Autoguider problem (Celestron mount+Meade DSI II+MaxIm DL)

[Farid]

Dear all,

Nice to greet you, I'm new at this forum, from Antofagasta (north of Chile).

I recently made some important upgrades to my current equipment for doing some astrophotography/photometry activity which requires good guiding, composed by:

- Celestron Nexstar 8 SE + Celestron Advanced GT mount

- Atik 314L+ as main camera

- Meade DSI II as guide camera

- Orion ShortTube 80mm as guiderscope

I have previous experience working with bigger telescopes and exposing/guiding through MaxIm DL, so I gathered the cables/drivers/etc to start, and my only problem so far is that my guiding system is just not working. After many tests and checks of some amateur forums, I don't find any answer. So my problem is this:

After the first setup, I can expose with the guider, but when calibrating, only the options to control through "Telescope" and "MicroGuider" seems to "do" something (I guess it's because the DSI is directly connected to my laptop via the RJ11 (Handset)->Serial->USB (computer) way); the MicroGuider option is useless, because when the scope attempts to calibrate, the scope is doing a rare slewing, bouncing back and ahead to reach the target, instead just moving a bit to re-center). "Guider Relays", and "Main Relays" don't actually move the scope.

So, the only useful option is "through Telescope", and the calibration looks decent in a first attempt (this actually moves the scope and does the "L" shaped calib, and when I go to "Track", the guider performs just well. But sometimes, at the "Calibration" or "Track" stage, the dialog window get stuck at "Moving telescope", and does not perform any correction at all. This is very annoying because seems like a communication error between the guider->Maxim->telescope, and don't know why. If I restart the Maxim software, sometimes the guiding process performs well the first time, but at second time, it's the same problem (2 reference images are attached).

A friend told me that the problem may be related to a (non-powered) usb hub to connect my laptop to the telescope/cameras. I am using a Macbook Pro with only 2 usb ports, so I have this 4-ports hub to connect the Adv GT mount, the Atik and the DSI cameras (I perform the control through a Windows XP VM). Because both the mount and Atik hardware has their own power source (external batteries), there are no conflict with them, but the DSI has no power source, then maybe the power consuption is higher, and maybe the laptop-5V-power (through the hub may be inefficient, causing these communication issue). 

Do you think this can be the problem? I can purchase a powered usb hub, but before doing that, would be very useful to have some feedback. I will also try using the 2nd usb port of my laptop, but this is not a safe bet (as far as I know, the usb ports can provide 5V power each, or they can distribute 2.5V separately when two devices are connected). If everything fails, I will also consider purchasing a Orion StarShoot guider, because this have a RJ11 end that can be connected directly to the autoguider port in the Adv GT mount... but I don't know yet.

That's all, sorry for the long post! I promise to send some nice images from the desert when the system is working well (I live very close to the Paranal observatory! (I work there as visitor guide as well )

Best regards,

Farid.

[Dave In Vermont]

Geesh! I wish I could help, but that's beyond me. Just thought I'd leave a quick encouraging note. I don't know where people have run off to day. Usually you'd have more replies than you could read in one sitting! I note that there must be some sort of major event happening. Nobody is about to speak of. This is most unusual. I'm sure it will reverse soon enough.

Have Fun!

Dave

[Farid]

Hi Dave,

Thanks for your reply, hopefully somebody could have and answer or hint about this issue. I just went to the desert a few days ago and it's the same problem, so I don't know how to understand the system yet.

Regards,

Farid

[StanRalph]

I'm new to this forum, but I always find useful info on it.  A couple of ideas here:

1. Astronomy USB interfaces are power hungry.  The typical USB interface should supply 500 ma per spec.   Your laptop might meet that spec for a single device.  If you use a passive hub, all hte devices will demand power.  Power demand can ebb and flow with all devices sometimes peaking all at once.

2.  Check all your devices for whether they are USB 1.1, USB 2.0, or USB 3.x     Hubs will handle the highest USB level that they claim, BUT  they may pull down thruput to the lowest common denominator of interface.   So your ultra-fast camera thruput may be impacted by your poke-along focuser.  Separate all hte USB 1.1 from everything else and run them through a separate hub.  Same for 2.0 and 3.x

3. On powered hubs:   Let's say you get a 4 port hub.  It must be powered by a 2 amp power adapter minimum (bigger is better).  Not all manufacturers do this simple math, so you end up  not getting the power per port that you deserve.  Kensington makes a 4 port hub that is powered by a 2.5 amp adapter.  They also make a 7 port hub that is powered by (you guessed it) a 2.5 amp adapter. 

4.  On hub effectiveness:   Most hubs, especially the passive ones, pass device identification and characteristics just fine, BUT this is not always the case, especially for the powered ones.  With any powered hub, you must test each device to determine if your PC recognizes it, particularly when installing drivers.

5.  OK, now for the laptop:  Laptops are notorious for NOT supplying the full 500 ma per port.  The vendors are expecting a mouse, not an imager.  A good powered hub can go a long way to eliminate an issue.

6.  Now for Windows:  This is simple.  Use only Windows 7 Pro.   Never use Windows 8.  It has a lot of problems.  Good news:  Windows 10 is much better; I'm testing it now.

7.  Finally, you have a complex setup with a lot of moving software parts.  I'd suggest that you start with only your guider.... everything else unplugged.  Get it to work reliably with the scope.  Then add the imager, using only manual focus.  If things are stable, then add the focuser.  Right now, we can't be sure what the issue may be, but if you take smaller steps, you can likely isolate the issue or issues.

Good luck!