Noise and diffraction spikes in live stacking

[Knmurphy1]

Hi folks,

this is my first post and I’m hoping some of you might have some advice.

I recently bought a QHY 183C camera and finally got to use it after endless weeks of cloud. There are two issues, the first is the diffraction spikes on the stars to the right. Any ideas what is causing these? I’m using a Televue 76 refractor. with a 0.8 reducer. So there should be no diffraction spikes. Or am I missing something?

The second is the diagonal noise throughout the image. any ideas on this? 
It’s a live stack of 50 x 30 second frames. 
I expect some noise as I didn’t use any darks but I just find these streaks unusual. 
Any comments would be greatly appreciated.

Kevin.

 

[bomberbaz]

Washing line, telephone line, tv arial or similar in the light path

[Knmurphy1]

3 minutes ago, bomberbaz said:

Washing line, telephone line, tv arial or similar in the light path

The object was very high, probably 10 degrees from overhead so I don’t think there was anything in the light path. Thanks for the input 

[ONIKKINEN]

Something inside the scope obstructing the light path, like a shiny screw or similar? Could be pinched optics too. Weird diffraction spike threads appear every now and then and often there isn't a solution 😮 . I have an extra diffraction spike on my newtonian, but only sometimes, and only on some parts of the image much like yours. No clue what is the cause, i am guessing some kind of pinching but have not bothered to figure out.

The diagonal noise is walking noise, which partly goes away with  taking and applying matching darks and completely goes away if you dither every now and then.

[James]

Whilst it's unlikely to be this I have seen similar spikes when I've had a small patch of dew on my objective. Last time was with M45 as well back in December. Was using a refractor, had no spikes on anything else bar the lower part of the image. Never did figure it out but ramping the dew strap up to 100% made it go away so I figured it was that...

James

Edit:  " ramping the dew strap up to 100% made it go away "  I guess if my optics were pinched due to cold it might get resolved with a bit more heat but I've imaged on many colder nights more recently and not seen this..

[bomberbaz]

Now on PC I can see this better, agree with the walking noise.

Spikes, could there have been a hair or similar actually inside the tube. A good clean would be my first course of action.

[James]

2 hours ago, James said:

 I have seen similar spikes when I've had a small patch of dew on my objective.

Just checked some notes... it was dew on the glass in front of the sensor, not the objective.. which might explain why I had only part of the image with similar spikes..

[Knmurphy1]

Thanks a million for the input  guys. Will investigate all of the above.