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orion skyquest 8" v. "skywatcher skyliner 8
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30-07-2009 7:32pm#1
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Hi
So you are thinking of getting a scope
Well first off just to say I dont own a dobsonian, but an SCT so maybe someone else will be able to add or subtract stuff to my answer.
First of all, do not be so fooled by rosy reviews from magazine. Magazines are dependect to a certain extent on keeping their advertisers happy and will be wont to put them out of favour to other similar astronomy magazines for advertising revenue.
1) The skyliner has a wooden mount whereas the orion has a metal one. This would possibly lead to the orion being more sturdy and less likely to wobble in the wind etc.
But......
2) I note that the skyliner has a parabolic mirror and is denoted as a 200p. Therefore does this mean the orion 200s have a spherical mirror? This is critical and dont part with your hard earned dosh without the answer.
Check this out http://users.zoominternet.net/~matto/M.C.A.S/mirrors.htm !!!
If the "s" means it is a spherical mirror then for an aperture of 8" not all the light will be focused correctly at one point and strangely enough it seems you will not get as sharp views as in the cheaper scope. hmmmmmmm
I note that nowhere does it say in the blurb if it is spherical or parabolic. Just that it gives great views!!!!!!!!!
So I would tend to actually say get the cheaper scope. If you can live with a bit more shake and roll you will be able to get better views when it settles down. You may even be able to change the rocker box later for a better mount at a later date. It all depends on what that "s" means and the type of mirror.
Good luck:)
DB0 -
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Hi
So you are thinking of getting a scope
Well first off just to say I dont own a dobsonian, but an SCT so maybe someone else will be able to add or subtract stuff to my answer.
First of all, do not be so fooled by rosy reviews from magazine. Magazines are dependect to a certain extent on keeping their advertisers happy and will be wont to put them out of favour to other similar astronomy magazines for advertising revenue.
1) The skyliner has a wooden mount whereas the orion has a metal one. This would possibly lead to the orion being more sturdy and less likely to wobble in the wind etc.
But......
2) I note that the skyliner has a parabolic mirror and is denoted as a 200p. Therefore does this mean the orion 200s have a spherical mirror? This is critical and dont part with your hard earned dosh without the answer.
Check this out http://users.zoominternet.net/~matto/M.C.A.S/mirrors.htm !!!
If the "s" means it is a spherical mirror then for an aperture of 8" not all the light will be focused correctly at one point and strangely enough it seems you will not get as sharp views as in the cheaper scope. hmmmmmmm
I note that nowhere does it say in the blurb if it is spherical or parabolic. Just that it gives great views!!!!!!!!!
So I would tend to actually say get the cheaper scope. If you can live with a bit more shake and roll you will be able to get better views when it settles down. You may even be able to change the rocker box later for a better mount at a later date. It all depends on what that "s" means and the type of mirror.
Good luck:)
DB
The link you just posted states "A parabolic's deeper, more complex figure focuses all incoming light rays to the same point, so images appear crisp and sharp, without any distorting effects of spherical aberration"
Although that is true in saying no spherical abberation is present it says nothing about other abberations inherent in parabolic mirrors such as coma , astigmatism and curvature of field
for some cheap even some odd midrange scopes using parabolic mirrors its quite possible to get a worse result than with a spherical concave mirror
Spherical concave mirrors are subject to only spherical abberation and this can be remedied by using combinations of concave, convex and aspheric lenses such is the case with Schmidt and Maksutoff optics which are used in catadioptric and compound telescopes respectively
Here's a good little guide on exactly what the abberations are
http://en.wikipedia.org/wiki/Optical_aberration
To the original poster, if you are willing to invest up to €600 you could get into the 10" range (even an 8" meade lightbridge would be much cheaper than the orion, for a little extra you could have the 10" one), i doubt you will find much of a difference between both of those scopes, however just because 2 ranges of telescopes can be assembled by the same factory doesnt mean all the parts are of the same source and standard. orion optics do provide better optics in their scopes, but whether or not you personally could perceive the difference, is still debatable. science vs sense0 -
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