Focusing problem on Skywatcher 150

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Focusing problem on Skywatcher 150

Postby hwatkins » Wed Jul 06, 2016 8:34 am

I'm the proud newbie owner of a Skywatcher 150. At last the skies cleared and I was able to find Mars with the finder scope and the lens that came with the telescope (28mm I think). I centred it all up and quickly swapped to my other lens, a 6.3mm. I also have a double barlow which I tried to use.
But it didn't matter how many times I swapped lenses, how I moved the telescope or set the magnifiction, with or without the barlow, I just could not see the planet through the second lens.
I should add that I haven't set up the motor yet and am manually moving the scope to keep the planet in view in the finder scope and telescope.
Just when I thought I was making progress I realised that I was in fact looking at an internal part of the telescope, a dark circle with a cross, the secondary mirror?
Where am I going wrong?
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Joined: Mon Jun 06, 2016 7:21 am

Re: Focusing problem on Skywatcher 150

Postby Aratus » Wed Jul 06, 2016 9:27 am

When changing eyepieces you will need to re-focus the telescope. Move the focussing in the direction which makes the 'circle and cross' gets smaller. It should eventually focus. Try increasing the magnification in stages, focussing each time' so the image doesn't get too dim to see after the eyepiece is changed. I strongly urge you to get the telescope aligned before trying to do any observing. At higher magnifications a finderscope may not be accurate enough to put the object in the field of view, and the object will move out of it very quickly. Once you lose it, at high magnification, it will be more luck than skill to get it back again.
I use an 11" reflector (Celestron CPC 1100) and a 3" refractor, (Sky-Watcher ST80) mounted on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI 120MM, ZWO ASI1600MC and Canon 1300D for imaging.
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Location: East Lincolnshire

Re: Focusing problem on Skywatcher 150

Postby Supercooper » Wed Jul 06, 2016 5:19 pm

Hi Helen,

There are sections on 'lining up your finderscope' and on 'Using the Finder' in my Guide about Finder Types: Link here> ... 827/g.html

The main thing is that the telescope has a much smaller field of view than the finder. It is important that the view through the finder (crosshairs) is exactly lined up with the center of the telescope field of view. For a star to be central in the telescope, it should be just about smack on the crosshairs (Astronomy term there!) This is easy to do during the day using a terrestrial object (Saves trying to move the telescope all the time!)

Have a look at my guide and take it from there. Best of luck...

I hope this helps. Anything else you need to know, please write back :o)

Cheers, Barry
For My FREE Telescope Help Website:

Using fab Helios f8 150mm Achromatic Refractor on SkyWatcher EQ5 - enjoing the views!
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Re: Focusing problem on Skywatcher 150

Postby hwatkins » Thu Jul 07, 2016 5:57 pm

Thanks for these, I'll have another go!
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Joined: Mon Jun 06, 2016 7:21 am

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