Lightweight Telescope

Celestial or terrestrial viewing? Zeiss monocular perhaps.

http://www.opticsplanet.net/zeiss-10×25-b-design-selection-monocular.html

Thats the one i use when hiking
Before that i was using minox 10×25 binocular

my only regret is the "ring " to focus is slow,
i am not sure how to say that in english but what i mean is you need more to turn it to focus than with the previous binocular i was using
so on fast moving animals it can gets annoying

anyway i dont regret the change, its light and the optical quality is good,
i dont bring it when hiking in France, but in Greenland and Patagonia i was really happy i had it.

Assuming, perhaps mistakenly, that you might want to use the 'scope for astronomical purposes:

As a "pro" stargazer, I have to agree. I wouldn't think of looking through a telescope with an aperture (diameter of main mirror or lens) of under 4.25 inches. The most compact, lightest weight, quality (important issue) telescope of that type is the Edmund Astroscan, a 4.24-inch reflecting telescope, and it weighs a lot by the standards of this community. Still, I've lugged it more than a few times into the back country and gotten mind-altering views. The same cannot be said of telescopes under 4.25 inches of aperture.

Below that aperture, you're stuck with low-quality 'scopes or ones that don't have enough light-gathering power to justify the weight.

My solution is binoculars (or in your case, a monocular), which if they have enough aperture, can provide a wonderful stargazing experience, especially in summer, when you can scan the Milky Way in Cygnus and Sagittarius. Personally, I find the 25 and 30mm versions a tad too small to give those "OMG" views. There are a ton of 42mm roof-prism binos that are relatively lightweight and give spectacular views. Get roof prisms rather than poro prisms, which weigh a ton more. (The 42mm bino look so alike because they are all manufactured by the same Japanese optical company and then rebranded by American distributors. Get the cheapest ones.

Mine are Barska brand 8 (mag) x 42mm waterproof binos that tip the scales at 22 oz, which is almost three times more than my Hexamid Single weighs. For me, stargazing is one of the main reasons to go out into the wilderness — to escape those danged, light-polluting streetlights.

You can get monoculars with the same optics if you look around, but don't go under 30mm for stargazing. It's the magic aperture number for most people. For older folks (your eyes begin to lose their light gathering power at about 14 as your pupilary opening begins to shrink, 42mm is far better.

Stargazer
http://www.perkins-observatory.org (check it out)

Hi John,

I’ve often wished I had a back packable telescope, too. However, I don’t think there are any commercially available options that really fit the bill (ultra-light, small, but with enough light-gathering ability for those OMG views that Thomas mentions). What needs to happen is for the amateur telescope making community to apply UL philosophy to a new telescope design. We’re not talking about an airline portable “travelscope,” but a true UL scope where every ounce is carefully considered. I think the possibilities are pretty exciting. My guess is it will be some kind of string, or single strut dobsonian reflector, like these:
http://www.stardazed.com/MoonsilverV.html
http://www.backyardvoyager.com/DS3Main.html
http://www.bbastrodesigns.com/6inchtravelscope.html

If someone came out with a 6 or 8” dob that weighs less than, say, 3 lbs. –that would get my attention.

Funny you should mention that. I was just thinking sadly about the best lightweight 'scopes I ever saw. The key is Thane Bopp's old skybeam design, as popularized by the greatest amateur telescope maker, Ron Ravneberg, now desceased, that I have ever met:

http://www.atmsite.org/contrib/Ravneberg/alice/ap.html

A classic example of the ultimately pared-down Dobsonian skybeam can be found at

http://www.stardazed.com/MoonsilverV.html

(Edit: Oops! I see that Daniel already mentioned this one.)

The trouble with such skybeam/ Dobsonian designs is that the Dob depends on gravity/ mass for its bearings to work properly. Light Dobs don't point so well, and they don't stay pointed.

Still, the designs have merit, for sure.

You'll have to build it yourself, though. The market for UL telescopes just isn't there.

Stargazer

P.S. Don't give up on the monocular idea. many is the night that I have stood in the dome at Perkins Observatory with a telescope as big as a corn solo at my side sitting unused as I scanned the Milky Way with 8 x 50mm binos or just marveled at the beauty of the sky with the binoculars I was born with, my own two eyes.

Knowing the sky is the best telescope.

del

>Afterall, scopes this small never prevented early astronomers from discovering most of our visible night skies!

Spoken like a true diehard (me, too!), but please note:

When Galileo pointed his small refractor for his patrons (i.e., beginners), they could see . . . absolutely nothing. It ruined him. I've had sooo much experince with showing beginners the stars. They simply can't see what a person with an experienced eye can see.

Thus, please excuse my fervency. With respect to the previous poster, forget about those 2 – 3 inch refractors/ field scopes. They produce lousy images for astronomy and simply aren't worth the weight. They are designed for other purposes. You're not going to get great planetary views with any telescope light enough to carry into the woods, so settle for low-power, wide field views of star fields, the Milky Way (and a few great objects like the Pleiades and and Beehive star clusters). A 42mm monoclular weighs maybe 12 oz, and you'll see that bear or bird or Milky Way field just fine.

Field scopes are "for the birds" (and the planets) certainly because they work at higher magnifications, but they are also for the birds because they fail the weight/ usefulness BP ratio, both in terms of astronomical and terrestrial use. I've carried them deep in the field and cursed them because of their weight and relative lack of usefulness.

Sorry about the fervency. Please excuse me. I have devoted my life to the endeavor of showing people what their universe looks like. I hate the thought of anyone painfully hauling a telescope into the field and not seeing the wonder and glory of the stars.

Stargazer

del

>I think "multi-use" is a key tenet of the UL philosophy, don't you agree?

Only if the fieldscope is really good for the full range of astronomical observing, which it is decidedly not. Having had my say, I now withdraw from this thread.

Stargazer

del

Thanks to all of you for this fantastic discussion and wealth of information. I certainly learned a lot here. Although the discussion of astronomy was very informative, my primary need is for animal/bird viewing, so I think I will check out the monoculars that were suggested.

If you're looking for a bird scope, look into digiscoping.

For astronomical viewing, something like a Takahashi Sky 90 would probably be about as heavy as I'd go with for trekking. I've seen some amazing planetary views such scopes — keep in mind that local planets are pretty bright, so you can get away with a lot more magnification on them then you could with deep sky objects, for which you'd need a much bigger scope.

I think it ought to be possible to build a pretty lightweight truss Dobsonian (some are built with PVC pipes, so it's probably feasible to build with a bunch of trekking poles), except for the mirror, which is basically a hunk of polished glass, and therefore not exactly a lightweight item.

There are a few Maksutov-Cassegrain (catadioptric) 'scopes out there that are a lot more compact than reflectors with comparable size, and are great for splitting the difference between the exquisite sharpness and detail you can get with an Astrophysics or TeleVue apochromatic 'scope and the extreme magnification you can get with a 10" Schmidt-Cassegrain like the larger Celestron and Meade "intelligent" scopes (with integrated GPS and automatic calibration, etc).

For viewing birds, local planets, and wide field astronomical views, I'd recommend something akin to a TeleVue Ranger.

http://buytelescopes.com/

Hm… it looks like the Ranger's gone from the lineup, unless I just have to dig more, but this would probably make for a good bird scope, as well as a good digiscope:
http://televue.com/engine/TV3_page.asp?id=32

"my primary need is for animal/bird viewing, so I think I will check out the monoculars that were suggested."
Astronomical telescopes are not good for that ,then…
For a start you would need an image erecting prism otherwise your image is reversed left to right (tha makes it hard to follow your subject) but even with that they tend to be too slow and cumbersome to use.
Better off with a good spotting scope or a monocular/binocular for weight savings.
Still try to have the exit pupil as high as weight size permits. The exit pupil is the size of the front element divided by the magnification .
A 10×50 has an exit pupil of 5 (in mm) . For the young ones around 7 is ideal, over 40-50 , 5mm is about as wide as your own pupil dilates.
Franco