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Maks as grab'n'go

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#1 Guest_**DONOTDELETE**_*

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Posted 17 August 2005 - 07:55 PM

Hi all!

I'm new to astronomy, and I'm still making some decisions concerning buying telescopes. I once had a 4.5" Newt, but I sold it because I found too bulky. Having decided that I will get 2 telescopes, one light for grab-and-go, mounted on a Altazimuth mount, and heavier one (like a 127 or 150 Mak on a Skyview Pro mount), I'm now thinking about what would be best for my SMALL, LIGHT, grab'n'go scope.

Right now, I'm seriously considering the ShortTube 80 because it is inexpensive, small and has a wide field of view.

I was wondering if a Mak 90mm would be a good buy for this application? I know that they have loooong focal lengths, so they are not suitable for wide field observations out of the box, but can I get a wide field by using a "high mm" eyepiece (such as 32mm or 40mm) or even a focal reducer?

My grab'n'go telescope should have a reasonable wide field, but maybe 2 Maks (1 small, 1 big) is not a good setup...

But I also thought that grab'n'go applications usually involve light polluted cities, where the best objects to observe are bright planets and stars/moon, so the Maks get an edge due to the absence of achromatic aberrations (I'm not considering APOs right now). Ideas/experiences? Do I get lots of vignetting using 32mm/40mm eyepieces on a 90mm Mak (such as Orion's)? Or with a cheap focal reducer (ATIK) or both?

#2 Rusty

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Posted 17 August 2005 - 08:00 PM

I'd consider as well the Celestron C5i (SCT) - very compact, and its an f/10, slightly shorter than the MAKs. The f/6.3 focal reducer will work OK on the C5, but focal reducers can't work miracles.

#3 Guest_**DONOTDELETE**_*

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Posted 17 August 2005 - 08:06 PM

Rusty, the C5i is very expensive compared to what I would like to spend on a grab and go scope. I was thinking of something I can take anywhere and be reasonably fine if it breaks or kids mishandle it. I was actually thinking specifically of the $219 Orion 90mm Mak vs the $179 Orion ST80.

#4 jrcrilly

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Posted 17 August 2005 - 08:09 PM

Hi, Rusty.

There are probably some N5i models still in the supply chain, but Celestron has dropped the C5 optical tube from current production. There's a C6 coming to replace it (rumor has it that one's gonna be an import).


Daniel:

One opportunity for a relatively inexpensive way to try a small Mak on a lightweight mount is Meade's Outlet Store. They are currently offering a 90mm Mak on a goto alt/az mount for under $300, and a 5" Mak on the same goto mount for under $500.

#5 jrcrilly

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Posted 17 August 2005 - 08:13 PM

I was actually thinking specifically of the $219 Orion 90mm Mak vs the $179 Orion ST80.


This might interest you, then It's $275 including shipping, so for very little more than the Orion Mak you get a Western hemisphere (Mexico) optical tube with a full goto mount. The Meade 90mm Mak is considered a pretty good one. The mount isn't great, but probably no worse than the Orion.

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Posted 17 August 2005 - 08:14 PM

The C5 seems to compormise a bit by allowing the focal reducer and capturing some decent higher mag on a small platform. Its a fine idea (though those focal reducers do cost something too!) I've gone a similar route but with the Intes. I can't tell you anything about it yet because I just got it today! :yay: :yay: :yay: :yay: :yay:
Typically, though, I think I would suggest a wide field instrument to complement the larger Mak wide-field instrument, so you have more variety and range.

There are lots of great ideas you will (I'm sure) hear form shortly. It might be beneficial to fill in some of the details: Is there a budget in mind ?(clearly you are keeping it on the low end). What are your grab-and-go conditions? What are you most interested in viewing? What's your sign? (o.k.,you an skip the sign).

Another thought...
Instead of larger Mak for you heavier instrument, go with a a larger aperture wide-field refractor (like the Orion 120). This will be fine when you actually get out to dark sites. Then you have your little mini-mak for observing the shallow-sky stuff from the inside of your light dome. This seems just a little backwards somehow, but seems to suit your needs (and with a budget I might add!).

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Posted 17 August 2005 - 08:32 PM

Thanks for all the help so far - answering the questions, I'd like to reserve my money for the "big" telescope. I just found the 102mm Celestron "spotting scope" that has a good review on Astromart.

Some requirements:

1) Weight around 5lbs, 3-4 preferred
2) 20" long or less (Celestron 102 is 21", which is fine)
3) I want to have some fun seeing planets. Don't want to see dots :), if I can tell there is a ring around saturn, I'm happy. If I can see the regular 4 moons around jupiter, even happier.
4) In a dark site, I'd like to be able to see Andromeda Galaxy and some other bright nebula.
5) Should accept camera adapters, I'd like to take pictures of the moon and, on a good mount with tracking, get some good Nebula and Deep Space in general pictures.

#8 wilash

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Posted 17 August 2005 - 09:07 PM

You can see a ring around Saturn and Jupiter's moons in the short tube 80mm refractor (I can even see them in my Mini Borg 50). For large objects such as Andromeda or the Pleiades, the 80mm refractor would be better. Certainly objects like the Orion nebula and the Double Cluster is easily in reach. There are hundreds of things visible with a short tube 80. Since you are getting a larger Mak as your "main" scope, the refractor would be better.

If you are doing astrophotography with a 35mm camera, your scope will need a 2" focuser so not to vignette the frame. If you are using this afocally, it does not matter. The Maks will have less (or no) chromatic abberation compared to the refractor.

BTW, I have a 5" f/10 Mak mounted side by side with an 80mm f/5 refractor and it is a great combination for observing. The refractor can also be used as a guide scope for wide-field astrophotography.

#9 moynihan

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Posted 17 August 2005 - 10:17 PM

I have a Meade ETX 90 tube assembly, that i use on a small german equatorial mount. On most DSO's, and on all solar system objects (except comets) it provides a more nicely framed,sharper, and greater contrast view, than my 80ED, (time for me to duck :tonofbricks: ).
That said, the little Mak is not what one would choose for say, M31, or M42 in its full extent, or the Pleiades. It is also not a good choice for leisurely scanning, then "zooming in" along the Milky Way, nor star clouds or dust features. The max field of view for me is about 1.5 degrees with the little Mak.
I should also add that i had to return 2 of the ETX 90 RA's i purchased, before the third one, which has really good optics. Of course, my 80ED has its own foibles, so :shrug:

I do not know anything first hand, about the little Orion Maks.

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Posted 18 August 2005 - 01:11 AM

Depends a lot on your grab'n'go conditions.
In my locale, the best I can hope for w/ "gab-n-go" are shallow sky objects, some nice doubles, and some brighter Messiers. i will disagree a wee bit with Moyni's opinion above (all else being I think entirely correct) that I do think M42 can be a fine site with a narrower fov, even if the "full extent" is lacking. But i digress. For my light-polluted skies, I could see a mini-mak (no color issues on bright objects, etc.). However, if my local conditions allwed for some viewing of dimmer objects, I would be looking into something more wide field.

An ED80 would give you something between I think.

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Posted 18 August 2005 - 01:15 AM

Also worth thinking about...
the "go" part of grab and go. When I think of something to toss in the back of the civic and go somewhere moderatly dark, I would take something with a wider field I think.

Some fellow on these forums had an interesting thought--that a poor man's 4" apo would be wf achro and a 4"-5" mak. There might be some sense in that.

#12 Rhadamantys

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Posted 18 August 2005 - 01:57 AM


Some fellow on these forums had an interesting thought--that a poor man's 4" apo would be wf achro and a 4"-5" mak. There might be some sense in that.


Hi

This is my exact opinion and not only for the "poor man" in fact.

I had the same needs as Daniel. I especially didn't want to spend 3000-4000€ on a 4" APO, as the scope would be travelling in a car, but also on my back, and sometimes under harsh climate (Temperatures as low as -30°C are common during winter where I observe). With these conditions, a premium 3in or 4in APO is out of question. The choice was pretty easy to make: I settled for a 4" Mak-Cass, which is cheap and compact. Quite frankly, those little maks are great for the money: collimation is very stable, and optical quality is usually adequate. If you really need wide field view, you can consider a 80mm f/5 or f/6 achromat which is equally cheap and good for this job but which I find lacking at higher magnification and would therefore make a fine addition to the Mak-Cass. A pair of binoculars could be another complement to the Mak.

#13 Oldfield

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Posted 18 August 2005 - 03:27 AM

Maksutov is portable in size and seems good grab and go, but it's rather long cool down time is making it not so suitable, they're long in focal length and it means intrinsically high power which requires thermal equilibrium to deliver performance.

#14 Topcat

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Posted 18 August 2005 - 06:48 AM

Another vote here for the short tube 80. I just bought one as a travel scope and I'm really impressed with the performance. Really nice wide field views. Easy to find objects. Light, works well on a decent camera tripod. I think it is a good value...$$$ to performance ratio.

#15 Harry Pulley

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Posted 18 August 2005 - 09:42 AM

My first scope was a 50mm f/12 refractor; how's that for quick? Believe it or not, you can see sunspots, a fair amount of detail on the Moon, the rings of Saturn and Titan, the main satellites and main cloud belts of Jupiter, the Andromeda Galaxy (as a smudge) and the Pleiades in such a small scope.

Later I borrowed a C90 for my quick grab and go scope on a camera tripod. It was OK but it had camera-lens helical focusing (twist the whole tube) which was annoying. I found the short tube hard to aim compared to a long refractor which you can "barrel sight". The current Meade maks have nice optics (when returned until you get a good one) but the mount is junk IMO with brass hardware placed into plastic which can be stripped VERY easily. I would avoid the cheap tabletop Meade Maks unless they have improved them a lot recently.

My grab and go scope for the past several years is an Omcon 308, which is an 80mm f/7 refractor with a single coated made-in-Japan doublet objective. I found the f/7 ratio to be a good compromise as f/5s aren't so great on the Moon and planets while f/9 and slower ratios make the tube waaaay too long for a small mount (just vibrates every time you breathe on it). With a 32mm Plössl eyepiece the 560mm focal length fits The Pleiades in with ease at 17x with a 3° true field, yet even being a cheap achromat ($300 CDN for OTA) it will do 140x or 224x on the Moon and Mars with 8mm and 5mm eyepieces barlowed 2x. It is NOT as good as a TV70 or TV85 for colour correction or high power sharpness but for the price I think it does very well.

The tube is 22" long with the focuser racked in and the dewcap off so it is quite portable. I can fit it into a small box along with a TV Upswing head and a Manfrotto tripod, 6x30mm finder and a bunch of eyepieces and filters; it backpacks and boats well (if I lose it, no big deal, cheap to replace compared to an 80mm apo). Weight is light, about 3lbs.

Only real drawback is the 1.25" focuser but that can be switched as the focuser assembly comes off (trouble is, most 2" 80mm refractor focuser assemblies cost most of what this whole scope did!). There is some colour on the Moon but a colour filter takes care of that.

With my 200mm f/9 Vixen CAT I use the Omcon as a deep mag finderscope and as a guidescope. With floppy mirrors, the small maks aren't the greatest guidescopes, so I prefer a refractor for that (my Vixen has a fixed primary). The Omcon's focuser has a lock knob which is great for guiding.

Harry

#16 Guest_**DONOTDELETE**_*

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Posted 18 August 2005 - 10:18 AM

These were all very good suggestions. I'm still between the ShortTube 80, Celestron 102 (achro) and a Mak 90mm. One problem I have along wiht the basic Grab'n'go problem is actually the tripod. I have no experience in this, and I know how a heavy equatorial mount can spoil the Grab'n'go experience. The problem is: the tripod.

I understand that if I go for higher focal lengths (like in the Mak 90), I'll need a way to control the beast. And using a regular photo tripod without an expensive gear head won't probably do, right? I was thinking about the AZ-3, it has slow motion controls. And anything over $200 or 10-12 pounds for a tripod would destroy the grab'n'go thing. Equatorials are out of question for me, because I'd like, if possible, to use this tripod for terrestrial observation/photography (not astro).

Do you people have any experiences to share about lightweight tripods? Slow motion controls are a must?

#17 Harry Pulley

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Posted 18 August 2005 - 10:33 AM

I agree that an EQ mount with counterweights, polar alignment, etc. kills the grab'n'go scope for both weight and setup time.

Personally I don't like alt-az slo-mo controls. Too much like an etch-a-sketch, the sky just doesn't move that way.

The tabletop Meade 90 mak I just poo-poo'd can be used either alt-az or equatorially by just putting it onto a tilt head or a little wedge. At least it doesn't have counterweights and sets up in little time. If only it used a little less plastic it could be good.

For a short focal length refractor I find the TeleVue UpSwing head works well, though it isn't cheap (I got mine used). No slow motion controls but a nice set of variable friction knobs to set of easily or hard it is to move the scope. I like this on a good Manfrotto tripod though the tripod that is sold along with the UpSwing (what's the whole thing called? Not the Gibraltar, a smaller one) is also good, though not cheap. The Manfrotto doubles as a standard tripod for star-trail shots too.

BTW, for terrestrial photography using a 1m focal length mak you will need a SERIOUS tripod, not a light one if you want to avoid blurr (mirror lockup might help). A short tube would work though.

Harry

#18 John Kocijanski

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Posted 18 August 2005 - 10:45 AM

I really love my XT4.5 for grab and go. It weighs only 17 lbs. and has a nice handle on the tube. It gives nice views. You would need to put it on top of something to bring it up to "adult height". I use a plastic lawn table. I have seen others with legs attached to the base.

#19 Guest_**DONOTDELETE**_*

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Posted 18 August 2005 - 10:56 AM

Harry, I can get sharp pictures on my Canon camera even on a very lightweigth (3lb) tripod if I use mirror lockup and a timer (assuming no wind :) ).

Is it realistic to control a 1m focal length scope with good 3-way heads with friction knobs? I know they work very well for cameras, but is it possible to point to follow stars (not implying astrophotography here) with this system? I'd expect it to be impossible, but I never tried it, so I can be totally wrong...

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Posted 18 August 2005 - 10:58 AM

I also have the Orion ST-80 and I really like it. (Its featured in my avatar after-all!) But though an amazing bang for the buck (and I would recommend every have one), it doesn't hold up on the moon and planets to other instruments out there in the budget range. So if this will feature large in your intended viewing, i would weigh in for the Mak or a longer focal length refractor. The Celestron 102 you mention might be perfect, though it will be considerablly larger and heavier than either of these other options. If you are set on the larger Mak for your "heavier"scope, then selecting a a slightly longer refractor might still serve as a companion scope and be suitable for the moon and planets.

Some other options which may stretch your budget a wee bit:
*Look for a TV Ranger on astromart. you can them for under $400 these days and they are much superior to the ST-80. I am amzed at how my Ranger works the moon, given its small aperture, fairly short f.l., and being a slightly enhanced achro.
*The new Orion express 80, for $400

Tripod Heads:

You can get a used Bogen head for reasonable price (but you will also need to put them on 3/8" threaded tripdos, like the Bogens.
The best ones for free scanning I think are the ones designed for video heads. They are designed for panning and thus allow you to lock in the alt and az movements separately. The 3130 heads are suitable for this...

http://www.buytelesc...ct.asp?pid=2689

I have this for my Ranger on a Bogen 3001 tripd and I think its great. I think this will also work for a Mak. Again, it depends on what you want to look at. The Bogen 410 head has slo mo controls which can be great for the higher fl instruments but these get more expensive and are heavier.

http://www.pictureli...duct.php?id=287

I see a future thread here:
A list oif suitable targets for light-polluted skies and small instruments!

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Posted 18 August 2005 - 11:09 AM


Personally I don't like alt-az slo-mo controls. Too much like an etch-a-sketch, the sky just doesn't move that way.


:roflmao:

I knew that motion reminded me of something!

#22 Patrick

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Posted 18 August 2005 - 01:14 PM

Do you people have any experiences to share about lightweight tripods? Slow motion controls are a must?



Hi Daniel,

You might want to look at the Helix Hercules Alt-Az Mount . This is a fairly lightweight mount with good motion control...not slow motion knobs, but controlled friction control. Put it on top of a Bogen tripod or surveyors tripod and you'll be set. You can also add digital setting circles (DSC) for object location.

Regards,

Patrick

#23 Guest_**DONOTDELETE**_*

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Posted 18 August 2005 - 01:36 PM

Thanks for all the help! The Helix Hercules looks top notch for telescope use, but it seems that the Bogen head (such as the 701RC2, which got very good reviews online) could have an edge for photographic use - and be good for telescopes at the same time. Since I want it for both photo and telescope use, I'll probably get a Bogen. I just hope a 7lb load (scope + accesories + camera) is not too much for it, it claims to take up to 9lbs. Adding it to the Celestron 102mm, I'll have 12lb total, which will be great as grab'n'go.

#24 Patrick

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Posted 18 August 2005 - 05:15 PM

Hi Daniel,

One of the problems you can run into with a photo tripod head and even a lightweight telescope occurs when the scope is pointing at the zenith and the tripod head has to carry all the weight of the scope perpendicular to the vertical axis of the tripod. Most light weight photo heads can't do it, resulting in creep or outright failure to hold the scope at all. What happens then is that the user tightens the friction knob so it won't move and then you've lost the ability to pan. I have a Bogen 3130 head on one of my tripods and it won't even hold my 20x80 binoculars without creeping.

There are fixes for this problem, however, such as building a sling to hold the scope off to the side of the head rather than on top of it. Sky and Telescope had an article recently illustrating how to build one.

Regards,

Patrick

#25 Guest_**DONOTDELETE**_*

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Posted 18 August 2005 - 06:04 PM

Patrick, that was very informative. I need something lightweight, since I want a sturdy tripod for my camera too. I heard that the AZ-3 suffer of similar problems, where you actually need to build a counterweight for the telescope - and the AZ-3 is heavy and it's not a Bogen...

In theory, the 701CR2 has a counterbalance spring and some other nice features for counterbalancing. But yeah, all this was designed for under 4lbs, and I can have a bad surprise look at zenith... Still thinking about it.


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