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Question from a novice

Started by Inge_S, 11/22/2005 10:36AM
Posted 11/22/2005 10:36AM Opening Post
I use mid-size telescopes regularly, and at present my workhorse is a 12.5-inch Portaball. Lately, however, I have been thinking about acquiring a small telescope for observation of extended objects. To begin with I checked the small refractor market. Very interesting, and a lot to choose from. However, I figured out that maybe a pair of binoculars would be an even better choice. The problem is that I know very little about binoculars, having only a very lousy pair of 10x50's at home. What should I look for when selecting binoculars for astronomy? Are there any pitfalls? I see that there is a very wide range of prices for the same aperture. Are the most expensive ones worth the price? Any recommendations as to brand etc? What about the second hand market?

Inge S
Posted 11/22/2005 12:02PM #1
Hi Inge,

It's hard to think of you as a novice at anything astronomical!

Most observers use binoculars as a very comfortable low-power adjunct to their larger telescopes. Low power binoculars can be handheld, but I've found that anything above 10x has to be mounted for serious work. You will find a wealth of information in the CloudyNights binocular forum (see links at top), but much of it is oriented toward beginners which, despite the title of this thread, you are not.

Since you are starting as a very experienced observer, it's less likely that you would put up with the optical defects of lower price binoculars that a beginning amateur would. These defects often include both CA and SA, causing color fringing and a loss in limiting magnitude. Because binocular objectives are so fast, field curvature in even the best ones also leads to fuzzy astigmatic edges.

I don't know your budget, but I have found that I am better off to get something good and keep it than to keep selling and buying what I have not been satisfied with. This led me ultimately to the Kowa Highlander 32x82 fluorite, which is so good it is replacing my 4" Apo for low power work. The price for the Highlander is between an NP101 and TMB115, and in my opinion worth every penny (see my CN review). Lower-priced alternatives that have received good reviews are the Fujinon 16x70 and Nikon 18x70.

Of course no binocular will have the versatility that a small Apo has in being able to cover high powers as well as low. The principal reason for this is the difficulty in keeping two parallel light paths collimated to each other at high magnification.

As you know, many extended objects require raw light gathering along with TFOV, so binoculars may not meet your expectations here either. Also, binoculars are typically not nebula filter friendly. In my skies, I can glimpse brighter nebulae like the NA and Veil in the 32x82 Kowa without a filter. For dim PN's, I blink an OIII in front of one eyepiece.

That said, you can do serious astronomy with something like a Highlander. In my mag 5.7 skies it will capture stars to about mag 12.5, galaxies around mag 10, split <6" doubles and give nice views of Jupiter and Saturn. I did the Messier Marathon with mine this year and got 106/110. It was by far the most pleasurable Marathon of the three I have attempted.

Good luck,
Milt
Posted 11/22/2005 11:14PM #2
Interesting advice, guys,
It is indeed, true, when comes to knowledge of the binocular market I belong to the dummy community. During one of my few trips to the US I tride a pair of hand held binoculars (7 or 10 x 50) which fully demonstrated that there is a difference between brands although they look very much alike. I'm not sure, but I believed those were Celestron binos.
Maybe I would choose a pair of big binos on some kind of mounting.
I have never tried to measure my pupil size, but I work with exit pupils of 5mm without any problems with my Portaball.
I consider a set-up (including the mounting) within 1000$. Not being in a hurry I may very well keep an eye on the second hand market for a while.

Inge S
Posted 11/23/2005 03:43AM #3
Inge,

I'll give up my 10x50 any day if I keep my ST80. The binocular is a good add-on, but no more than that.

Dmitri