Re: [ATM] 4-1/4" Mirror Suggestions and Thoughts Wanted

["Scott Ewart" <scotte@frontiernet.net>]

Dave,
    Just as others have, I too would have recommended a 6" or 8".  But 
if you are going to build a 4.25", I would keep it short.  One of the 
advantages of a small scope is the ability to get a wide field.  I 
have a 4.5" f/5.5 (I also have 3 larger scopes) and can see well over 
2 degrees with a 1.25" eyepiece.  And the 3mm Tele Vue Radian is a 
great eyepiece if you want high power.  A well made 4.25" mirror well 
still look good at 200x and beyond.  I do it all the time.

Scott


----- Original Message ----- 
From: "Dave Tabor" <david@tabor.com>
To: <atm@atmlist.net>
Sent: Tuesday, October 10, 2006 10:52 AM
Subject: [ATM] 4-1/4" Mirror Suggestions and Thoughts Wanted


| Hi, fellow, ATM'ers...
|
| I'm a beginning ATM'er, who made his first 8" mirror (f/6.25) last 
winter.
| I used it to build a travelscope, which works very well, but as I'm 
told is
| common with ATM'ers, it's my work-in-progress.  I recently modified 
the
| trusses, going from 4 straight to 8 diagonal.  Now I need to re-fix 
the
| balance a little, and I'm planning to switch to ebony star and 
teflon to
| make it smoother.
|
| I'm going to be assisting my 10 yr old daughter with her first 
mirror, and
| she's decided that smaller is nicer, so we've purchased a 4-1/4" 
mirror kit.
| She'd like the scope to be shorter, so it fits her size better.  I'd 
like to
| keep usable for as many different types of things as possible, to 
help keep
| her interest in astronomy peaked.
|
| If I guide her toward an f/6, it would be shorter (25.5" focal 
length), but
| would need a 3mm eyepiece to get up to the 212x theoretical maximum
| magnification for a 4.25" mirror.
| If she went with an f/12, it would be easier to get the 212x for 
viewing
| planets, etc., but might limit it's uses.
|
| Being an beginning amateur, and not having the experience to fall 
back on,
| I'm wondering what suggestions, thoughts or recommendations the 
group has
| regarding good usable scope configurations using a 4-1/4" mirror?
|
| Thanks,
| Dave
|
| _______________________________________________
| 

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