Indeed. The world IS full of new ideas and new thinking. But SOMETIMES, things old are still better. Take me for example…
Another case in point… The Vixen Polaris mount. This is an old mount design, having gone out of production LONG ago. It was superseded by the Vixen Super Polaris, then later, the Great Polaris, which really is too bad.
Now today, there is MUCH emphasis on “Grab and Go” telescopes that can be moved out into the yard for “Quick Looks.” And despite what some people seem to think (I am a C14 owner) sometimes I DO like viewing through smaller scopes because of the wide fields.
Now, I have tried small refractors on Alt-az mounts several times already, and frankly, I was not feeling the love. Let me explain what MY issue was.
If you use your scope with eyepieces that are similar in weight (for example, all ll 1.25” eyepieces weighing 2 to 4 ounces) the issues I am going to cover below may TOTALLY not be an issue for you. But they were for me… Here goes.
First, previous to the Celestron 80ED, the small refractors I tried just left me disappointed. YES, they offered decent wide field views, but I just found them unsatisfactory for anything else. The only exception was the Stellarvue Nighthawk, which was actually quite excellent, but expensive and still with enough color to be a problem on the moon for me. Recently, in a last ditch effort to satisfy myself once and for all, I bought a GOOD QUALITY 80mm, the Celstron 80ED. I reviewed it elsewhere, and my initial impression was that it was a really superb small scope, but too small. Also, I just was NOT happy using it on the Alt-Az mount. See, this small scope LOVES my T4 Naglers, and they LOVE it. My 22mm T4 is jaw dropping in this small scope, and the 5mm Radian makes high power work quite excellent for such a small aperture. The problem occurs when you CHANGE from a heavy eyepiece like the 35mm Panoptic to a much lighter eyepiece like the 8mm Radian. When you make this change, it plays havoc with the tube balance. In the case of the Gibraltar mount I was using it on, this meant that I had to constantly play with the tension adjustments to get the smoothest, lightest movement. But if I balanced the telescope to be neutral with heavy eyepieces, it would be nose heavy with light ones and creep, or worse, it would nose-dive if you took the eyepiece out and didn’t have one hand on the OTA. It was also VERY hard to hold the scope in position when going from the low-power “Spotter” eyepiece to the highest powers. You could either attempt to hold the telescope steady, or you could tighten up the tension adjustments if you needed both hands, but now you had to re-adjust the tension. Sometimes, the safety undercut on many eyepieces would sometimes snag when removing an eyepiece, causing the scope to move slightly. Now, in defense of the Gibraltar, I had this same problem with the Unistar Deluxe I tried. I constantly had to balance or play with the elevation tension. The Unistar took a standard Vixen dovetail however, which made re-balancing a bit easier if you had a Celestron style dovetail (Full length), but here too, I found it easier to adjust tension rather than attempt to constantly re-balance. Frankly, of the two mounts, I preferred the Gibraltar. It is craftsman like in its manufacture, and elegant to look at. It moved well, and the height was better with the refractor because I could use it sitting in a standard chair. I found it to have slightly more fluid movements than the Unistar. In addition, the Unistar on a standard tripod was pretty tall making it necessary to stand when viewing lots of the sky. But those are totally my personal preferences. The real issue with both of these mounts was the constant hassle of re-adjusting tension to keep the scope from creeping with heavy eyepieces, but still allow tiny, precise, and SMOOTH movements.
I also tried and Meade AZ-3. I LIKED the gear drive, because it totally eliminated the eyepiece balance issue, but after owning it and after using it, I found out that these mounts are problematic. If you adjust the tension on the elevation pivot so that the mount is easy to move by hand in elevation, it will cascade back when you tilt the scope up to zenith. If you tighten it enough to prevent it from cascading near zenith, it will be to stiff to move fluidly. You can use the slow motion control for fine movements, but long, slow, graceful sweeps in elevation simply weren’t possible. The Vixen variant of this mount uses a counterweight, but that seems to defeat the goal of having the lightest mount possible. Still, the geared movement REALLY appealed to me. This is because I just didn’t have to worry about tube balance. And as smooth as the other Alt-az mounts moved, I myself PREFER a geared slow motion control because they are very precise, and I can move in precise directions and steps.
In retrospect, I realize that the balance and friction hassle of the Alt-Az mounts I had tried were greatly detracting from accepting the small refractors I was using. And again, MY eyepieces are rather extreme in weight difference, so if you are using eyeices that only have a few ounces of difference between them, then I am sure that either the Unistar or the Gibraltar would be SUPERB choices, because you simply wouldn’t have this problem. But I LOVE my T4 Naglers. If I couldn’t use them in a scope, I wouldn’t own it. Anyway, looking back, I now realize that the C 80ED was being somewhat unfairly judged.
And because I juged the small scope/Alt-az proposition once again as not working for me, I did what I do when I am not absolutely thrilled with something, and put the 80ED up for trade, along with the Gibraltar mount.
But a funny thing happened. While I was waiting for a trade to present itself, I continued to use the Celestron 80ED, and within a couple of days, the absolutely stunning optics finally won me over. Yes, it is STILL a bit small, but in side by side comparisons with my Vixen 140, I was just becoming more and more impressed with how much it COULD do for such a small scope.
I came to the conclusion that with a small GEM mount, I might actually be HAPPY with the small scope, because I PREFER using Slow Motion controls, and the GEM would NOT have balance issues or creep issues. I also prefer the true north/south/east/west movement of a GEM over an Alt-az mount. When using star charts, it just seems easier to find things by moving along RA and DEC lines, and this is difficult to do with an Alt-az except at zenith and at the horizon. To put is succinctly, I thought I had a preference for a GEM mount, and by putting the C 80ED on the smallest high quality GEM available, I might decide to keep it.
So, the problem was: WHICH GEM.
The GEM would have to be very compact, and very light. It couldn’t weigh much more than the Gibraltar. Ideally, I would be able to carry the mount and telescope outside in one trip. Because it was going to be use mostly at relatively low powers (17x to 120x) I decided I could eliminate the motor.
The EQ1 and EQ2 mounts don’t appeal to me. Next…
Now, I considered using my LXD55. I thought I might buy an LXD75. They are cheap even new, and I would have put it under my Vixen 140, then taken the LXD55 with Vixen HAL 110 legs and used it under the refractor. But now we are into having to have a power source, and one of the key attributes of a Quick Look scope is that it needs to hit the ground running.
For THIS application, these mounts are a BIT heavy. I wanted lighter. The GP mounts and even the SP mounts are both about the same as the LXD55, so there was no point in looking at one of them. See, I DID like the simplicity of the Gibraltar. I DID like being able to lift everything up and carry it out in one trip. But these GP type mounts were just a LITTLE over the limit, and if I was going to make TWO trips, well, I would bring out the Vixen 140!!!
So finally, I turned to the Polaris because it had some GREAT characteristics. It is small, light, and it has good build quality. But it ALSO has a big TRICK which I will tell you about later that seems to have escaped a lot of people. This special trick makes the venerable old mount something unique, and in my opinion, quite desirable.
First, for the basics. This is a small, nicely made equatorial mount that has a carry capability of probably 10 to lbs. It is the PERFECT size for a small high quality refractor, or something like a 6” MCT. Fit and finish are quite qood, and overall, it has a nice appearance. The weight of the the complete mount WITH counterweight (but no scope) is only about 19 Lbs. This is only about 6 or 7 lbs more than the Gibraltar or the Unistar (with tripods). And of course this was a GEM, which with its geared drive was going to easily be worth the extra weight to me.
Some of the quirks are important to note, but not so important as to disqualify this mount from serious consideration. The most notable on this mount (In my opinion) is that the legs are fixed in height. Now for me, for the small refractor I have on it, the height happens to be perfect. But it would not do for a longer instrument than The Celestron 80ED that sits on it now. I have to lower my observers chair to view at zenith (which is SO not a problem for me, because I HAVE an observer’s chair). Versions of this mount were made with adjustable legs. In fact, I think that there were three variants of tripod, one being with longer adjustable legs, one being with shorter adjustable legs, and of course the fixed height one. But the solid legs make the mount light and rigid.
The second quirk is that the only motor drive I know of that is made for Right Ascension was a crude solution, in that the motor was attached to the RA housing with a metal bracket and a hollow metal tube acted as a coupler that simply slipped over the motor shaft on one end and the RA drive shaft on the other, with set-screws to hold it clamped to each shaft. The PROBLEM with this design is that there is no adjustable clutch as with the later under-hung motors as used on the Super Polaris and Great Polaris mounts. Now to me, a GEM only makes REAL sense when it has a motor, and having a clutch that lets you slip the telescope in RA is preferable to using the clamp on the shaft as a clutch. This is because this clamp is not really that linear in grip, so as the RA shaft rotates in its housing, sometimes the friction will vary quite a bit. I think that this lever is really intended as a LOCK, and not a clutch. But if you use the motor on this mount, you can’t use Slow Motion controls in RA at the same time. So, that is a nit, but not a small one. I woud prefer being able to use slow motion controls without having to physically disconnect the collar from the drive motor. The later designs simply let you de-clutch the motor to use slow motion controls. But I don’t really use this scope at more than 120x and at that power, the motor seems so far to be unnecessary. So, maybe old habits are at play here. But maybe not. More later….
The third quirk is that the head does NOT take a dovetail. Not only that, but the way the head is designed, a later Vixen pattern dovetail won’t CLEAR the grove in the top of the mount (which oddly has a profile that looks like an INVERTED dovetail) so you can't simply tab holes in the bottom of an existing dovetail to bold it to the saddle. You basically HAVE to use rings boldted to the tabs that project from the front and rear of the central box. This is too bad really, because dovetails are a far better solution, allowing for quick changes and easy rebalance. But in fact, it isn’t THAT big a deal if you intend this mount as the dedicated mount for a small telescope, where you want something light enough to carry out in one trip
The 4th quirk is that the spreader on the older Polaris mounts depended on the presence of the accessory tray to work. There are tabs on the legs and the accessory tray screws into them and is held in place by small wing nuts. I don’t like messing with small screws in the dark. This means that the tripod legs cannot be simply collapsed by lifting the spreader. The good news is that the tabs that extend from the legs are slotted, so that you CAN adjust them to present a taller, narrower configuration which makes it easy to maneuver the mount through doors, but if you get it TOO narrow, might risk a tip-over. With mine set to a medium width, there is still ample room to clear the door frames when taking the scope in and out. But if you are going to put it in the car to travel you absolutly need to take the accessory tray.
The final quirk is that it uses a threaded counterweight shaft, and a threaded counterweight shaft takes, well, a threaded counterweight. This means that unlike later GEMS, if you want a weight, you have to get a Polaris weight. But mine came with a weight that was heavy enough to balance the Celestron 80ED, so I am fine with this. And in some respects, I LIKE the threaded shaft. The weight is awkward to start, but once you have it screwed on a couple of turns, it won’t slip or come off. And with a smaller scope, leaving the weight on when moving the scope really doesn’t make it all THAT much heavier. But I would have preferred a smooth shaft. My guess is that later shafts will fit it, but again, because this is a DEDICATED mount, I am OK here.
With me so far, Vern??? Good. Ok. Then what we have here is a very compact German Equatorial Mount that is superbly well suited for a small telescope, being light enough to carry out with the scope mounted. Total weight of the COMPLETE assembly with tripod, head, scope, diagonal, counterweights and shaft, and accessory tray is…26 Lbs. That’s right. 26 lbs. This is EASY to lift and carry with two hands, and fits through a standard doorway without even having to slightly turn the legs to crab through the opening. And if that is not enough, They ALSO have...The TRICK!
Here is the neatest trick you will ever see. The Polaris has one attribute that no other GEM mount currently made has. Because of the way it was engineered, it is easy to use it as a dual role mount!!! Most people don’t realize this, but the Polaris can be configured for either GEM operation - OR - Alt-az operation. In other words, you don’t NEED to use a counterweight! And the head assembly without the counterweight only weighs a bit more than the Gibraltar head. Couple that with a lighter tripod, and the Polaris configured for Alt-Az operation weighs almost the SAME as a Gibraltar. Oh maybe 2 or three pounds more, but it is pretty stinking close. It probably weighs close to the same as a Unistar mount.
Study the picture, and you will see what I mean. On the Polaris, the complete RA housing actually sits BETWEEN the altitude upright supports. The base of the mount is designed so that the RA housing can be pointed straight up. Notice in the picture that the “Saddle” on the Polaris also sits much CLOSER to the RA axis. This is because at the time, there wasn’t really much of demand for Declination motors, so there the mount wasn’t engineered with enough space between the saddle and RA housing to accommodate one. As a result, when compared to a CG5 style mount, the telescope sits in much closer to the centerline of the mount, greatly improving the center of gravity.
On the later Super Polaris and derivitives (AND the CG4, which is closer to the Super Polaris in design than to the Polaris), the RA housing sits above the Altitude uprights, so if you attempt to point the RA shaft to zenith, the RA housing tilts to the back causing the center of gravity to move well off from the centerline of the tripod. Also, the declination shaft housing on these scopes also was extended so that the Dec motors could clear the top of the RA housing. If you were to attempt to use these later mounts in Alt-Az mode, this moves the CG ever FURTHER out. When you and another 6 or 7 lbs of telescope, you are in a dangerous configuration because of the possibility for a tip-over. Now even if you mount CAN be configured in this way (most of the CG5 clones won’t allow elevations this high) you will most likely have to use counterweights to be comfortable… So now you are looking at something like 40 lbs. total weight.
SO the REAL trick is that when using a small refractor with a Polaris configured for Alt-Az operation, the counterweight and shaft are simply unnecessary. In fact, in this configuration, having a dovetail would have worked AGAINST me, because it would have extended the CG of the configuration out an inch or so, while the ring mounting keeps the OTA quite a bit closer to the center of gravity.
So now I have TWO mounts in ONE. I have a small, non-motorized GEM, which allows me to track using the RA slow motion or a motor if I should decide to ad one (on the fence), OR I can use in in Alt-Az configuration. In Alt-Az mode, I can manually slew the mount in azimuth, and use the slow motion cable in elevation, which keeps me from having to worry about balance or tension adjustments. As an ADDED bonus, the DEC slow motion extension shaft and knob act as a PERFECT little handle for moving the scope in Azimuth.
Here are the numbers… When configured in Alt-az mode, the mount, WITH telescope, rings, diagonal and 6mm Radian, weighs ---------- 19 Lbs ------------. I can lift that with one hand. Easily. And it goes through doors with PLENTY of clearance. Even in EQ mode, the whole thing weighs only about 26 lbs. I can carry that with two hands. It isn’t the weight so much as the bulk in this configuration. I can LIFT it with on hand, but the top- heavy nature makes it better to use two. In Alt-Az configuration, the mount is bottom heavy, but in Polar mode, it wants to tip if you lift if from the base of the head.
I can carry the mount outside in Alt-Az configuration and change to GEM configuration in about 60 seconds. To convert from Alt-Az to GEM, simply scew in the counterweight shaft, loosen the lever that holds the RA housing, and tilt it down so that it rests against the Latitude adjustment screw. 60 Seconds. There is literally nothing else to do. You COULD rotate the OTA in its rings if you want the focuser knobs to be parallel to the ground, but GEM users don’t seem to care as much about where the focuser knobs are because we are used to them not being parallel to the ground. It is SHOWN in the pictures this way though, because my guess is that most users would orient it this way if they were using it mostly in Alt-Az mode. An important point here though. The orientation as shown in the picture, with the Dec/Altitude control OVER the focuser knobs is optimal. The reason is that with it set to the other side of the mount where the knob is BELOW the focuser, the knob will hit the mount when attempting to get near zenith. The culprits are the Longitude adjuster bracked, and the polar alignment azimuth adjuster. They will obstruct the knob when it is run Uunder the focuser. But if you LIKE it this way, and you intend to use the mount ONLY in Alt-Az mode, well, they can be REMOVED!!! Like I say, it is almost as if the engineers INTENDED this mount to be used in Alt-Az mode. But the reality is that I actually kind of prefer the knob running over the focuser, and I DO use the mount in GEM mode (for now... Old habits die hard), so for now, I have left them on...
I can configure the mount so that the focuser, Elevation, and Azimuth knobs are within a couple of inches of one another. This means that I can go to either knob in the dark without any fumbling. And I can use one hand for the slow motion controls, and one hand for the focus. The lock levers are another two inches away, and the scope can be configured so that they are all on the same side of the mount. This means that if you want to make a BIG movement of the scope, you can simply flip the unlocking lever, pivot the scope, and re-lock. Now, you CAN use the declination locking lever kind of like a clutch, keeping it tight enough to prevent creep but still allow the scope to be moved, but the movement in altitude, but the movement in elevation won’t be quite as smooth as a Gibraltar or Unistar….
How is it to use? In a word, WONDERFUL…In EITHER mode.
When working with charts in GEM mode, the geared controls make it a SNAP to locate objects. This is because you don’t even need to use the setting circles (Which ARE very nicely done). The reason this is true is because one complete rotation of the Declination knob moves the mount 5 degrees. One complete rotation of the RA knob moves the mount 6 degrees. Even without accurate polar alignment, star hopping is still much easier to me when the mount moves more or less parallel to lines of Right Ascension and Declination, and with the wide field of the 80ED, you can home in on an area of the sky even after a LONG jump with great precision. If I have to move 10 degrees south of a particular jump-off point, two complete turns of the DEC knob get me EXACTLY that far. Of course this has always been on of the reasons I liked GEM mounts. I find it MUCH easier to star-hop because of the ability to move along lines of RA and declination when using charts. Double Stars are the hardest to find, and often the ONLY way I am successful is to use good charts and work from prominent starting positions.
In Alt-az mode, I can lock the DEC knob, and never have to worry about tube balance. I can either leave the RA knob loose and use the DEC knob on its long shaft as a handle to point the scope, or I can use the slow motion controls for a more positive sweep.
Another benefit is that focusing at high powers is SIMPLE. With the Gibraltar and Unistar, I was always bumping the target out of the center of field when focusing if I left the tension light for easy movement of the OTA. Even the torque of the focuser knob would sometimes be transmitted through the tube causing it to tilt up or down. And when changing from light to heavy eyepieces or vice-versa, I had to either remember to tighten the tension, or hold the OTA in place by hand, which could be almost IMPOSSIBLE when going from a 22mm T4 to a 5mm Radian. The telescope would just want to MOVE on me. I was SO frustrated trying to use these other mounts because I DO change eyepieces so much, and I was constantly having to fuss with the tension adjustment knobs. The Polaris totally eliminates these issues.
The controls being closely grouped makes manual movement of the scope in EITHER configuration very precise. I like to do methodic sweeps, and the slow motion controls please me greatly.
As for stability, the setup is rock solid. The short solid legs are flex-free, and dampening is ultra-fast, even without vibration suppression pads. The C 80ED/Polaris is even more solid than my CGE/C14!!! I can smack the mount and there is NO wobble. It has IMMEDIATE dampening.
There is one IMPORTANT note to make here… When the Celestron 80ED with 2” diagonal is used on this mount, even with the focuser cell shoved right up against the rear mounting ring, the scope is tail heavy. Only a tiny little bit, but it is tail heavy. When used with lighter 1.25” eyepieces, the viscous motion of the declination axis is enough to hold the scope in position, but when using heavy 2” eyepieces, you DO need to clamp the Dec lever. This means that you almost have to use the slow motion control for Elevation. I should also point out that if you do this for a long, long time (maybe several years of usage), having this much of an imbalance may cause premature wear of the worm gear. Hard to say. But at any rate, this problem even exists for this particular scope combination when the scope is used in GEM mode, but my opinion is that the loading in Alt-az configuration is a bit heavier than when used in GEM mode. And I personally just am thrilled to be done with tension adjustments and high-power focusing issues.
So, the Celestron 80ED with its superb optics is FINALLY getting some love. And it was the MOUNT all along that was the source of my displeasure. Suddenly, the whole concept of a grab and go scope is finding FAR more favor with me because the mount just WORKS so well. You have to see how cool this is to believe it. I considered a Polaris long ago, but just never really felt that the small achromats scopes were worth it so never pursued it. But now, having a very high quality small scope is making SENSE for me, because I finally found an Al-Az mount that I LOVE, and it was CHEAP. In fact, I have only had the mount a couple of days, but already I am finding that I like using it in Alt-Az mode as much as in GEM mode, and for terrestrial use, when configured for Alt-Az mode it is absolutely fantastic!
Finally, this thing breaks down into one of the most incredibly compact packages you can ever imagine. The head itself will fit in a shoebox with room to spare because of the way that the RA housing tucks in and the tripod is tiny. Some of the Mini-mounts are a bit smaller, but at what point is small enough actually "Small enough."
So, the old Polaris mount turns out to have a really neat trick up its sleeve. If you are a small refractor lover, and have experienced any of the frustrations I have documented here, the Polaris mount may be the solution to the problem. I would call it "THE" Alt-Az mount for GEM lovers, bringing you the best of both worlds.
Aart Olsen was kind enough to diplomatically point out an error in my Polaris review. Aart caught a mistake regarding the use of the RA knob. In the review, I mentioned that one revolution of the knob moved the mount 6 degrees. In fact, it moves the mount 10 MINUTES in Right Ascension. In fact, I was thinking 1/6th of an HouR, and sometimes hard math like this gets me confused, so I got my minutes, degress, and rotations all goofed up.
My regrets for the mistake, and my thanks to Aart for catching it and taking the time to let me know.
|All times are in (GMT-8:00) Pacific Standard Time Zone|
|Astronomy News | Telecope Classifieds | Telescope Auctions | Telescope Reviews | Telescopes | Telescope and Astronomy Forums | My Account | Help | RSS|