regards Andrew

Have you tried comparing an old working flat with the new failing one. They should not be that different just the odd dust mote. Images might help us see what might be happening. Regards Andrew

The speculation comes from the refractor but the confirmation from the sct! Regards Andrew

I didn't realise you had an SCT 🤼‍♂️ Regards Andrew

Not by me I am afraid. Regards Andrew

It's a steep learning curve. Focus is hard but lack of it destroys images as can poor seeing. Just practice practice and more practice. Try on a star first to judge the conditions then move to Mars. Regards Andrew

No Takahashi can see through cloud with or without diffraction spikes. Neat trick. Regards Andrew

Never had one but my mounts often got dripping wet even in a RoR obs. You could enclose it in a well ventilated box e.g. with Stevenson screens or a copper box where the condensation will form more on that. Regards Andrew

As long as its water proof just leave it. Regards Andrew

An addict always has a reason for their behaviour. 😉 Regards Andrew

I think they are bosons and in the ground state like to stick together. A 10:1 focused might transform the to fermions which would keep them apart so not a good marketing ploy. Regards Andrew

I'm so dizzy, my head is spinning Like a whirlpool, it never ends And it's you Tak, making it spin... Enjoy Andrew

Best kept secret ever! Nice to see them on the range. Regards Andrew

How well balanced is the mount? Regards Andrew

This compares the O2 and the dark they look compatible to me. Similar background etc. Regards Andrew

Here it is stretched as mine. The second peak is, I suspect, the amp glow and hot/warm pixels appearing as expected. Looks ok. Regards Andrew

Ok post the file and I will do it in The Sky X as I did for mine. Regards Andrew

Looks reasonable once I realised the second bit after the min and max were coordinates. Can you post the histogram stretched similar to mine so we can compare them? Regards Andrew

Learning is a life long process and at my age relearning is now dominant. 😱 Just to be clear, if your lights were exposed at the same temperature and exposure as the lights then they should have a higher mean level (I know you had temp difference). If they don't something is wrong. I always take darks in the dark and telescope covered to avoid light leaks. Don't use scaled darks with CMOS as amp glow is nonlinear with time and the different (short v long exposure) readout modes can cause issues with bias frames. Regards Andrew

Dave here is a very short dark of mine 0.5s You can make it looked combed if you stretch it enough. Regards Andrew Regards Andrew

I suspect the comb is due to the quantisation noise I mentioned above. I run my ASI 1600mm with 16bit raw gain 139 offset 50 bandwidth 80. Regards Andrew On second thoughts it may be the stretch from 12 to 16bit that causes the comb.

Yes at your gain you have a read noise of 3 to 4e rms with a gain of 5 e/adu giving 15 to 20 adu rms. Try something like 50 to 60. Check you darks are not clipped at zero but show a good gaussian like distribution . Regards Andrew