To good to be true?

Trido (Justin) · #1 25-07-2009, 10:33 PM

Andrews currently has a Skywatcher 130x900 Newt for $199. Now I am sure the mount is terrible, but that seems awefully cheap for a Reflector of that size. The mount isn't a big issue because the focal length is long enough to build a Dob mount for it as someone on these forums suggested to me. This is a very tempting offer as the size is right for what I want and the money I have right now so tell me, is it to good to be true?

http://www.andrewscom.com.au/site-section-10.htm

renormalised (Carl) · #2 26-07-2009, 09:10 AM

No, that offer is genuine and at that price it's a steal!!. If you got the scope and replaced the mount with an Ioptron cube or mimi tower, you'd have a great scope/mount combo

Looking at the mount that is on the scope...it's alright. OK for visual observing but I wouldn't be using it for taking piccies...not unless you're just going to stick with afocal photography or simple planetary/lunar stuff with something like a Meade LPI or Celestron NexImage. Even then, I'd be finding some way to make it a little less rickety and more solid so it didn't vibrate too much in wind or if you bumped it.

mental4astro (Alexander) · #3 27-07-2009, 03:12 PM

Sounds good to me,

.

TJD (Trevor) · #4 27-07-2009, 06:12 PM

mount looks good to me

with a scope that cheap and good i would rather buy that then a new finder

Mike21 (Michael) · #5 30-07-2009, 12:38 PM

Why make a Dob out of it? The mount has an RA drive included! I'm sure that the GEM will be at a better height than a Dob too.

Mike.

rogerg (Roger) · #6 30-07-2009, 01:06 PM

I'd leave it as a GEM unless setting up the mount and taking the mount places is too unweildy or bulky. The EQ mount will be wobly etc but for visual persnally I'd stick with it rather than a dob mount. The free motor that comes with it will be useless.

I started off with a York N114 Skyrover and that was very rewarding. I'm sure this would give similar satisfaction, seeing as how chinese products has brought down the prices since I bought my 114 in 1998.

Roger.

jjjnettie (Jeanette) · #7 30-07-2009, 01:34 PM

I'm sure you'll get lots of enjoyment out of this scope.
You can always upgrade later if the astronomy bug bites hard.

Jeeps (Sam) · #8 30-07-2009, 02:41 PM

Would it be better to go with that spherical mirror or the Skywatcher 130 x 650P EQ2 with a Parabolic primary mirror which andrews also has advertised (with motor) for $199?

cheers

mental4astro (Alexander) · #9 30-07-2009, 03:13 PM

Try to steer away from 'spherical' mirrors. They are "quick & cheap to make by machine, & require no real hands on reworking to figure correctly" (Paraphrasing here from another IIS member's contribution, sorry I can't remember who). Spherical mirrors are used in scopes with a focal ratio greater than f/8, as the 'error' presented by such a shape is reduced, more mimicking a parabolic mirror. Should you use any really long focal length EP, or focal length reducing accessory, the image will be compromised.

Any good reflector worth its salt will have a parabolic mirror ( with a few exceptions ).

You can keep the GEM and make a dob mount for it. The reason I recommend a dob mount is they are very easy to use, easier than an eq. mount (I'll dare anyone to disproove this,

, he says asking for trouble). If you are just starting out, I advocate dob mounts or alt-az mounts. Set-up time is bugger all, and less frustrating to use.

I have a SCT that has both a eq. mount & alt-az. I rarelly use its eq capability. I only set it up in eq. at star parties because I would use it to view the planets at high power, & its tracking motor makes it easy for novices to view, & 'NOT TOUCH THE BLOODY TELESCOPE', ( I really don't have anger management issues,

).

If the mount is woobly, then your enjoyment of it will match the wooble. Dob mounts also need to be stable, but if you make it yourself to overcome the shortcomings of the original mount, you really only gain. You WILL use your scope more. This equates to more cred. in convicing the other half that a more expensive new scope if worth it ( argue with that one,

).

Shano592 (Shane) · #10 01-08-2009, 02:07 AM

What mental4astro hass said is true.

The spherical design is a flawed design.

Go with parabolic, if the option is before you.

hulloleeds · #11 01-08-2009, 11:39 PM

Quote:

Originally Posted by Jeeps

Would it be better to go with that spherical mirror or the Skywatcher 130 x 650P EQ2 with a Parabolic primary mirror which andrews also has advertised (with motor) for $199?

cheers

My brother called Andrews with the very same question. After consultation (which I'm not suggesting is worldly or anything) he went with the parabolic one. Should arrive this week.

Jeeps (Sam) · #12 02-08-2009, 12:19 PM

Quote:

Originally Posted by hulloleeds

My brother called Andrews with the very same question. After consultation (which I'm not suggesting is worldly or anything) he went with the parabolic one. Should arrive this week.

After a bit of googling i came up with the same conclusion.

Cheers

mental4astro (Alexander) · #13 02-08-2009, 08:17 PM

Need futher proof of the difference with a spherical v parabolic:

I've taken delivery of a 76mm Celestron Firstscope, with a 300mm focal length. Nice image in low power, just. With the central field in focus, using a lowly kellner EP, the outer 1/3 is just out of focus. Worse right on the edge. That is because the light from the primary is not arriving at focus at the same place, which it does with a parabolic shape. Tweeking the collimation screws on the secondary holder really helped improve the image quality. A better EP would help a little more, again.

I'll be using it as an overgrown finder, for which its spherical shape is neither here nor there as it is not the main scope for viewing. It is by no means grotesque. It suits my needs as a kick-ass finder. I just would not want it as my main scope for viewing.

Mind you, at f/4, it is a very fast telescope, which would make the problem of a spherical mirror even worse. But it was a concious decision,

. Really.

hulloleeds · #14 02-08-2009, 10:09 PM

Quote:

Originally Posted by Jeeps

After a bit of googling i came up with the same conclusion.

Cheers

I'll post further information when I see through it later on the in the week.

Though, if you do order it, don't read what I say before your first light. That would be spoiling.

Those first scopes were certainly interesting looking, I must admit to considering such a purchase. Initially, I purchased my dob because very recently I received my gallileoscope, another possible finder and extremely built (plastic) for concrete based impacts

hulloleeds · #15 04-08-2009, 10:42 PM

I have seen through this scope, now. Only at jupiter and the moon, though.

Without motor, (and maybe with - you might want to buy batteries (c or d size, i think) in preparation), challenging for a newbie to find objects.

EP's seem a bit cheap. They seem cheaper than my skywatcher 8 dob ep's which are same size but look a bit more well built. I just got a couple of 29$ plossl's from Andrews today and they are better than my bundled ones.

All in all, I got the sense that the scope was no better / worse than what you would get from a smaller scale scope compared to the other one. I did not try the same EPs as I was using in the dob and it would be unfair to make any further judgements accordingly. Especially making it work in inner brisbane.

I don't think you'll be disappointed.

Jeeps (Sam) · #16 05-08-2009, 12:50 PM

Thanks for the feedback. I've been using a CHEAP CHEAP CHEAP one of these (but not a skywatcher):

http://www.andrewscom.com.au/images/.../76x700az1.jpg

which was given to me many many years ago. It's hard to navigate, you can never get the viewfinder to line up, it's wobbly and when you move the tube and release your hand from it, it drops to some random position LOL

Still, i've viewed a great many things from it (mostly just planetary & moon) and been able to navigate the sky a little bit. I've always said to myself that i'd get a GOTO because i find it so difficult to track objects with this cheap scope, but i think that might have more to with the build quality of the scope and super unstable tripod mount that came with it.

So i've decided that i don't want to to do astrophotography and that i want to start looking at deep space stuff and i won't be travelling with the scope. I reckon if i get a decent scope with a proper mount i'll be happy without having to get a GOTO because i've gone so long with a wobbly unstable cheap scope. I'm starting to think i might as well save a bit longer and get a big dob...

cheers