What eyepiece should I use with a Tasco 76 mm reflector?
I have recently joined the SPA and was hoping you could answer a
query regarding my telescope. It was a Xmas present last year : TASCO, 76MM ALUMINISED MIRROR, 280X REFLECTOR FOCAL LENGTH
700MM, with 5 MM AND 20MM EYEPIECES
I PLAN TO DO SOME PLANET SPOTTING AND WOULD LIKE TO KNOW WHAT EYEPIECE YOU WOULD RECOMMEND AND WHAT YOU THINK OF THIS TELESCOPE IN GENERAL, would appreciate your comments – John H
Tasco telescopes have a rather variable reputation. Some are good and some are bad. As for how good yours is, the only way to find out is to try it and see!
But as for which eyepiece to choose, I would strongly advise getting to know how to use the telescope and the sky with the 20 mm eyepiece to start with. I know this only gives a power (magnification) of 35, but you will find the 5 mm eyepiece very hard to use to begin with. It should give a magnification four times greater than the 20 mm eyepiece, namely 140, but this may be pushing it as far as the telescope is concerned. You probably have a Barlow adapter as well, which is intended to multiply the power of any eyepiece by whatever factor is printed on it, either 2x or 3x. However, these are usually rather poor quality in these cheaper telescopes, so don’t expect too much of it.
If you want to get an additional eyepiece, get a 10 mm or thereabouts. This will give a sensible power of about 70, which should show a fair amount of detail on the Moon and planets as long as the telescope’s mirror is up to it. But try the telescope with the existing eyepieces first, before splashing out. It is probably not worth getting a better Barlow first as the existing eyepieces are probably not up to much and it would be wasted. Also read my reply to another question about these small reflectors.
It would take virtually a whole book to describe fully the use of the telescope (and indeed I have, Stargazing with a Telescope), so really it is up to you to test it out for yourself. A good test is to first look at the Moon and make sure you have a good, sharp, clear image with little or no false colour at the limb. Also examine a bright star image – it should appear circular on both sides of the focus position. If it is distorted, or elliptical, then there is a problem with the telescope which may or may not be fixable.
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