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Losmandy GM-8 Mount



I remember my excitement the day when my new 6" Maksutov Cassegrain telescope arrived. It was a thing of beauty - compact, beautifully designed, clearly well built and best of all - exotic. I quickly attached the scope to my Taiwanese equatorial mount (about $230 retail) and waited for the sky to clear up so I could get first light with the scope.

I have always had a fondness for high quality optics in small packages. If given the option, I will always pick quality over aperture. Compactness over bulkiness. There is something very appealing about having a telescope setup that is small, fits easily in my car and can be packed away easily. I have never really liked having to set up (and especially break down) heavy equipment (especially at 5 am and zonked out of my mind). For this very reason I have shunned big, bulky telescope setups. In fact, I consider it my first axiom for telescopes:

Axiom I - Always choose quality observing systems in compact packages.

At the time, Mars was at opposition and I got my first glance at the planet through my wonderful new scope. "Wow, if I can only get the image to steady" was the first thought that went through my head when I tried to focus the image. After a few attempts the planet had zoomed out of the field of view and I had to reposition the OTA only to try again. Finally, after much effort, I was able to focus and track the planet manually. But, boy oh boy, did it take practice.

I quickly started to realize how much the shakiness of my mount was beginning to take away from my viewing sessions. The view of a planet, moon or deep space object looses something in the translation if it is dancing around a bit before settling down. It also becomes frustrating to see your view vibrate as if someone just sent electricity through the sky - just because someone walked by or touched your scope.

In other words, the mount was very difficult to use. It was always "getting in my way" for observing. I found that I was spending more time trying to adjust and use my mount than I was observing.

At more serious events, some observers asked "Wow, nice telescope! What's up with the mount?" It was then that I realized that I had committed perhaps the most common sin among amateur astronomers - I had spent all of my efforts in an excellent optical tube and eyepieces, no attention to the mount. After all, a mount is B-O-R-I-N-G. You cannot look though it, it simply holds the scope. The mount is the "supporting actor" for an otherwise excellent show, but it certainly is not the "Star" (the OTA is certainly the 'Star').

Contrast this to another scope a C-11 which was perched on top of a Losmandy G-11 mount. It was truly larger than life. At first, I thought that it rivaled the big 18" dobs in size. The owner of the scope (a good friend of mine) had just purchased it and had the legs fully extended. Man was it BIG!

One look through his C-11 scope provided me with what I call an "epiphany" for that evening. The views of the scope just looked good. I could actually grab the OTA, shake it and still not see the field of view move much at all. Wow! There is something about a solid mount that imparts quality.

The mount was also very easy to use. All I needed to do is point the scope in the direction that I wanted to observe, find the object and view. The mount took care of the rest. No levers, no clamps, no manual tracking. My world was rocked and my whole view of traditional telescope mounts began to shift that evening.

My original view was "Get an compact mount which is rated for your telescope's weight." My new paradigm now shifted to "Get the most solid mount that your money can buy." I loved the views through the solid G-11 mount, but was taken back by how BIG it was. Was I going to have to enter the world of huge telescope setups to get this kind of performance? I realized that my first telescope axiom was about to change or bend somewhat.

So, I had to make a decision, shaky compact mount, or big solid mount? Which would it be? If my thesis is small and compact, and the antithesis is big and solid, can I come to a synthesis of some sort - small and solid? I began to search for options.

The Options

My search for a mount made me realize how few options there really are. I noticed that the mounts fell into 3 different catagories: (1) Inexpensive decent mounts, (2) High quality, but for smaller OTA's, (3) High quality, big and heavy mounts.

Inexpensive decent mounts

The first category was exactly the type I now owned. It is the Taiwanese mounts that are so popular today. A good example of this is the Orion SkyView Deluxe mount. After using the mount for some time I have come to the conclusion that they are excellent for smaller refractors and maybe a few small reflectors. The mount can handle about 12 pounds max, so it is limited to small short focus refractors up to about 4" and that is pushing it. It is best used with scopes around 3" and reflectors to about 5". Since I was already in this category, I did not even consider this in my quest for a new mount.

High Quality but for smaller OTA mounts

The second category was high quality mounts, but they can handle up to about 16 pounds. Example of this kind of mount are the Vixen Polaris and Great Polaris mounts. My Mak weighs about 16 pounds so I already knew that I was going to max out this mount before even buying it. A few quick emails to some owners my type of scope quickly told me that the mount was adequate but still suffered from a shaky bottom line. Comments such as "It is okay for visual observing, but not for photography," and "Vibrations dampen in about 4 or 5 seconds" told me that it was NOT what I was looking for. In my opinion, these mounts are excellent for small to medium size refractors up to about 4", small to medium reflectors up to about 6" and maybe SCT's up to about 5".

The Big and The Bad - Heavy and Expensive Mounts

The last category was in the big, expensive, heavy duty mounts. Here there is a quantum leap in price and size. Examples are the AstroPhysics mounts and Losmandy mounts. I already knew that the G-11 was out of the question - was there anything else?

Enter The Losmandy GM-8

When I was at the Fall Star Party in Chiefland last Fall, I saw a beautiful setup of a Losmandy GM-8 with a 4" Takahashi refractor. The owner had it set up in a Kendricks Observing tent. One look quickly told me that this mount was the sythesis of my prior thesis and antithesis. It was small, it was compact. It looked relatively light and easy to break down. It also looked solid. A quick Q&A session with the owner of the mount revealed to me that the mount can conservatively hold 30 pound OTA's - I had found the mount that I was looking for. I immediately ordered one.

Seeing the Losmandy GM-8 for the first time gave me my second "epiphany" for telescope mounts. Enter my new axiom for telescope mount design:

Axiom II:

1.The mount should be compact and store easily
2.The mount should be transparent, and easy to use. and get out of your way. In other words, it should "get out of your way, and not be noticed. Remember, the mount is the "supporting actor", not the "star" of the show.
3.The mount should provide excellent overall stability and allow the OTA to "do its thing" - perform. It should not detract from it.

Operation

The combination of extremely high quality optics with a solid mount produces results that are magical. The combination of these two elements synergistically combine to produce a result that transcends that of either two alone. The basis of the mount is not to add to the overall performance of an excellent scope, but to provide the overall support to the optical assembly so that its performance can be maximized. In other words the purpose of the mount is to become "absorbed" by the optical assembly and provide the logical extension to the scope.

The GM-8 for all practical purposes does exactly what it is supposed to do according to the above axiom for telescope mounts. I willl describe the mount in 3 different aspects: in its (1) Ease of Use, (2) Transparency , and (3) Support.

Ease of Use

The GM-8 is very easy to use and is easy to set up and break down. Setup/breakdown is done in about 5 minutes max. The head unit fits nicely in the Doskocil Extra Large Case and can store with many accessories with it. The tripod folds up and stores easily in a larger tripod bag - such as the ones made by Tiffen.

One useful accessory is the Tripod Knob Set available for $45 directly from Losmandy. These knobs allow you to attach the Equatorial Head unit directly to the tripod without the use of any allen wrench tools. You simply screw them in and the mount is secure to the head unit. It makes setting up the mount quick and easy.

The whole mount breaks down to very small parts for easy storage. The largest part to store is the tripod itself. The head unit, if stored in the optional Doskocil Case takes up very little room at all. I have my entire mount and telescope stored in a small closet in my guest bedroom.

Actual use of the mount is very easy. All you need to do is plug in the power, polar align, turn on the tracking motors and simply point to the object you are looking for and observe. The tracking motors are fully clutched so there are no levers to turn or release when you want to find another object. All you need to do is move the OTA to the next object and start observing.

All in all, the mount is VERY SIMPLE to operate. It has virtually no learning curve. Any beginner can start using the mount as soon as the get it.

Transparency

The GM-8 mount seems to virtually vanish in actual use and allow you to operate and control the OTA unit. In other words, it provides all the functions needed to successfully OBSERVE and not figure out how to operate the mount itself.

Tracking on the mount is superb and is flawless if the scope is polar aligned correctly. The tracking is so accurate that if an object is centered in the field of view and is left for some time (if you happen to wander off to look through some other scopes), expect the object to still be in the field of view. I have found this to be true regardless if the tracking is for deep sky, lunar or planetary observing.

Polar alignment is simple with the optional polar scope. It is fully illuminated and of high quality. All you have to do is orient the inner scale in the general direction of the Big Dipper and Cassiopeia and align Polaris and 2 other finder stars in "slots" that are in polar scope. Once that is done, you are very accurately polar aligned!

As stated earlier, since the mount is fully clutched, viewing objects is simply a matter of moving the OTA to the object desired and looking at it. You never need to flip a switch, release a lever or change any settings. It is legitimately a point and look mount. It is very nice to find a difficult object and have the GM-8 mount AUTOMATICALLY begin tracking that object without any other effort on your part. It makes life easy!

Support

The GM-8 mount does an excellent job providing solid views without any vibration or twitches whatsoever. The OTA remains on target regardless if I need to touch up the focus or slew an object to the center of the eyepiece. The mount is so solid that you can grab the OTA, shake it and still have almost no vibration at the eyepiece (of couse when you do shake it you will see it move, but vibrations dampen in less than 1 second).

The mount is solid enough to push up magnifications way beyond the 300x point. All elements of the mount seem to pull together nicely (tracking, solidity of the mount) to keep the viewing both enjoyable and effortless.

Construction

The construction of the GM-8 mount is of top quality materials and should last a lifetime. The construction is entirely of black anodized aluminum and stainless steal.

However, one last accessory should be considered. The gear covers that come standard with the mount are vinyl slip on covers. I would highly recommend the aluminum covers. At $70.00 for the pair, they are quite pricey, but very well worth it. I have heard at least 2 stories of destroyed stepper motors due to the accidentally hitting the motors.

Summary

The GM-8 mount at a retail price of $1700 is worth every penny of its asking price. If your OTA weighs up to 30 pounds, it is well worth consideration. It provides excellent, solid support for the telescope, is extremely easy to use, and does not create any problems of it own to tend to. All in all, it seems to vanish, or allow the OTA, the real star of the show, to show its stuff. It provides support that is synergistic that allows performance that transcends that of the OTA's ability alone.

The GM-8 combined with any medium sized high quality optical system provides a system that simply cannot be beat for performance in regard to portability. It comes highly recommended. Like any high performance astronomical equipment today, it comes at a price and can take up to 6 months to acquire - but the price and wait are well worth every cent.

Specifications:

R.A. / DEC. AXIS

The GM-8 is made of all machined aluminum and stainless steel and black anodized. All of the hardware is made of stainless steel. The mount utilizes dual axis aluminum worm gear tracking with stainless steal bearings. Each axis has 160 oz/in stepper motors. The GM-8 has variable slip clutches on both axes and has a one knob design.

The head unit is made of 1.250" diameter aluminum shafts and has a fully locking, unique tangent arm design altitude adjustment between 0-64 degrees. The altitude adjustment has a large knob for easy alignment. The equatorial head's weight is 21 lbs.

The mount has 3.500" diameter laser engraved setting circles in 6 minute R.A. / 2 degrees DEC. The telescopes are attached to the mount via a dovetail saddle-plate that allows for the interchanging of any tube assembly.

The fat stainless steel weight shaft has a safety knob and is removable from the mount. The GM-8 comes with a 7 lb counterweight., but I use an 11 lb weight. There is also a 21 pound counterweights available. The mount also has a axis polar scope, which works in

Northern and Southern hemisphere. Keep in mind that the polar scope is optional.

The instrument weight capacity is conservatively rated at 30 lbs.

Tripod:

The tripod is all black anodized machined aluminum. The tripod height is adjustable from 27" - 43" and folds up for easy transporting. The tripod weight is 15 lbs.

Dual-Axis Electronics:

The GM-8 also has a dual axis electronics for tracking. The hand control box has diamond pattern push buttons and R.A. and DEC. reversing switches. The Control Box also has a panel dimmer.

There is three guiding rates; 30%, 50% and 2x sidereal rate and three setting rates; 4x, 8x, 16x sidereal rate and super fast 32x HST (high speed transfer) for fairly quick slewing across the sky. The electronics also has 4 quartz tracking rates: sidereal, solar, lunar, king.

The mount also has Periodic Error Correction (PEC) for very accurate tracking and programmable DEC Backlash Compensation (TVC). The mount works off any 12 volt DC battery it is rated at 500ma power use. The control panel is tiltable for easy access.

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