Dust I asssume ??

[halli]

Hi

I attach an example of some doughnut shaped artifacts on an image which I am assuming may be dust somewhere in my optical system !??

Two are really prominent and there are some more which are a lot fainter

They almost look like a star out of focus and I'm sure I can see the usual chunk out of one side of one which I normally see on an out of focus star which is caused by intrusion of the focusser on my 130pds.  I guess this might give a clue as to where they might be located.  

I presume if they were on the camera sensor then they would appear as dark solid dots ?  

Perhaps they are on the primary or secondary mirror ?  

I do use a foam tube on the scope to stop dewing of the secondary but cant think how this may be involved !

I guess flats may help eradicate them but feel I want to physically remove them and would love to know if anyone has had a similar issue and where they may be located and to confirm that they are actually dust !

Thanks for any info  leading to their annihilation !!!

[Freddie]

Likely to be on the cover over the chip, rotate the cam and if they move with it, they are on the cam. Flats is the way to go though as they would remove them and help with the image processing as well.

[ghostdance]

I reckon you've discovered two new planetary nebulas, the long lost sisters of M57 :D

(Sorry, just couldn't resist. Er, I'll get my coat.... )

[halli]

Yep either that or some UFOs !

Anyhow I guess its getting into the discipline of flats that is needed.

I still would like to get rid of the primary cause though !

[nucdoc]

I have the same problem, two similar spots on my image.  I have attached flat that I took tonite, I have exaggerated to contrast to show these, on my image last nite there were only two.  I rotated the camera several times, made no difference. I cleaned and examined the camera and scope but can see nothing to explain these. Ran the focus thru its full range, no effect either.

Scope is a Celestron EDGE HD 11, camera is a mallincam Universe.  Would like to know what i can to to get rid of these as well.

Flat is below

[ghostdance]

Good heavens! Canada now....It's an invasion!

M57's popping up all over the place.

Wish I could help, but I'm only a flat-earther visual type.

An intriguing problem tho, this calls for Sherlock...

[PeterCPC]

Looks like out of focus dust to me. Try cleaning the sensor and lenses in the imaging train off using one of those air blowers.

Peter

[Freddie]

If you rotate just the cam and they move with it, they are on the cam. I assume that's what you mean by rotating cam made no difference. If focus adjustment does not change them, then again indicates they are on the cam.

[andrewluck]

If you want to know exactly which optical surface the dust is on then take a look at this calculator: http://www.ccdware.com/resources/dust.cfm

Andrew

[ghostdance]

Luck? Andrew?

Colts fan?

[andrewluck]

Ah yes, must be me! There's a couple of mistakes on the website though, they have my height wrong and seem to have divided my age by 2...

[halli]

Thanks for the comments - the link to the calculator you posted Andrew should help to point to the surface to be cleaned - just need to look up some facts re my camera now ! Thanks very much.  (So you obviously deny playing for Indianapolis then !)

[ghostdance]

Ah yes, must be me! There's a couple of mistakes on the website though, they have my height wrong and seem to have divided my age by 2...

Bet you'd make a better-looking QB tho..............

(OK OK, I confess - I'm a longtime Broncos fan)