Re: [ATM] ATM chinese puzzler

[Ken Lowther <hermit@outofoptions.org>]

Well, whatever, he must have steadier hands than me.  I don't think I could do
knife edge or Ronchi testing with a hand held device.  Well, at least not with
few enough lines to make Ronchi usable.

Ken

Quoting Michael Peck <mpeck1@ix.netcom.com>:

> At 21:32 07-04-04 -0700, Guy Brandenburg wrote:
>
>> So that's the puzzle: assuming that my American
>> businessman's report is reasonably accurate, then what
>> was in that 'fan' device? How can a 3 to 5 second test
>> of an otherwise untested mirror tell for sure whether
>> it's any good or not, and if not, what needs to be
>
> Somehow all the posts in this thread ended up in my trash bin. You must
> have inadvertently been caught in one of my many spam traps.
>
> Anyway, I would make the same guess as earlier posters did. It's probably
> an LED and ronchi grating or knife edge, maybe with a small telescope for
> easier viewing. I think all the mirrors in the 3-6" range being shipped out
> of China are reported to be spherical, so a quick look should be good enough.
>
> And now, some old-timer's reminiscence. My very first telescope, which my
> parents bought for Christmas in - probably - 1966, was an Edmund 4 1/4"
> f/10 reflector. It had a spherical primary (guaranteed 1/4 wave!), a
> rectangular diagonal that was glued to a stalk, aluminum tube, rack &
> pinion focuser, and something like a 6x30 finder. It was mounted on a GEM
> with maybe 1/2" shafts and cast iron housing and the head sat on a cast
> iron pier. It came with a 1" f.l. Kellner eyepiece, 1/2" Ramsden (no metric
> nonsense then), and 2-3X Barlow. As I recall that model was advertised at
> about $80 in the 1966-67 Edmund catalog.
>
> According to the inflation calculator at <http://www.bls.gov/cpi/home.htm>
> 80 1966 dollars had the same buying power as about $460 today. A quick look
> at Orion's web site shows what looks like a dozen or more reflector models
> at that price or lower, including Dobs as large as 8" for under $400.
> That's about the same price as Edmund's top of the line 8" model sold for
> then, which would have been way out of my parent's price range.
>
> Personally I'm not inclined to scoff at those Chinese optics, or begrudge
> those Chinese optical workers their jobs. They, and Meade, Celestron, Orion
> et al. are making stuff available that a 12 year old kid could barely have
> dreamed of owning 40 years ago, at much lower prices relative to average
> North American incomes, with probably the same or better overall quality.
>
> Mike Peck
>
> _________________
>
> Michael Peck
> email mpeck1@ix.netcom.com
> Wildlife photography page http://home.netcom.com/~mpeck1/index.html
> Amateur telescope making http://home.netcom.com/~mpeck1/astro/astro.html
>
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Hermit, holed up in Youngstown, Ohio
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