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Just Joined with an ETX 80

David55

By David55
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David55

David55

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I'm not exactly sure why I've suddenly developed an interest in astonomy. It might be that the recent coverage of the Apollo missions, following the unfortunate death of Neil Armstrong, reminded me of watching the first moon landing in 1969 and the huge enthusiasm and optimism everyone felt at that time. Or it might be that BBC programme with Brian Cox and the chap that played guitar for Queen. Either way, I've spent far too long- for someone who must get up ay 5.15 each morning- sitting in my back garden after midnight peering, with little real understanding, at the pinpricks of light far above.

Which telescope did I buy? An ETX-80 'tabletop' system which I got at a very good price from my local - read 40 miles away- dealer. This is my review:

This refractor telescope has a relatively small aperture, but I was still able to have a good view of a very small, but bright, Jupiter the first night I used it, complete with 4 moons and two brown bands. The ETX 80 has a focal length of only 400mm, so the two supplied eyepieces of 9.7mm and 26mm give magnifications of just x41 and x15 respectively. Both eyepieces seem to be reasonably good quality being lighter versions of the Meade 4000 Plossl series. The 'scope also includes a Barlow lens which has the effect of increasing the focal length to 800mm, thereby doubling the available magnifications to x82 and x30. Unexpectedly, I found the quality of the Barlow to be pretty good. The only problem with introducing it is that refocussing takes about 20 turns of the slightly awkward focus knob.

Refractors, particularly those with short focal lengths, suffer from chromatic aberration- or false colours around the edges of bright objects. This was present on the ETX-80 but, as far as I could see, it was only visible on darker objects against a bright background, like the branches of a distant tree against the sky. And even in this case, it wasn't too bad, depending largely on whereabouts you looked through the eyepiece. Used as an astronomical telescope I saw almost no effect at all.

When I first tried the 'go-to' capability, I was disappointed. It didn't seem to align correctly and it would report a motor error after a few minutes. The motor error was probably caused by using the 'scope in sub-zero temperatures, which has a very negative effect on the voltage output of the battery pack. I overcame this by using a mains powered 12V supply in place of the batteries. I found later that the battery pack was sufficient, and no faults were reported, if the temperature was several degrees above freezing.

The alignment problems I had were due to me being too keen to get going and not following all of the instructions correctly. After watching the videos that came supplied with the 'scope, I recalibrated the motors (not as difficult as it sounds) and reset the time (it seems that the built-in clock can't maintain its accuracy for more than a couple of weeks) and everything dropped into place. Now when I set it up the ETX-80 slews to its calibration stars, which appear in the middle of the view needing very little adjustment at all. As do the targets I set it to find.

Since then my only problem has been that one of the worst winters for many years has allowed very little opportunity to see the stars at all. But in the short periods of clear sky I have seen lots of star clusters, the Andromeda galaxy the Orion nebula, some double stars and so on. But the most exciting thing so far has been seeing Saturn with its rings for the first time late one night. Well worth standing in the freezing cold.

I've been reading lots of astronomy books in the overcast periods between 'good seeing' and am looking forward to using the ETX-80 on the warmer nights of spring, especially with the additional lens and x3 external Barlow I purchased, which will give me a magnification of up to about x120 with the 9.7mm lens. As a note, the maximum reasonable magnification for an 80mm scope is about x160, so I'll not be far off the maximum.

Is this scope for you? Well, the quality of the tube, the eyepieces and even the Barlow are surprisingly good. The 'go-to' function works very well once set up correctly. And it can be used quite effectively in the daytime to provide huge close-ups of the birds on your garden feeder.

However, the limitation is the relatively small 80mm aperture which means that deep space objects are harder to see and that the amount of magnification available for planets is a little limited. For the same money, a reflector telescope with about twice the aperture could be purchased, which would give let in four times as much light, but doesn't have the 'go-to' capability.

So there's the choice, a dimmer image, but a scope that can find the objects you want to see, compared to a brighter image, but far more work finding things to look at.

I'm still in two minds- but what I really want are some clear skies without which, either telescope is useless.

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sologuitarist61

sologuitarist61

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Hi David and welcome to SGL. I'm afraid you have hit on the main problem with astronomy, and that is 'how much aperture do you need?' This is a problem that most of us still grapple with I'm afraid. Good luck in your new hobby and I am sure that you will get many differing responses!

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David55

David55

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Two other good things about the ETX 80. First that the position of the eyepiece makes it very easy to use the scope on a windowsill. Tonight, for example, I saw Jupiter high in the western sky at dusk and not wishing to stand in the cold, I set the 'scope up on a windowsill and was rewarded with a super view of the planet plus bands and three, later becoming four, moons. Strangely the view through a closed window was better than with the window open. I guess the warm house air mixing with the cold garden air was causing lots of distortion.

The other advantage is to use the goto feature as an easy way of moving the ETX in azimuth and elevation without having to touch the 'scope at all- and therefore avoiding the vibrations caused.

Actually, I had a super evening overall. M42, the Orion nebula looked great magnified 32 times. M31, the Andromeda galaxy was as clear as anything can be when it's two and a half million light years away. And then, best of all, just a few degrees below Andromeda, my first observation of comet Panstarrs.

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jason.p

jason.p

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Welcome David. Don't know much about your scope but from what you've seen so far (well done on Panstarrs) it's proved it's worth. Aperture fever is something which affects most amateur astronomers. Unfortunately along with scope envy, there is no cure, you just have to fight it as long as possible.

Good luck and clear skies :smiley:

Jason

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ronl

ronl

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Hi David welcome to the lounge,

Observing the night sky is all about enjoyment,

it doesn't matter how you view it, it's what you personally get out of it,

a very good report by the way.

Enjoy.

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