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Gibraltar Mount Questions

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#1 mikiek

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Posted 07 April 2009 - 10:19 AM

Have been considering getting this mount/tripod for my NP101. I have not been able to determine how the scope mounts to the head. It appears that the head was designed to accept the clamshell bracket that came with the scope. If so how does that attach? Does it screw into the head? Is there a quick release for it?

Here's another question. I currently piggyback the NP on my SCT. I have 2 rings on the NP - on each is attached a dovetail saddle (I think that's what they're called). On the SCT is a dovetail rail and I am able to slide the NP on to the rail. This has worked well as it is easy to install and I can keep the rings on the NP even when it's stored in the case. Does the Gibraltar mount have some way to mount a dovetail rail so that I can use the same system as I use with the SCT? I'm really hoping to avoid having to take the rings off when I use the NP on the Gibraltar.

#2 Jim7728

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Posted 07 April 2009 - 11:12 AM

mikiek

The clamshell attaches to the Gilbralter cradle from the bottom with 2 wing knob screws. A TeleVue/Viven dovetail adapter part #AVT-1011 can be bolted to the bottom of the clamshell and can be used on both Gilbralter mounts and ones that have a Vixen saddle. Don't know if that will work with your SCT, but here's a link to the part.

AVT-1011

#3 dtsmith

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Posted 08 April 2009 - 10:09 AM

My assumption is that there is a way to do it, but unfortunately I can't point you in the right direction. If you can easily keep the rings, it might be worth it. I was never entirely comfortable trying to get two relatively small bolts through their holes while balancing the scope at the same time. It just didn't seem like an elegant solution to mount a scope.

#4 Jim7728

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Posted 08 April 2009 - 08:31 PM

was never entirely comfortable trying to get two relatively small bolts through their holes while balancing the scope at the same time.



I found that keeping one stud(without the wing knob) in the clam shell ring helps with getting the ota set into the cradle more quickly, but agree a dovetail clamp system would be easier.

#5 HUsher

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Posted 09 April 2009 - 05:22 AM

I use mine with a WO Megrez 90, which doesn't have a clamshell and I was worried about attaching using just one screw. So I got a dovetail holder made which fixes to the two holes on the plate (cost me £50). I then just slide the dovetail in :) and it has the other advantage of being adjustable to ensure proper balance (which is critical to get the mount to work smoothly). The one thing to watch is the size and length of the dovetail retaining screw - it needs to be small and short otherwise it won't fit in the gap. But once we got that sorted it works great. :jump:

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#6 Eddgie

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Posted 09 April 2009 - 09:15 AM

A word of caution... And I know it will bruise the feelings of the other posters, but forums are for people to share experiences.

My own experience using a similar scope is that this mount is somewhat problematic when used with eyepieces like the ones you have (I own similar telescope AND eyepieces).

Th Gibralter is a beautiful mount. Truely. However, I found balance to be incredibly frustrating.

If you find yourself going from your 31mm Nagler to your 3 or 4mm eyepieces, or Nagler zoom (I constantly find myself swapping from superwide fields to high power in my TV 101), you will find that the balance changes SO dramatically that you will CONSTANTLY be fiddling with the altitude tension screw. Of all the Alt-az mounts I have owned, I actually found the Gibralter to be the POOREEST choice for this kind of usage.

After 2 weeks of the Gibralter, I had so many nose-dives when changing eyepieces that I couldn't stand it.

The problem of course is that to get the big eyepieces to balance, for low power sweeping, you have to mount the scope so that the balance point puts the front of the telescope pretty far foward of the center of balance as compared to when used with high powers. You will want it this way because that is your 35mm is your "Sweeping" eyepice, you will want the scope to flow in both axises.

And when you want to zoom in on a target, you will have to TIGHTEN the alt lock before you pull the heavy or the scope will nose dive. Of course then it won't want to BUDGE with the 3-6 zoom for minor movement to center your target. So you will have to LOOSEN the tension. screw..

Then you will want to move on to the next target. So now you have to TIGHTEN the tension screw...

And so on, and so on..

Think about this long and hard. Try to recall your typical viewing with the scope while piggybacked, and if you find that you DO follow this kind of pattern, I think you will find the Gibralter to be tedious to use.

It is a BEAUTIFUL mount, and if you use for example ALL 1.25" Televue Plossls, the Gibralter will be a lovely mount to use.

But having looked at your eyepieces, I think you will not find it so practical and will tire of it quickly.

Diskmounts cost a lot, but the reason so many NP 101 owners seem to like them is because they eliminate this kind of tedious fiddling.

Or, do what I did.. Pick up a used LXD55 for $275. All of that is eliminated and even if you don't use the Go-to, you still have motorized sweeping and NO worries about balance.. The penalty is that it weighs only a little more, but I can still carry out the mount in one trip and the scope in another. Setup time is less than 5 minutes.

Good luck if you get the Gibralter. They are BEAUTIFUL mounts, but not particularly pleasant to use when used in the fashion I mentioned above. If you are only going to use it for low power sweeping and don't change eyepices a lot between light and heavy, you may find it delightful.

Regards.

#7 dtsmith

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Posted 09 April 2009 - 04:02 PM

Yup, I found the same thing (having to regularly adjust the Alt knob when changing eyepieces), but it didn't bother me quite as much. It became second nature after a while. I ultimately went with the DM not because of the balence issue (although it definately is an improvement), but because of the vibrations when focusing at high power.

#8 Jim7728

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Posted 09 April 2009 - 05:20 PM

Whenever I go from heavy 2" eyepieces to light 1.25" , I tend to rebalance the TeleVue ota by slightly loosening the clam shell ring and sliding the ota up or down rather then relying solely on the tension knobs of the Telepod. The clamshell ring makes this a effortless procedure , imo. Your viewing styles may vary. ;)

#9 mes

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Posted 09 April 2009 - 06:48 PM

I found a relatively simple solution to the balancing problem that has worked well for me.

The first part of the solution was to invest in the Televue Brass adapter which allows for less of a difference in weight between my lightest and heaviest eyepieces.

The second part of the solution was to use the threaded hole in the mount that is normally used for the encoders to add a 3rd tension knob. Using this allows me to not have to tighten and untighten the supplied tension knobs - which I could never set correctly after adjusting.

I posted some pictures of the how I added this knob on the thread titled 'Riser for TeleVue Gibraltar'...which is currently on page 3 of this forum.

web page

#10 7331Peg

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Posted 10 April 2009 - 01:23 AM

I fought that balance issue for over a year with my TV102 and finally gave up. It was very frustrating. I really wish Televue would make the Gibraltar head with larger bearings - it would make it a much more attractive mount for the longer and heavier scopes. The fluid motion makes it a joy to use with a lighter scope and 1 1/4" eyepieces, but the balance frustrations and sudden nose-dives with 102 were just too much. The DM-6 eliminated all that.

John

#11 mikiek

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Posted 17 April 2009 - 09:44 PM

Wow - you guys got me scared now! I didn't realize rebalancing was going to be such a big deal. I typically switch between a Pan 27, 13 Ethos and 8 Ethos. Don't know the exact stats but I think weight is fairly similar. But I sure don't want to have to mess with adjustments like loosening a clamshell or having to remember to lock the Alt tension just to change an EP.

Is the Discmount the only option for a system that I don't have to be continuously fiddling with?

#12 Joe H

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Posted 17 April 2009 - 11:58 PM

Universal Astronomics Unistar (heavy version) is a nice mount and will easily handle the 101 while changing eyepieces.

#13 7331Peg

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Posted 18 April 2009 - 02:43 AM

A less expensive option is the Tak Lapides Teegul - about $525 at OPT. I picked one up a few months ago and I love it. Need to put it on a good tripod, though. I have it on a TV Gibraltar and it works great on 80 and 90mm scopes. The TV102 will work on it, but there is a significant amount of vibration when trying to focus because the mount uses a saddle plate that attaches at a 90 degree angle to the tripod, and the Gibraltar wasn't designed for that. After you balance the scope and lock the clutches, the slow motion controls are a pleasure to use. But if you have significant differences in eyepiece weights - such as a 31mm Nagler and a T6 Nagler - you'll have to re-balance to get the vertical slow motion to work properly.

#14 mikiek

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Posted 18 April 2009 - 05:58 PM

OK - well now I'm a little confused. Bare with me, it's the first I've thought about my refractor on it's own tripod.

I've been hearing 2 complaints about the Gibraltar system.

1. Balance issues when changing EPs.
2. Jiggles when focusing or slewing.

#1 I'm assuming is a mount (head) issue. Yes? Would the larger Gibraltar head (for the NP127) help at all?

#2 I would think is more of a tripod issue? I thought the Gibraltar tripod was supposed to be fairly sturdy.

#15 7331Peg

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Posted 19 April 2009 - 03:47 AM

Mikeiek,
You're right - number one is a mount head issue. From my perspective, the bearings on the Gibraltar head are just not large enough for a scope with the weight and length of a TV102. I know people who have used shorter scopes on it, such as the TV85, and they have far less problems. I had an SV90 on it at one point, and it worked much better, although there was still vibration while focusing. I haven't used the head designed for the 127, so I'll leave that to those who have.
With regard to number two, I never experienced a problem with jiggling while moving the scope. But focusing the TV102 was always a problem, and again the length of the scope had a lot to do with it. In order to hold its position, I would have to tighten down both bearings, which causes almost a tuning fork type of vibration between the scope and the mount head when focusing at higher powers.
The Gibraltar tripod is fine. The Teegul mount throws the weight of the scope away from the center of the tripod, so I get some vibration as a result. The Gibraltar tripod was designed for mounting a scope directly over the center of the tripod, not for side mounting. Hope that helps.

John

#16 Eddgie

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Posted 19 April 2009 - 07:02 AM

To be fair, the balance issue is NOT limited by ANY means to the Gibralter. I have tried several Alt-az mounts and found a similar problem with all of them. That problem being the issues around balance and changing from heaviest eyepieces to ligtest eyepieces.

ALL of them have worked fairly well when using light eyepieces of similar weight.

Most have NOT been good when used with eyepieces like 35mm Pan then jumping to a 5mm Radian. For all of them, I felt like I was always dorking around with the tension screws. First having tighten when changing from heavy/light eyepieces to keep from having a nose dive, then having to tweak the tension to get smooth motion AFTER the eyepiece was in. The tension that works for a Nagler zoom is MUCH different from the tension that works with a 31mm Nagler for slight altitude changes.

Personally, I tried maybe 5 Alt-az mounts and experienced the same thing with all of them, but the Gibralter was the worst.

I never made the leap to the Diskmount or the Half-hitch, but to me if you HAVE to have an Alt Az, these would be the top choices, and of these, my own preference would be the Half Hitch. These guys have THE alt-az mount solution in my own opinion. They have given a very thorough look at the shortcomings of the Alt Az design and to my mind, have perfected it (but that is because I like slow motion and Diskmount does not provide this).

BUT.. I didn't BUY one.. By the time you configure it on a tripod and add Encoders and a DSC computer, you will have let go of some serious money. AND... It won't be that much lighter than my own recommendation.


I use an old Meade LXD55 mount on a pair of Vixen HAL 110 legs. This setup weighs only a bit more than one of these other mounts, offers ELECTRONIC slow motion control for sweeping and panning, have BUILT IN digital setting circles, and you never ever ever need to touch a clutch for changing eyepieces. And wait, wait, this news JUST OFF THE PRESSES - AND you get HIGH POWER TRACKING MOTORS built in FREE

The problem with the LXD 75 and new CG5 is that the tripods are overkill for a 4" refractor.

So, you can spend FAR more money on a top of the line Alt-ax mount and get an acceptable alt-az mount, then throw $400 more on it and get electronics, or you can pay $275 for a used LXD-55 that weights maybe 7 lbs more. For either the Diskmount or the Half-hitch, my bet is that you are looking at a two trip setup, and I do that with my LXD55/TV 101 all the time. Takes 2 minutes longer to set up. (4 or 5 if I actually want to do an true alignment so I can get Go-to).

A really superb Alt-az IS a great tool, But to get a really superb Alt-az ain't cheep, and you STILL won't get the advantage of a tracking motor for high power work.

Good luck with your decision. Consider it carefully though. Most people that use them will tell you they love their Diskmounts or Half-hitch mounts, and I believe them.

I will tell you that I never met an Alt-az mount that I liked (unless it was Go-to).

Once again, the classis Cloudy-Nights two-camp battle-lines are drawn.. LOL.

#17 7331Peg

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Posted 19 April 2009 - 01:46 PM

I agree completely with Eddgie - if you want vibration-less focusing at high power on an alt-az mount, you're going to have to go for the Disc Mount set up. Probably also true with regard to the Half Hitch, but I've spent enough money on alt-az mounts that I stopped before getting to the Half Hitch. Would love to try it, though. But with regard to the DM-6, I am always amazed that I can track a planet at 250x and adjust focus with NO vibration - and I'm observing from a wood deck fifteen feet off the ground. The DM-6 is on their tripod, and that makes a huge difference also.
Best advice is to attend a star party somewhere and try out the various alt-az mounts to see what works for you - and save yourself a lot of time, money, and aggravation!

John






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