Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Recommended Posts

Recently got an LX10 8" SCT in very nice condition. Superb views at 50x. At 200x with a 10mm Series 4000 ep I can't get tight focus on anything but the Moon (which is well enough focussed to see atmospheric movement). Jupiter however won't focus well enough to see banding which is clear at 50x. Is the issue eyepiece or me? Collimation would seem to be reasonable as the 50x is so good. Grateful for advice please.

Share this post


Link to post
Share on other sites

It may simply be a combination of poor 'seeing' and the scope not at thermal equilibrium. The image breaks down rapidly at higher magnifications when conditions are not perfect, and also focusing itself is more difficult at the higher magnifications. I always check colimation on the night at the beginning of the session (or part way through if seeing settles down and the view improves) and this is done using the highest magnification you can get (your shortest f/l eyepeice plus a barlow if you have one) - and while checking through the eyepiece on a star image you get a very good idea of the atmospheric conditions.

ChrisH

Share this post


Link to post
Share on other sites

Hi Ya Ageing and a very warm welcome to the SGL mate, as Chris says its probably more down to the seeing than the actual scope itself, you say that collimation looks ok, the more you observe, the more you will get used to the seeing conditions, just comes with experience, as Chris says, best to just set up and leave the scope for an hour if you have time, just pick a star fairly bright, but nice and high in the sky, centre in the FOV and just de - focus slightly, this gives you the magical "airy disk", just spend a little time on the focused star (the smallest point of light you can focus to) if its moving and twinkling this shows you the state of the atmospherics (the star being nice and high in the sky to limit the seeing) just de - focus the star either side of focus and if the image is boiling and wobbling just out side of the central point of the de -  focused star - then the atmosphere is unsteady and the seeing is very poor.

I try to observe things when they're at their highest point in the sky, be it a planet or a DSO, try to wait when they are near to the meridian (an imaginary line which runs from due South, up the sky and overhead and to Polaris) - this is when you have the least amount of atmosphere to look through and should be the steadiest air, giving better seeing.  With experience you will know how high each object appears depending on your latitude as the seasons go by the sky changes and different objects become visible different times of the year.

Some nights the views are absolutely awful, other night slightly better and on a few nights, the atmosphere is rock steady, last month when Jupiter was near to opposition, I think i had a few nights of fantastic steady air, the views of the Great Red Spot and surrounding areas of Jupiter were probably the best I have seen in quite a few years , the colours were so vivid, I've been used to quite a pale looking GRS, more redder than I have seen it for such a long time.

Hope that helps a little Ageing and once again welcome mate to the ASGL.

Paul.

Share this post


Link to post
Share on other sites

As said, it is most likely poor seeing. For me X200 is a bit top end on Jupiter and seeing needs to be right. I have known X120 give similar results on my scopes and I know there is nothing wrong with them, even the Moon was a washout.

The other thing it could be is not allowing enough time for the scope to cool if you have had it indoors, it can take well over an hour for these SC scopes. At x50 it will appear all is well but you don't need to go up the scale much for washed out Juptiers.

Alan

Edited by alan potts

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.