what reasons can it have when integrating sony a7rv subs with astropixelprocessor that the stack show a lot of artefacts when a single sub does not, especially when the light pollution gradient is removed?

What were the conditions in which you took the data, lots of light pollution and such? The horizontal pattern is interesting indeed, how does the integration look like without calibration data?

Hi Stefan @elgol,

Thank you very much for sharing your issue.

This looks very similar to one of the following issues:

• sensor interference due to a bad camera connection cable and or
• inproper dark frames to calibrate the lights, make sure that the darks properly match the sony camera for iso/exposure and temperature. If that solves it, it is clearly a characteristic of the sensor. If it does not solve it, i would investigate the camera cable.

These kind of interference patterns are quite common when using cheap and/or damaged cables. Oh and it could even be interference from a bad usb port, but it is less likely.

Is the camera new?

A single sub will have the pattern only very ! hard to see, when stacking multiple frames, the noise pattern comes out more clearly since you can not calibrate it away apparantly.

Mabula

Hi Mabula, Hi Vincent,

it must be consequence of severe lightpollution substraction since with subs made on La Palma I did not have this on several stacks.

I bought the Sony a7RV and the Sigma 200mm f/2.0 new for fun and simplicity. No calibration frames, no cables (camera sd cards with remot timer), no autoguiding... vacation from mono so to say.

Here is a single 4 min sub at f/2.0, ISO 320, done with a ioptron HAE43ec, no autoguiding which works almost as good as with AG

Here then the 2,2 hours processed stack for the love of the universe's colors:

The lens has -1.3 ev vignetting so some aperture vignetting at brighter stars, still ok for me. Thisd works without flats for me when using APP and its superb lightpollution tool, which I intuitivly use since 2018 on almost all stacks. You get background neutralisation, LP correction and vignetting gone at once manually! 

Of course I wish that pattern does not occur under bortle 5 like that before. though I guess these lamps' brightness from these crazy neighbors here are to bright in my new home and worsen this.

stefan

Hi Stefan @elgol,

Thank you very much for your response. 

The striped artefacts that you referred to can not possible be introduced by APP's Remove Light Pollution Tool. There is no algorithm there that would create such a banded pattern. That pattern is definitely in your bias or dark current form the camera's sensor for sure. It can be sensor characteristic or like I suggested, caused by electromagnetic interference, that is by far the most likely cause I think, because over the years it has almost always been this case if an APP user shows something like this. In the case of electromagnetic interference, the pattern will always have a random nature where you see the bands formed. Each data set will show it differently. If it is really the sensor, the pattern will not be random but each time the same.

I can image that depending on the data, the problem is shown in some cases and not in other cases. Has to do with exposure time, capture conditions etc...  And a tool like Remove Light Pollution can reveal such a problem in the sense that it makes it easier to see. If the LP tool was responsible, you would see that banded pattern inverted in the model view. Did you check how the correction model looked with the show model button?

Those La Palma image look great ! Perhaps the condition that created the banding was not present then, maybe the USB cable was better attached or maybe the humidity was clearly lower, a problem like this can be hard to track down. If you see it again though, please do some testing with the USB cable and perhaps a different USB port if you capture with a laptop. 

I have also seen that this banding problem can manifest more clearly if the exposure time or temperature outside is clearly different than moments that the banding is not there after capture.

Mabula

@mabula-admin Thanx so far Mabla

Stefan

Allright Stefan 😉