Edmund Scientific 3001/4001

One of each currently listed out there, and neither seller wants to ship. A number of nice scopes – classics – are up ‘LPO/PUO’. Isn’t that market best suited to front yard signs and Craigslist? To me, listing LPO/PUO nationally is just a grab for attention and a statement of laziness – “I want money, but not to earn it.” “I’ll take it to UPS/FedEx, but you deal with them…” Rubbish.

And that is certainly their choice for whatever reason they have. But it doesn’t do me any good, so I started thinking… and thinking… and dozing… and thinking… Classics are nice ties to the past, sometimes to quality from the past, true. But we have quite good quality right now if we are willing to pay a reasonable cost – a cost which in many cases is equal to or less than the cost of a classic of the same capabilities. A cost which includes some sort of warranty, eh? I like ‘classics’ – I cherish classics, but they are not the ‘best’ – they are old, they are used. The plusses in classics are the metal lens cells and focusers (and mounts and tripods) – less slop, play, wiggle, flexibility than many contemporary plastic versions.

And speaking, generally, of ‘capabilities’… EDs and APOs, unless absolutely required for some task, are overrated. Refractors are nice, but the ‘obstruction free’ light path (referencing the secondaries of reflectors, etc ) is a fallacy. The refractor lenses themselves are obstructions of such a nature as to require special glass to minimize the effects of their obstruction. I’ve sampled EDs, and then looked thru a nice newt – and the realization came quite quickly that except for certain instances, reflectors are better – not perfect, but decidedly better, for the money spent and the views received. I’m not ‘against’ any sort of telescope – I have many refractors and I like them, I’m going to keep them, but the reflectors are better – more aperture for less money for less trouble.

But back to what to do about a 3001/4001 substitute…

Buy a nice Skywatcher 6″ Dobs! I don’t actually have a 6″ reflector at the moment – lots of 114 / 4.5s, 127s, 130s, 8s, 10s and so on, but no 6″!

Well, I feel I need one for reference anyways, and a 6″ Dobs can rather easily be yoked and 3K1/4K1’d… well, perhaps not exactly “easily”, but easy enough. And I’d rather have an f/8 than an f/5, anyways, so a $315 6″ Dobs sounds attractive as a starting point. You get stuff and a warranty – that’s always nice!

Now, the yoke, the yoke, the yoke – well – steel or alu? Plates or tubes or both? Welded, bolted, brazed… oh, the options, the options. I’m thinking, at the moment, welded tube frame, full slo-mo-ish gearing (no tandems), wedged base and at least motor slewing if not tracking if not goto, yeah? yeah.

The 3001/4001 had tandems – reset needed after so many degrees movement. blyech. If you have a 3001/4001 full yoke, you get full rotation. Not saying you have to use it, but it’s there. How to move it about? Hmmm. Belt drive steppers is a reasonable answer. I think, skip the clutching – this is y2K+19, so powered manual slewing is fine and doable and extends to tracking and goto rather well. Geared (100~200:1) stepper driving small belt drive pulley (6~10T) driving large tube drive pulley (40~80T) – shooting for overall ratio of 600~1500:1 I like faster stepper speeds, to a point, so some gearing is necessary to begin with. And I don’t need huge, instant slewing – 2~12°/second would be nice.

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