weird stars..

[all-on-black]

Ive got a problem with a couple of my images.

The other night I got 40x60sec exposures of m45, with a dslr at iso 400.

The problem is, although ive got lots of nebulae, and it appears to be in focus, the very brightst stars have a big halo around them. One of them have such a big obvious halo that you can see the shape of my scope with the focusing tube poking in.

This isnt star bloat is it?

Am I not in focus? I used BYE to get the FWHM down and used betelgeuse to focus on.

Could it be colimation issues? The halo is dead centred around the star though..

Any ideas??

[Daniel-K]

can  you upload a image?

[sidelight]

With the modded camera?  I had similar and it turned out to be UV light as mine 450D is full spectrum modded.  My filter didn't block UV light, only IR.  Look familiar?  http://stargazerslounge.com/topic/199640-i-can-see-the-scope-in-my-images/

Cheers

Ross

[all-on-black]

Thats exactly it! So i paid out for a camera that is no good as it is. Smashing. Now ive gotta get an external filter i guess, that or remove the glass altogether?

Ive got some uv filters that fit on the end of camera filters so i may test first by putting one in the imaging train somehow.

Thanks for your help!

[sidelight]

Test first. Its just what I found, this only.manifested for me when I removed all the internal filters after messing up fitting the internal replacement and getting internal reflections. It may not be the answer.

Cheers

Ross

Sent from my GT-N7000 using Tapatalk

[all-on-black]

Out of curiosity, what filter do you use between camera and focuser? Didnt think that was do-able?

[all-on-black]

The JPEG below is what I ended up with.. Not nearly as bad as yours Sidelight but the same effect:

 

[sidelight]

Out of curiosity, what filter do you use between camera and focuser? Didnt think that was do-able?

On my setup I have a 2" IR/UV filter screwed on the front of the coma corrector.  Thats what cured it.  Originally I had an IR only filter.  Got this effect from long exposures (after stretching) once UV was getting through.

Cheers

Ross

[Russe]

With the modded camera? I had similar and it turned out to be UV light as mine 450D is full spectrum modded. My filter didn't block UV light, only IR. Look familiar? http://stargazerslounge.com/topic/199640-i-can-see-the-scope-in-my-images/

Cheers

Ross

Who did your mod? I'm thinking about doing the same...

I would need a different CLS clip after isn't it and could I consider narrowband??

[sidelight]

Who did your mod? I'm thinking about doing the same...

I would need a different CLS clip after isn't it and could I consider narrowband??

I modded it myself.  Spent a morning locked away and used Gary Honis' site to make the changes.  I originally bought a replacement filter but couldn't get it square in so ended up with internal reflections.  Decided in the end I wanted to play with narrow band, and the only thing the camera ever connected to was the scope so focusing lenses wasn't an issue, so I removed all the filters.  The coma corrector is rarely removed from the front of the camera so wasn't too worried about dust.  

I now use a 2" UHC and a baader UV/IR screwed on the front of the MPCC and all seems well.  I must get around to doingmore than thinking about narrow band.  But the clear nights are so rare at the moment I seem to spend a chunk of them looking at a pile of equipment and thinking "I'm sure this goes together somehow, I just can't remember how". 

Cheers

Ross

[Russe]

I modded it myself. Spent a morning locked away and used Gary Honis' site to make the changes. I originally bought a replacement filter but couldn't get it square in so ended up with internal reflections. Decided in the end I wanted to play with narrow band, and the only thing the camera ever connected to was the scope so focusing lenses wasn't an issue, so I removed all the filters. The coma corrector is rarely removed from the front of the camera so wasn't too worried about dust.

I now use a 2" UHC and a baader UV/IR screwed on the front of the MPCC and all seems well. I must get around to doingmore than thinking about narrow band. But the clear nights are so rare at the moment I seem to spend a chunk of them looking at a pile of equipment and thinking "I'm sure this goes together somehow, I just can't remember how".

Cheers

Ross

Lol. I know how that feels - I've actually written a file on how to setup my astro gear and every now and then I give myself the mental challenge to run through a setup before I fall asleep...

[sidelight]

I have the CLS filter I used to use but swapped that to a UHC filter a while back.  Got fed up with fighting the colour cast.  I still plan to use it an unmodded camera for wide field but that something I will probably leave until its a little warmer for playing.  I need to work out how to nicely mount the camera to the scope or maybe get a dual bar? Not decided yet.

Cheers

Ross

[Langy]

Don't know if this is related at all, but I decided to get the cheap xBox webcam out last night.

Jupiter had that halo round it just like the image above, now that is the first time I have ever had that (only used it 3 or 4 times) so put it down to atmospherics.

[all-on-black]

Hmm, I have an unmodded 500d that I use and see if that does the same thing. I bought my 450d already modded, but I thought it was modded, turns out it's just got a single IR filter removed and replaced with something else that cuts out the IR a little less than the original. I thought I was buying an infrared camera basically. But nope!

Maybe I should rip it apart and pull out the whole lot? Is that a fairly easy process? Lots of little tiny screws from what instructions I've seen about..