Newbie help! Reflector scope images seem fuzzy...

[Alan_UK]

Hey all,

I'm new to the forum (posting anyway) so hello all!

I got a 70mm skywatcher for Christmas and I've been loving looking around the night sky with it! I'm amazed at the detail possible with even such a small scope.

However, a friend of mine (after learning that I was interested) has let me borrow his 10" Meade Lightbridge Reflector scope. The detail is immense on low magnificantion (i.e. magnification that my other scope is capable of - around 40x or so). However, once I bump the magnification up to around 140x (9mm lens with a 1270cm focal length) I can't seem to focus in on big objects properly. Last night I was looking at Jupiter and it seems unable to focus to a sharp image - always looking 'fuzzy'. This suprises me, as with such a big apature I would have thought that this magnification wouldn't be a problem?

Does anyone have any idea what the issue could be, and how I could resolve it? I'd love to see Jupiter at a high level of magnification!!

Thanks!

Alan

[CGolder]

could be a number of factors, bad seeing condition's being the main reason, then with mirror collimation and having a decent eye piece.

[rowan46]

welcome to sgl. There may be a few things going on firstly was the scope cooled down. a reflector needs to be cooled first otherwise the mirror will be contracting whist you're looking through it. secondly jupiter is getting lower on the horizon now thus making more atmospheric interference on the image. the clearest pace to look is towards the zenith.. Its been very windy the last few days which will affect the seeing and also quite a bit of high altitude very thin cloud which will affect transparency. And thirdly it may need collimation.

[Alan_UK]

Thanks for the quick responses!

I believe that the eye pieces are pretty good, so I don't think that it would be that... Seeing conditions could be an issue! Does anybody know of a decent website that provides cloud cover / seeing condition forecasts over the UK? I'm checking out the met office website at the moment (and then obviously actually going outside once it is dark!) but it doesn't seem all that accurate.

Rowan, how long would it take such a scope to cool down to have stopped contracting?

[Uranium235]

If you want to see what happening weatherwise (updates every 15 min) goto sat24.com, that will give you a good idea of whats coming your way too (be your own weatherman!).

Scope cooldown times depend on the size of the primary mirror (it could be anything up to 40min), but 30 min should be more than enough of yours.

[John]

If the scope has been transported it will probably need to be collimated. If the collimation is out you will not be able to get crisp images at medium to high power.

The observing conditions and low altititude of Jupiter could also come into play but I would have thought a 10" scope should be able to deliver decent views at 140x despite those issues - my 10" newtonian was showing a crisp disk and a number of well defined cloud belts on the planet a couple of nights ago - that was at 150x.

I usually leave my 10" around an hour to cool down.

[tomw28]

Does anybody know of a decent website that provides cloud cover / seeing condition forecasts over the UK?

I have signed up to CalSky, where you can have a variety of emails about the days astronomical events, including the weather that shows a recent satellite image and a detailed forcast for the next few days. sat24.com is also good.

As for the actual scope, sounds like it needs collimating to me. Have you got a Cheshire or a laser collimator?

Tom

[JohnDenim]

Looks like were buggered for tonight.

[Alan_UK]

Great info all!

I don't have either a laser or Cheshire collimator, but I'll look into getting one.

Doesn't look good for tonight, but that site will be a great help!

Next time I get a chance I'll leave it to cool for a bit longer, collimate the scope and see how I get on then! I'll let you know!

Thanks all!

Alan

[brantuk]

Which make of eye pieces were you using? Quality can make a big difference. As well as seeing, cool down time, object altitude, collimation, barlow, etc. Getting it all correct at once takes patience, and a little luck thrown in too

(I keep ep's warm in my pocket before using - can help)

[JohnDenim]

(I keep ep's warm in my pocket before using - can help)

Like fisherman and maggots?

[Capricorn]

You have several things most of which have been covered.

Collimation, cooldown, eyepieces, finally the mirror is likely to be spherical. A spherical one simply will not deliver the quality of image.

A 10" lightbridge is on a slightly different scale of quality.

[BAZ Senior]

Have a look at this site, there's loads of good info regarding collimation, without frying your brains., and compiled by a member of SGL.

Astro-Baby Telescope Help

[brianb]

Look at the weather pattern, that's a clue. When the weather is unsettled, the seeing is always mush ... I've known it to be so bad it was hard to focus a 80mm refractor at only x24.