Jessops TA 800 x 80 reflector

[David8]

I'm new to astronomy and like many others have been fascinated by the
subject over the years, but not done anything about it, apart from
binoculars (too shaky). My kids have bought me one of the above, and
inspired by Brian Cox's programme, I have been out in the garden, over
the last few nights in the cold (ice forming on the scope).

Not much success though, I can see the craters of the moon quite
nicely and I think that Jupiter is just to its left in the January
sky, but if I put the 20mm eyepiece in, without the Barlow, I cant
find Jupiter, and with the Barlow I cant see much at all - what am I
doing wrong? The field of vision is so small, its difficult to know
what I am looking at.

Any tips, or is the telescope of insufficient quality anyway?

Regards

David Edwards
Buntingford

[Robin Scagell]

Hi David,

I think you have discovered the reason why you need the finderscope to be accurately aligned! Even with the 20 mm eyepiece it is surprising how small is the field of view of the telescope. You have to find an object by day using the main scope, then adjust the finder so that its crosswires are exactly on the same object. But this assumes that it's easy to adjust the finder, which is often not the case on cheaper scopes. 

The reason for this is usually that the tube of the finder is not held tightly by the collar that surrounds it, so the telescope doesn't move as you adjust the screws. The trick is to put a bit of tape around the tube so that it's held tightly by the collar. Even then they can be hard to adjust, but at least that's the intention of the system.

Once you have the finder accurately aligned you should be able to find Jupiter. If not, start by finding the Moon and aiming the finder at some obvious feature (such as the end of the terminator or shadow line). The main scope should then be showing the same feature. The Moon is large enough that you can see how far out you are. 

If this isn't the answer come back and we can explore other possibilities. The Barlow should work on the Moon, but usually the Barlows with the budget instruments are rather poor and while they give the magnification stated, the quality is so poor that you are better off without them.

Let us know what happens.

Robin Scagell

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