Funny looking stars

[Saturn488]

Was just going through my stacked images now and noticed my stars zoomed up really close look bloody weird.

Equipment
- ASI178MM-C
- ES 102mm APO
- LRGB filters

Could this come down to weather condition or a focus issue?

[glend]

Mostly lack of focus would be my guess, but you have some fogging there as well. How are you focusing your setup? Do you have a focus mask?

[billdan]

I thinks its dew / fog on the camera window glass.

Well it was with my QHY12, I have a dew heater now in front of the camera (wrapped around a spacer between the OAG and camera) to heat up the air in front of the glass.

[Saturn488]

@glend
- I use auto focus in Sequence Generator Pro
- I do have a mask but don't need it due to the auto focus

@billdan
- I have a dew band on my scope and on the ZWO camera glass

I was thinking it's the size of my sensor on my camera that is really small.
I did check all my LRGB and the stars looked sharp (Green/Blue they are dim due to the type of filter). It only happens after stacking.