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TV102 on Half Hitch smoothness Youtube video link

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#26 Denimsky

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Posted 09 May 2009 - 11:43 AM

The Half Hitch mount is very different from other mounts than I use. The beauty of the mount is that I don't have to put almost no tension to each axis. As the result, the mounts operates super smoothly yet the mount is balance regardless the direction that my scope is pointing. I've never had this kind of experience before. Usually, if I balance the scope horizontally, the scope starts being unbalanced pointing toward zenith. To overcome this, I needed to tighten up the altitude axis with other mounts. You don't have to do it with the Half Hitch mount.

The disc break on the altitude axis can hold the eyepiece change without any image shift.

The emphasis on the Half Hitch mount is smoothest motion while being balanced. So, I think that you need to use the TV Equalizer to go from your heavy eyepieces to Ortho eyepieces. Intermediate eyepiece weight difference can be covered by the included balance trimmer.

I heard that Charles will make a new optional heavy duty balance trimmer weight. That will help your situation if you don't want to use the TV Equalizer.

#27 Scott99

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Posted 09 May 2009 - 01:39 PM

Most of my eyepieces are fairly similar in weight, I'm not that worried about the tube being unbalanced during observing. If the 35mm Panoptic is a problem I have some 2-inch Plossls that are much lighter. I'm just trying to figure out exactly what happens during the process of changing eyepieces.

I change eyepieces too often to use a balance trimmer, for me it needs to be simple.

Do you set the disc brake on the altitude axis once and leave it on, or do you engage it before you take an eyepiece out? Does everyone that use a larger/longer refractor (say 102mm f/8 or bigger) have to use the balance trimmer, or is it feasible to go without it if you can use eyepieces that are similar in weight?

I guess that's what it comes down to. To change eyepieces during a star-hopping observing session how many adjustments have to be made to the mount, including brakes, any tension adjustment, and balance trimming. The available information is somewhat confusing.

It sounds like the mount's motions and slow motion controls are extremely smooth. But it comes at the price of having to use a brake to change eyepieces, yes? And possibly adjust a balance trimmer every time for some eyepieces.

With the Teegul you can find a happy medium where the tension on the altitude axis is enough to keep the scope in place during eyepiece changes, yet still loose enough to move the scope around by hand and use slo-mo controls.

However, it sounds like the halfhitch's motion is smoother and easier. And the slo-mo controls on the Teegul are somewhat stiff & clunky in feel.



#28 Denimsky

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Posted 09 May 2009 - 02:08 PM

Scott,
I need to engage the break to change eyepieces, but the break is much better compare to tension mechanism on other Alt-Az mount. There is no image shifts so I don't find it is cumbersome to use the break to change eyepieces. Again, the mount operates with almost no friction so I don't think that it is possible to change eyepieces without engaging the break.

I'm using the mount for TSA-102(102 mm f/8) and TMB105 (105mm f6.5).

I don't have to use the balance trimmer between my Pentax XL 40mm, Pentax XW 20mm and Pentax XW 7mm. I don't have any other similar weight eyepiecs so I'm not sure how the mount will act with a little more weight differences, but then you can use the balance trimmer in that case. The balance trimmer have few small dot marks so that you can easily know where you need to put the trimmer to balance the scope.

For big weight differences (Pentax XW and Ortho or Plossl), I need to use TV Equalizer adapter.

The break also works as the tension adjustment. With putting small amount of friction, the mount can handle more weight differences without using the balance trimmer, but I don't adjust the tension at all. I just use the mount without putting any tension.

#29 Mike Sandy

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Posted 09 May 2009 - 03:03 PM

For any mount you would ever use, it seems to me like you have a choice - either have enough drag in the Alt axis to hold still with an unbalanced load applied (drag that you have to overcome to move the mount), or have silky smooth and delightfully light motions with little or no drag (can you spot my bias?). To do that, you have to have the ability to quickly rebalance the system when you change the balance point. The Half Hitch falls into the latter line of thinking.

To change a eyepiece you take a turn or two on the disc brake adjuster and the scope is essentially locked. Change the eyepiece and release the brake, then use the trim weight to reset the balance point. The process is simple and quick, adding two or three simple steps.....but they are added steps. You do have to think a bit and try to reduce the weight differences if possible (see the TV Equalizer here). The return for this small addition work (work that is required only when you make a eyepiece change that involves a significant weight difference) is a mount that is so smooth and drag free that it really does just get out of the way and let you view - and it does that the entire time you are viewing. If you boost the magnification for some planetary viewing - the slow motion controls will make it easy to keep the object centered.....if you don't use quality slow motion controls - you are missing something special.

I really like the Half Hitch.....any scope up to 4" would do fine and many larger scopes would as well. I haven't tried a DiscMount....I've heard they are great especially for the bigger loads, but if your scope fit the Half Hitch - it is the mount that sets the standard.....for now.

#30 billyo

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Posted 09 May 2009 - 03:12 PM

DH,

Interesting report on the Half Hitch.

When you use the brake to set a certain tension will the tension (that you set by the brake)remain the same as the mount is moved?

Thanks.

#31 Denimsky

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Posted 09 May 2009 - 03:30 PM

I set only slight amount of tension and I don't feel the tension that much while I'm moving the scope or using the motion control.

#32 Mike Sandy

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Posted 09 May 2009 - 03:36 PM

DH,

Interesting report on the Half Hitch.

When you use the brake to set a certain tension will the tension (that you set by the brake)remain the same as the mount is moved?

Thanks.


In a word.....Yes. If you add drag with the disc brake, there will be drag in the system, so you do have that option. I try to completely release the disc brake so there is the absolute minimum drag in the system. Even with things set this way there is a fair amount of tolerance for weight changes. I switch between Tak LE's (but I use the equalizer) and an Ethos and there is not much rebalancing needed. Eyepieces changes between different LE's don't require any action to rebalance the mount.

#33 CESDewar

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Posted 09 May 2009 - 08:14 PM

I watched the video but it doesn't tell me much - I certainly have at least that same degree of freedom with my Tak Lapides-Teegul mount.

I would be very interested in seeing comments from someone who has used both the Half-hitch and the Teegul. Certainly, the tensioners on the Teegul are nice - I can use a scope even when it's quite out of balance without a problem - something I'm not sure I could do with the Half-Hitch as I see frequent references as to the need to get the scope well-balanced.

I do like the orientation of the half-hitch - I was thinking at one time of having a machined arm to allow the Teegul mount to have the same benefit (upwards extension and offset so the mount would be centralized over the tripod), but the scopes I use are all short and the offset is not a problem in viewing at the Zenith with any of them.

#34 Bart

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Posted 09 May 2009 - 09:19 PM

Wow! After seeing the video and how smooth that mount is, I’ve been inspired to get to work and SuperLube my SVP.

#35 Quintessence

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Posted 10 May 2009 - 01:52 AM

Ignoring references to specific mounts, let's compare the physics of keeping a scope pointed by using friction to overcome imbalance versus balancing the load. The two are not equivalent.

Using friction to overcome imbalance has three UNAVOIDABLE consequences: 1.) The torque required to START the altitude axis turning will be greater than the torque needed to KEEP the axis turning; 2.) The torque required to turn the axis in one direction will not equal the torque needed to turn the axis in the opposite direction because one direction works with gravity and the other direction works against gravity; and 3.) The torque required to turn the axis in each direction will vary with elevation. Effect number one can be partially mitigated by carefully choosing the materials in the friction sandwich, but the other two effects have no mitigations. The UNAVOIDABLE result is that the tradeoff for not having to balance the load is movement that is asymmetric, nonlinear, and too complex to be truly predictable and intuitive.

For a low-friction axis, the load must be more or less balanced. There is always a little friction, so the balance does not have to be perfect. But a lower the level of friction will require better balance. This is the downside of a low-friction axis -- it requires balance. But this is a downside that has several effective (and potentially complete) mitigations. First, if you don't change eyepieces during the course of an observing session, then there aren't any balance shifts. Second, balance shifts can be minimized by keeping the physical sizes and weights of your eyepieces similar. Third, you can add features to the mount (or scope) that make it EASY to neutralize the balance shifts caused by switching eyepieces. And fourth, you can create a mechanism to add in small amounts of friction to adjust the sensitivity of the balance requirement.

The upside of the balanced, low-friction approach is that you have maximally optimized motion control and "feel." By trading easily managed balance adjustments, you get sports car like feel as opposed to truck like feel. You get a system that is symmetric, linear, and predictable.

There is not a correct answer to the balance versus friction argument. One must choose based on personal preference. But the physics is what it is -- all marketing claims aside. The high friction/no balance approach and the low friction/balanced approach are distinctly different. One does not really substitute for the other in the same way that a truck does not substitute for a sports car. The missions are different. It does not surprise me that each type of mount has its advocates.

One thing that the video does effectively demonstrate about the Half Hitch is that the balance does not shift with elevation changes.

Charles

#36 Doug D.

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Posted 10 May 2009 - 08:57 AM

I would be very interested in seeing comments from someone who has used both the Half-hitch and the Teegul. Certainly, the tensioners on the Teegul are nice - I can use a scope even when it's quite out of balance without a problem - something I'm not sure I could do with the Half-Hitch as I see frequent references as to the need to get the scope well-balanced.


I have owned a Lapides Modified Teegul (with after market 6" slo-mo knobs) and a DM-6 and have tried them with multiple scopes. My best short answer is this: I still own a Half-Hitch II but the Teegul and DM-6 are now sold.

I've posted about this a few times in past so I'll just point out a couple things again. All 3 mounts are excellent and each has its "exceptional" qualities. Without question, none operate as smoothly as the HH and the "motion" knobs (they aren't really "slo-mo") are superb: responsive, completely backlash-free, and great for high mag tracking of solar system objects. Factor in the weight, highly accurate DSC's and rigidity and you have an unbeatable grab and go package, which is clearly what Charles had set out to accomplish when he designed it (and he is still tinkering and tweaking the design).

The Teegul is an interesting mount. I really liked mine a lot (by the way, my reference OTA for this Teegul and HH comparison is a 105 Traveler with Mark V BV). It was also "smooth" (all 3 of these mounts are) and surprisingly easy to balance (depending on saddle plate/saddle used). The stock slo-mo knobs are poorly positioned IMO (and plastic!!) but when extended with 6" aluminum knobs they were a delight to use. It was also easy to track at high mags with these controls and although they do have some "backlash", this doesn't really diminish their utility. The tightening/tensioning screws were surprisingly effective and helped a lot with eyepiece changes and other balance issues. It is hard to argue with this mount as being anything other than a solid, utilitarian performer - perhaps the pick of the 3 if budget is most important. If you want DSC's, however, I think your options are limited with the Teegul unlike the HH and DM-4/6, which were clearly designed with DSCs in mind.

The DM-6 is a triumph of clean, "simple" and solid design. If it is heavy artillery you want to mount on an Alt/Az, this may be what you are looking for. I used this mount with an NP101 (with one of Tom P's excellent tripods), TOA 130 and an AP 140. The Tak and AP are both beasts and while the DM-6 was up to the task you really require a serious set of legs or pier. I used it with a Berlebach UNI24 but the big OTAs really needed more - probably a G11 tripod or Berlebach Planet for example. I wasn't happy with all that weight off to the side with the big scopes but the NP101 worked beautifully with the DM-6. All that you hear about the DM-6 is pretty much true. When balanced up correctly it is smooth, jiggle free and accurate (i.e., DSCs). The orthogonality of this mount is the key I guess, it is like the rock of Gibraltar. Stiction is minimal as it should be, and you can swap out a little planetary EP with a Volkswagen and I think it would hold steady - ok, I'm exaggerating, perhaps something a little lighter like a Nag 31. On the downside, the DM-6 is bowling ball heavy and it lacks slo-mo controls (and I know the argument that it doesn't need them - but I personally like them). To be fair, the DM-4 is probably the mount for comparison to the Teegul and HH (weight complaint goes away) but it still lacks slo-mo and puts the scope off to the side (the Teegul does too but it is narrower and on a 6" platform it is less of a concern). I wasn't thrilled with selling the DM-6 but at the end of the day my reasoning went as follows: if I'm going to drag out the AP 140 for visual and have to lug out the DM-6 and a G11 quality tripod to do so, I might as well use my GEM instead. No way is an ~ AP140 or TOA 130 ever going to be a grab and go, LOL.

You aren't going to be making an egregious error going with any of these 3 mounts. On balance though, I just like the design philosophy, build and especially the smoothness/performance of the HH II with my particular set-up. Your mileage may/will vary. In any event, the HH comes with clear instructions for set-up and set-up is pretty easy but you gotta set it up right for it to perform like a dream.

And as I always like to point out when discussing quality mounts, the tripod is a critical but often underemphasized requirement for high performance. My advice - simply don't skimp on a set of legs. Personally, I think ~$500 (new) is the "entry level" cost of a quality tripod for these mounts. I may get grief for saying this but I have tried a lot of tripods as well and when it comes to wood - Berlebach and AP/Baader set the standard IMO; and for CF - Gitzo 3 or 5 series. :waytogo:

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#37 Doug D.

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Posted 10 May 2009 - 09:11 AM

The problem with being a "windbag" is that I tend to go off on tangents - I realize I didn't really address your question directly CESD....!

I'd say both the HH and Teegul are comparable in terms of effects on balance upon swapping accessories (EPs) with big weight differences. After all, they both work best when the OTA is very well balanced. I'm pretty much a BV user nowadays and the biggest swap for me is to go from a pair of Pan 24s to ZAOII's. The balance weight on the HH more than compensates for this difference.

Bear in mind though that while the HH may not be as tolerant of "imbalance" as the Teegul with tensioners (and the DM-6 especially), tensioning/drag on the bearing surfaces will always give you a "performance" hit whether you are talking about "stiction", friction or smoothness. The HH needs to be set up properly but set-up is easy and well worth it for the performance out the other end - at least it works for me. It would be tough for me to now go back to any other Alt/Az I suspect.

I see Charles has provided a much better explanation of the balance-friction issues than my meanderings allowed. He is the designer of the HH but I'm a user so I can at least vouch for what he is saying in terms of real world use.

Perhaps I should put it this way, I'm willing to give up a little in terms of tolerance for imbalance in order to obtain an unparalleled level of smoothness and balance along the range of the Alt axis (the latter is quite an accomplishment in my view).

#38 Waduino

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Posted 10 May 2009 - 12:03 PM

Doug. Thanks for the effort in that response. I've been wondering about these 3 mounts for a while and sharing your experiences is invaluable.
BTW, the Traveller, bino-viewer, Half-Hitch is a work of art.
Wad.

#39 Doug D.

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Posted 10 May 2009 - 06:59 PM

Thanks Wad - hope it helps.

#40 CESDewar

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Posted 10 May 2009 - 09:39 PM

Yes - thanks for your comments - it's very helpful to hear from someone who has actually used all of the mounts in question. I have the Teegul for my smaller scopes, and a DM-6 which I use with my NP-127, although I am going to try the NP-127 on the Teegul just for interest to see whether it works (my fully loaded SCT8 at 21lbs actually works reasonbly well on the Teegul, so the somewhat lighter NP-127 in spite of the greater moment might be ok at a pinch in no wind).

I do like slow motion controls for tracking at high power - the DM6 is smooth and very nice, but for me just not nearly as easy to track at high power, but then again it's probably because I crank up the tension enough to cover switching between a 2-4Nagler zoom and a 26T5. Personally, I find the idea of employing a brake when changing EP's to be fine rather than compromising the motion by cranking up the general tension.

I'm hoping at some point to see the HH in person and try it out - it certainly sounds like a fine mount!

#41 7331Peg

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Posted 11 May 2009 - 01:42 AM

Doug,
I wouldn't worry about the "windbag" post. I've got both the DM-6 and the Lapides Teegul, and you've described both of them very accurately and very fairly as well. For anyone wanting to make a choice between the three mounts, your description is MUST reading in my opinion. I'm itching to get my hands on a Half Hitch sometime soon.

John

#42 Doug D.

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Posted 11 May 2009 - 07:07 AM

Thanks for the kind words John.

#43 Scott99

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Posted 11 May 2009 - 05:05 PM

thanks very much everyone for the excellent user info. Even got the dm6/dm4 added in there!






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