Astronomers Anonymous by Steve Ringwood

Author:Steve Ringwood
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

(The phrase ‘caveat emptor’ is no less significant in buying astronomical instruments than in buying any other type of goods. When the bug bites, there are plenty who will provide an apparently serviceable glass window on the universe that later turns out to be a mere chink of fragmented plastic.)

Dear Steve,

I have been given a high quality 1 ″ lens refractor for Christmas . It boasts scratch resistant plastic lenses, a finder (apparently somewhere in the box but I can't find it), an eyepiece providing a magnification of 2,500 times, a Sun filter specially commissioned by the Braille Society, a two legged tripod, and a really nifty white enamel tube. I have tried to read the instructions but am finding this difficult as they are in smudged pictorial script. Can you advise me?

Leo

Birmingham, Alabama

Dear Leo,

Heavens, it is vitally important that you take these steps before you go any further. Measure with utmost care the volume of space between the lenses (there's one each end of the tube). Put this space in a sealed plastic bag. Wrap the Sun filter in a handkerchief and smite with a 15 lb sledgehammer. Bury the glass fragments with due ceremony if you want to. Isolate the plastic lenses and place them in a pre-heated oven for 35 minutes. Although their subsequent removal from the oven will reveal an unsightly mess, the result will be far more useful than the original product. So far as the bipod is concerned, you will only find this useful for staunching a really bad nosebleed.

Take the enamel tube and cut longitudinally along the (obvious) seam. Flatten out using a rolling pin until all the wrinkles disappear. Mark out parallel dotted lines every 12 mm. Mark out parallel dotted lines perpendicular to these at intervals of 8 mm. Carefully fold along dotted lines, scoring with a blunt hacksaw blade beforehand if necessary. Check resulting cube of metal is 90 degrees true using a trustworthy setsquare. Place cube in the bin. Keep the bag of space. (It’s the only bit really worth keeping.)

Although it has to be acknowledged that there are still examples of poor quality (nay, even scandalous) telescopes about, their availability is much less prevalent than previously. One of the reasons for this is that good quality mass-produced telescopes are now so affordable that cheaply made pretenders cannot compete! The golden rules are first to seek advice before purchase (from a local astronomical society) and second to buy from a recommended telescope supplier.

Suspect instruments, normally having an aperture of 50 mm or less, will have a single feature betraying their underperforming nature. The lens itself will have a delimiting diaphragm almost immediately behind it, preventing all but the central 10 mm or so to be employed. This is because only this portion of the poor quality lens is able to provide a (barely) usable image. This diaphragm should not be confused with field stops properly found in good telescopes; these will be further down the tube.

Galileo also used lens delimiters.

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