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Hello Group,

There seems to be some less than accurate comments about the Losmandy
GoTo system so here is a quick summary of what it can do:

The Gemini system comprises 2 new servo's, hand paddle and a control
box.

Estimated street price around $US1500.00, much of the tooling has
been done, with final software testing being done at present.
Northern hemisphere opertaion seems to be pretty bullet-proof, the
multi-star alignment being the only current major bug for S.H. users.

The test control electronics have all the databases as listed on our
web site

However, there may be database changes/software upgrades with the
commercial EPROM release.

The system points well with a single star alignment and a polar
aligned mount, but using 2 to 4 stars the mount does not need to be
polar aligned. Multi star alignment in the N.H. accounts for poor
polar alignmnet, atmospheric refraction, flexure etc...but only as
well as 4 stars can allow. I'm told it works very well in the
N.H....a new EPROM (yet to be tested) is on its way to the S.H. to
fix the multi star errors currently seen here.

Using T-Point (Bisque) I could get the system to be "dead-nuts" on
every time when driving the mount with The Sky.

LX200 protocol works well, with only the SYNC feature disabled. Users
can set date, location and PC time from the PC to the Gemini
controller.

With encoders attached the mount can also be positioned manually, yet
still be electronically slewed (you go back to 4096 encoder accuracy
after a manual move, but re-aligning on one star/object after the move
puts you back to several million counts per rev resolution)

Noise level....not as quiet as the Astrometrics GOTO system, but then
again if slewed at 800x the system is significantly quieter than say
a Meade LX200. Tracking accuracy...yet to be quantatively tested, but
on visual inspection, the drive seems very smooth, with no hint
of "jitter" sometimes seen with the current stepper drive.

The menus are accessed with a standard Losmandy 4 button paddle.
Press N or S to go up and down through Menus. Press West to execute to
go deeper into that menu, press east to go back. After 10 minutes
you'll be a wiz.

The motor torque is impressive. With 12.5" RC and 55 pounds of
counterweight the test G-11 did not stall at 1000x This is not however
a recomended payload ;)

Given the Gemimi system does not need a PC, but can be PC driven and
T-Point modelled, I'd say at the price the new GoTo will be pretty
hard to beat.

Regards
Peter Ward
(Losmandy's Australian dealer)

pjward@... wrote:

Hello Group,

There seems to be some less than accurate comments about the Losmandy
GoTo system so here is a quick summary of what it can do:

The Gemini system comprises 2 new servo's, hand paddle and a control
box.

Estimated street price around $US1500.00, much of the tooling has
been done, with final software testing being done at present.
Northern hemisphere opertaion seems to be pretty bullet-proof, the
multi-star alignment being the only current major bug for S.H. users.

The test control electronics have all the databases as listed on our
web site

<snip>

Sure appreciate the information on this system. I am already daydreaming
about slewing around the sky with it. I hope the guiding turns out to be
as good or better than with the Losmandy digital drive and motors.

Rockett Crawford
----------------------------------------------------------------------------

Capella's Observatory (CCD Imaging)

Thanks for the information.

I'm particularly interested in the encoder support. If I understand
you correctly, the scope can be moved manually, the GoTo
functionality continues to work as before without needing any extra
calibrations etc. and the only problem is that after such a
manual move, the pointing accuracy drops to a resolution 4196 ticks
per revolution.

I was looking at using these encoders instead of the standard
losmandy encoders:



here's a better picture of them on a G-11 from their old (and nicer
looking site)



These are 8192 encoders using a 4x ratio giving a total of 32768
steps rather than the normal 4096 steps.

I first saw these mentioned at the end of this review of the
SkyCommander which seems to suggest that they will work fine with the
SkyCommander:



SkyCommander's site says if you have their latest software (V4.0)
it'll support 32768 steps.

As I said, I was looking at getting this mounting kit and these
encoders at 4x ratio, and now that the Losmandy GoTo is out I'd like
to make sure the GoTo can handle them.

So my question is that do you know if the Losmandy GoTo will handle
32768 and is the sample rate high enough that even with fast manual
scope movement ticks are not lost?

As a separate question to the group, has anybody had any experience
with these encoders and their Losmandy mounting kit [which uses the
same holes in the mount as Losmandy's own encoder mounting kit],
either with the Deep Space Navigator interface or connected to a
SkyCommander? In e-mails with Brian Kidwell (the designer of Deep
Space Navigator and the Losmandy mounting kit pictured) I have been
told that the method used on the moutning kit is far superior to the
Losmandy encoders as it elimnates completely any clutch problems.
Here's what I was told and would appreciate any comments about this:

"The Losmandy kit has some real problems with locking down the
telescope for heavy loads and this can affect the position of the
gear train. The alignment can be affected when the scope is locked
and released repeatedly. Our mounting kit eliminates this problem
entirely and higher resolution pointing is gained at the same time."
...
"The shaft has been flatted on one side but only where the gear sits.
The gear is bored round with a set screw. Tightening the lock nut
over the gear and releasing will cause some movement of the gear
before the end of the night. In addition, the knurled nut he
provides to lock down the scope makes it very hard to get a real good
lock down for accurate tracking during photographic exposures. My
kit has none of these problems as the lock nut has not contact with
the primary drive pulley."
...
"One of the main points [of Deep Space Navigator's Losmandy mounting
kit] to notice is that the locking nut [the large octagonal shaped
silver thing at the bottom end of the RA axis between the mount and
the large pully gear] ins place on the threaded shaft before the
pulleys are installed. When the locking nut is tightened or
loosened, there is no effect on the pulley. The holes on the flat
sides of the nut are for the tightening tool I provide with the kit.
This allows easy lock down of the nut to the maximum tightness
needed to prevent movement of the mount. This is especially helpful
if you are doing astrophotography."
...

[And with respect to SkyCommander and 8192 step encoders here's what
Kidwell had to say (and I would be interested in experiences of
anyone using 32,768 CPR with the SkyCommander):]

"If you want software that is easy to use with your telescope and you
want the highest resolution available for a reasonable price, then
you should use Deep Space Software and The Deep Space Navigator. I
have many customers who have tried the other systems and have then
purchased our system. They have done this as they were not happy
with the other systems accuracy. If you read the information about
the Sky Commander carefully, I believe that you will not find mention
of using the 8192 CPR encoders with gearing that would increase the
resolution of the encoders beyond the 8192 CPR. While the Sky
Commander may be used at 8192 with very deliberate (slow) motion of
the telescope, you may find the need to recalibrate due to missing a
count or two from time to time."

--- In Losmandy_users@..., "GC GC" <gcert1@i...> wrote:

Thanks for the information.

I'm particularly interested in the encoder support.

The Gemini Goto system will support up to 32768 counts per revolution.


Regards
Peter Ward.

P.S. Early Losmandy encoder kits did suffer from some encoder movement
when the either clutch knob was turned. The current kits have thrust
pins and washers, which fixes the problem...plus they look a whole
lot better than the DSN kit ;)

Regards
Peter Ward.

P.S. Early Losmandy encoder kits did suffer from some encoder

movement

when the either clutch knob was turned. The current kits have

thrust

pins and washers, which fixes the problem...plus they look a whole
lot better than the DSN kit ;)

But they don't have the resolution of the DSN kit. As is often
sadly the case, form wins over function (but not usually with
Americans I find).