114 short tube reflector Q. Anyone like to move their's?
Hi all,
I'm looking at making a little dob for my kids, they being 3 & 5, I was thinking of using a short tube 114 reflector as a table top dobbie.
There are two types on the market: one is an f/4.4, 500mm focal length, the other is the same one as above, but with a barlow lens in the focuser to make it f/9.
I'm sure that these scopes use spherical mirrors, but for my purposes, it will only be a low power proposition.
* My question is, is it posible to remove the barlow from these synthesised f/9 scopes to restore it to its original f/4.4? Or just stick with the barlowed option? With a half decent EP, might the f/4.4 be reasonable?
I know of the 76mm Celestron FirstScope as a table top model, I've got one, but the 114 models are much more adjustable for collimation.
Last edited by mental4astro; 30-03-2010 at 02:05 PM.
You cannot remove the internal barlow from a short tube Newt. and achive focus. The barlow effectively double the focal lenght to reduce the inherent aberrations found in a spherical mirror. I have attempted it several times but get no where near focus even with extension tubes etc. I would avoid any sperical mirror of that F/L and get a decent 114 Newt. with a parabaloid mirror. They give surprising good images at high power with minimal coma whereas the barlowed versions image breaks down at even moderate magnifications.
Do not get the one with the barlow in the focuser. The performance of these silly things is generally poor when compared to proper newtonians and the barlow makes collimation near impossible.
So, does anyone have a 114X500 they'd like see go to a good home? No mount needed, finder and one or two eyepieces would be great. Paraboloid mirror asking too much ? For my purposes, I'm OK with spherical.
Hi, first let me say that the adviced is right stay away from the barlowed 114. Orion makes an excellent short tube 114 on an eq mount. I own one and easily did the M-110 and a lot more with it.
For some one with tools and skills turning it into a dob would not be a problem.
I am somewhat of a pack rat especially as getting scopes here is so darn difficult.
? For my purposes, I'm OK with spherical.
