[gregbradley]

I bought Raki's AP1600GTO a few months ago and drove to Melbourne from Sydney to pick it up. A great road trip that included the Great Ocean Road and some skiing at Buller.

I have used several mounts. Meade LX90, Vixen Sphinx, Mountain Instruments 250, Takahashi NJP, Paramount ME (Still have that), Software Bisque PMX (sold to Erik) and now AP1600GTO.

The only reason I sold the PMX was I could see the AP RHA scope and heavy imaging train, thermal blankets, dovetail plates, rings were at the ragged edge of its capacity and I would get some really nice guiding but everything had to be perfect. I think it handles loads up to about 30kg perhaps 35kgs but the 40kg rated load is a bit optimistic. Still a nice mount and many very good nights of tracking with refractors showed it to be a beauty. It was something of a reluctant sale as only a few months before I saw the best tracking ever with my then AP140 scope at my dark site using this mount.

The AP1600 is more of a competitor to the Paramount ME. I have both and I like both. The PME'sonly advantage over the basic AP1600 is the home switch. I also like the clutch release knobs of the PME. In all other ways I think the AP1600 is superior. That does not mean the PME is no good. Far from it, its still an amazing mount.

The AP1600GTO had these aspects that appealed to me:

1. AP 's total professionalism and amazing competence and practicality. The super high standards they run at.
2. Everything I have ever had from AP was the absolute best and worked without tinkering and was best in its class.
3. The mount can be retrofitted at home with absolute encoders and home sensor for unguided tracking with no PE for around US$8000 or less.
4. AP states a maximum of 5 arc secs/pixel PE as opposed to SB who rate PME 11 at 7 arc secs.
5. It breaks down into 2 major parts easily for transport.
6. It has a complete set of accessories, dovetail holder etc.
7. Its rugged and durable and has a 105kg rated capacity, which knowing AP is proabably conservative rather than my experience with the PMX which was slightly overstated.
8. I liked the idea of an AP mount with an AP scope.
9. I was disappointed by the very unprofessional and flubby way SB handled the PMX release. Quality control seemed to be lacking although to their credit they made it good and they give quite good customer care.

The mount is heavy but it breaks down into 2 parts via a clever interlocking dovetail system. Its very secure which was something I was concerned about, but looking at it the engineering is such that it would be almost impossible for it to pull apart and detach once connected. Each component is heavyish but manhandleable by an average man. This is clever. Each component would weigh a lot less than a PME 11. PME I think must be less heavy than PME 11 as it is reasonably manhandleable (I think, its been a while since I put it on the pier it stays on, it wasn't that heavy). The PME is perhaps at the ragged edge of portability, the AP1600 is heavy but handleable.

The through the mount cabling system is smart and well designed and plenty of room without crowding.

The altitude adjuster is a very clever unit with a large hand grabbable handle which makes fine tuning very easy and its also easy to turn whereas the PME altitude adjuster is quite hard to turn when its loaded with a scope and gear.

The counterweight shaft is around 50% thicker than the PME and PMX which would mean less flex.

Styling is classic but PME 11 looks very nice and PMX is an attractive mount in its pinky red colouring.

The control chip is also easy to change over to the latest which is a plus. SB mounts would require a new motherboard and would be quite an operation to strip the mount down to replace it.

PMX had a nice set of power outlets and USB hub on the dovetail plate that I used occasionally although the USB is a little sensitive to startup sequence so if it dropped out it was a little extra work to get everything reconnected.

The hand controller is rugged and quite large but easy to use for the AP1600. I also like the joystick unit of the PMX and to a lesser degree the PME's joystick (harder to do fine adjustments). You can easily turn down the slew rate with the controller to make fine framing easier. Quick and easy. Also there is an easy to find stop button so if the mount is about to slew your scope into the pier its easy to hit that and it stops it so no need to only have your cursor over the X symbol on the slew box when using Sky X.

The mount is fully compatible with the SkyX via a free Ascom driver and there is also a more advanced driver system that is a replacement for a lot of Sky X controls. The free driver comes with a timer so I use that to make sure the mount stops at a certain time so no risk of hitting anything.
I find Ray Gralaks programming (author of Pempro) to be a step above mosts and his software is rugged, reliable and it just works. Pempro is one of the first astro programs I have found to be able to use first time without some oddity. It just works and does its job without the need to dive into the manual or try to debug or it won't connect to the scope and mount etc etc.

I am able to use TPoint and construct a Tpoint model more easily than with the PMX as slew limits don't get in the way of a successful slew.

Go to accuracy is as good as PME and PMX which are both excellent.

The clutch system on the AP is much better than both PME and PMX. Its kind of stiff when loose and you tighten it from there. But if stopped it could slip if it had to. No risk of slippage from imbalance. Nice and secure.

The motors sound very powerful and indeed they are the same motors as used on the AP3600 El Capitan mount.

Most importantly is the tracking. My PMX had a replacement worm and when tuned up with a nice TPoint model and accurate polar alignment
routine of TPoint was giving around 1.5 to 1.8 arc secs guiding. Very nice.

Pempro PEC curves help and so does a good Tpoint model with tracking corrections enabled.

PME is also very good. I am not sure what the guide errors are but with a MMOAG it will track the CDK17 10minutes and very round stars at 3 metres. Impressive. I also like the simple turn a knob to release the gears for easy movement and balancing of the scope on the PME. It works really well. I am not sure why SB moved away from this as I rate that as a nice feature. PMX 3 way switch keeps you on your toes. Its good so long as you remember to never unload a camera or try to unload the scope without the 3 way switch set to lock. You could potentially smash a scope or drop a camera if it started to slip from a large imbalance if you did not set it to the locked position. I damaged an RCOS scope on the MI 250 mount that way one time. Not pleasant. It had allen key locking clutches (don't go to a dark site and forget to bring the allen keys - oh wait, I did that once! grrrr a beautiful clear night as well).

The AP1600GTO without PEC was running at less than 3.5 arc secs. I think it was around 3. With PEC and using PHD2 guiding (it gives superior results to Sky X autoguiding) I am often running just under 1 arc sec (lowest seen is .62 for about 5-10minutes then it went to .78!). Typical is around .9 to 1.05 arc seconds. This is the most accurate guiding I have seen from any mount.

PEC was very easy to upload into the mount.

It handles the 43kgs of the Honders easily like it was nothing. The PME handles the 80kgs of the CDK17 and gear also very easily. Both are heavy duty mounts.

I do like the home feature of the PMX and PME. You can get that with the AP and there may be a kit to install that at home. If you install the encoders that comes with a home switch as well. But the AP works from a known park position and it always knows where it is. Computer crashes do not affect this. So you could have a computer fail and restart it up and the mount will still be aligned. Rugged and robust is how I would describe its operation. PME is also pretty rugged and PMX a bit less so as its integration with software meant at first a little bit easy to make drop out (the software that is) and with later versions of the Sky X that is now more stable and reliable.

Price wise a new AP2600GTO is USD$11,000. PME 11 is around $15,000. I can't see the extra $4000 just for a home switch so the AP is much better value for essentially a higher performing mount tracking wise (at least there stated PE levels) with a lighter countershaft, no home installable encoders, also SB is prone to changing mounts specs with no backup or concern to existing purchasers of earlier models and no backwards upgradability. AP does. Its a bit like Fujifilm giving free substantial firmware updates over several years for a model whereas other manufacturers either don't and fix bugs with a new model or only give firmware updates to fix major flaws not real improvements like Fuji gives.

So yes I feel it was a great decision and the mount is exceeding my expectations and I plan on one day installing the encoders to have a mount capable of 10 minute unguided tracking with no PE.

Also access to the genius Roland Christen. I bought the mount 2nd hand, I had a computer crash and I had to switch computers and wasn't sure how to do a fresh startup. He answered personally same day and followed up with several postings as well as another technical staff member. SB also have reasonably good support, not as fast as that but they do answer your questions but it may take a week or two. So AP gets a big tick for customer support.

So yes I highly recommend an AP mount and it is a very well engineered and thought out piece of astro equipment that basically disappears into the background when you are imaging. You can concentrate on the imaging and just depend on the mount to do its job once setup. Exactly what you want and somewhat rare in this astrophotography world where fixing up and modifying gear to make it work is too often the norm.

As the mount is the most important component of the astrophotography setup its well worth considering investing that bit extra to get a reliable fussfree mount that will give many years of round star imaging.

Greg.