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APM TELE-OPTIC GR-2 ALT-AZ MOUNT
As should be obvious to those of you who have read my prior mount and/or scope reviews, I consider EQ mounts
a necessary evil for purely visual astronomy. A well built, properly-functioning Alt/Az mount is faster to set
up and faster to use than an EQ mount. The key to this, of course, is finding an Alt/Az mount that will work properly
with your refractor. Having already found at least two Alt/Az mounts that fit my needs (the Tele Vue Gibraltar
and the Vixen Alt/Az Custom D), reviewed elsewhere on this site, I had forgotten that I had ordered the APM Tele-Optic
Gr-2 mount from Bill Burnett at ITE some time ago. When I read that several had been spotted at RTMC, I called
Bill, who told me my mount was in and ready to be shipped. It showed up this morning.
The best way to describe the mount is to show it to you. Below are several pictures showing the mount with and without the counterweight shaft attached. Above is the mount with my AP 130 F/6 attached using the standard AP rings bolted to a mounting plate I bought from Anacortes and manufactured by them for their Yang refractors, which use the same type of AP mounting rings. (More on the mounting plate issue below.)
The description of the mount and its construction as given by Bill at the ITE site is as follows:
"Designed, patented and built in Germany, this mount is designed to work with most telescopes up to 40 to 50 pounds tube weight in the azimuth mode with ultra-smooth turns. Both axis are ball bearing supported and adjustable by 2 hand knobs for different pressures (shown in the image). The mount is made from black anodized aluminium and stainless steel. The mount is designed to work on any tripod from Vixen, Baader, Meade, Losmandy, Davis & Sanford, or Celestron. The counterweight-shaft is constructed of stainless steel and has a diameter of 20 mm. It can accomodate counterweights up to 40 pounds. The optional counterweights supplied by ITE are also made from stainless steel.
The mount comes with a plate to hold the INTES MK66, MK67, MK69, MN69, MN71 and the INTES MICRO A-703, A-603, MN76, or MN56."
The only confusion I had once I got this mount was whether it was the "standard" (in German, 'standart') or the 'Deluxe.' The APM website notes the distinction as follows:
"Giro-2 Standart Mount: This mount is designed to handle tubeweights of about 20~25 pounds on each side ,side, using our strong woodtripod GIRO-2 Deluxe Mount This mounts holds on either side up to 50 pound telescopes without any problem if the mount is used on our strong woodtripod."
I have a note pending to Bill Burnett to find out the answer to this question and will update as soon as I am informed by him of the answer.
The photos show the mount on one of my Meade Field tripods. The hole in the mounting base mated up perfectly with the center screw that comes up from the center of the tripod. (I have found the Meade field tripod a VERY sturdy and rock steady base for my 40 pounds of Fujinon 25X150 binos. They were an equally sturdy and steady mount for the AP 130 and this mount, even with the AP binoviewer, Barlow, and two Panoptics in the binoviewer. The weight of my 31 "Terminagler" didn't seem to phase it either. A good, steady, and cheap tripod.)
SET UP AND INITIAL IMPRESSIONS:
My first impression was, "you have got to be kidding!' The thing looked just too simple to work. The moving parts were minimal, and the simple friction knobs to control Alt/Az movements looked like low tech at its best. It couldn't work, could it?
One thing I refused to try was the mounting plate that came with it. Thin, green painted or anodized metal labled "Mizar", the plate looked too flimsy to support anything heavier than a ShortTube 80. I had purchased a mounting plate from Anacortes (shown in the pictures) and a look at the mounting system for the Gr-2 mount showed that the spacing of the two 7mm (?) Allen bolts in the head would let it mate to the Anacortes plate. Since that plate looked about a million times more solid and MUCH better machined and finished out of better materials, I bolted the AP rings to that. Maybe I was overly cautious, but the 'standard' (?) Mizar plate just looked too flimsy to make me feel secure. (However, the Mizar plate is intended to hold an 80 to 100mm TMB, etc., so it may be prefect to handle scopes of that size, I simply didn't want to chance it with the heavier 130.)
Set up consisted of putting up the tripod. Taking the base unit with the plate and rings already attached, tightening down the azimuth screw, and then screwing the center screw up into the base of the Gr-2 head. I then attached the counterweight shaft and the counterweight.
It was with some caution that I loaded the AP 130 f/6 into the rings ("hold you hands under this honey
while I secure it, and then stay there while I check it.") Step back, check everything - and I am pleased
to see that all is secure and, from a bit of preliminary shaking to check it, pretty damn steady! Now wait for
the sky to darken and the scope to reach equilibrium.
HOW DOES IT WORK?:
In a word - GREAT! Once it is balanced ( loosen the Alt knob and slide the scope and -at first- the binoviewer and two eps and later the diag and the "Terminagler" - up and back in the rings until it is balanced. Then tighten the Alt knob again and you are done.
Once that is done, with the right amount of tension on the knob, the scope moves crisply to where you want it, and then stays there. Vibration with two 5 Tak LE eps in the binoviewer when focusing on the Moon dampened far more quickly than the Vixen Alt/Az. Viewing was steady and 'clean' even with the Barlow in front of the binoviewer (although that was REALLY pushing it last night - the seeing being the limit, not the mounting.) I found that I could move in 'broad strokes' or in small, incremental moves along the Moon's surface - all I could ask from ANY mount.
Deep sky use. Binoviewer out and Maxbright 2" diag in with the 31 Nagler on board. The sky is getting some high clouds to the South, so I spend a very pleasant hour and a half 'cruising' the North and Northeastern skies. The only way to describe the way this mount worked was pure pleasure. The only limitation I found was that, given the physical size of the mounting plate I had chosen, it would from time to time hit the tripod leg just before I hit the zenith. This would not happen with a slightly shorter mountingmount plate. When it did take place, I just moved the scope a fraction in azimuth, and then I could point straight up! No "Dobson's Hole" for this Alt/Az mount!!! The FIRST AND ONLY Alt/Az mount that was able to point straight up and not be any bother at all, as shown in the pictures.
If you look at the pictures, you will see that the scope rides fairly low on this type of mount. I observe sitting
down (I'm an old fart) but found that even at the zenith, the Starbound chair at a lower setting let me observe
in complete comfort. You could, if you wish, use a tripod that extends up higher.
I am in love. It may look crude, but so far, it does all that I have asked without any of the drawbacks of the
other mounts. And it is VERY reasonably priced. I wonder if it really will hold 40 or 50 pounds as claimed, assuming
this is indeed the 'Deluxe' (?) model. (Please read the comments on this above.) Until I get this issue resolved,
I, I am not sure if I want to put my AP 155 in the mount just yet. When I get the answer from Bill and work up
the courage, I will update, and let you know if it works and if the 6" is a happy as its smaller brother in
this mount. In the interim, highly recommended for 5" (or 5.5" if you have a TV 140) or smaller refractors
etc. I am impressed.