[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: ATM 6" Dob: How Easy? How Cheap? How Heavy?
From: malsing@borg.ae.usr.com
>...you may also want to consider the cost for accessories.
>Some of these accessories are mandatory for a pleasant
>viewing experience and others can wait till you have a
>little more experience and cash.
>Mandatory..
>Eyepeices (2 or 3 ranging from low power to medium power. $50-$75 each)
>Finder Scope (maybe $50 - $100 - or Telrad pointer)
>Maps (you don't need to drop $250 on "hardcovers" to start)
>Get later..
>Collimating eyepeice (Cheshire/Sight tube - $50)
>Lunar filter ($25 - $50)
>Color filters/LPR filters/Solar filters -> (NO SUN TILL YOU HAVE ONE!)
>Illuminated reticle eyepeices
>Any other fancy stuff/gizmo needed to dazzle your freinds
I'm too much of a cheapskate, so here are some alternates to the above:
Eyepieces: Paul Rini's surplus eyepieces for less than $20 a pop.
Excellent value, especially on a slower f/ratio (f/8) light cone. See Ads
in Sky & Telescope or Starry Messenger.
Finder: If you're starting out and only looking for bright stuff like the
moon/planets I've used a 12 inch length of PVC pipe as a sight tube. If you
want to get fancy then tape some thread across both ends in a crosshair
fashion (use thick thread, like dental floss - so you can see its sillouhete
against the dark sky)
Collimating eyepiece - for an f/8 mirror, a 35mm plastic film can with a
small hole punched in the middle of the cap is accurate enough. Wrap some
tape around the can to make a snug fit in your focuser.
Color filters: Get them used for about $5-10 each.
How about an inexpensive focuser? On an f/8 system a friction fit focuser
is adequate - that means any pipe with 1 1/4" I.D will work just fine with a
nylon thumbscrew added. Browse the aisles of your big hardware/plumbing
stores for ideas. PVC couplings/adapters are quite popular. (My ten inch
f/7 has this kind of focuser. On high power viewing I slap in a barlow and
the light cone is about f/15. . .that's easy to adjust/focus for any
eyepiece by twisting and sliding!)
Bottom Line: Look for Astromart, Astro Ads, or Starry Messenger on the Web
and find some great deals once in awhile. . .or make it yourself.
Scrounge for scraps from friends, wood shops, metal shops, and dumpsters.
The expense is in time, gas, phone calls, and hearing "no" from time to
time.
I was lucky with my ten inch f/7. Someone had a length of sonotube in their
attic that was from an abandoned ATM project. I used exterior grade 3/4
inch plywood for the project. It doesn't look good in daylight, but who
cares? With alt az setting circles (a ten inch protractor on the elevation
disk and a tape measure wrapped around the circular base) and a 286 laptop I
can find Mercury in daylight. . .with no finder scope on the OTA. (Want the
QBASIC software? See Tom Stock's web page. Your obsolete PC can be a
telescope pointing system!)
Hope this helps keep things inexpensive, yet effective.
Tom Krajci