Decisions, Decisions

Joe Shuster

"There are too many choices in this hobby." I didn't say that but a poster on an astronomy group did and he captured the essence of one of my pet observations about our hobby. It's not really a complaint. Choices are (mostly) a good thing for the consumer. If the market is short on choices then the consumer can be exploited by the vendors - value, quality and product variety often suffer in "dry" markets. But a flush market - many products, many vendors - has its own problems. Vendors - especially small ones - can struggle because it is difficult for consumers to know about their offerings or their existence. The publications in astronomy enjoy sharing product and vendor information with consumers in articles and in advertisements. In fact, one publication, "Astronomy Technology Today", is devoted to discussions about astronomy equipment from vendors and customers. But there are limits to making the customers aware of products and aware of distinctive features that make one product more appropriate for each user.

Thinking back to the "olden days", you had few choices. For example, your choice in refractors was achromat or apochromat. Now you have choices of doublets, triplets, FD, ED, fast, slow, binoviewer-ready, and/or semi-APO. Some vendors are offering automotive style color choices instead of the traditional vendor color coding - more decisions to make!

The same evolutionary diversity shows up in mounts, eyepieces and cameras where the selections are overwhelming and the specifications are complex. I think I can demonstrate how wildly choice-glutted this hobby is using an accessory at the back end of the cost and sophistication scale. I'll do it with my curious collection of four 50mm 2" extensions.

Now you might not even know that 50mm 2" extensions exist and you might not understand why you'd want one. These accessories have a couple important niche applications. I use one to help me with astrophotography. I have a short tube 80mm refractor. It's fine for visual use with the upgraded focuser I installed. But when I use it for photography the focuser tube needs to extend nearly its full length to focus the image. As the tube extends more and more it loses rigidity and it sags very slightly because the tube gets less support from the focusing mechanism and the OTA. This can result in the photo chip being slightly off-axis and the camera shows the vibrations of the extended focuser tube. The classic solution is: a 50mm 2" extension.

The extension has 2" wide barrel to fit into the focuser tube. The extension then exposes a 50mm deep and 2" wide tube to accept my camera (or a 2" eyepiece or a 2" diagonal). The camera focuses at the same net distance from the objective lens, but the focuser tube is now 50mm more tucked into the focuser body and the OTA. That little bit gives it the strength to hold firmly and keep the camera aligned along the optical axis.

Now what could possibly be complex about picking a 50mm 2" extension? That's what I thought. So I found the first one (actually the cheapest one) that popped up on Astromart and I was in business. The stars in the pictures didn't wobble and didn't show the coma that existed before. But there was a kind of glow. It turns out that the inside of the extension is black anodized to reduce reflections but the surface is still smooth, so off-axis light was producing rings around bright stars and generally losing contrast. So my first extension - let's call it "Alpha" - had a problem.

After some shopping I managed to find another vendor that claimed better interior matting to reduce reflections. This challenger offered a grooved surface that probably reduces reflections by 50% or more. The vendor also claimed other features I didn't even know I cared about. First, his adapter is a one-piece unit instead of a two-piece threaded unit. I didn't even know Alpha came apart! Plus the extension I call Beta has the benefit of a compression locking mechanism instead of the classic setscrew.

In astronomy's earlier days eyepieces, diagonals and other inserts were held in place by tightening a setscrew that dug into the side of the thing being inserted to hold it in place. Sure, we made a mark on the inserted tube and sometimes there'd be a scratch if you twisted the object. But no one cared much. Somehow, though, someone started caring about the cosmetics and some vendors introduced a system of a thin copper band in the female part of the focusers and diagonals so that the setscrew forced the band to evenly compress around the inserted object. This hugging action clamps the item in place without marring the barrel. So now that compression locking is the standard for telescopes and diagonals, I guess it follows that the 50mm 2" extension industry would feel the pressure to introduce compression locking, too. Beta's compression feature is important to everyone who cares about scratches on barrels.

But Beta's maker didn't stop there. Another increasingly common feature of eyepieces and diagonals is a "safety catch". Before safety catches, the barrels on eyepieces and diagonals were smooth on the outside (except of course for the scratches and pokes from the old fashioned set screws). So with a smooth barrel if you didn't tighten the setscrew enough you'd spontaneously hear metal slipping on metal, then a short silence and then the thud of your eyepiece and/or diagonal crashing to the ground. Gravity is so heartless.

Somehow, after dozens of years and thousands of thuds, a vendor developed the safety catch on the barrels of eyepieces and diagonals. The safety catch consists of an indented band of the barrel. So you can slide an eyepiece into the telescope and even if you slightly tighten the setscrew the eyepiece won't fall off because the setscrew or compression band will catch on the lip between the indented safety catch and the normal front end of the barrel.

Beta has a barrel that includes a safety catch - an advantage over Alpha's retro smooth barrel. Even worse for Alpha: I discovered that the location of Alpha's setscrew was too deep into the female part of the extension. This meant that anything inserted into the Alpha would have the setscrew past the safety catch indentation. This would totally eliminate the benefit of the inserted object's safety catch. Beta was smart about safety catches so its compression ring was at the perfect depth for an inserted object's safety catch.

With these features - better light damping, single-piece construction, compression ring, prudent set screw depth and safety catch - I was sure this had to be the pinnacle of 50mm 2" extension technology. So I bought Beta and that could have been the end of the story.

But then I won an auction on eBay for some nice eyepieces and thrown into the lot was - yes, you guessed it - a 50mm 2" extension. This was advertised as a Meade product, but there was no hint of Meadeness anywhere. Like Alpha and Beta there were no markings or trademark vendor styles. I could have just set Gamma (as I call it) aside or resold it. But instead I checked to see how it compared with Alpha and Beta. It has a two-piece construction like Alpha, but I had come to realize that just about everything - eyepieces, barlows, diagonals, etc. - had two- or more- piece construction and none of those accessories spontaneously unscrewed during use. Maybe that "one-piece" thing wasn't so critical.

When I checked Gamma's internal reflections I gasped. Its interior was ruled like Beta, but the paint on Gamma seemed to swallow light. I lost some respect for Beta when I saw Gamma's inky interior. And Gamma had TWO setscrews for its compression ring. I don't know if it was better - compression is compression. But it was 100% MORE. I started to think that maybe Gamma would displace Beta in my 50mm 2" extension depth chart. But then I noticed that Gamma didn't have a safety catch. I kept comparing Beta and Gamma closely. (Alpha had long since been relegated to the box of "stuff I probably won't ever use again.") I found a distinctive feature on Beta that I didn't notice - it had proper filter threads so I could screw a standard 2" filter on its end unlike the un-threaded Gamma.

So while I pined for Gamma-like interior light damping, I kept Beta as my primary 50mm 2" extension. It had some great features except for the darn interior. Then, just when things were settling I won another eBay auction with some miscellany. Yes, a fourth 50mm 2" extension stowed away into my collection, this time from the premium optical vendor - Tele Vue.

I have a couple of Naglers. I have Powermates. I know Tele Vue makes great stuff. So I was somewhat excited that the Tele Vue extension was in the lot of stuff I bought and I looked forward to comparing the Tele Vue with Beta and Gamma.

When Delta (what else?) arrived it made a dramatic entrance. Instead of the naked accessories that preceded it, Delta arrived in an official Tele Vue box. (Technically it's a white generic box with the Tele Vue sticker.) If you don't now how important boxes are in astronomy try to sell two identical eyepieces on Astromart - one with and one without a box. You'll find that astronomers are willing to pay a premium to get an object that has its original box. It seems to be some sort of litmus test about the moral character of the seller (and presumably his/her passion for equipment care).

This product had nothing anonymous or generic about it: It proudly boasted a Tele Vue label and announced its hometown of Suffern, NY. I hoped for an Al Nagler signature on the extension but there wasn't one. This product had more than pedigree - it had identity. The sticker on the box indicated that this was an "X2T-0008". I can only guess that Tele Vue plans to make as many as 9,999 different 2" extensions with various depths and features. I was privileged to be looking at an early model.

So what how did Delta compare? What did it add to the feature stream? Well, its interior is ruled and anodized much like Beta, but it's less reflective than Beta although not as good as Gamma. It has filter threads like Beta, but is without a barrel safety catch like Alpha and Gamma. It has a setscrew like Alpha instead of the trendier compression rings of Beta and Gamma. In the early comparison and analysis, the most distinctive feature of the Tele Vue extension was its box and label. But then I took a closer look at the setscrew.

Unlike ALL its competitors, the setscrew on Delta is captive. With a captive setscrew, you can't unscrew the thing until it falls out. If you've ever lost a setscrew in the dark you know how frustrating that can be to find it. (I have a theory that much of the missing matter in the universe is non-captive setscrews that I have dropped in grass at night. My recovery rate is 0%.)

Furthermore, the size of the setscrew is impressive. All the others had standard, tiny setscrews - 5-6mm in diameter. Those can be hard to handle when you are wearing gloves in the winter. But Delta has a honking 10mm handle. I suspect you could find it in the dark and tighten it wearing boxing gloves. I'm confident it's the best choice for winter night operations when we're all gloved up. So the famous Tele Vue reputation for design distinction went beyond cosmetics even in this humble 50mm 2" extension.

So how does this meandering tale tie into the problem of too many choices? First, I learned that buying impulsively without researching the complexities of the technology got me the weakest of the four products. In other words, know what you need before you buy. Of course this presumes you can determine exactly what you need - another complex avenue of research.

Second, it is clear that none of the items dominated. There isn't a perfect choice - merely a choice between imperfect products. You can't reasonably expect to find a product that has 100% of the features you'd like. There will always be patches of greener grass with other products you encounter. Expect compromises.

Next, if the manufacturers had done some research they might have applied some of the lessons of their competitors to build a superior product without compromise. But most manufactures tend to be driven by internal engineering so they miss or undervalue some of the features of their competitors' products. The product variety I encountered is definitely not beneficial to the consumer because it increases the level of feature tradeoff instead of reducing it.

Fourth, big names don't necessarily ensure a safe purchase or the best product. Even more, demonstrated expertise in one area doesn't necessarily extend to other areas. Don't expect a big name to simply buying or increase satisfaction.

Finally, purchase your products with the expectation that you might misjudge your needs or you might be disappointed by your decision. Alpha was bought on the used market and I could sell it for what I paid. Gamma and Delta were virtually free in their eyepiece lots so I can sell them without a loss. Beta was the only full retail purchase and I'll probably keep it as my "starter". But I could also absorb the small retail/used product discount loss if I decided to sell it. Having an "exit strategy" for your purchases is an important part of the buying process. This is more important as the price of the products increase.

Like my colleague said at the beginning: "There are too many choices in this hobby." That's certainly better than too few choices. But it's important to approach your purchases - big and small - with a strategy appropriate for the astronomy hobby's intimidating set of product choices.

Published in the November 2007 issue of the NightTimes