Evolution6 vs. Star Discovery ?

[Ptarmigan]

It is time to retire my homemade 6"newt (mirrors need recoat and tube/mount is heavy/inconvenient)
time to buy a nice new all singing goto 6" !

The problem is how to decide between the Celestron Evolution6
http://www.firstlightoptics.com/nexstar-evolution-telescopes/celestron-nexstar-evolution-6-telescope.html

and the Skywatcher Star Discovery.
http://www.firstlightoptics.com/az-goto/sky-watcher-star-discovery-150p.html

Cost = vast difference ! Evo6 = £1089 , SD = £385

Collimation = Evo6 more stable; SD at f5 more critical than my old f8 ?

Optics = Evo6 - Celestron's 6" well reported well reviewed well established
SD optics unknown unreviewed.
Evo6 longer lifetime ??
Evo6 needs a focal reducer to f5, SD has a barlow to f10

Mount = if eventually I was to get into AP with a wedge ( not a prime consideration at the mo.)
Evo6 has a worm gear drive and good az-tracking reports but unclear if the new mount is up to it.
SD is unknown drive and probably not capable (the manual says mount ok for camera+lens - very tempting )
Meanwhile AZ AP, as in this thread,
http://stargazerslounge.com/topic/228101-the-no-eq-dso-challenge/
might be fun and the short exposures needed in that mode may be ok on the unknown SD drive and is ok on the Evo6

Portability = both are small and lightweight, but the Evo6 may be more robust ?

What have I forgotten ?
Is there a killer blow in favour of the Evo6 ? At the mo. I am tempted by the SD just to see what that astonishing price point is capable of !
Thanks for reading.
 

[Avocette]

Optics = Evo6 - Celestron's 6" well reported well reviewed well established

SD optics unknown unreviewed.

I had, perhaps wrongly, been assuming that the SW OTA optics would be identical to the SW Explorer version.

[John]

I'd imagine that the Star Discovery 6 would have the same optics in it that the other Skywatcher 150mm F/5's use - ie: pretty good. I can't see that Synta would make a set especially for this scope. Looking at the pics of the scope the secondary supports look somewhat thicker than the ones used on other SW newts. If they are actually thicker I guess the diffraction effects they produce would be that little bit stronger perhaps ?

The Celestron 6" SCT's are tried and tested and do seem have a strong following both here and over the pond.

I reckon the deep sky performance would be around the same, although the SD 6 would have twice the field of view with a given eyepiece than the Evo 6 which is nice for framing the larger DSO's and DSO groupings. I think the Evo 6 might give more satisfying planetary / lunar views and a decent image scale could be achieved without recourse to barlows / very short focal length eyepieces. The Evo 6 would need dew prevention measures though so budget for a dew shield and / or heated dew band.

Both the scopes are made by the same company of course, beneath the branding.

A 6" GOTO scope for less than £400 is quite an achivement by Skywatcher although I suspect the Evo 6 is probably the better engineered scope, overall.

[Ptarmigan]

Thanks  Avocette and John, very interesting and thought provoking.

Good point about the field of view, I tend to favour star fields and DSO groupings over planets ( I think , maybe, perhaps ! ) but planetary nebs and glob. clusters disturb that assesment
always like to tease out a faint fuzzie, not sure why !
I see what you mean about the thickish vanes. (jury still out on the diffraction aspects, might have to go to the physics area to debate that one but certainly more blockage will result from thickness )
Ok on the dew, and since I posted I also thought about cool-down time.
Being a bit of a lifelong sceptic I wondered about the eonomics of reusing existing optics or cutting corners in new production to achieve a price point.
I think you are right, more likely on the mechanics. Or perhaps better/cheaper/more recent electronics and programming efforts ?

Thanks guys, lots to inwardly digest there, at the moment my swingometer is drifting SDwards lol!

oh what's this on Beeb4 " Truth about meteors " ?? >>>>>

EDIT Oh, re-run of the Chelyabinsk (sp?) programme

[Ptarmigan]

Looking at the pics of the scope the secondary supports look somewhat thicker than the ones used on other SW newts. If they are actually thicker I guess the diffraction effects they produce would be that little bit stronger perhaps ?

Good point,

perhaps,

I used to think so as well, but recent reading about diffraction occuring along an edge has recently persuaded me that it is the _total_length_ of _edges_ in the light path that cause the diffraction.

so the thickness should only cause blockage.

(ot)

and that is another reason that 3 1/2 vanes cause less diffraction than 4 ( 2 acrossways iyswim), but perception of the 6 spikes resulting from the 3 vanes may be aesthetically more disturbing than the 4 of the conventional arrangement ?

(/ot)

[John]

You could be right. Vixen use quite thick vanes on their catadioptric scopes and they seem to do OK. Skywatcher make a sales point of the .5mm vanes in their other newts though so they can't have it both ways !

The curved vanes on my 12" dob don't show spikes at all but the diffraction is still there of course, just spread more evenly around.

Are you considering any other options ? - there must be something else between £385 and £1089.

[Ptarmigan]

Yes indeed !

and

Are you considering any other options ? - there must be something else between £385 and £1089.

Yes I am but outside the context of this particular question !

It is a long story !! are you sitting :)

I was originally thinking of the Evo9 but that is quite a considerable instrument, I think, and the money and size invested might preclude buying something larger !

Then there are the dobs in the 8" to 12" range but, ,

after a few decades of hop-ing the skies I am quite tempted by one of these newfangled GoTos !

( I please myself in the belief that I know my way round enough to get me ne to within 1/2deg of somewhere, but it is that last little bit in the eyepiece that causes the time warp and the interval between clouds seems to decrease with every year, or maybe I am just slowing down ? )

This way, if I go for a replacement 6", on a quicky tripod that I can treat like binos to dodge the rain, it still leaves the field ( and funds) open for when my ideal big dob arrives on the market !!!

But yes, point taken, there are many contenders that confuse my brain cell so all suggestions very welcome !

OH EDIT --

and I should have said that the push-to ability of the new encoder strategy on the SD seems to me to be a big advantage in the matter of dodging the rain

ie. if the clouds threaten then push it whilst you can

if the rain does not threaten then amuse oneself with the alignment etc.

but unless I am mistaken, with the Evos and similar scopes one MUST use the aligned hand controllers to do the slews come-what-may ?????