Telescopes

© Norman Sperling, January 15, 2011

A recommendation by Sky & Telescope magazine last month, following a [.pdf] review last July, rekindled an old glow. The Astroscan telescope - my first big project - was once again named one of the 3 best inexpensive telescopes ... 34 years after it was introduced!

I remember its development clearly.

It was meant to be a superior first telescope, and it is. It has also proven to be a superior second telescope: folks keep it after they graduate to something bigger, and use it for a quick session, and as a convenient portable. Because people keep their Astroscans, remarkably few are offered on the used market.

Robert Edmund was taking over Edmund Scientific Company leadership from his father Norman. Norm has enjoyed retirement in Florida ever since. Robert had studied business management and knew how to run a going concern in changing markets. His telescope line was not doing well. Telescope leadership belonged to Criterion, Unitron, Questar, and Celestron, and Edmund Scientific wanted to earn its way to the top tier. The Astroscan was his opening salvo.

Robert Edmund hired me as a consultant in 1975, when I was 28. I was planetarium director at a private school, an hour's drive north of Edmund's. I was young and unknown and had even rougher edges than now. My ideas were unconventional, and entirely untested in the market. I contributed to a lot of Edmund's smaller astronomy projects, too.

I had observed observers observing in amateur, public, and school settings, and discovered that some of the wisdom of my elders wasn't wisdom. Telescope setup took frustratingly long, mountings were clumsy and shaky with narrow pivot points and long overhangs, eyepieces were tough to squint through, and views were underwhelmingly faint and dull. To improve on those, I preferred quick setup with minimal moving parts, stubby bodies, wide fields of view with wide exit pupils and bright contrast, lightweight and cheap. Those all shouted "Rich-Field".

Dr. Harvey Davis of the Lansing Astronomical Society introduced me to the principles of rich-field telescopes in the late 1960s. He was a friendly young math prof at Michigan State, where I was an undergrad. In the early '70s my friend - everybody's friend - Roger Tuthill made an RFT with an optical window (the success of which spurred us to do the same with the Astroscan). Roger's scope had a conventional cylindrical tube with a simple handle, so the only characteristics in which it was a predecessor of the Astroscan were the window and being an RFT. It didn't sell well at all.

No one in all history had ever gotten Americans to buy a LOW-power telescope, and we knew this was a huge hurdle. I assured Edmund that the telescope would please its users, but I explicitly never promised that anyone would buy it, and I wondered whether the expensive project would ever turn a profit. When Marketing VP Jack Sharff claimed that people would buy it, I thought that was bravado more than business sense. Sharff assured me that making it "popular" was his task, not mine. A good thing, because I understood almost nothing about marketing back then.

I wanted to make the eyepiece's exit-pupil an enormous 6 mm, because that's about the widest a dark-adapted human eye can take in. So, figuring from that, I championed a 4 1/4" f/4 (which the company nudged to f/4.2 for manufacturing convenience). Astroscan's richfield view - 3 degrees wide - means that finding things is easy, and keeping them in view is easy. It also means that hundreds of deep-sky objects are unusually contrasty, making them more obvious to beginners. The tradeoffs are minor: no astrophotography (which we wouldn't wish on novices anyway), planets look too tiny, and only a few double stars would look good. But any novice scope would only show pleasing detail on Jupiter and Saturn, the other planets being too small, featureless, and/or faint. So we swapped decent views of 2 objects (Jupiter and Saturn) to get superior views of hundreds of deep-sky objects.

I expounded on telescope design, exit pupils, and surface brightness in "Of Pupils and Brightness", Griffith Observer, January 1985.

At least as important as the optics, I wrote Astroscan's behavioral specifications. I remember blathering on and on for maybe 2/3 of a page singlespaced that I could have shortened enormously had I known the term "user-friendly". I didn't have the term, but I did have the concept. In beginner telescopes, it meant minimizing adjustments to fiddle with, and shortening the setup time (competitors, then and now, often take 15-20 minutes). Our setup time target was 3 minutes. We got it down to 10 seconds, and NO user's attention-span is too short for that.

While I did the optical and behavioral design, a brilliant young optical engineer, Mike Simmons, created the mechanical design that satisfied our needs. Simmons figured out that pushing the tube into the mounting made sense, and Simmons figured out that the ball-in-socket would work best. He was right. He advocated a very large sphere, with just the focuser-end of the tube sticking out. However, manufacturability, aesthetic appearance, and the awkwardness of a large-diameter sphere pointed the company to a smaller sphere, with more of the cylinder sticking out. This, however, is top-heavy, so to balance it, 2 semicircular slugs of cast iron surround the mirror. The extra weight, and the need for it, offended Simmons, and he left Edmund's soon after. I haven't seen him since the early '80s.

The shell satisfied all my specifications, including being nearly student-proof (it's meant to be checked out by students and carried home on a school bus). An industrial designer did the detail work. It's cast in 2 pieces of ABS plastic (one with the focuser insert, one without) and glued together.

In the fall of 1976, just before the first ads came out, I asked Robert Edmund what amount of sales he'd consider successful. He said 800 units by Christmas. Privately I thought that unlikely. Well, they sold 3,000 Astroscans in those first 3 months, which taught me another business lesson: there are DISeconomies of scale, as well as economies of scale. For example, the company couldn't produce the telescopes fast enough, and had to add shifts. Part of the optical design was meant to use an excellent, but slow-selling eyepiece that Edmund had a thousand of. They ran out, and had to scramble, buying every eyepiece on the world market that could possibly work - some Astroscans were shipped with Clave Plossls worth almost as much as the entire scope! Robert Edmund soon had Penn State's Dr. David Rank design the RKE eyepiece line, stimulated by the need to make a new eyepiece for the Astroscan. I'm happy that the company has sold in the neighborhood of 100,000 of them.

It was Robert Edmund who selected and hired and coordinated all the various people whose work combined to make Astroscan a success. He paid for all the work and assumed all the risk. He paid me quite well. In addition, the Edmund family and company ALWAYS treated me exceptionally well, and very often did me favors far beyond a conventional business relationship. Then and now, I regard my relationship with Edmund as one of the best I have ever had. I consulted for them for 9 years, 1975-84, but I have been a customer of theirs for 50 years, and endorse them as a fine set of people.

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Nobody since then has hired me to design a telescope, and such a project is beyond my personal resources. But I still get ideas.

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Parts of this post appeared on the Old Scope list in February 2002.