Focusing Problems

[Moon Lander]

OK, here's time for my really dumb question. Last night was one of the first clear nights since I got my scope (200PDS). I had collimated it and then lined the finderscope up by looking at a house aerial in the distance. That was fine and I could see the aerial through the eyepiece when in the centre of the finderscope. It was a little blurred, but I assumed that was just because it was too close. When I came to look at the sky, the finderscope was full of stars, but I could not get anything to focus through the eyepiece. I tried the 28mm that came with the scope and the 13mm Ethos we have just bought. Everything worked fine through my wife's scope.

Has anyone any bright ideas what I might be doing wrong? Is it just not collimated properly, or is there something obvious I am not doing (and yes, the lens caps etc were off!). Any help appreciated. Thanks.

[TheThing]

The only dumb question is the one you never ask.

I'm assuming you have the Dual Speed focuser (IIRC that's what DS stands for?)? Where you focusing with the coarse focuser or the fine focuser? The fine focuser will take an awful lot of turning to get into focus.

[shaunster]

Maybe the focuser doesnt have enough travel to focus those eyepeices? and an extension may be needed

[Merlin66]

Do the same experiment with the distant aerial but use the 28mm and Ethos eyepieces....

The difference in focus position between the aerial (in focus) and the stars (in focus) should only be a few mm INWARD travel.

[Moon Lander]

Thanks for the advice so far. I will try the aerial focus again (at least the cloud shouldn't get in the way of that!). I do have the dual speed focuser and tried with both the coarse and the fine with no success with either. It would also be good to see the moon one night as that is a much bigger target to try to get it to work on.

Shaunster, you may have a very valid point, but I would have expected the eyepiece they supply with the scope to work with it?

Thanks again.

[NGC 1502]

Hi, yes, the eyepieces supplied with the scope should work with it. You can

pinch a bit more outfocus by not having the eyepiece fully inserted into the

focuser. But if you try this, make sure you have enough inserted to prevent

the eyepiece falling out.

Even if the collimation is off, you should see something.

I'd try what's been suggested so far, & if nothing sorts it, maybe try contacting

a local astro club or the supplier.

Good luck, Ed.

[adamh]

Hi,

The 2 inch eyepiece will only focus with the supplied 2 inch extension tube, this should be in the box somewhere.

My 1.25 in eyepieces focus well without the extension tube, and only the 2 to 1.25 reducer. However my 6mm will not focus with the 2to1.25 reducer that came with the scope, but I can't recall if inward travel was the issue with this one.

Hope this helps,

Adam

[Moon Lander]

Hi Adam,

Thanks, you may be a life-saver (ok, slight exaggeration!). I was about to post again as I tried focusing on the moon last night and failed again. I wondered what that tube in the box was for. Us newbies really need an idiots guide to putting everything together. Thank goodness for SGL

When I get the next clear night I'll try this and let you now how I get on. Thanks again.

David

[Steve C]

I had pretty much the same issue when I got my Orion 8" newt, soon realised I'd have to pull the ep's out the focuser slightly in order to get nice crisp views.

Getting a 1.25" extension saved all the messing about

[Moon Lander]

The moon came out again tonight (very briefly) so I tried the extension tube - it worked!!! The moon was beautifully focussed using the 28mm EP that came with the scope. I tried the 13mm Ethos as well, but the cloud cover came over before I had chance to try properly. However, it did look like I might need a further extension tube for this to focus.

Thanks to all for the advice, and particularly Adam for the solution.

David

[Moonshane]

I also find that my 13E focuses a little further out than my other eyepieces even though they are also TV. thankfully I have a Skywatcher low profile focuser with the built in additional extension.

this is always a 'better' problem than not enough in travel of course as you can always add extension

[adamh]

David,

Glad it's working for you.

Adam