When good isn't good enough - but the seeing is fantastic

I was reading some stuff online yesterday about huge, inexpensive binoculars and it got me thinking about inexpensive refractors. Essentially the author, Ed Zarenski, seemed to be saying that while he would hold onto the large, inexpensive binoculars he was testing, he still prefrred the smaller, high quality ones he owned. He could see more with the large, lower quality pair - but he could see better with the smaller ones.

I'm suspicious of my own elitists tendencies of late when it comes to the views through small, high quality refractors, so I decided to put this idea to the test, The Moon was only one day past full, so the only thing worth looking at tonight were double stars and planets. I set up an inexpensive, 100mm F5 Celestron and let it go head to head with my smaller - and three times as costly - 80mm ED from Orion. (The larger scope had cost me $125 on the used market - the smaller $400.) The smaller scope has a longer focal length, so it was difficult to make an exact comparison, but I used the same eyepieces in each and fooled around with shorter focal length eyepieces of the same design in the larger scope to roughly balance the power.

The result? The Inexpensive scope goes on the used market. I keep the 80mm ED and maybe I'll get a 100 mm scope of similar quality at some point. But this was not an easy conclusion to reach until the skies totally quieted down and the scopes both cooled down completely. At first they seemed to be giving similar quality images - and as I reached for faint stars in M34 and the Pleiades, I felt the larger scope did have an edge - as it should. As the cliche goes, there's IS no substitute for aperture - well, at least they're didn't used to be for me. But I can't help it. Now I'm in love with pure, crisp, high contrast images. I suspect this is an acquired taste. Hell - it has to be. It's taken me fifty years to get to this point ;-)

That's true, actually. It was roughly 20 years ago that a dealer let me try out a used Televue Genesis. That was the premier, 4-inch refractor of that era and it's still regarded as a very good scope. I not only rejected it after a week, but I hardly gave it a fair trial. I was just absolutely into bigger is better and the scope I wanted was the 16-inch Meade light bucket I ended up buying. It was terribly sloppy, but boy could it bring in distant galaxies!

In case someone thinks there's an ultimate right and wrong in here somewhere, forget it. There isn't. There's just what's right for you and what's wrong for you at any given moment. Right now, what's right for me is small, high quality refractors. What was the difference I saw? Not much, but very real. For example, Castor was high overhead and both scopes split it beautifully. Did I mention that seeing conditions were near ideal? They were. For an hour or so I had something approaching what the Chinese are seeking by building telescopes in Antarctica. Anyway - Castor split with gorgeous diffractions rings from both its brighter components making love, intertwining with one another. In the large, sloppy scope they intertwined more - in fact a lot more light seemed to be in these rings. I'm not sure if that's good or bad, but for me the view in the 80ED was simply cleaner. Same interaction, but with far less light in and around the diffraction rings.

I switched over to Saturn, quite close to the bright moon in the east. I cranked the power up on the 80 - using a 3.5 Hyperion for 171X - and for the first time this season - with any scope - saw the Cassini Division in the rings. (Last year that was a simple target - absolutely common place - but this year the rings are tilted less from our viewpoint and so it's difficult to see.) Hey, 171X is above the 160X that represents 50X inch, generally considered the upper, useful poweer limit. It wasn't until then it dawned on me how damned good the seeing was - and how many high clouds were moving in from the approaching snow storm! Oh boy. I was two wrapped up in my testing to appreciate observing conditions.

I switched to Rigel. This is a nice test for a small scope. Bingo. There was its faint companion, not at all lost in the glare of that blue giant. This was as clear as I had seen Rigel's companion any time in any scope. That meant the 80mm was performing beautifully which meant seeing conditions were very good. I quickly switched over to the 100 mm, trying a 5mm and 3.5 mm eyepiece. The 3.5 only gave 142X in this scope - so I wasn't pushing it to its limit, but it should have been plenty with which to see Rigel's companion. I could see it - i think. But the view wasn't nearly so good. You simply could not get the brilliant Rigel to settle down the way it did in the 80mm. And that was the clincher for me. On Castor the 100mm gave a good account of itself. On Rigel it didn't. But the bottom line for me is simple - good isn't good enough. I really want excellent. And that goes against my core approach to things. I'm usually not this demanding. But I can't help it. I like what I like and I like the view through the quality refractor - period.

So I understand why Ed - faced with the undeniable proof that he could see more stars in the same of sky with inexpensive , 25X100mm Celestron binoculars, still preferred his 16X70 Fujinons which cost two or three times as much and showed less, but showed it better. It sounds like optical snobbery, but I agree.

Oh - and did I seek the Holy Grail? You bet. Did I get it? No.

I'm talking about the Pup - the white dwarf that circles our brightest star, Sirius. It's getting easier to see these days and so I check often. Rigel is a nice warm up to this task, but the problem here isn't how close the two stars are to one another, but the extreme difference in brightness. In the case of Sirius the primary is -1,5 and the white dwarf is 8.5. With Rigel the numbers are .3 and 6.8 for a difference of 6.5 magnitudes - which means Rigels is 398 times brighter than its companion. sounds like a lot. But the 10 magnitude difference between Sirius and its Pup means a difference in brightness of 10,000 times - so you comparing 400X with 10,000X! See the problem - boy this magnitude stuff adds up ;-) Polaris is a similar case and there the magnitude difference is 7 - that's 630 times, very manageable, even with the 66mm scope. In each of these cases it's like trying to the glow of a cigarette next to a searchlight - only with Sirius the cigarette's being smoked by a flea!

In any event, for a change Sirius wasn't popping all over the sky with brilliant spikes when I looked at it in the 80mm. In stead I saw a wonderful set of diffraction rings. But it was dancing in those rings and blotting out any sign of the Pup. Ah well.

Why didn't I open up a larger scope? Simple. The clouds were closing in big time.

But this night had one more lesson in it - if you want to have good observing experiences, you have to observe. During most of my career as an amateur astronomer I would have stayed indoors on this night. I just wouldn't bother when the moon was that bright. But I have more control of my time now that I'm retired and I don't miss any chance to observe and so these excellent seeing conditions caught me by surprise, but I certainly enjoyed them. Last night's lunar eclipse held a similar lesson - I really didn't want to go to a friend's house where a small group had planned to observe. Just seemed like too much of a hassle for what was probably going to be an event obscured by clouds. Well there were plenty of clouds - and plenty of eclipse - it was a terrific event. Bottom line - you want to observe, observe.