First light report - Orion Atlas Pro Alt Az

[The_bluester (Paul)]

Having talked about it for a couple of years I finally took the plunge this week and remounted my CPC925 on the Orion version of the AZ-EQ6, last night was my first chance to try the mount outside the confines of the garage.


Forgive me if this is not much of a formal review, it is more some initial thoughts on using the mount.

Firstly on arrival, the mount and tripod arrive well packed and protected as you would expect, well packed in foam for the fragile bits and double boxed. Once out of the box, setup only took about ten minutes.

The supplied tripod is quite sturdy, at least for visual use, anyone with an EQ6 will be familiar with it in operation. Mounting the head is the same as an EQ6, just spread the azimuth adjustment bolts and sit the mount head in the recess and wind in the captive retaining bolt, which also serves as the fixing point for the eyepiece tray/tripod spreader.

Once set up you are faced with the choice of using Alt Az or EQ mode, changing between the two is easy, without an OTA mounted, just loosen the Alt locking nuts, wind the Alt jackscrew up until the thread disengages and gently lift the head to 90 degrees via the counterweight shaft, locking it in position by means of a bolt which is normally stored in a spare hole on the side plate of the mount. When you turn on the mount, the first selection after it initialises is which mode the mount is in, it remembers your selection so if you switch off in Alt Az mode, it is pre selected on next power up needing only an "Enter" button press to confirm. EQ6 users might miss the "Comfort beep" though as it does not beep on initialisation or on completion of slews.

In Alt Az mode the alignment is simple, make sure first that the tripod is reasonably level, mount your OTA and balance it (Easiest to do while in EQ mode and mark positions) and then with the OTA facing north while the face plate faces south, switch the mount on and follow the simple instructions on the handset for a three star alignment. The only difference here between this alignment and my old CPC mount is needing to know more stars by name and manual site and time settings in the handset compared to the GPS ease of the CPC. Anyone with an EQ/Synscan mount will be familiar with the setup.

In Alt Az mode the goto's were pretty good, particularly as I really did not spend much time getting the electronic alignment spot on. Tracking appeared good and objects stayed pretty still in the EP for a decent time.

I played around with Alt Az for a little while and then reconfigured in EQ mode, making a rough polar alignment using the polar scope on Octans. In EQ mode it tracked nicely and was pretty accurate most of the time for Goto slews, but again, I did not spend much time on the electronic alignment, simply making a one star align on Sirius and then getting on with it. It was a little off slewing to Jupiter however my last goto of the night was to 47 Tuc, which was placed near the middle of the FOV at around 100X mag in a Plossl. The moon rose shortly after that so I packed up for the night.

Now on to the real standout for me. I remounted as I wanted the ability to use an EQ mode but Alt Az is often much better visually, but I was becoming more and more frustrated with slewing times and inability to manually point. With the dual encoders on this mount it does exactly as advertised. Loosen the clutches, point it where you want it, tighten the clutches again and it just keeps right on tracking, either in EQ or Alt Az mode. You can prove it quite easily by doing a goto on an object, manually pointing away from it a bit then hit enter again on the hand controller and it promptly slews right on back again.

The only disadvantage I can come up with (Apart from spending $2200) compared to the original CPC mount it that there is greater susceptibility to vibration if the scope is bumped but I think that relates more to my flimsy little narrow dovetail and the fact that the CPC mount appeared to be exceptionally good in that regard, you could really manhandle it without inducing any shakes. The polar scope illumination is a bit overwhelming as seems to normally be the case on the EQ6 and others even at the lowest illumination level, I could still pick out Octans though.

On the other side of the coin, the tracking with clutches released is a godsend as it makes Alt Az use with tracking AND manual pointing for quick target changes possible, and in EQ mode the altitude adjustment is so far ahead of the EQ6 variants that it is just not funny, no more bent and binding Alt bolts!

All in all I am a very happy camper right now.

[The_bluester (Paul)]

I forgot to add, I balanced the scope without an EP attached and then went and added a 1KG monstrosity EP (ES 82 degree 30mm) and an F6.3 focal reducer just to put the weight even further off axis and the mount still tracked and slewed with ease on both axis. And the clutch arrangement on this mount is substantially easier to use than either the CPC mount or an EQ6.

[barx1963 (Malcolm)]

Nice report Paul.
I've never seen one of these mounts in action, are you bringing it to Snake Valley?

Malcolm

[The_bluester (Paul)]

Yep, I have no other mount now.

[Camelopardalis (Dunk)]

Are you using a Vixen-style dovetail Paul? My C11 has a CGE/Losmandy style dovetail and it's rock solid in the puck. I find the vibration on my EQ6 comes through the tripod. I've wondered if a field tripod would do a better job with that kind of load onboard.

[The_bluester (Paul)]

Yes, mine is a vixen style. I put it on the scope ages ago while it was still CPC mounted to attach a counterweight to. It is solid in the puck but feels a little springy otherwise if you tap the OTA. I will fit a wide dovetail eventually but given I am pretty much purely visual it is not much of an issue.

[Camelopardalis (Dunk)]

Yeah the wider dovetail should reduce the flex a bit. At least you'd be able to use the Vixen one for a guide scope

[The_bluester (Paul)]

Just so long as my wife does not see mention of that slippery slope, greased with money (AP)

[The_bluester (Paul)]

Having now used my mount for a couple more nights I thought I would add to this.

Actually, not much to add. I took the mount to the Snake Valley camp on the weekend just gone and used it more or less from dusk to around 3AM both nights with a good few hours during the day in between with a solar scope mounted up.

My only issues over the weekend were an ordinary polar alignment (really ordinary on Friday and a bit off on Saturday night) which is the operator not the mount, plus the resulting ordinary pointing accuracy in goto that resulted from that and only doing a one star alignment on the hand controller.

Ignoring the operator induced issues, it just worked. Goto was acceptable, pretty good in the region of the alignment start (Sirius) and progressively worse the further away from that point in dec.

The secondary encoders meant that manually re pointing was still able to be done without issue and what tatty alignment I had on the hand controller stayed there still so you could re point to an object after a rough goto and it would still slew back to Sirius reliably.

Not really sure what else to say, apart from that on the next outings I think I will stick to AltAz operation as even an SCT ends up with the EP in inconvenient spots on a GEM. The only reason I have for not doing so is to force myself to practice my polar alignment so I can do it more accurately and quickly if I should decide to try my hand at simple AP.

[The_bluester (Paul)]

Also and related, I cobbled together a cheap power system for SVAC. I bought a 13.8V 12A DC power supply from Jaycar for $70, cabled it to an Anderson plug and put it in a battery box with the SLA from a jump start pack, cabled in parallel (Isolated by disconnecting the Anderson plug) and wired out to two lighter sockets panel mounted in the box.

my only gripes were that the cooling fan on the power supply is a bit noisy, which I will probably fix by cutting a hole and fitting a much larger, slower turning PC fan to the case, and if left connected to the battery the fan ran with the supply turned off, so it is obviously a DC fan on the output of the supply. I may get a high current diode to keep it from backfeeding the fan when switched off.

I don't see any great changes required, it ran the mount and SCT heaters (Hungry) for hours on end without issue and even after four or so hours running on a warm day while the solar scope was mounted, the PSU was still nice and cool even with the lid on the battery box.

I am not sure if I will remove the PSU from the box and use it by itself at home by running DC cable out of my shed or leave it as is so any power bumps are floated by the battery.

[Camelopardalis (Dunk)]

You should be able to get a pretty decent polar alignment with the AZ-EQ6 because the altitude and azimuth adjustments are easier to use and make precise adjustments. On the regular EQ6 it's more of a challenge

Regardless, a 2-star alignment improves things significantly over a 1-star alignment as you've given it a second point of reference. Unless you've got a near perfect polar alignment, the extra few seconds to add the second alignment star make an appreciable difference to the goto, though not necessarily the tracking.

[The_bluester (Paul)]

Yeah, adjusting it was easy, the error was in the operator rather than the mount. Once pointed at a target it just needed the occasional tweak in dec to keep things in view.

I a thinking of alt az mode because a lot of stuff I am enjoying at the moment is near the SCP and it is far easier to point there in alt az than eq mode.

[Camelopardalis (Dunk)]

Yeah it's tough to beat Alt Az for a SCT visually

[Amaranthus (Barry)]

Polar alignment works great on this mount with the polar scope, provided you've got reasonably dark skies.

[The_bluester (Paul)]

Yes, the first setup I did was with the polar scope and it was pretty good (though I have not checked the polar scope alignment yet) but at the recent camp the problem was skies too dark so many stars to choose from to try and pick out Octans. That or it was off by more than half the polar scope FOV, leaving you guessing.

The usual problem does apply though, the polar scope screen is illuminated by a red LED in front of the polar scope itself so it tends to wash out both stars and background if it is turned up bright enough to see the markings, a common issue by what I can see.

[Amaranthus (Barry)]

Right - I have to turn the LED to 2% to make it useable. But I'm at a very dark site, so it is fine there. The key is to find the Octans trapezium.

[The_bluester (Paul)]

Actually, next time out I was planning to try out a little planetary imaging cam through the scope to see if it is sensitive enough to get a star image and use that to drift align.

Not really much of an issue for me as I will almost exclusively be doing visual and the EP positioning is much more convenient in alt az.

[The_bluester (Paul)]

Hmmm, only just noticed that I autopiloted my thread title and it is wrong, it is of course an az/eq not an alt at.

[Camelopardalis (Dunk)]

Originally Posted by The_bluester

Actually, next time out I was planning to try out a little planetary imaging cam through the scope to see if it is sensitive enough to get a star image and use that to drift align.

Should be plenty sensitive. Check out Metaguide or the Drift alignment feature in PHD2, for example, they support lots of guide/planetary cams.

[The_bluester (Paul)]

The weather looks reasonably promising tomorrow night so I might download some software and have a crack. With a quarter moon there would not be a whole lot else to do given I seem to have gravitated to deep sky objects.

Still relatively unimportant given I am primarily a visual observer and plan to use Alt Az most of the time, but it would be handy to see how it goes by way of pointing accuracy with a good PA and two or three star alignment instead of one star.