wimvb

In this case, that's correct. But generally, flats are taken under "day time" light conditions. But here there is so much light pollution that even lights have a high intensity level. I used DBE in Pixinsight with only eight samples along the diagonals in order to reduce the vignetting. This never affects weak structure such as the blotches. I start to suspect the quality of the bayer layer or the antialiasing layer on the sensor. Ordinary interference as in Newton rings could create blotches. That would not show in darks, and be masked in flats. This would be a very serious quality issue for Sony.

That wouldn't surprise me too much. The sensors that zwo uses come from various "families". Larger sensors are generally used in consumer cameras. Smaller sensors may be developed for machine vision an surveillance applications. Some basic on sensor image processing isn't unheard of. Otoh, that should affect darks and lights alike.

I don't think the drivers have a gain conversion table. I wouldn't trust the e/ADU, only the set value of 120. No idea, really. As you say, the values should be divisible by 4. I'm not sure it's data corruption, because that would more likely corrupt the whole file.

It seems from the light frame, that the offset is already low. However, several people reported the same problem, with the same camera model. To me, that suggests a camera issue, rather than a flats issue. The uncalibrated light frame has the same colour blotch. It is also very weak, and needs to be stretched a lot to reveal any signal.

The suggested solution is to lower the camera offset. Have you tried that?

Cool! Always nice to see physics in action. Unfortunately that other variable is just outside your fov.

It has been raining so much lately, that my property IS slowly turning into beach front. A few days ago, I spotted swans in this lake-to-be. When it starts freezing, this will be a great place for kids to go ice skating.

Nowadays only clouds are active, it seems. Nice pic.

I think you can safely lower the exposure to one minute, or iso to 400. There is basically no information to the left side of the histogram, so you are losing dynamic range. Otoh, if you overexpose the stars, you will end up with star cores that are difficult to repair. Try to find the exposure time that works best for you. Neve mind what others are using. Your gear + imaging conditions are unique for you. That's why it's important to experiment to find the best settings.

That's a very nice Pleiades, especially for the very short integration time. You will need more data to bring the noise down.

Yes, but a guidescope in those rings, on a finder shoe on a scope mounted in guider rings. That looks like a recipe for differential flexure, imo.

No walking noise. In fact, almost no drift at all between exposures. Very accurate tracking.

Yeah, but I must have thought that no needle can be fast enough to keep up with video signals. 😁

Are imaging nights getting shorter already? Oh my, I haven't even started yet.

I wonder how many patents we have between us. Mine are only illusionary.

Some careful stretching later:

No one ever said that astrophotography is easy. Welcome to the club of problem solvers. (Or as they say in the software business: "there's always one more bug.") 😋

Those zip files are rather large. Lights.zip now at 1.3 GB and loading ...

NICE! I've heard that Microsoft ICE does a good job. Also PixInsight has several tools for making mosaics.

Isn't that a zoom lens? 😉

Besides the already mentioned focus issues, you might also revise your calibration and stacking process. Your masters still have a lot of hot pixels. Plus there are a number of dust bunnies that can be removed by using flats.

Great report, Göran. And I'm not jealous at all. 😉 For as Orup put it : "Jag har bara regn hos mig". Have fun down under.

Great start in AP. What does "BPM" stand for?

Interesting. I would like to see the transmission curves for these filters. IDAS are generally good quality LP filters, but if the zwo cover glass isn't as good, what are the chances of the combination causing unwanted reflections?

When I was a kid, I got the idea to hook up a simple audio tape recorder to a tv, to record programs, but I didn't have the means. Only a few years later did I see a vhs recorder.