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Regarding Refractor Mounts: Your Thoughts

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#1 Koala117

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Posted 26 July 2013 - 11:39 PM

This post is not intended to weigh benefits of what actually exists, nor what is actually possible. It is only intended to see what you all think assuming the following criteria were true. It's meant for fun but also because I am curious to see what other, more experienced members would do if the following 'What If' scenario were, in fact, reality. =) That said, let's get started! :::


If we were to pretend that Alt-Az and Equatorial were 100% equal in:

- Portability
- Weight
- Size and Form
- In every single way that I haven't thought of to add to this list

In other words, if the only specification that mattered when picking a Refractor Mount was the way the the mount functioned, Alt-Az style or EQ style, which would you choose?

Why?

#2 carlcat

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Posted 26 July 2013 - 11:55 PM

If I'm following you correctly, I would pick a GEM because my main focus is high power viewing of planets and moon so clock drive tracking is very important.

#3 KWB

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Posted 27 July 2013 - 12:04 AM

For use with a small refractor,I'd choose an Alt/Az mount for overall simplicity. If the choice was for a larger refractor,that would depend on how much larger and what it's primary useage would be.

#4 mayidunk

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Posted 27 July 2013 - 12:23 AM

I have both a decent Alt/Az, and a decent GEM that are used with refractors of various sizes and focal lengths. However, for me it's not which mount for which scope, but which mount for the kind of viewing I'll be doing. For quick looks, or sweeping around the sky, I'll use the Alt/Az. For any other viewing where I might be camping out on an object, or doing high-power viewing with a more narrow FOV scope, then always the GEM.

#5 Koala117

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Posted 27 July 2013 - 01:03 AM

carlcat: Yep, you got it! I fixed the wording a bit, just in case, though. hehe. That's a good point that you bring up about high power, too! It makes staying on target with my 312 very easy, no matter the power.

Kenny: Same. Though, I'm conflicted a little bit, in regards to smaller, myself. Example: I'd like either something like an ST80 or a 70mm, longer FR Vixen on a Porta II, for my next scope. On one hand, an Alt-Az would be convenient for cruising around with no real set target. On the other, something like the ST80 can come with a lighter EQ which would be nice for tracking.

That's what got me thinking about the question in my OP. Both types of mount would be nice for both scopes, while the price would be similar(around 270ish, i believe).

Bob: Seems that others like the 'quick look' style of Alt-Az, like you do. I currently have an EQ, myself! :) Though, I suppose a very light-weight EQ wouldn't take much effort to set up. Just point at Polaris and poof, we're off!

-
And so, I like reading all these replies, so far. Seems like there's lots of variables that come in to play when deciding on a set up and the mount for it. I have a while before I'll be getting another but it really is hard to choose, based solely on the way a mount functions, for me anyway. :)

edit: I know I mentioned specific scopes and such just there. But, for this thread, I'm mostly interested in the benefits that others find in Alt-Az vs. EQ, all things being equal. And since the mount style itself will be a big consideration for my next setup, I'm enjoying this because I know there's so much that I don't already know. I just don't know *what* it is unless I ask, so here we are! hehe =)

Edit2: I've actually inquired about mounts to a fellow member recently via PM the other day and got some good thought there, as well. They mentioned photo tripods which I didn't include in my OP. I should have included them. They're not side-saddle but they are technically alt-az, I think? Though, I don't know how well camera tripods work with longer FR scopes but they did say that with fast scopes, they work well. Just thought I'd add that to the mix. Blarg, so many questions! =)

#6 KWB

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Posted 27 July 2013 - 01:53 AM

Hi Mike

My opinion is based upon my experience,overall knowledge of the constellations and star or Messier targets with in them, and while combined with my present desires,I still can't justify to the newer advocates to this hobby recommending the specific use of an EQ mounted 80mm,shorter focal length telescope(possibly even driven) to another observer. To me this is simply not essential. What is the point? A small 80mm telescope designed for widefield or the potential for maximum sky coverage using 82° designed eyepieces with no real predesigned objectives needs really not to be driven and a quality Alt/Az mount like the Portamount make tracking a target like Jupiter a cinch at 150X if that's your singular purpose for the evening. If money is an object,sure,a mount like the EQ2 can be used in the Alt/Az mode to make using the mount even easier to use. It can also be used in the EQ mode as well,the slow motion controls used either way are an big asset IMO and IME.

#7 Astrojensen

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Posted 27 July 2013 - 02:21 AM

In other words, if the only specification that mattered when picking a Refractor Mount was the way the the mount functioned, Alt-Az style or EQ style, which would you choose?



German Equatorial, no question. Apart from my 12" dob, I observe exclusively with GEM-mounted refractors, as I find this mount to be the most flexible of them all. Also, I highly appreciate the tracking ability when I need it or the simple push along on one axis, with the DEC firmly locked down, reducing the chances of losing an object due to unwanted movements. I also like to use the setting circles to find objects, mostly daytime planets, without relying on motors or electronics.


Clear skies!
Thomas, Denmark

#8 Koala117

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Posted 27 July 2013 - 02:36 AM

Kenny,

That's definitely giving me something to think about, for sure. I know that if I had a wide-field scope, i'd be using the EPs that come with them for quite a while as it is. Maybe pushing 100x, maximum. I don't reckon a ton of super accurate tracking would be required at such low magnification.

That means, if I'm not planning on hounding one single object all night, I could do well with an alt-az, I think. Or, if I ended up absolutely needing to, I could always use an EQ as an alt-az for a little while. :D I think it was Jon Isaacs that I've seen mention that EQs can be alt-az in a pinch! I know I've read that before somewhere here, though. My memory is icky sometimes. I'm glad you reminded me of that part. =)
--

Thomas,

thank you for replying! I also like tracking with my EQ mount. Since I'm still in the 'deciding' phase, I figured I should ask here for deciding on a mount style, should I decide to get a wide-field. One thing I've noticed, without ever having used an Alt-Az in a long long time, is that Alt-Az does have an advantage in the 'I don't have to keep turning my tube/diagonal to keep things in an easy-to-view position' category. =)

As for setting circles, my EQ has them, though I'm basically lacking experience to use them. I can recall my lattitude which helps with finding Polaris but that's about it, thus far.

#9 Jon Isaacs

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Posted 27 July 2013 - 06:04 AM

In other words, if the only specification that mattered when picking a Refractor Mount was the way the the mount functioned, Alt-Az style or EQ style, which would you choose?

Why?



For me, through I have both GEMs and ALT-AZ mounts, for a refractor, it's almost always an alt-az mount with slow motion controls, i.e. the Vixen Portamount.

Alt-az mounts are simpler, lighter, and with the slow motion controls, still track nicely at high magnifications. Alt-az mounts are nice for sweeping regions of the sky at low powers. My refractors are all 4 inches or smaller and of shorter focal lengths. If I owned a larger refractor, I would use an EQ mount more often.

As far as an ST-80 on an EQ mount, the ST-80 is primarly a low power telescope and not so well suited for high magnifications so buying an ST-80 on a EQ mount doesn't make a lot of sense.

As a note, your current EQ mount can also be used as an ALT-AZ mount. Instead of aligning the RA axis with Polaris, you point it straight up at the Zenith.

Jon

#10 RAKing

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Posted 27 July 2013 - 07:39 AM

I would use a GEM every time.

Once your GEM is polar aligned, the RA axis is the only axis that has to move to track an object. It's less drain on batteries -- OR it's easier on you if you are tracking manually.

Cheers,

Ron

#11 Scott in NC

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Posted 27 July 2013 - 08:02 AM

I have both a decent Alt/Az, and a decent GEM that are used with refractors of various sizes and focal lengths. However, for me it's not which mount for which scope, but which mount for the kind of viewing I'll be doing. For quick looks, or sweeping around the sky, I'll use the Alt/Az. For any other viewing where I might be camping out on an object, or doing high-power viewing with a more narrow FOV scope, then always the GEM.


+1 My thoughts exactly!

#12 hottr6

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Posted 27 July 2013 - 10:30 AM

Tracking is very, very important to me. I cannot afford a tracking alt-az, so that means GEMs.

Oh, and equatorials just look cooler. :cool:

#13 astrophile

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Posted 27 July 2013 - 10:48 AM

I've always needed an alt-az mount around, mostly for the reasons Mike has excluded from this discussion :grin:. So I love my GEM for all the reasons stated above. But...a solid alt-az w/tracking would cover most of that and make me reconsider keeping both. Then function-wise it would come down to the GEM's RA-sweeping ability vs. the Alt-Az' reduced gymnastics requirements...but with most of those unmentionable factors lurking in alt-az favor too... would be a hard decision!

#14 Eddgie

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Posted 27 July 2013 - 11:31 AM

Even if they were not the same weight, I still have an overwhelming preference for GEM mounts.

First, for the tracking.

Next, most Alt Az mounts require fussing with clutches to keep from experiencing nose dives when changing from heavy eyepeices to light ones. This is one of my most serious complaints about most Al As mounts. It seems that when you have the tension set so that the mount moves easily, it will be more inclined to nose dive when you change from a very heavy eyepiece to a very light one.

Low power sweeping... The GEM will sweep in arcs that track the sky. When you get to the end of an arc, you can move a star from the bottom or top of the field to the opposite side, then sweep back in the other direction. You get perfect coverage of the sky.

Much easier to star hop with a GEM. This is because even if you are jumping off from quite far away, once again, even with a less than great polar alignment, the GEM will move in "Known" directions. If the chart says the target is 10 degress south and 5 degrees west of a bright star that is near the northeast horizon, it can be less than intuitive to move an Alt-Az scope In the exact directions. With a GEM, one knob moves the mount north/south and one east west, but here we are talking about with relation to the astronomical north/south/east/west. With an Alt Az, you are moving geographic north/south/east/west, and these are two very different things when you move away from zenith.

And did I mention tracking? I use my C5 as my "solar observatory" Even though I am viewing at 50x to 75x, seeing is always fluctuating. When I have a good window, I don't want to loose it because of having to reposition due to the target drifting from the center of the field.

And none of these benefits require more than a casual polar alignment.

Just my own opinion. There are super-lightweight GEMS out there and I vastly prefer them to even the best Alt Az mounts I have ever owned.

#15 Maverick199

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Posted 27 July 2013 - 11:39 AM

I have both a decent Alt/Az, and a decent GEM that are used with refractors of various sizes and focal lengths. However, for me it's not which mount for which scope, but which mount for the kind of viewing I'll be doing. For quick looks, or sweeping around the sky, I'll use the Alt/Az. For any other viewing where I might be camping out on an object, or doing high-power viewing with a more narrow FOV scope, then always the GEM.


+1 not to mention I would go GEM if AP too is in the equation.

#16 Starhawk

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Posted 27 July 2013 - 12:00 PM

The basic question was just Equatorial or Alt-Az, and I've used several flavors of both.

Alt-Az does make super-light mounts possible, and I have used this in the form of the Unistar light mount as well as the original Vixen Polaris, which has an Alt-Az mode. This is neat in its immediate understandability if you aren't thinking in astronomical coordinates. However, it results in a lot of moving around to see anything in the sky, and for refractors, the eyepiece can be at chest height or crawl on the ground height depending on where you are looking. There is no simple tracking solution, so if you are guiding the mount by hand, as I had to do with the Polaris, you're constantly turning both axes. When using a powered Alt-Az mount like the little NexStarGT mounts, the change in eyepiece height is the biggest problem, along with the threat of tripod collision making the best viewing area in the entire sky, the zenith, unreachable.

I have also used several modes of Equatorial:

Single arm fork: Putting a refrator on an old C5+ mount is a neat experience since the OTA swings about its own center of gravity. In an equatorial configuration, you can look right at the zenith, and the dead spot in the sky is going to be right near the North Pole, which has little to recommend it, anyway. The only mounts similar to this today are the powered NexStarSE mounts, which don't allow the pleasant experience of just unlocking the axes and swinging the OTA to exactly what you want to point at. The limited size of the old C5+ mount also means there is no equivalent option for OTAs larger than an 80mm ED scope. This could probably take a TMB 92SS, but that's really about it. But it does everything a GEM with a clock drive does. If I was to try to put something into production today, something like this would seem to make a lot of sense.

A conventional GEM with no clock drive does have the possibility of moving the eyepiece all over the place, again. However, even without a clock drive there are some major advantages. First, the mount moves along the sky, so dead reckoning is not as baffling as it is in Alt-Az space where the mount directions don't align with the sky chart. For tracking, you can get a little beat going where if you watch how far the mount advances with a given amount of turn and how often that is needed, you can count seconds and give it a turn and stay on an object, even while other people are looking.

Finally, the full-up powered GEM with a refractor on it is a very powerful system, indeed. It is very tolerant of changes to the telescope shape factor, though the amount of swing means people need to stand back while it is traversing to another part of the sky. But there are very good reasons Fraunhofer settled on this mount, which unfortunately is called "German Equatorial" instead of its rightful name (Who knows- maybe we'll start calling the Nobel the "Swedish Prize" at some point).

-Rich

#17 Kutno

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Posted 27 July 2013 - 12:02 PM

Next, most Alt Az mounts require fussing with clutches to keep from experiencing nose dives when changing from heavy eyepeices to light ones. This is one of my most serious complaints about most Al As mounts. It seems that when you have the tension set so that the mount moves easily, it will be more inclined to nose dive when you change from a very heavy eyepiece to a very light one.


Hi Ed,

When it comes to lighter alt-az mounts, I agree with what you say - Note: I acknowledge you are talking about "most ... mounts." There is one, heavier, mount that I believe provides a solution to the problem you highlight: Last night, I had the privilege to use a DM-6. Switching from a 16 oz. 6mm Delos to a 4.2 oz. 5.1mm XO was a piece of cake. The mount's stability was superb.

#18 McUH

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Posted 27 July 2013 - 12:08 PM

Well, I'm Alt-Az man and never used GEM so I'm not sure about this, but can't every GEM be used in Alt-Az mode by fixing one axis? If so, then assuming weight, stability and everything else is equal (impossible in reality I guess), the GEM is correct answer since it provides both possibilities.

#19 Jon Isaacs

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Posted 27 July 2013 - 12:09 PM

For use with a small refractor,I'd choose an Alt/Az mount for overall simplicity. If the choice was for a larger refractor,that would depend on how much larger and what it's primary useage would be.


:waytogo:

I think that is about the long and short of it. One cannot really divorce weight, size and ease of use from the equation. It's like asking, which scope would I use, my 4 inch F/10 refractor or my 12 inch F/5 Newtonian if both were the same size and weight?

Jon

#20 Kutno

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Posted 27 July 2013 - 12:40 PM

In other words, if the only specification that mattered when picking a Refractor Mount was the way the the mount functioned, Alt-Az style or EQ style, which would you choose?

Why?


Mike,

Buildings surrounding main viewing sites have always precluded me from lining up a mount with Polaris; thereby causing me to never consider an equatorial. Computerized wonders today may eliminate this issue; however, living in an urban environment has also caused me to take into account the blender-decibel noise some GEM motors create, disturbing the sleep of my neighbors. The last thing I want is to have someone drop a potful of water upon optics that required many hours of work to acquire.

#21 russell23

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Posted 27 July 2013 - 12:44 PM

I have a Vixen Superpolaris mount set in alt-azimuth mode on a set of Al Canarelli legs. It is very rugged and handles my Vixen 140NA. Alt-azimuth is my answer but I don't take images and prefer point and star hop. I don't use a finder scope either. So I have no use for an EQ.



Dave

#22 Gord

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Posted 27 July 2013 - 01:32 PM

I have both a decent Alt/Az, and a decent GEM that are used with refractors of various sizes and focal lengths. However, for me it's not which mount for which scope, but which mount for the kind of viewing I'll be doing. For quick looks, or sweeping around the sky, I'll use the Alt/Az. For any other viewing where I might be camping out on an object, or doing high-power viewing with a more narrow FOV scope, then always the GEM.


+1 My thoughts exactly!

+2, it's all about the use case for me.

Another point I've found important to me over the years is to have "enough" mount. Undermounting is no fun. And I find undermounting with an alt-az more painful than with a GEM due to how much more you have to interact with the mount.

Clear skies,

#23 Astrojensen

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Posted 27 July 2013 - 02:29 PM

Buildings surrounding main viewing sites have always precluded me from lining up a mount with Polaris; thereby causing me to never consider an equatorial.



If it has setting circles, you can use them to polar align, without needing to even so much as cast a glance at Polaris.


Clear skies!
Thomas, Denmark

#24 Scott99

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Posted 27 July 2013 - 02:58 PM

definitely prefer EQ mounts - I use a Teegul most of the time, whenever I break out the Mach 1 equatorial it's like ahhhhhhhhhh...tracking! Easy viewing at zenith!

for me the advantage of alt-az is no counterweights, lighter mount weight, small mount size. My equatorial mount has electronic slo-mo, so I'm not missing that.

the other buzzkill of alt-az mounts is that it's difficult to avoid hitting the legs with the refractor, usually a height extension is required if you want to view the zenith cleanly. And that's the darkest part of the sky.

Also the Mach1 can be used with a 6-inch refractor with the clutches completely loosened for easy movement. I can switch 2-inch eyepieces in & out without the scope moving with the clutches off, use the electronic slo-mo, move w/ fingertip pressure, etc, all without having to mess with the clutches all night.

they're both MVP's in my book, the Teegul can be set up in about 30 seconds and it weighs less than 10 pounds. For 4 inch refractors you're at lower powers than a big scope, tracking's less important, it's a perfect combination.


#25 Scott99

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Posted 27 July 2013 - 03:09 PM

Mike,

Buildings surrounding main viewing sites have always precluded me from lining up a mount with Polaris; thereby causing me to never consider an equatorial. Computerized wonders today may eliminate this issue; however, living in an urban environment has also caused me to take into account the blender-decibel noise some GEM motors create, disturbing the sleep of my neighbors. The last thing I want is to have someone drop a potful of water upon optics that required many hours of work to acquire.


wow, observing from the mean streets of the city! sounds like some tough conditions. You could still use an EQ mount though, if you're not using GOTO there will be no motor noise, and you won't need close polar alignment.

For visual use I can usually do polar alignment very quickly. If you level the tripod then altitude will be set correctly from the last session. Then you could point north using a compass, probably getting within a couple degrees of Polaris.

some mounts, such as Astro-physics, can also be polar-aligned based on any object you can see the sky. They can do a simple 2-star alignment, or be aligned using the Sun while it's up.







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