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| Edmund Astroscan meets Orion StarBlast |
In the left corner, telescopic champion for over forty years...my classic Edmund
Astroscan 2001 wide-field telescope which dates from 1977. In the right corner, da' contender...my fresh-from-the-box Orion
StarBlast, which boasts quite a few similarities to the vintage
Astroscan--but some major differences as well. Our contest tonight is intended to decide which of these two stylish instruments is best equipped and capable of traveling the world in search of clear skies and faint fuzzies; which, in other words, will join me as principle observing equipage on my next deployment--stargazing from both shipboard and shoreside sites. And may the best telescope win!
The rules are simple; both telescopes will be tested for image quality (including incidence of coma, a common artefact of short focal-length, wide-field optics), focus across the field of view, and ease of use. Identical eyepieces will be used to view a variety of deep-sky objects in the evening, to include M45 (the Pleiades), M42/3 (Orion's famous nebula), and the Hyades. If skies remain clear in the morning comparisons of Saturn, Jupiter and Mars will be attempted.
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| Well, we can easily see who's taller. |
Despite very different mountings, these two telescopes are actually quite similar; the
Astroscan's spherical lower body moves freely on a triangular cast aluminum base while the
StarBlast moves ALT/AZ (Altitude/Azimuth, or side-to-side, up-and-down) on a quasi-Dobsonian wooden mounting. Both 'scopes us single-power (1X) finders; the Edmund offering has a cast-aluminum peep-sight while the more techie Orion instrument has a battery-powered red-dot finder (again, 1X) which works in essentially the same way as the peep-sight. Both are also quite portable; the
Astroscan (at 12 lbs)has a shoulder-strap and the
StarBlast (at 13 lbs) a built-in handle
Optically these two telescopes share very similar designs; the
StarBlast has a 113mm (4.5") parabolic mirror as compared to the
Astroscan's 106mm (4.25") primary, both with focal ratios of F/4.0. This gives the
StarBlast a focal length of 450mm (18") and the
Astroscan an f/l of 425mm (17"). These are
very close numbers; in fact the only significant difference (on paper) between these two optical systems is that the
StarBlast's primary and secondary mirror are fully collimatable--they can be adjusted for better performance.
Astroscan's optics are pre-collimated, which means that the owner doesn't have the option of "tuning up" the 'scope.
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| The primary mirror collimation knobs on the StarBlast are visible in this photo. |
Will this make a major difference tonight when I focus both telescopes on the Pleiades and alternate views through their identical eyepieces? I don't know. I have my suspicions and a few expectations,
but I'll keep those quiet until I file my report on tonight's comparisons.
Clear Skies, Folks!
AND here we are, nearly a week later...still waiting for a clear (or moderately clear) night. Honestly, I love Virginia--I was born here and have lived most of my life in this region--but it can be very difficult sometimes for a lifetime amateur astronomer!
ReplyDeleteWell it took a week, but last night a cold front came through and wiped the constant cloudcover aside. I took the StarBlast out to Iowa Point, a memorial park on Naval Station Norfolk which looks out over Hampton Roads, and set up on the trunk of my car for First Light. The comparison run with the Astroscan will have to wait, I suppose--THAT telescope is safely stowed in its neoprene bag back at the house--but I spent an hour checking out the StarBlast "solo" and have to say that I'm pretty happy with the results!
ReplyDeleteFocus was good across 2/3 of the field with coma becoming very evident around the edges, which I expected due the nature of a short focal length Newtonian. The crescent moon was sharp and beautiful at all magnifications (40mm, 17mm and 6mm Eyepieces providing 40x, 26x and 75x respectively)--I was especially pleased with the view while sweeping the Terminator with the 6mm EP; for a wide-field scope the view of Luna was pretty durn impressive!
Performance was good on DSOs as well--despite the level of local light pollution--M42's "fish head" was clear and the Trapezium cleanly resolved in the 17mm EP while the 40mm captured M45 very nicely. I even picked out the Double Cluster--only a few degrees above the horizon toward Hampton.
Optically I'm pretty happy with this little scope. The red-dot finder worked well (though I'm an old RA-finder man and it'll take some time to get used to using a zero-power) and the table-top "Dob" mounting performed nicely enough though I might dig out my old EQ-1 and drive motor and re-mount the tube for public events.
SO...very nice optics, a decent finder and an easy-to-use mount that moves like silk. Overall, considering the price ($165) I would say that this is one heck of a neat little 'scope. I'm glad I took the plunge!