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Help me find the right alt/az mount!

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#26 Herenomore

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Posted 24 May 2009 - 02:12 PM

It's not as easy to perfectly position a planet at the outer edge of the sweet spot on a high-power EP as it is with slow motion controls.


Yes, it is. It just takes a little practice with the mount


Well I should have stated: "It's not as easy for me to perfectly position.... - this is not a practice issue as I've had my DM-6 for a couple of years and I don't think I need any more practice on it ;) - it's a matter of personal preference. You can't have your cake and eat it with a mount like the DM-6 - you can adjust the friction so it's buttery smooth, but then you run into issues when swapping EP's (which I do rather frequently), so I need to crank up the friction enough so I'm not constantly taking out the wrench to adjust it (I would find the DM6- a lot more useful if there was just a knob on the outside to adjust the tension). The advantage of a mount with slow-motion controls for me is that I can have the friction high enough so I can swap even a 31Nagler with a small Ortho without having any re-balance issues, while still having micro-smooth adjustments via the slow motion controls.

With the DM-6 tensioned to allow the same EP swap, I find when viewing at 250x+ that it is not easy at all to get an item perfectly positioned and I've had several other observers try as well with no more success - YMMV - but this is definitely something that each person should determine for themselves as you will find much disagreement on this issue. And only those people who have spent considerable time using both type of mounts are in a position to really judge the relative convenience of each style of mount.

CESDewar:

I was referring specifically to my experience with the DM-4 and I apologize if my comment splashed over to your experience with the DM-6. It was unintended. I agree that everyone's mileage varies and that one's preference is based, at least in some part, upon what one is used to. I'm just wondering if your experience with your Teegul and one of your lighter scopes (I assume you don't mount your NP127 on it) can readily be up-converted to the DM-6, a wholly different animal capable of handling weights up to 50 lbs. Even if, hypothetically speaking, slo-mo controls were added to the DM-6, I wonder if you could even turn the knobs with a 30-40 lb scope on the mount? I suspect we'll never know.

Anyway, holding a fast moving planet at high powers constantly at the center is probably the most difficult thing an observer with a push-to mount can do. As I understand slo-mo controls (and from some hands-on experience with them), one control moves the scope up and down and the other moves it right and left. So, unless the planet is moving solely in either one of those directions, you need to operate both controls simultaneously to track it so as to keep it constantly at the center (I presume that tweaking first one control than the other would allow the planet to drift off-center in one direction or the other). Assuming for the sake of argument that this (with possibly an occasional re-focus tweak) is easy enough to do with your Teegul and one of your lighter scopes, I don't see this as being any different than what I accomplish with my DM-4 and SV105. I just need one less hand to do it. Again, as you suggested, a preference based upon personal experience.

Lastly, I'm very surprised you need to adjust friction for an ep swap. I don't have to do it with my DM-4 and the DM-6, with its larger friction plates, is way less sensitive to weight changes than is the DM-4. Is your scope balanced properly? If it isn't, repeated increasing/decreasing the friction won't cure the problem (only makes it more annoying) and may be contributing to the matter you described of holding planets at center. You really should talk to Tom Peters about this. I picked up my mount at Tom's place 4 years ago and he spent about 3 hours with me balancing up my SV105, showing me how to use the Sky Commander, talking astronomy, etc. Since then, I've had re-balance one more time after the friction plates broke in. Regardless of whether what I've described is causing what you've described, it is certainly worth a call to him to find out.

Sorry about the long post but it can be blamed upon the near constant rain we've had here for the past week. Hope your Memorial Day is fun...and dry!

Tom

#27 Doug D.

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Posted 24 May 2009 - 07:48 PM

Ron,

I agree with Charles - the ideal would be a couple of tripods, one for when you need to travel light and one for when you don't mind lugging the extra weight. That was the reasoning I used for having both the UNI-24 and the Gitzo 5530 (now 5531 I think?). But I recently got the AP/Baader tripod for the Mach 1 and I just had to shed the Uni-24. Sorry you missed it but I'm regretting selling it already and it hasn't even been shipped yet, LOL.

As for clearance at zenith, I can tell you I was plenty worried about whether the HH II SkyCommander plate - let alone my OTA - would clear the 6" base of the UNI-24. Charles thought it would and Charles was correct! And the 105 Traveler does reach zenith without getting hung up. The Gitzo has a narrower base so will be no problem.

I realize you may be entering the "analysis paralysis" zone so I hope I'm not making it worse. The Gitzo is rated for over 50 lbs I think but that is a lot more weight than you are thinking about.

My suggestion is this, get the HH III (fine choice by the way!!) and put it on your Oberwerk just to get a feel for it with your SV90. You can certainly get the Gitzo quickly and hopefully, the same is true for the Berlebach through Teton. My thinking here is that it might become more obvious to you, which way to go with a tripod decision when you've got that jewel of a mount in hand. One thing is for certain - you will be graduating from the Oberwerk and either the Gitzo or Berlebach will be a big step up and spoil you for high quality tripods forever!

And who knows, maybe another exceptional tripod deal will come along on Amart in the meantime.

just a thought,

Doug

By the way, I will try and take a picture of my Traveler, HH II and Gitzo 5530 in "zenith" position for you. I may have the time tomorrow - for now the Traveler is riding in style on the Mach I - and its a beautiful thing!!!

#28 Scott99

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Posted 25 May 2009 - 11:57 AM

>>>>Anyway, holding a fast moving planet at high powers constantly at the center is probably the most difficult thing an observer with a push-to mount can do. As I understand slo-mo controls (and from some hands-on experience with them), one control moves the scope up and down and the other moves it right and left. So, unless the planet is moving solely in either one of those directions, you need to operate both controls simultaneously to track it so as to keep it constantly at the center (I presume that tweaking first one control than the other would allow the planet to drift off-center in one direction or the other). Assuming for the sake of argument that this (with possibly an occasional re-focus tweak) is easy enough to do with your Teegul and one of your lighter scopes, I don't see this as being any different than what I accomplish with my DM-4 and SV105. I just need one less hand to do it. Again, as you suggested, a preference based upon personal experience.

Interesting, when I observe I move the planet to the extreme side of the FOV with the slo-mo and then relax and watch as it works its way across the FOV. When it reaches the other side I re-position it back to the other edge again.

yes, with the Teegul it's 2 knobs but you don't even think about it, you just quickly tweak both and the planet is in place again, then you wait & watch. The movements are the same every time you adjust and it instantly becomes intuitive and automatic, I don't even think about it, it just happens. Even newbies that never do astronomy can quickly adapt to using the slo mo to track in an instant - I just tell people "use the knobs and you'll figure it out" and it works!

These threads are interesting - a lot of this depends on the way that one observes. On the Teegul I like to use small to mid-size refractors with no finder. This is critical - for every object viewed I put in a big 2 inch eyepiece to use as a finder (and I enjoy the low power view of all DSOs too). I usually do star-hopping or dead reckoning (sighting along the tube) to find and center the object and then switch to higher power, and often switch again until I find my favorite view and then I stare for a while.

Other people like use DSC to get the object into the FOV. That way you can put something like an Ethos in and cruise the skies all night long without taking it out. Sounds fun but it's the direct opposite of the way I observe. I hate having to set up and align things and I consider it a waste of my observing time, no DSC's for me.

After using refractor dob-type alt-az mounts for many years I absolutely detest having the scope move when I pull the eyepiece out. So any alt-az mount I use must have enough friction to let me constantly switch ep's without having to adjust anything.

I could see the discmount-style mount working for planetary tracking if it's smooth and easy enough to move. I'd like to try one, but for me the Teegul was love at first sight! It's not perfect but it's close for me and the small size and low price make it near perfect.

I'd like to try a DM4 but with my scopes I'd definitely need the extension above the tripod, which further complicates things and costs another $200. The Teegul lifts the scope high enough so that only a small area around zenith is un-accessible.

#29 Quintessence

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Posted 25 May 2009 - 12:59 PM

I absolutely detest having the scope move when I pull the eyepiece out. So any alt-az mount I use must have enough friction to let me constantly switch ep's without having to adjust anything.


The Half Hitch deftly solves this problem by including a brake on the altitude axis. It's a true caliper disc brake so it doesn't impose any torque on the axis (thereby accidentally turning the axis a little) when you tighten or loosen it. The brake control is conveniently placed next to the altitude slow-motion control knob, and it literally takes about one to two seconds to apply it or disengage it (using only finger-tip pressure). It also has a progressive engagement feature that allows it to be used to apply a small amount of drag for tuning the "feel" of the axis. (It's a lot faster than adjusting a clutch and requires no tools.) Because it's a true disc brake, any applied drag is extremely smooth in it's action.

I agree with you that using motion control knobs is so easy and intuitive that even complete beginners catch onto it in seconds with little or no instruction. Tracking with motion control knobs requires little skill while "nudging" takes a little practice.

Tracking planets within a couple of hours of the meridian is a lot easier than has been described. It does not keep both hands constantly busy. Although the effect varies with latitude, the path of planets in the zone of optimal observation is dominated by movement in the azimuth axis. One generally ends up making several periodic corrections with the azimuth control for each correction with the altitude control. Using the Half Hitch, I generally track in azimuth with my left hand (sometimes continuously) and make occasional corrections in altitude with my right hand. The right hand is mostly free for focusing. With a little practice, the whole procedure becomes just a "automatic" as "nudging." And overshooting the desired correction essentially never happens -- at any power.

Slow-motion controls have been popular for so many years simply because it's a very effective and efficient methodology that is very direct and pleasant to use.

Charles

#30 sxinias

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Posted 25 May 2009 - 04:49 PM

For a low cost solution, there is always the new SkyWatcher AZ GOTO mount and steel tripod for about $250.

Joe

#31 kwkee

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Posted 26 May 2009 - 12:39 AM

For mount, my suggestion is don't skip the money by going for cheaper solutions. A good mount can be used on a few different scopes so it is worth the investment.

I have tried cheap solutions in the past, but end up selling each one of them and gotten into more expensive mounts. Thinking back, I would have save more by going into a good mount at the start.

I realised that most people put in a lot of consideration into scopes but not mount which is really a pity. A good mount can last a long time and would probably outlive every of your scopes. So it's worthwhile investment. I don't understand why some people spent thousands on scope but skimp heavily on mounts.

Having said that, I like Half Hitch mount the best. Yes, it's expensive, but you probably don't need another azi-alt mount anymore. I like precision, so no matter how smooth a DM can be, the use of nudging can never be as precise as the use of slow-motion. That what finally leans me towards HH.

#32 Ron B

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Posted 26 May 2009 - 09:12 PM

...my suggestion is don't skip the money by going for cheaper solutions. A good mount can be used on a few different scopes so it is worth the investment.

I have tried cheap solutions in the past, but end up selling each one of them and gotten into more expensive mounts. Thinking back, I would have save more by going into a good mount at the start.

Having said that, I like Half Hitch mount the best. Yes, it's expensive, but you probably don't need another azi-alt mount anymore. I like precision, so no matter how smooth a DM can be, the use of nudging can never be as precise as the use of slow-motion. That what finally leans me towards HH.


Totally agree, I have been down the same road of many of the others for the search for the right alt/az mounth.

Doug, thanks again!
I will probably go with the UNI 14; but I absolutely love the idea of the SV90 going out the door on a Gitzo and HH with total weight close to 20lbs.

I agree with you and Charles and you have got me wanting to pick up a Gitzo, but right now I am WAY over what I had planned to spend.

Charles, sorry I brought my fear of past experiences with mounts into the discussion of the Half Hitch. I actually am confident of the HH ability to handle even more than what I currently have; can't wait to get it! :jump:

Ron






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