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Alt-Az Mount for a Tak TOA130

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#1 Mauikj

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Posted 30 May 2013 - 07:05 PM

Hello Everyone,

I've been trying to decide between a DM6 and a T-Rex mount for my Takahashi TOA 130. I couldn't decide between those two but was leaning towards the DM6 on a berlebach planet tripod. Then I just noticed a review for the new Nova Hitch mount. I like the design and that it will get tracking in the future. Also, I have heard that the DM6 and T-Rex have some balance issues when pointed towards the zenith, and the Nova Hitch does not. And with the weight of a TOA130 (and very front heavy with the triplet lens) I was concerned with balance. Does anyone have any thoughts or feedback about these mounts? I know they all have great reputations but as it will be a pretty big investment I want to get the one that will work best for me. I really just want it to use to scan the sky in the most effortless way possible. I am hoping for some feedback from people who own or have used one of them - unfortunately I don't think anyone near where I live (Maui- Hawaii) has one so I'll have to make a choice without ever trying one out.

Thanks in advance for any input.

KJ

#2 crazyqban

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Posted 30 May 2013 - 07:50 PM

I had a TOA-130F on a DM6 with a Losmandy G-11 tripod and it was a super stable and smooth setup. I really enjoyed it and miss it till this day. The G-11 tripod was mega quick and easy to setup. From the trunk of my car to set-up and ready to observe was about 2 minutes!!! I don't have any experience with a T-Rex so I cannot comment on that. Also, I have a Nova Hitch coming soon but I haven't used it yet so I can't comment on that either. I decided to go with the Nova Hitch because of the tracking feature. Once I receive it, I will be able to comment on it. I would hold off until there are some tracking Nova Hitches out and about in the field in the next month or two before making a decision. Then there should be some Nova users that are mounting a TOA-130 on it.

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#3 Mauikj

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Posted 30 May 2013 - 10:29 PM

Thanks Sergio,

Maybe I'll consider the G11. I can't wait to hear what you think of the Nova Hitch, seeing as you had a DM6 you could compare them. That is a great set up with the TOA 130 on it. Again, thanks for your feedback it is really helpful. I I just need enough restraint to wait for the Nova Hitch reviews to come in (with tracking).

#4 crazyqban

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Posted 30 May 2013 - 11:01 PM

Yeah, it ain't easy but I feel that the tracking feature is a game changer.

#5 prichardson

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Posted 30 May 2013 - 11:15 PM

Series of Nova Hitch pictures and commentary here:

http://www.chesmontastro.org/node/9915

#6 Tamiji Homma

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Posted 31 May 2013 - 01:08 AM

Hi KJ,

I use DM-6, T-REX, and Half Hitch mounts with various scopes/binoculars and tripods.

From left to right, TSA-102S/Super Half Hitch, APM 100ED f/5 binoculars on HH, and Kowa Highlander 82mm f/5.5 binoculars on HH:
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TMB 130SS f/7 on HH/Losmandy HD tripod:
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William Optics FLT 152 f/8 on DM-6/Losmandy FHD tripod:
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Intes MN-86 f/6 on DM-6/Losmandy FHD tripod, this is my heaviest load, close to 50lb with binoviewer:
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WO FLT 152 f/8 on T-REX/Berlebach Planet:
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TMB 130SS f/7 on T-REX/Binoscope Tall Tripod:
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Pentax 100 SDUF f/4 on T-REX/Berlebach Planet:
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Here is my take on Alt/Az mount:
1. Tracking is nice for only high power.
2. Tracking is not necessary for scanning skies (wide TFOV)
3. DM-6/FHD takes most load and solid among three mounts.
4. There is very little difference between DM-6 and T-REX with 6" f/8 refractor or smaller.
5. Half Hitch is my choice if portability is priority.

I use Half Hitch most with Kowa Highlander binoculars and T-REX with Pentax 100 SDUF II/TSA-102S almost everyday.

Looking at Prichardson's APM 180 f/6 on NH, it does look very good :)

Tammy

#7 Mauikj

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Posted 31 May 2013 - 02:16 AM

Aloha Tammy,

Wow that is quite a collection you have - beautiful set ups. Thanks for sharing and all the tips and photos. Do you think the DM6 or the T-rex have any balance problems when moving towards the zenith? It seems the Nova Hitch would have less issues, but again I've never tried them. Also, do you think the slow motion controls are useful (DM 6 doesn't have them). Again, thanks for all your very helpful advice

#8 crazyqban

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Posted 31 May 2013 - 03:38 AM

Series of Nova Hitch pictures and commentary here:

http://www.chesmontastro.org/node/9915


Thanks :)

#9 Kunama

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Posted 31 May 2013 - 05:59 AM

I don't think you can go wrong with any of the 3 options above. I went with the T-Rex fitted with the Robin Casady Saddle and Dovetail for my TSA120.
With the clutches set 'just right' it has the smoothest action and then for high mag you can use the slo-mo controls.

#10 Tamiji Homma

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Posted 31 May 2013 - 12:36 PM

Do you think the DM6 or the T-rex have any balance problems when moving towards the zenith? It seems the Nova Hitch would have less issues, but again I've never tried them. Also, do you think the slow motion controls are useful (DM 6 doesn't have them). Again, thanks for all your very helpful advice


Hi KJ,

I don't think DM-6/T-REX are particularly more vulnerable pointing to zenith than Half Hitch. In general, pointing zenith is a challenge, not only clearing tripod legs but also any imbalance to any direction gets amplified with visual back change (eyepieces, binoviewers, eyepiece turret, finder scope).

Here is TMB 130SS f/7 pointing zenith with binoviewer. It is my typical setup for high power planet/lunar observation. Binoviewer is about 26 inch from the ground, very low. In order to make a little more comfortable, say you increase the tripod height. Now it is difficult to see low sky. Then you would do, turning binoviewer to side so that you can reach eyepiece (2nd photo). By turning diagonal to get comfortable viewing position, it adds rotational moment to system. It sometimes becomes issue with Half Hitch since it is much more sensitive to unbalanced system. DM-6 has the best tolerance to unbalanced system when you change visual back. System stays put when you change single eyepiece from 4mm Zeiss ortho (62 grams) to heavy ES9-120 (1,290 grams). You won't miss a target by changing eyepieces.

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Here is my opinion:
1. When system balance does not change often, Half Hitch mount gives the best viewing experience. After careful two axis balance, system moves as if there was no weight in system. Best system to scan Milky Way.
2. DM-6 gets most stable feel and robust, trouble free system and HEAVY.
3. T-REX performs very much like DM-6 until 6" f/8 refractor. Slow motion control is a plus.
4. Slow motion control is a nice-to-have, not a must-have. You can track planet at over 300x without slow motion control easily. You'll learn how to do it.
5. Half Hitch becomes annoying (move by small force) when you need to apply force to focus (large helical focuser)/to turn zoom eyepiece/to switch power (Denk power switch). It is too sensitive to such force.

By the way, you usually don't look at zenith all the time :)

Tammy

#11 Quintessence

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Posted 31 May 2013 - 01:21 PM

Just to clarify, the Half Hitch is no longer available. The current model, the Nova Hitch, is a heavier-duty mount with a COMPLETELY different slow-motion control system having MUCH different properties. Other than both having two-axis balancing and similar overall configurations, the Half Hitch and Nova Hitch are NOT related at all.

Charles

#12 Mauikj

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Posted 31 May 2013 - 01:28 PM

Aloha Tammy,

Thanks again for all the feedback (and again WOW you have some nice set ups!). And you're right I don't observe a lot at the zenith, I was more concerned with the balance issues as I move the scope towards it. Your answers are again very helpful and I think I'm leaning towards the DM6. It just seems hard for me to believe that a mount could be so smooth that I would not need tracking or slow motion controls to keep an object centered - but I guess the DM6 is that good. And I rarely go over 250 power.

And thanks Prichardson for the link to the Nova Hitch pictures, they are very nice. I would love to get to one of those star parties some day and check out all the great stuff.

#13 Goodchild

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Posted 31 May 2013 - 03:07 PM

If choosing between DM-6 and T-Rex, the slo-mo controls on the T-Rex would make that an easy choice. I don't own either one, however, my understanding is that they both are comparable in load capabilities and my experience with slo-mo is very positive. Slo-mo vs. nudging--no comparison.

#14 prichardson

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Posted 01 June 2013 - 12:48 PM

And thanks Prichardson for the link to the Nova Hitch pictures, they are very nice. I would love to get to one of those star parties some day and check out all the great stuff.


Unfortunately, none of that equipment is mine. :bawling: I just happened across while researching alt-az mounts. Good luck in your decision.

Philip

#15 davidmcgo

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Posted 01 June 2013 - 02:07 PM

If choosing between DM-6 and T-Rex, the slo-mo controls on the T-Rex would make that an easy choice. I don't own either one, however, my understanding is that they both are comparable in load capabilities and my experience with slo-mo is very positive. Slo-mo vs. nudging--no comparison.


I don't know how comparable the TRex is for really heavy set ups. My DM6 on a Stellarvue TSL7 stand handles a 10.25" f17 Dall Kirkham which is 4.5 feet long and around 38 pounds, probably over 43 with diagonal, eyepieces, and finder. I hand track at up to 450x with that load. I'm pretty well at the limit of the tripod and use VSPs but the walnut legs, built in center column, and adjustable height makes it work for the cass, a 8" f6 Newtonian, or my 130 f 8 AP. The counterweight shaft option makes it incredibly smooth in azimuth even with the big cass, using only an 11 pound weight although it is very usable without it.

The DM6 handles any of these set ups with ease and I never feel the need for slow motions. It has become my quick setup " grunt and heave" mount.

Dave

#16 mark8888

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Posted 01 June 2013 - 02:43 PM

The DM6 handles any of these set ups with ease and I never feel the need for slow motions. It has become my quick setup " grunt and heave" mount.

Dave


Same here. I've hand tracked a TEC 140 on a DM6 at all sorts of high mags, for hours at a time, and never felt the need for slo-mo controls.

#17 Goodchild

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Posted 01 June 2013 - 03:19 PM

Can you track w/o slo-mo? Sure. But it's much easier and more satisfying with slo-mo. IMO, the DM-6, and others, would be a much improved mount with slo-mo controls.

#18 Jim7728

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Posted 01 June 2013 - 04:11 PM

I like the simplicity of tracking with one hand on the refractor diagonal or panning handle of an alt-az mount provided that I'm using Ethos, Nagler and Delos type widefield eyepieces. :)

#19 Mauikj

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Posted 01 June 2013 - 04:38 PM

All great feedback everyone. I had the Tak out last night trying to get eta carina in the short window it is visible here and the GEM mount made me crazy with the meridian flips - plus all the twisting and turning of the binoviewer as it moved about. So I'm really appreciative to everyone who gave me their feedback. I'll probably wait to see more reviews of the Nova hitch but I think the simplicity of the DM6 has most caught my eye.

Again, thanks for all the great feedback :bow:

#20 mark8888

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Posted 01 June 2013 - 08:49 PM

Can you track w/o slo-mo? Sure. But it's much easier and more satisfying with slo-mo. IMO, the DM-6, and others, would be a much improved mount with slo-mo controls.


Just out of curiousity, around how much time have you spent using the DM6, and with what telescopes and magnifications?

#21 Quintessence

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Posted 01 June 2013 - 10:34 PM

Without entering any pro/con commentary into the discussion, let me provide some numbers as fuel for thought.

Let's say that you are using a Nagler eyepiece at 300x. Then the total field of view is about .27 degree or a little more than 16 arc-minutes. Let's say that for "tracking" without slow-motion controls, one grasps the star-diagonal at a point 20 inches from the axis of rotation. If "tracking" in 5 arc-minute steps, which represents a third of the field of view, then one would have to execute a controlled movement of just .029 inch. "Tracking" in 5 arc-minute steps is fairly coarse -- not really fine enough to keep a planetary image in the "sweet spot." But even these rather large steps must be repeated about every 20 seconds (assuming the object is not too far from the celestial equator).

Obviously, the task is easier for larger scopes like an 18-inch Dob -- because of the larger working-radius through which the movements are executed.

I will leave to others to argue the merits/practicality of tracking by direct manipulation of the OTA. I am prohibited from such commentary. But having some basic numbers can help sharpen and clarify the discussion, adding a measure of objectivity.

Charles

#22 Goodchild

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Posted 01 June 2013 - 10:35 PM

mark8888,

None, as I stated above. But I still have no doubt that slo-mo would improve the mount.

#23 mark8888

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Posted 01 June 2013 - 10:57 PM

You stated above that you didnt own either one, but with such a strong opinion about it I'd assumed you'd at least USED one once or twice, or extensively. And being that your opinion is so very different from that of others who have actually used the mount, I had thought it was interesting.

#24 Doug D.

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Posted 02 June 2013 - 05:53 AM

In my opinion adding slo mo to a DM-6 would pretty much require a fairly significant redesign resulting in a fundamentally different mount - the simplicity, rock solid performance, capacity and compact (albeit heavy) form factor of the current DM-6 are what still attract me to the mount as it is now. It just plain "works" and if it ain't broke........?. Would I prefer slo mo capability? Yes, in a blank sheet theoretical way I suppose so, but in practice I'd say I rarely felt limited by the DM mounts' lack of slo mo.

I onced owned a DM-6 and TOA 130 - the only limitation for me was the poorly suited set of legs I had at the time not the mount or even the front heavy TOA.

BTW, I think Tammy's comparative analyses earlier in this thread are spot on (with regard to DM and HH mounts at least - I've not used a T-Rex) but as pointed out do not necessarily apply to the current Nova Hitch, which is quite distinct from the earlier Half Hitch generation of mounts (great performers in their own right). I'd love to try a Nova with my 140 some day.

It isn't simply a matter of which of these mounts is "best" but what might be best in terms of your gear, requirements and expectations. Fortunately or unfortunately, only each of us individually can make that determination.

#25 tomcody

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Posted 02 June 2013 - 09:06 AM

With binos, you really want a CAA (camera rotator) on the TOA when using a GEM, it helps a lot and keeps the binos safe from accidentally dropping them when adjusting angle. As for the DM6 balance, the new Disk Mount dovetail saddles are offset to make balance better at zenith (you can see the offset holes in the saddle plate on the Diskmount web site). I had no issues with balance with a DM6 and Tak FS128.
Rex






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