Simple scopes, simple joys - and Nova Scorpii too

Nova Scorpii - I put it at about 6.8 this morning - but I was using familiar comparison stars that weren't that good for this purpose. All I'm sure of is that it has dropped significantly from my previous observation two days ago. That said . . .

It's a cool morning - a bit misty, but clear. The ground is slippery and white with frost. But there are early hints of spring in the air. My hopes for seeing the moon rise tonight in total eclipse are dim, as the forecast is calling for clouds.

But at 4:30 am it was clear and dark, so I decided to test what I had heard about the problems with using a correct image, prism diagonal. Essentially, the claim is this causes a significant loss of light, and has problems at higher powers. (BTW - the one pictured, from Orion, so far is the only correct image, 90-degree star diagonal I've been able to find and theybury it deep on their Web site and only half-heartedly recommend it for astronomical use.)

So undoubtedly the prism diagonal steals light, the ultimate sin in astronomy, but you couldn't prove it by me. But let me back up because I have recently broken with conventional wisdom on binocular usage and in the process found a really inexpensive - for the moment - and possibly good alternative scope. But fo rnow I have sold my large binoculars and parallelogram mounts and replaced them with simpler, less expensive short focus, 80mm scopes. I have a couple Orion ShortTube 80s and an Orion/Celestron Starseeker. The StarSeeker has it's own, computer-driven mount which works surprisngly well so far. One Orion ST is on an Orion EQ-1 mount, set in alt-az position (not very satisfactory) and the other is on a Celestron Alt-Az mount and tripod that sells for $100.

I like the Celestron Alt-Az a little better than fooling with the EQ-1, but . . . It has it's problems. I find it extremely hard to adjust for the correct tension in altitude motion. But once you have it roughly pointed, the slow motion controls working wonderfully. (I have a nagging feeling I;m doing something wrong - missing some very simple, mechanical detail.)

So what's the deal here? Well, I found that while the parallelogram mounts are wonderful works of engineering and construction, people didn't seem to use them much when I had them set out for visiting groups. Perhaps they simply look imtimidating - look harder to use then they are. But more importantly, I found the large binoculars problematic for kids. They aren't that easy to find objects with (yes, I fooled aorund with various mounts for red dot finders on them) and the eyes of some kids are simply too close together to properly adjust the binoculars to them. What's more, adding the proper instruction to focus first the left eyepiece, then the right one, just became too complicated for the time-frames I work within and so I started considering the small scopes as an alternative.

First, I looked at why I wanted the binoculars in the first place. Simple.Low-power, wide-field views, that were oriented the way we see them with our eyes was the main reason. Great for learning the basic layout of the moon, as well as enjoying a few stunning objects, such as the Pleiades, Coathanger, and the Andromeda galaxy. Oh, I can get much more than this out of binoculars, but again, working for restricted amounts of time with those for whom this is all new, that's about the limit of their usefulness.

Well, you can accomplish the same thing with a short-focus, 80 mm scope and I think it's easier, better, cheaper, andmore versatile. Put in a 25mm Plossl and you get 16X and a roughly 3-degree fov. Focus is straight forward, and since I use a 90-degree, correct image diagonal, there's no disorientation from the naked eye view.

This correct image business is interesting. Having a correct image view makes for a simpler transition from the naked eye to the magnified and brighter view through an instrument. I don't think this is trivial. I think even experienced observers may not fully appreciate the tansition they have made, though they have grown used to it. OK - I'm reaching around in the back of the drawer. But there's no doubt in my mind that for one simple and important task - learning the basic geography of the moon - a right-side up, low-power view is best. So for this task I have been using binoculars - even hand held, 7X50 binoculars (or smaller) are fine.

But, by switching to the short-focus scopes I gain several points. First, the image is steadier because the scopes are mounted. Second, I can easily increase the magnification to 40 and even 80 power. (I use a Barlow to maintain decent eye relief at high power, another thing that's helpful for beginners.)

What have I lost? Well some portability if you'recomparing with handheld binoculars. But scope, mount and tripod are much easier tomove around than a good - but cumbersome - parallelogram mount and tripod. So the most important thing I lose is viewing with two eyes - this is natural and I do like it - but you can also gain a special sense of the reality - the transition from naked eye view to telescope - if you keep both eyes open. People instinctively close one eye when looking through a scope, but it is more relaxing to your facial muscles if you learn to view with both eyes open. And I get fascinated, sometimes, when I let my brain tune in the view from the eye not looking through the scope - or try to meld both views.

What have I gained? Cost. The optical isntruments are roughly the same price - but a good pararllelogram mount and tripod are much more expensive than a simple alt-az one. I've also gained the flexibility of changing the power by changing the eyepiece and by using red dot finders - a bit more awkward to mount on binoculars - but you can certainly find stuff easier.

So what about this business of using correct image diagonals? Well, first, they are pretty hard to find. Everyone sells the 45-degree correct image diagonal, but they are uncomfortable to use for anything much above 45 degrees in the sky. Orion does sell a correct image, 90-degree, prism diagonal, but I have been hard pressed to find them elsewhere. (I bought a Celestron "erect" image 90-degree prism diagonal - but that's not the same beast - the image is reversed left-to-right in it. )

The conventional wisdom - and honestly, I do believe it is correct - is that the prism diagonal uses up more light than the conventional mirror diagonal, especially at higher powers. But again, maybe I'm just not demanding enough because what I did this morning was point the little scope at Albireo and note which faint, neighboring stars I could see in this rich field - both at 16X and at 40X. I switched back and forth between the correct image diagonal and a traditional, Meade mirror diagonal. The correct image showed me brighter stars at both powers. That's the opposite of what should happen, so let's assume I had a lousy mirror diagonal and a very good correct-image diagonal. The bottom line is for new observers, and for casual observing, logic tells me the prism isn't as good, but in the field I just can't see enough of a difference to get excited.

I had great fun this morning - after running my test - using the little scope with the correct image diagonal to enjoy the wonderful blue and gold of Albireo, track down and make an estimate on the current magnitude of Nova Scorpii, see what the Gallilean satellites were doing around Jupiter in thier constantly shifting dance, check out Mizar's three companions, and take a look at the full moon, setting silently in the west. As I changed from one thing to another I walked about the yard and road, easily avoiding trees and setting the socpe up anywhere I wanted with little attention to any detail other than pointing it. It was light enough to easily carry in one hand.

Bottom line - I was using this little scope the same way I have used large binoculars in the past - but with much more flexibility both in power and in movement and the experience was thoroughly enjoyable. Yes, I know - this is why "grab 'n go" scopes are popular. But too often they are also extremely expensive because people don' want to tolerate the little purple and green fringes around the edges of the full moon and other bright objects - but these simply don't bother me.

Now - about that cheapy version. Did I mention I found an incredible bargain?

I went looking the other night at Optics Planet to see if they still sold the $100 Celestron Alt-Az mount. I was thinking about getting a second one. But in my search I stumbled across a 70mm, short-focus Meade refractor on an alt-az mount. (Meade 70AZ-ADS.) It included a dinky finder which I have no confidence in, but also two Super Plossl eyepices - sound decent - And a 2X Barlow. The price for this whole outfit - with softcase - $119! What's going on? I checked other place and saw it selling for $180 - and at one place I saw it for $280. (They actually have an F10 version at a still lower price, though I don't think the eyepieces are as good and it would be twice as long which may make it a bit more awkward to use. )

Oh hell - I bought it. My rationale is I could easily sell one of the ShorTube 80 scopes - with or without mount - for more than the $119 - and this deal even had FREE shipping! So is this one of those too-good-to-be-true bargains? Maybe. stay tuned. I'll let you know after I get it and have a chance to play.

I felt a little like Opus, the Bloom County cartoon penguin, who got so excited about TV ads for a Ronco Salad Shooter he bought a room full of them. I was tempted to buy four or five of these little scopes right on the spot - mentally selling other stuff to keep the budget balanced, But I'll get one first. And I'll probably end up keep my ST 80s as well because I think they're going to work really well in my public observing programs. And if this doesn't work out I'l write about that as well. Won't be the first time somehting made sense to me in theory and proved entirely unacceptable in practice.