[g__day (Matthew)]

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

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 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 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!