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A/A for a TV 102

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#1 noah way

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Posted 28 January 2010 - 11:46 PM

I have a TV 102 on the way, and am considering Alt/Az mounting options for it. I have a Vixen Porta, which was fairly solid with a 7.5lb 80mm F6. It settled down quickly at moderate power.

With the longer, heavier OTA and higher mags that the 102 is capable of, I'm doubting the ability of the Vixen to do the job. A wood tripod would probably help quite a bit. I've also got a line on a Teegul Lapides, and was hoping some more experienced AstroNuts could keep me from seemingly endless rounds of trial and error ...

#2 Lt 26

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Posted 29 January 2010 - 01:13 AM

Noah way, I use TV Ash Gib5 with good results. It is sturdy and does not cost a ton like some. The Ash wood is one pound heavier than the Walnut and the Gib5 has larger brass Alt bearings. Total weight 21 pounds but the 102 needs something to keep it planted. If you use the TV clamshell it will take all of 7 seconds to mount plus you don't have to hold the scope, just steady it. The Gib5 has a wider fork so a little more room to set the scope in, I would not want it tighter. I only extend the legs halfway use VSP on hard surfaces and spikes in the grass. Yes it will get very close to zenith.

Sorry I am not very experienced yet but I am working on the Astronut part. Now I will get out of the way while the experienced Astronuts fly in with better if not more expensive advise. Have fun with your new TV 102.

Dereck

#3 7331Peg

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Posted 29 January 2010 - 02:42 AM

Looks like you've already realized that the length and weight of the TV102 is going to be an issue, which is half the battle.
I have not tried it on the Gibraltar 5, but my experience with it on the smaller Gibraltar mount was very frustrating - both from the standpoint of trying to keep it balanced as well as eyepiece vibration when focusing. Length and weight were the main causes of the problems.
I also tried it on a Teegul, and while balance wasn't a problem, vibration while focusing was (and that was using a set of TV rings, not the clamshell, and a Losmandy style dovetail) - and again, it was due to the length of the scope. A few people have modified the Teegul by putting a counterweight on the side opposite the saddle, which would probably take care of most of the vibration issue. In fact, there was one of those for sale on Amart a few weeks ago.
What I have found is that the TV102 works great on both the DM6 and the largest Stellarvue mount - the M7 - and also on the MG5, in both cases on the Stellarvue tripods.
Another option would be a Giro type mount, but you'll need a good solid tripod, and you'll have to watch the balance carefully or the scope will get away from you.
No inexpensive solutions here.

John

#4 noah way

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Posted 29 January 2010 - 10:06 AM

Slow motion controls are a requirement, so TV mounts are out.

#5 Eddgie

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Posted 29 January 2010 - 10:29 AM

Your requirement for Slow Motion makes the selection more difficult. There are very few Alt Ax mounts with slow motion.

Half Hitch comes to mind. While very expensive, if I were going to purchase an Alt-Az mount (which I won't do again), it would be a Half Hitch I think.

Sadly, when I went to their web site, it seems like they only sell complete packages with encoders and DSC computers. When they first started selling mounts, the price for JUST the mount was about $800. If I were FORCED to buy the complete package, I might go to something like the Minitower instead.

And maybe you should too... LOL.

#6 swsantos

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Posted 29 January 2010 - 11:48 AM

I use the TV102 on a Half Hitch II with the encoders and it works very well. The encoders are great and if you find it affordable its a great choice. He also has the "quarter hitch" which is less expensive and has no encoders. My understanding is that the quarter hitch is equally up to the task and that it is the encoders only that it lacks so it might be what you are looking for. If you go to halfhitchtelescope.com you will see some pictures of the mount holding various scopes, some of them TV102's. Mine is the one with the picture of Captain Kirk in the background.

#7 noah way

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Posted 29 January 2010 - 12:16 PM

Someone could try to talk me out of slow motion controls, but from what I've read they are one of the drawbacks to TV mounts, the other being viewing at zenith.

#8 GShaffer

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Posted 29 January 2010 - 12:41 PM

If slow motion controls are a must.....you might consider one of the old vixen polaris or super polaris mounts. They are designed to be used in Alt-Az mode giving you the ability to have either Alt-Az or EQ mount.

#9 Eddgie

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Posted 29 January 2010 - 03:49 PM

I have to tell you, I personally would never own another Alt-Az mount without slow motion controls.

The main reason I like slow motion controls is not JUST for the "Slow Motion" but rather becuase the axises both lock into place. This makes it possible to simply mount the telescope and not worry about balance when changing from eyepieces like 31mm Nagler to a 5mm Nagler (which used to be a pretty common swap in my Televue 101). There is never any messing with tension clutches and never any worry about a bad noze dive. And changing eyepieces at high power is painless with a GEM

I know that some of the more expensive mounts can handle a swap like this (Discmount) but at a very steep price.

After messing with a bunch of Alt-az mounts, I finally just decided that a GEM mount really wasn't that much more trouble. A mount like a Vixen GP weighs only a little more than a stable Alt-Az and you don't have to worry about balance. And you really don't have to Polar align them. Even if you just set the latitude scale once and point the mount approximatly north, you still get all of the major benefits of a GEM.

Oh, and of course, you can throw a battery powered motor on it and have TRACKING! LOL.. I like tracking.

I get the appeal of Alt-az, but to me, a lightweight GEM simply did not seem like any more trouble, and then I got slow motion controls in both axises AND a motor if I wanted one. And for half the price of a really top quality Alt-Az. And with the high power capability of the Televue 101 (and of course your TV 102), you may find that tracking is quite desirable.

I also like the more methodical sweeping of the GEM. rather than move at diagonals to right ascencion and declination, you are always moving celestial North, South, East, and West. This is extremly useful if you are doing a coordinated search or sweep, and makes star hopping using charts much easier.

I know people love Alt-az, but if you want slow motion, a used Vixen GP is an elegant, light weight alternative that offers a lot of benefits. I was far happier using my Televue 101 on a Vixen GP than I was on any Alt-Az mount I tried.

Start checking the weight of some of the better Alt-Az mounts with Tripod and what you will find out is that the Vixen (or older CG5 with Aluminum legs) simply does not weigh that much more.

The key question to ask is this:

Will I carry the mount out with the telescope on it? If the answer is "Yes" then every ounce might matter.

If the answer is "no" and you see yourself taking two trips, it is EXACTLY as fast and ALMOST just as easy to go in and grab a Vixen GP. The entire mount WITH counterweigt for a TV 102 is just not that much heavier than a high quality Alt-az mount. The entire mount with small counterweight simply doesn't weigh that much.


I personally was far happier with my TV 101 on a Vixen GP than I was with any of the Alt-az mounts I tried. But then I was not as happy with that as I was with Go-to, but I would choose a Vixen GP over any Alt-Az mount made.

Good luck with your decision, but the Quarter Hitch or Half Hitch looks to me like the best Alt-Az solution. IF I were to do another one, I would get one of these in a heartbeat. I could NOT live without slow motion and will never fight the balance battle vs. easy movement battle again.

Good luck with your decision. It is a difficult one for sure.

#10 JoshH

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Posted 30 January 2010 - 03:30 PM

I've used a TV 102 on my Alt-Az setup, which is a Unistar Deluxe on a Meade Field Tripod. All I can say is it was just fantastic; the mount completely gets out of the way. As long as you level the tripod, and balance the scope in the Alt motion, it works really really well, and I never had a problem when changing out heavy eyepieces. This mount does not have slow motion controls, but I didn't find the need for them. Viewing at Zenith is more comfortable seated with the length of the 102; to avoid this you would need a really tall tripod. For the money you can't beat the Unistar IMHO.






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