Advice needed!

[amigaman]

Just took delivery of my NexStar8 GPS telescope and am now hearing astro_baby's words ringing in my ears about the extra equipment. As I understand it, I'll need a dew strap, a dew cover (do they come heated?), and power supply. Anybody got any tips on what to buy or not to buy?

I've also been looking at Sky at Night magazine, which recommends the Teleview Ethos eyepeice. Has anybody had any experience with this eyepiece and will it be good match for my scope?

[ottUp]

You will almost certainly need anti-dew equipment, as SCTs are very susceptible to dew (because of the large corrector lens on the very front, right in the moist air).

Advice: go slow. Start with passive anti-dew measures (i.e. a dew shield). You may find that's sufficient, depending on your conditions and your observing habits. Dew straps work very well, but are a substantial complication and if you don't need them, nice to avoid. (They result in lots of wires to tangle, and substantial power draw on your battery.)

Yes, you can get heated dew shields (AstroZap is one brand). Or the more traditional approach would be dew straps under a non-heated dew shield. If your conditions are bad enough to require heating, you'll probably need 3 or 4 dew straps: main OTA tube, finder scope and/or telrad, eyepiece. No good having your main OTA clear if you can't find things through the finder, or see through the eyepiece.

A simpler option is to have a hair dryer at your observing site. Mains current if you have access to it, or a 12V unit if not. A quick blast of warm air from the hair dryer into the dew shield tube, and onto the finder and eyepiece, will buy you an hour of clear observing time, and this may be a better choice than dew straps.

In practice, I use my non-heated dew shield all the time, a 12V hair dryer fairly often, and the full dew-strap installation (I use Kendrick) only rarely. My observing sessions are not usually more than a few hours - typically public demonstration star parties. If you are into all-night astro-imaging, you'll need heaters for sure. If I am using any kind of heat (hair dryer or dew straps), I bring a separate battery just to power the heater.

- Richard

[Astro_Baby]

Giggles - hate to say it but.........

[AndyH]

Hi.

Defo get a dewshield. Try that first and see if that keeps off the dew by itself.

As for eyepieces..................

You've got an F10 system, so it's more forgiving on eyepieces. A lot of these modern, expensive eyepieces, are designed for fast refractors and newtonians, like F4.5 to F6.

For example, my personal preference for eyepieces under 10mm in focal length I use Ortho's and the better eye relief 'pieces like the TMB/Burgess/HR planetary's. Over 10mm I use 'old fashioned', but still brilliant, erfles and konigs and the magnificent University Optics MK80 32mm for the widest view at F10.

As previously mentioned, take it slow and seek opinions from as many folk as possible.

Cheers,

Andy.

[amigaman]

Thanks the replys on this site always a great help always points me in the right direction

thanks guys and girls