View Full Version here: : Alpha centauri - how to make you want to throw away your new scope...
I remember as an 11 year kid getting my first scope: a 50mm Tasco refractor. It used 0.96" eyepieces (remember those?!?) and I "invested heavily" (for a kid!!) by going and buying a new kellner and a new orthoscopic eyepiece for it.
I remember the "headlights" of Alpha Centauri shining brightly at me: an easy target for even this modest scope.
A decade later, I got a 10 inch dob for my 21st birthday. A whole new world of DSO awaited that I couldn't even imagine with the 50mm refractor! So, night after night I was looking at globs and galaxies under dark skies. Planets and double - nah, they can wait...
16 years later, I get a new scope: CGEM 925. Finally, good optics and tracking - time to take a look at those doubles... BUT WAIT!! Alpha Cen looks worse in my new scope (admittedly with bad conditions) than it did with the old 50mm refractor as a kid!!
HELP!! Is the scope terrible? Are the conditions that bad??? :(
Well, now I know... Alpha Cen has changed!!! Who'd a thought it?? Stars changing faster than my scopes!!! :rofl:
How to give a person a scare!
19-06-2011, 03:20 PM
Perhaps the eyesight has deteriorated over time from when you were 15yo?? :P
19-06-2011, 03:23 PM
Couple of things first. Seeing has been awful in the past few days. Is your scope collimated? Check these first then check back.
19-06-2011, 04:07 PM
twenty years ago you could almost resolve Alpha Cent. with a pair of binoculars (you could easily if they were 15x or more).
It is a lot tighter now.
Alternatively - go back to a refractor!
19-06-2011, 04:13 PM
Loads of factors affecting compared to ages ago (depending on how long ago) pollution including smog and light pollution and variable seeing condition compared to many years ago.
From what I gather the the CGEM 925 should be a good scope better than a 50mm refractor.
Actually you are right - in 27 years of telescope use my eyes are no longer perfect... :(
Of course it is a good scope! I just didn't expect a double star to change on me!! :lol:
I can relate wholeheartedly to your tale Grant. I had very clear memories of what this double looked like in my 1980 Tasco 114mm reflector - 2 beautiful glowing gems side by side with interacting airy disks. I was also worried about my eyesight when I dug my old scope out and set it up a few years ago. I put it down to poor seeing and not letting the scope cool. It wasn't until I put my new 8" on it I realised something fishy was going on :lol:
Looks like its all downhill until about 2025, then about 2075 before we'll get a similar distance apart again (just doing some quickly playing in Starry Night).
You're right - we must be getting old when we notice the stars have moved around...;)
19-06-2011, 09:17 PM
I hear you Grant - all the way:lol: . I started with a 60mm Tasco Refractor in the early 1980's. I still maintain to this day is was a reasonable quality for it's time. I do recall the Tasco's of a year or two later were lighter in weight, and "felt" cheaper. But my goodness did it get a good run. I pushed that 60mm into every corner of the sky. It ended up as a finder scope on my homemade 6" f6 Newt! I also recall Alpha Cen looking a little wider than these day. And I also remember what it was like to have teenage vision! :lol:
19-06-2011, 11:22 PM
Don't worry, Alpha Centauri and other bright stars look like crap through both my 12" and 8" dobs, both premium optics.... I do have slight astigmatism in my eyes so that probably contributes, but also the spider, dirt/dust/crud on the optics and central obstruction conspire to create mangled images of bright stars. That, and typical seeing conditions. Fainter stars tend to look much cleaner in both my newts. I remember back in the days of good seeing before this cursed year, fainter stars at 500x in the 12" presented nice airy disks, still pounded by seeing, but still it started to approach those false and non-achievable delusions of perfection you find in startesting textbooks!
Funny you mention alpha centuari being harder to split now days. I was only talking to an old guy the other night about it as we stood under the stars. He is not an astronomer as such but used to use his theodolite to track down planets and bright clusters occaisionally and he mentioned A cent. I told him of my own anxiety now of finding it harder to split in my telescope which is much larger than the 60mm I first saw it through over 35 years ago. I think it would seriously challenge his theodolite now ... I hope? ... Or else I will have to work out how to explain to my wife why I want to sell my big scope to buy a theodolite :)
23-06-2011, 08:04 PM
Having recently re-acquainted myself with an identical 4" refractor to the one I first split A Cen with 25 odd years ago, I can confirm that it is definitely a lot harder! At first I thought the optics were rubbish, but eventually came to the conclusion they were as good as any I've seen.
Not sure I agree with the big dobs and central obstruction thing, through a 25" on the same night you could still park the USS Nimitz and the rest of the US first fleet end to end across the gap between the A Cen components. I initially struggled to see Siriuis and the pup at 550x - I wasn't looking far enough away :-)
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