Consistent light bloom with Asi294mc Pro

r4duffy

These are initial shots with new setup, Celestron RASA 8 + ASI294 MC PRO

Shots are over-exposed to illustrate the area of bloom.

Any insights? I don't see the bloom on darks or flats.

Thanks!

katherine.tsai

Hi Sir,

1. It seems like the reflections inside the optical system, could you have a check and reconfirm?

2. Did you turn on the cooler when you capturing?

You can turn off the cooler next time and see if the bloom still there.

r4duffy

Cooling was off on the Andromeda shot, it was on on the Veil shot.

I’ll do another round of tests tomorrow evening.

Overall those were three sessions a few days apart with and without cooling. It’s odd how consistent the bloom is.

Thanks!

katherine.tsai

OK we will wait for your info.

Since the bloom will show whenever the cooling is on or off, so it is possibly not related to the cooling.

You can check the optical system to see weather it has reflections inside.

r4duffy

Hi Katherine, I finally had a chance to do some additional testing.

For the images attached below I rotated the camera 90 degress from normal. As you can see the bloom rotates with the camera so it is definitely not optical reflections or anything related to that. It appears to be a large hotspot bloom area within the camera itself.

Please see the attached images and advise. Thank you.

katherine.tsai

Do you have other telescopes? You can try it with other scopes.

Or you can check the camera sensor to see whether you can see something on the sensor or on the protection glass.

mcerono

the patch rotated when you rotated the camera = its not the camera or sensor.

to me this looks like lightpollution and a not so well collimated scope. you lightpath is obviously not centered on the sensor. these are stretched images you are showing and I have similar results with the moon out or heavy light pollution. use flats and abe/dbe in pixinsight to get rid of it.