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Image upside down.

Posted: Tue Feb 21, 2012 5:19 pm
by vauxhall
From my question,you will realise that I'm an absolute beginner.My telescope is a Jessop reflector TA800-80.The image I see is upside down.Is this correct or have I assembled it wrongly?

Posted: Tue Feb 21, 2012 5:43 pm
by David Frydman
That is correct.

Ordinary astro telescopes such as lens telescopes and mirror telescopes give upside down images.

This is historic because extra lenses are needed to give an upright image, and this was extra cost and degraded images.

Nowadays things are more complex, but a simple Newtonian gives upside down images although the image can move around at different telescope angles.

With a mirror diagonal on straight through scopes you can get a laterally reversed image.
And photographers also get different orientations.

With a DSLR camera a prism is used to get right way round images, some old ones gave upside down or reversed images.

So basically you can meet all sorts of orientations.

This why a binocular needs prisms to get upright images.
It would be much simpler without but the images would be upside down.

Old opera glasses and field glasses give upright images by using a negative eyepiece. The disadvantage is a very narrow field of view.

One quickly learns to move the scope correctly with a little practice.

Regards, David

Posted: Tue Feb 21, 2012 5:43 pm
by dazcaz
This is normal on a reflector. You are doing nothing wrong. ... -Down.html

Posted: Tue Feb 21, 2012 7:32 pm
by Brian
Welcome to the Forum! :)

Also, don't be tempted to try using the maximum claimed magnification of x399 with your telescope, the image just won't stand up to that power. The maximum useful magnification under good conditions will be nearer to x160, but you will probably find that x100 is a more practical value,