Why are the stars in my ZWO 178MC so bloated? The dimmer stars seem to be okay. What can I do? Minus Violet filter?
http://www.astrobin.com/309992/?nc=user
http://www.astrobin.com/309992/?nc=user
ZWO Bloated Star images
Hello. This looks like an optical problem and not necessarily the camera. Could you describe your setup?
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I am going to take out my light pollution filter. It wasn't an expensive one. Get my setup down to the bare minimum, and see where I go from there. I need a clear nite off though. 
I have a 178mc also and I have some bloated stars on my last two stacked images, but not on the ones before . I have thought mine come from a bit of dew forming on the lens. I haven't confirmed this yet, but that is what I suspect.
Other threads on other forums are blaming the glass covering the sensor (as supplied to ZWO by Sony). It may depend on what type of filters you have.
I have the ZWO filters and I have it.
One member in our club wrote me:
"Seems that you are experiencing the reflection of the camera protect window. It's an AR32 type of glass and it happens on combination with certain type of filters. You can read more here http://www.astrobin.com/forum/c/group-forums/zwo-asi1600mm/asi-1600-mmc-halos/"
I have the ZWO filters and I have it.
One member in our club wrote me:
"Seems that you are experiencing the reflection of the camera protect window. It's an AR32 type of glass and it happens on combination with certain type of filters. You can read more here http://www.astrobin.com/forum/c/group-forums/zwo-asi1600mm/asi-1600-mmc-halos/"
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Joe, you didn't list your OTA in the image metadata - what were you shooting with? I had a really similar issue when using my 178MC-C with nikon lenses; in my case, getting the back focus dialed in on the mount adapter reduced the bloat a lot. I also added an extra IR/UV cut filter; supposedly the window on the 178MC is a cut filter, but I remain dubious, and my stars seem tighter with the filter than without.
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