M35 - 24/03/2007

That's a nice cluster alright. Good work Mike.

I would also say that the stars look 'lopsided', but also, there looks like trailing from bottom-right to upper-left direction. Maybe that might not be the reducer then? I hate to be knit-picking (rather, I'd hope it would be seen as constructive criticism!), but some of the larger stars look like they have a merged tiny double companion to their 4'o'clock position. I have encircled the ones below to show what I mean:



I hope this doesn't mean all your hard work in getting the tracking right was in vain!

Seanie.

Hi Michael, certainly a nice shot. I wonder if it might be worth your while looking through the individual frames. It might be that just or two frames are a little bit dodgy. Removing these from the stack might make the image a lot better. I'd be very surprised if that mount of yours would exhibit trailing over 20 seconds. I suppose the trick would be to see if it is all images or just one or two. Could the mount have gotten knocked out of polar alignment? Actually no that cant be the case or you would see a more consistent trail.

You've certainly gotten the focus bang on. It amazes me what that ST8 can do with 20 second exposures.

I'm so looking forward to seeing what you get when you are guiding and taking much more lenghty shots!

Dave,

Looked into this issue a bit more last night. I think alot of it is down to the focal reducer to be honest. It appears to be causing coma or some other form of distortion. When I try to guide, the star the guider picks up is primarily circular BUT with a fainter tail heading directly away from centre, which I interpret as coma. This of course makes it difficult for the guider to work as it tries to figure out which part of the star is the centre.

I was out last night imaging M97 with no focal reducer. When guiding at this focal length (3metres), I had perfectly round stars from my exposures (which were all 10mins). The guide star was also nice and round on the autoguider chip. However, at this focal length, the FOV is small and the imaging scale is 0.47arcsec/pixel.

So, I must re-evaluate my options on how to proceed with the 12". Must try and find a better quality reducer.

Regards,

Michael,

I have a .5 reducer which I never got to use. Wanna give it a go. Its called a Paul Rini reducer, picked it up for a song on e-bay. If you wanna try it your welcome.