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A couple of questions and hopefully some recommendations from the
group. It's been quite a while since I've had a scope for
observing, but the bug has bitten again. Years ago, I had a Cave
Astrola on a GEM and a few years after that, a C-8 on a fork mount.
Currently, I'm most interested in a Celestron 9.25, but I don't
like Celestron's mount.

Question 1. Would the Losmandy GM-8 be adequate with the 9.25 or is
this overkill for visual use only?

Question 2. Are there other mount options for this instrument?
Actually, I always thought the fork mount was fine for visual use,
but it's no longer available for the 9.25.

Hi Jack,

From my limited understanding, the GM-8 is a fine mount for the C9.25.
David Silva uses exactly this setup, and is quite happy.

Robert.

--- Jack Metcalfe <jlmetcalfe@...> wrote:

A couple of questions and hopefully some recommendations from the
group. It's been quite a while since I've had a scope for
observing, but the bug has bitten again. Years ago, I had a Cave
Astrola on a GEM and a few years after that, a C-8 on a fork mount.
Currently, I'm most interested in a Celestron 9.25, but I don't
like Celestron's mount.

Question 1. Would the Losmandy GM-8 be adequate with the 9.25 or is
this overkill for visual use only?

Hi Jack. Congrats on getting back into the hobby! I recently acquired an
older CG9 (the C9.25 on a Losmandy G9 mount) and really like it. The C9.25
seems to be slightly superior to other commercial SCTs that I've looked
through. I have to admit that the focus micrometer that is built into mine
(it's the older model) is a wonderful, wonderful thing. Too bad that don't
still include that feature. If I bought one now, I'd probably add the JMI
aftermarket DRO.

The mount is a good match for this instrument for visual use only. No, it's
not overkill. IMO, it's not enough mount for this scope for prime focus
photography.

There are a couple of things you should know about the GM8 mounts in
general, and the G9 in particular. My G9 shared a "stiction" problem with
the GM8s, particularly in DEC. A replacement teflon bushing from Scott
Losmandy resolved this problem, although it introduced a minor issue: the
DEC clutch must be tightened more to achieve the same amount of resistance.
IMO, that's a minor irritation, compared to the stiction problem, which was
a HUGE pain-in-the-***!

There are two downsides to the G9 mount compared to the GM8, and one
upside. First, it came on the infamous extruded aluminum tripod that
Celestron and others use on many of their mounts. Calling it a tripod does
serious offense to all legitimate tripods in the world! <g> I knew about
this problem in advance, so it wasn't a surprise. Fortunately, I had an
older Celestron SP mount with the nice hardwood legs. I swapped tripods,
and the improvement is dramatic. Still, I lust after the GM8 tripod and
will probably invest in one someday soon.

The second issue was a complete surprise, and quite a disappointment. I
have seen people state over and over that the G9 head is the same as the
GM8, but when I disassembled it to clean and relube it, I discovered that
IT HAS NO NEEDLE BEARINGS ON EITHER AXIS! There are simply polished
aluminum bearing surfaces. There are washer-type roller bearings at the
clutch-end of each shaft.

I asked Scott if needle bearings could be press-fitted into the shaft
housings, and he said that it would be difficult and expensive. Bummer.

The upside of the G9 is that it comes with the G11 saddle plate, instead of
the smaller GM8 one. This helps me immensely because I have an older GM100,
which uses the G11-style dovetail system. All my OTAs, SBS assemblies,
etc., are completely interchangeable.

Question 2. Are there other mount options for this instrument?
Actually, I always thought the fork mount was fine for visual use,
but it's no longer available for the 9.25.

IMO, the current G9 is a pretty good deal. The C9.25 OTA on its own sells
for only $100 less, and I assume (I know, I know...) that you could
probably sell the mount for a lot more than that. Maybe not.

You might consider a Vixen GP-DX mount, if you can purchase one with a
wooden tripod instead of the aluminum one. Other than these two mounts, you
pretty quickly get up into the price range of the G11- hey, that's not a
bad idea! (IMO, if you can afford the price difference, which is about
$500, get the G11.)

Cheers,
Paul Sterngold

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There are a couple of things you should know about the GM8 mounts in
general, and the G9 in particular. My G9 shared a "stiction"

problem with

the GM8s, particularly in DEC. A replacement teflon bushing from

Scott

Losmandy resolved this problem, although it introduced a minor

issue: the

DEC clutch must be tightened more to achieve the same amount of

resistance.

IMO, that's a minor irritation, compared to the stiction problem,

which was

a HUGE pain-in-the-***!

Gee, this sounds familiar....so Scott has already had this fix in
his bag of tricks for the G9. When I emailed him about replacing the
nylon clutch washer with teflon on my G11, I got the impression from
his response that it was a new idea. Nothing was said about the fact
that he already did this on the G9. Hmmmm...curiouser and curiouser.

Bill

I thought someone would pick up on that; and if I remember correctly
someone posted that they thought that Scott was not too impressed
about the teflon fix in general.

I wonder if he has since found out there is a long term problem with
the fix since he first recommended it himself.

--- In Losmandy_users@..., "Bill Faatz" <faatz1@l...> wrote:

There are a couple of things you should know about the GM8 mounts

in

general, and the G9 in particular. My G9 shared a "stiction"

problem with

the GM8s, particularly in DEC. A replacement teflon bushing from

Scott

Losmandy resolved this problem, although it introduced a minor

issue: the

DEC clutch must be tightened more to achieve the same amount of

resistance.

IMO, that's a minor irritation, compared to the stiction problem,

which was

a HUGE pain-in-the-***!

Gee, this sounds familiar....so Scott has already had this fix in
his bag of tricks for the G9. When I emailed him about replacing

the

nylon clutch washer with teflon on my G11, I got the impression

from

his response that it was a new idea. Nothing was said about the

fact

that he already did this on the G9. Hmmmm...curiouser and

curiouser.

Bill