weird looking stars

[emyliano2000]

Hi guys.

Could somebody tell me what is making my stars look like this?

The photos were taken with my full spectrum modified 600D, 2" IDAS LPS-D1 filter and TS65 quad imaging refractor.

I had the same problem when using a clip in filter.

This is the stacked image

And this is a single raw file

Thanks

Emil

[Davey-T]

Looks out of focus.

Dave

[knobby]

Looks slightly out of focus to me

[knobby]

Snap ?

[emyliano2000]

Just now, Davey-T said:

Looks out of focus.

Dave

I always use the Bahtinov mask and the Bahtinov Aid in APT and always have it spot on.

[LukeSkywatcher]

3 minutes ago, Davey-T said:

Looks out of focus.

Dave

Yep...........out of focus.

[Marky1973]

Did you stack in DSS? If you did you need to switch off Hot Pixel Detection....that can cause those funny looking stars. 

Although the focus does look a bit out...

[knobby]

Well weird then 

[Davey-T]

7 minutes ago, emyliano2000 said:

I always use the Bahtinov mask and the Bahtinov Aid in APT and always have it spot on.

 

Check in live view zoomed in to maximum to be sure

Dave

[newbie alert]

Check your focuser as may have slippage....

[Sunshine]

There's a hundred star tests going on there!

[michael8554]

If you're positive that focus was spot on, then dew perhaps?

But more likely focus wasn't .

Michael 

[Jonesdee]

10 hours ago, emyliano2000 said:

I always use the Bahtinov mask and the Bahtinov Aid in APT and always have it spot on.

I also use a Bahtinov mask and the Bahtinov Aid in APT and have had exactly the same issue with my 80mm refractor - spot-on focus according to the focus aid, but definitely out of focus when checked in live view at 100%.

I wondered if it was because I used Arcturus to focus and it was too saturated for the Aid to  work accurately.  Something I am planning to check.

[The-MathMog]

Indeed just looks out of focus. Is there anything optically that you change after focusing? Filters, spacer, anything? And do you only focus in the beginning or during the session?
If you only focus at the start, dropping temperatures during the night, or even just a scope that hasn't cooled yet, will change the focus over time.

[Jonesdee]

Seems that this issue has been discussed here before:

 

[david_taurus83]

I have tried both Bahtinov aid and focus aid and couldn't get on with them. Live View is best.

[emyliano2000]

I'll  be out tonight, I will check the focus again and take a 120sec exposure to see how it looks like.

 

[carastro]

Definitely looks like focus to me.   Even the suggestion of the cosmetic tab being ticked in DSS I am not sure about as that normally eats into focussed stars and these stars look to be too big to be in focus.

Quote

Check your focuser as may have slippage....

Provided APT focus aid is working as it should, this might be another thing to consider.  I was frustrated no end when i first started imaging as every-one kept saying my images were out of focus and I knew for certain I had focussed.  It took me a little while to realise my draw tube was slipping even with thE focus locking nut tightened. 

I have never used APT focus aid, I always use just the Bahtinov mask and manually focus it.  

Carole

[emyliano2000]

I found out that it was indeed the focus. ?

[knobby]

Glad you got it sorted 

 

[LukeSkywatcher]

When i said it was a focusing issue, i hadnt noticed that you are using a refrac. I was thinking along the lines of a reflec and that the dark spots in the centre of the stars was the secondary mirror showing.

Glad its all sorted now.