questions about Atlux

[Julien]

Hi everybody !

I'm Julien, from Switzerland


I have a few questions, especialy for g__day. I have read your Atlux review.
In fact I'm interesting by this mount but I'm in doubt for some points :

- The Vixen website says that the maximum loading weight is 22 kg. But what is the maximum if it's used for astrophotography ?

- Vixen gives, for the PE, two value : +/-7" without PEC and +/-3,5" with PEC. I have found a site (in french) where several PE are logged : http://demeautis.christophe.free.fr/ep/pe.htm There are three graphics for the Atlux, two are good (between 5" and 10") but one is around 10" or 15". So. is the Atlux quality constant enough to be sure to have +/-7" (or better) ? g__day what is the PE of your Atlux ?

- Last point, the hand controller. The Atlux is now sold with the "StarBook" system. I have read a comparison between the SS2K and the Starbook here : http://www.groupeastronomiespa.be/SSvsSB_V1.02.doc.pdf It's seems that a lot of options that were present on the SS2K have disapeared. And for some options you have to pay an extra.:sadeyes:


Julien

[g__day]

Julien,

Delighted to help if I can. After owning the Atlux for about 8 months with a lot of use – here are my impressions and answers to your questions.

1 - The Vixen website says that the maximum loading weight is 22 kg. But what is the maximum if it's used for astrophotography

I’d say the Japanese are conservative and it can definitely do 22kgs for imaging with carefully tuning and balancing!

I currently have 3 OTAs and Losmandy saddleplates, dovetails, two CCDs and electronic focusers on the mount – basically requiring about 25kgs to counter balance – and the mount handles this very well. Using the SkySensor2000-PC I have slowed the motors speed down using gearing for high loads – which has intelligent slews for optimal torque and no instant race and slow down.

Can the mount image under this load – absolutely – I did 10 minute shots – on a resume from power down (no re-alignment check) slew to two stars – dead on target for each (pointing is usually about 2-3 arc minutes, and as good as 34 arc seconds for me if you really hone things and use MaxPoint). I took 8 consecutive 10 minute shots of Acrux – with no PEC or guiding at 2.3 metre focal lengths (a 9.25 SCT), see here for the typical results which left me very pleased! (mind you the OTA needs coliminating)!

http://www.iceinspace.com.au/forum/showthread.php?t=30298 (http://www.iceinspace.com.au/forum/showthread.php?t=30298)

Tracking I have had some issues with in the past (whilst pointing has been spectular – which is strange to say the very least - as tracking and point are the two sides of the same coin - in that tracking is just real time pointing). I have used PEMPro and MaxPoint to improve polar alignment and tracking is getting better after a lot of effort and issues with SCT mirror flop confusing things. But I intuit tracking in polar aligned mode - with just a 2 star align is better than anything else until you have really perfected polar alignment!

When I guide – using MaximDL – I typically see a sinusoidal tracking error of +/- 1 arc second every 6 - 8 seconds (my pixel size is about 0.517 arc seconds / pixel – yeah I know - I should be around 2-3 arc seconds / pixel for my viewing conditions).

If you tune it well – it can image very effectively under quite heavy loads and do it consistently. I image in a astrolab - protected from the wind which probably helps matters.

2. - Vixen gives, for the PE, two value : +/-7" without PEC and +/-3,5" with PEC. I have found a site (in french) where several PE are logged : http://demeautis.christophe.free.fr/ep/pe.htm (http://demeautis.christophe.free.fr/ep/pe.htm) There are three graphics for the Atlux, two are good (between 5" and 10") but one is around 10" or 15". So. is the Atlux quality constant enough to be sure to have +/-7" (or better) ? g__day what is the PE of your Atlux ?

Last I measured I still had RA tracking rate issues and I had readings between +/- 3 arc seconds to +/- 5 – a few days later. Let me re-run these tests for you once the skies are clear! But basically I’d say the PE is as stated as a worse case. The build quality is really good – the only issue I had was the DEC gears needed slight repositioning to eliminate slop – which the shop could have done in 15 minutes and took me almost an hour! I would love to do a Dr Clay supercharge on this mount – I reckon it would be incredible then!

3. - Last point, the hand controller. The Atlux is now sold with the "StarBook" system. I have read a comparison between the SS2K and the Starbook here: http://www.groupeastronomiespa.be/SSvsSB_V1.02.doc.pdf (http://www.groupeastronomiespa.be/SSvsSB_V1.02.doc.pdf) It's seems that a lot of options that were present on the SS2K have disappeared. And for some options you have to pay an extra.

I have heard few solid reviews of the latest (version 3 I think Atlux) with the StarBook controller. But my gut was the SS2K was a raw powerhouse of a brute (at times poorly documented) and requiring the latest EPROMS 2.10 to give ultra reliable PC / network connectivity. In contrast the Starbook looks like a fancy toy (subjective call) and leaves me feeling it’s a bit of a gizmo. That is only my subjective first impression – I have no hard data on that – but check more later.

* * * *

My continued wish with the SS2K – was its software developers had better documented its capabilities and left it as open source. It has resume features that can be a bit quirky and its tracking needs just a bit more polish – that I could do if I could get to the code base!

If I was to step up from this mount – it would be to a Losmandy Titan, a Tak EM400 or 500 or a Paramount ME – but if wishes were horses…

Others here (Gerald Sargeant and Lars Hansen) I believe also have used the Atlux– interesting to hear their views!

[Julien]

Yes, but Takahashi is Japanese and it gives two values.

With or without PEC ?


I know, I have it (with a Vixen GP). The french documentation is good... hum, I think, I have never seen the original documentation. In fact it has not been writen by Vixen but by Medas, the importer for Switzerland and France.
In fact I was hoping I could use the ss2k with the New Atlux, but it seems that the electronic has completly changed.

I have sent a message to the Vixen Yahoo list to have more informations about the Starbook


In fact the EM400, was one of my first options but it's a little bit too expensive for me, especialy in Switzerland where a EM200 is around 2000 US $ more expensive than in USA.

The Paramount, I have the chance to use one of them. I'm a member of a society which own a Paramount ME : http://www.foams.ch , http://www.pleiades.ch/albums/userpics/10006/89.jpg :)

[g__day]

The normal logic is 1/2 to 2/3 the rated carrying capacity - but this might derive from the USA where many dealers commonly state the total weight carrying capacity, meaning it includes OTA + counterbalances. This gives them a reasonable delta for machining quality issues that the more conservative Japanese often over compensate for with higher quality.

The Takahashi I can't talk to other then recognise they have stellar reputation. I guess you could also consider an AP900 if the wait isn't too long.

What I haven't tested is how much better or worse is the tracking with significantly less weight (i.e. if I took off an OTA - would my track go up in leaps and bounds?). I know the Atlux could handle a C14 for visual, not sure how people have found it for imaging at that weight and focal length - be interesting to ask around.

The +/- 3 - 5 arc seconds where two runs with PEC off - but let me check I hadn't goofed imaging scale, cause with PEC on it said 2.1 arc seconds - (I may have had imaging default at 1 vs 0.517 arc seconds per pixel) - I'll check that tonight!

* * * *

The English SS2K manual poorly documents the process (and how to tune it) of how a 3 star alignment actually compensates for polar mis-alignment in equatorial un-aligned vs equatorial aligned mode. My best tracking seems to be just marginally in 2 star unaligned mode, then next best is two star polar aligned mode with PEC. If I do initial alignment dead right (remember I face minor but discernible SCT mirror flop) -tracking is great - if I do it slightly wrong well every 10 seconds my guider executes a slow down RA by 1 arc second pulse (so 6 arc seconds a minute fast on tracking - regular as clockwork). How the (3rd and 4th ) parameters for the polar alignment are calculated and then correspondingly effect tracking aren't documented well enough for someone to just figure the optimal compensation parameters once and enjoy perfect tracking for life!

[Julien]

Ok, thank you.
Maybe you could send your PE and a graphic there : http://demeautis.christophe.free.fr/ep/pe.htm (skywalker.14141 [at] wanadoo.fr)


I haven't a permanent observation place. I'm not sure it's a good choice in this case.

[g__day]

I'll try a PE run tonight and post an image.

[g__day]

Well a day time test - imaging at 1/1000 of a second for an hour gave RMS 2.905 Periodic Error +5.3 / -4.7 without PEC and +1.9 / -1.8 with PEC.

After sunset I'll run it again with 1 second exposures and see if results are consistent

[g__day]

Without PEC with 1 second exposures, which it calculates RMS: 1.402 and Periodic Error: +5.1 / -3.7. I can e-mail you the PEMPro data PE Curve if you desire. PS I have blown uploading PEC data 3 times - now - its horrible - seems to be cumulative adding PE - so I have to read how to I clear PE. Maybe its beacuse its in 3 star polar align mode - see what I mean about poor documentation. When I go to record PEC - with no guide input - it says it is recieving corrections - like from where I'm wondering? I will switch to polar unaligned back to polar aligned and this might just clear the bad PEC data - fun and games with these undocumented behaviours you have to learn through every step of the way.

Attached is an example of MaximDL's auto-guide tracking error graph. I am running in polar aligned mode - 3 star alignment with PEC off at present until I clear it and figure how the PEC load went horribly wrong! Basically once I uploaded PEC by playback - the PEC shot through the roof - 3-4 times worse - probably meaning I hadn't calibrated the guiding corrections correctly!

So without PEC this is the guiding corrections required to track NGC 2070 - using a 127mm MAK with a Meade DSI - RA corrections are the X axis. Observe corrections are random and a bit under 1 arc second :)

[Julien]

The PE seems to be very good. Even better than the Vixen specifications.
I think I will buy an Atlux. But before I need to spare some money.


In the french manual it is said : "Cancel" is to clear the PEC data. When the mode in the PEC menu is set on "Cancel" and you push on ENTER, the saved PEC value will be reset to 0
Maybe this can help you. I hope my translation is not too bad

[Gerald Sargent]

I used an atlux with SS2KPC and found the weight carrying capacity very
good, although I never pushed it to its limits. The most I ever had on it
was an Intes MN61 a 6" refelctor together with an 80mm refractor and a
70mm guide scope and STV, various camera and bits that added up to
quite a bit of weight. I took is new in its box to Duckadang a few years
back and Dennis help me to set it up - he knew the SS2KPC and did a
superb job of polar alignment and showing me how to use it. So well that
it took 2 minute unguided images. Since that time it has had a bit of
use until I "broke it". The negative plug to my metal cased PSU pullled out
and dragged across the case (which was connected to the negative rail)
with lots of sparks. Result one of the encoders was damaged. This was
repaired very rapidly under warranty by Vixen and the unit resumed its
faithful service until my next exercise at "breaking it". I switched off and
next night went to resume use and it started to behave weirdly, took me
a whiule to figure out that it was tracking backwards. Solving this problem
became a saga of immense proportions. It was caused simply by the reversal of motor directions in the hand controller. How this came about is a complete mystery, it has been reported that static cam affect the hand
controller. Once this had been identified and corrected it resumed its
usual excellent performance. I am getting on in years and found that the
weight of the head was getting to be too much to lift so it was with
reluctance that the unit was sold (very quickly for purchase cost) and
sent to the USA, where the Atlux with SS2K has never been available.
I managed to get a brand new Astro Physics Mach 1 which I am now
trying to learn to control. It is a superb piece of machinery, but how
I miss the essential simplicity and ease of use of the SS2KPC, whose
software I think was better. I have also used a sphinx with the starbook
and found it tedious to use and the mount had bugs, axes impossibly
tight when new - returned for adjustment, and still had bugs causing
oscillation of movement when doing a synch near the zenith - very
difficult to stop. The lack of PEC and problems with the autoguider which
seemed intermittent caused me to sell that - at a shockingly reduced
price - lost a lot on that one, which I replaced with a new GPD2 and
SS2KPC, bit heavier than the sphinx but at least with the versatile
SS2KPC. I would not touch an Atlux with Star book with a barge pole,
especially as the Mach 1 is about the same price - or less. Sadly Vixen
have put a lot of faith - missplaced - on the Star Book and in their
reluctance to give customers and answers to the hundreds of queries
that have been submitted. I think their mechanical and optical engineering
are still up to standard, but on the software side they have to my mind
gone out on a suicidal limb. Just my views for waht its worth. Gerald.

[g__day]

Gerald,

My thoughts exactly, I'd prefer a good used Atlux SS2K to a brand new Atlux Starbook - at least until they sort out the starbook software bugs. If you had more $$$ consider an Tak NJP

Matthew

Julien - thanks - the English SS2K documentation lack sufficient detail, I'll try clearing PEC with the cancel!

[Gerald Sargent]

For Matthew, not a Tak the software is too lacking in facilities, ie no pec
for a start. I think their engineering amybe OK but I prefer to go to a
bigger AP if I wanted to handle a big load, the 900 is a superb device,
and like all AP's everytthing is get-at-able, motors, worm adjustmente
etc all set out in the manual. Gerald

[Julien]

Gerald, Than you for your e-mail



In fact, starbook has PEC since the firmware v1.2, build 34 (18 may 2007). I have written to the Vixen yahoo group and one of the authors of the review I mentioned in my first post answered me. I will send him an e-mail to have more informations about the things that have changed since the release of the review.

An Astro-Physic could be a good choice if I can buy it directly in the USA. In Europe it's to expensive for me. For example, the AP900GTO is ~8500 $ in the USA and 8500 euro in Europe (1$ = 1.55 euro). But are those mount easily transportable ? I have also heard that there is a very long waiting times to have one of these mounts.