Skywatcher Coma Corrector and 2" LP filter

[jl694]

Hi everyone,

I received a Skywatcher 2” light pollution filter in the post today. I was really impressed with its performance when I looked through it at a sodium streetlamp.  

However I came into difficulties when I tried integrating it into my imaging setup with a Skywatcher Explorer 150P. I wanted to have the following arrangement:

Canon DSLR --> M48 adapter--> Skywatcher 0.9X Coma Corrector --> Skywatcher LP filter

However, the 2” thread on the coma corrector is inaccessible due to a ring which I can’t seem to unscrew as it appears to be glued in place (see http://www.flickr.com/photos/111922926@N08/12108027363/ to see what I mean). Therefore I can’t attach the LP filter to it. The filter is threaded on both ends, so it is possible to combine everything by switching the coma corrector and LP filter in the arrangement above, but it is impossible to reach focus with the telescope as this adds another 8mm or so along the optical axis.

Has anyone else encountered this problem? If you have the same coma corrector, is the 2” thread accessible at both ends? Should I just invest in a clip filter for the DSLR instead?

Thanks,

James

[Kropster]

I have the setup that you want to achieve... filter, coma corrector, M48 camera adaptor.

It looks like the ring needs to be screwed further into the coma corrector... looking at mine, I see more thread for the filter than yours is showing.

If I can work out how to insert photos here, I will post a couple!

[Kropster]

Got it!

[jl694]

Thanks Kropster! Your image really helps. Does your ring seem glued on too? Mine won't budge in either direction

[Kropster]

I can't see any glue visible on the thread.

Looks like special spanner that fits the two slots would be needed to adjust.

Is yours new? Perhaps you could return it?

Sent from my XT890 using Tapatalk

[jl694]

Been in touch with FLO who I bought the coma corrector from. Turns out to be a manufacturing defect so I'm exchanging it for a new one. Hopefully I'll be shooting LP-free images next week

[Kropster]

How unlucky was that?!

Better luck with the next one.

[astrorabbit]

Just ordered the same kit, glad to know there is a known issue and will look out for that. Those special spanners are often used in the cycling industry so a larger bike shop or one with a decent workshop may have one that fits. Sometimes needle pliers will work... Just be very careful round costly optics!

[Kropster]

I think taking a spanner to it could cause problems and certainly invalidate the guarantee. Best left to be the manufacturer to make any adjustments.

Sent from my Hudl HT7S3 using Tapatalk

[astrorabbit]

This is very true, leave any tinkering untill the warranty has expired!