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I have a prospective buyer for my G11G w/ LW tripod.? They know that the tripod will have to be upgraded to the heavy-duty tripod.? They plan to do DSO and planetary imaging with a 12” Meade SCT. ?Likely with and without a 0.63x FR/FF.? The F.L. of the scope at f/10 is 3048mm and at f/6.3 is 1,920mm.? They estimate the total weight of the imaging setup to be 50 pounds.

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My questions are…?

• Is 50 pounds pushing to limits of the G11G w/ Heavy Duty Tripod for imaging?
• Is a F.L. of 3,048 or 1,920 pushing the limits of the G11G w/ Heavy Duty Tripod for imaging?
• Would they be better off with a G11T?

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, ZWO AM5N, NINA 3.0 / ASTAP, ASI2600MC Pro / ASI533MM Pro, Sky-Watcher Scopes, Canon L Lenses....etc

Hello Jim,

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It is my belief that yes you will be pushing the mount, the G11G,? you could be taxing the G11T also though not as bad.? I'm assuming that there is a dew shield involved too.? Either mount you will need the FHD tripod or one of those tripiers.? Stability starts at ground level, always.?? Also I'm assuming the scope is on a Losmandy bar, my opinion a cradle would be better but surely put you over the top.? Guiding should also be done with an OAG or ONAG, my opinion too.

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That was at F10,? at F6.3 you should be better.

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I had a C14 with a Homeyer cradle and a G11T, but I was visual and planetary.? That was three years ago, don't have the scope and my Neighbor has the mount.

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Joe

Is the G11G 60 pound spec for visual?? I usually use 2/3 or 3/4 of the stated load capacity for the imaging spec.

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

Jim,

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The stated imaging payload of the G11G is 60 pounds.? Many people with heavier and longer scopes are imaging on a G11G with good results.? My friend is imagining with a 10" f/8 Newt that is well over 65 pounds with good results.?

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I routinely load the 20+ year old G11G mount with over 60 pounds and image with it.? My guiding is very good, still well under 0.5" PE.? I normally image with the bespoke Parallax / AstroTech130mm f/6 SDT which has an oversized steel tube and 3.7" focuser and a Losmandy Side-By-Side saddle plate with ADM ALT/AZ aiming device and Meade LX200 10" f/6.3 SCT with 3" Moonlite focuser etc. etc.? this is a very heavy payload.??

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I think the buyer should not have a problem imaging with a G11G and 50 pounds of payload.?

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Thanks Joe and Chip.? I average around 0.8 to 0.9 arc-seconds RMS using a 200mm FL guide scope and ASI120mm camera in the city with a 25 pound imaging setup.? I rarely get any better than 0.75.? I don't recall what I get at a Bortle 4 or 2 site.? I am not sure this is typical of the G11G or just my mount.? I don't want the buyer to get a mount that will not meet their expectations.

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

How well a mount can be guided is complicated and almost all of the factors are beyond the mount itself.? Mount mechanicals, autoguider app tuning and configuration, primary imaging camera pixel size to guide camera pixel size ratio, guide scope mounting stability, guide scope camera stability, seeing air stability, cable configuration, wind, power stability etc., etc. all contribute to guided PE.? Any and all of this and more can and will screw up a night of imaging.??

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People like to blame the mount and there are some that are a little better than others.? But most of the time the alleged "bad" mount is just a victim of who owns it and the environment in it is used in.? ?

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Hi Jim!

Im the prospective buyer, im really appreciative of the care youre putting in to this sale, seriously.

. I Just deforked my Meade LX200 12" and its on a losmandy dovetail i got from losmandy directly.

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With this OTA my primary targets are planetary, and there is no real guiding used during those imaging sessions. I do want to try and experiment doing DSO, and for that, i would absolutely be using an off axis guider. I have a couple to choose from. That will be reduced using a vintage starizona SCT reducer corrector ive inherited. Also this is the high end of my weights . I will also be using it with a 102mm explore scientific for most of my real DSO work.

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so,?

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12" mostly for planeraty, no reducer used

12" for DSO experimental imaging using a Starlight Express Active optics system i also inherited, this would be reduced by .63

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102mm refractor for more serious dso imaging

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8 inch C8 with a reducer for most of my SCT deep space imaging.?

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THanks!

Francisco

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and i will be ordering a heavy duty mount from losmandy sometime next month, i dont see myself putting the 12" on there with the lightweight tripod.

One more thing, the meade SCT OTA bare weighs around 36lbs. add in the dovetail, and imaging equipment, and dew shield and im just over 50lbs, i know this is pushing the limit, but im so excited to get in to a losmandy mount.

Francisco

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With any luck it will be clear enough tonight to do a PHD2 guiding run.? I adjusted the RA worm to ring gear spacing and I want to make sure I didn't mess things up.? I also found some loose grub screws.? I will contact you Tuesday PM.

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

On Mon, Feb 10, 2025 at 12:01 PM, Francisco wrote:

and i will be ordering a heavy duty mount from losmandy sometime next month, i dont see myself putting the 12" on there with the lightweight tripod.

One more thing, the meade SCT OTA bare weighs around 36lbs. add in the dovetail, and imaging equipment, and dew shield and im just over 50lbs, i know this is pushing the limit, but im so excited to get in to a losmandy mount.

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Francisco, a 50 pound imaging payload is not really pushing the limit for guided imaging on a G11G mount, not at all.? My C14 fully loaded with double dovetails and Moonlite focuser and the imaging gear was over 60 pounds, I had no issues with it.? I am routinely 5-10 pounds over the official 60 pound imaging payload value and use an ASIAIR for imaging which is not quite as good at guiding for some reason as using PHD2.? But the small PE difference makes no difference in the data or finished images so I don't sweat it.? ?

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Hello Francisico

Congratulations on your G11G and Welcome to the group. I am routinely? imaging at <1 AS RMS on G11 with 53 lb counterweight for my 10 in RC at 2040 fl using OAG. Balance is critical for me and changing to Michael Hermans high friction clutch pads was a game changer. The stock nylon clutch pads just did not work for me.

Have fun

Ron

Hi Francisco,

Welcome to the group.?

Weight limits are SO problematic. To start it's barely a relevant measure, but marketing people had to find something simple they could use in their ads to out spec their competition. Now we're all stuck with it. ?

Hence the sarcastic commentary of "is that in 'Chinese' pounds",? or? "the rule of thumb is divide by 3 for AP" (easy to remember) or "is X makers rating real?" and now it's "it's X for visual and Y for AP" ,

(which ignores the question is that short exposure planetary or long exposure DSO AP? )

You get my drift. ???

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Moment of inertia is the actual factor thst matters (Mass x distance from the axis of rotation). Its a bit messy to put that in an ad, much less explain it, AND it's only one factor in "suitability for a purpose" which is the? right question to ask.

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Kudos to the seller BTW who obviously has super high integrity. ???

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I won't get into it here, other then to say there is a big difference between a long f/10 refractor and a f/10 SCT? that might be of equal weight when it comes to "can this mount handle it"?

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You'll fnd it discussed if you search or browse in the forum archives which i highly recommend anyway. It's a resource of all things about Losmandy. many of which you (and I) haven't yet thought to ask. ?

I jest a bit in fun, but it really, is a bit overwhelming in the best possible way.?

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Long exposure AP at 3k mm FL is super challenging for reasons too numerous to mention. I've learned here that? the fundamental challenge is how to methodically isolate the cause of an observed issue and then how to go about fixing or reducing it. It takes experience.?

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That's what I have come to appreciate about this group after I bought my used? older G11 mount.

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There are many VERY experienced people and SMEs in this and related Losmandy/Gemini groups that are very generous and willing to share their knowledge and experience, which IMO is way more important than any of the multitude of factors that will impact achieving your desired results at one point or another.

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FWIW, Losmandy makes an adapter for Meade tripods. A lot of? mounts are sold with this adapter and a Mead tripod before Losmandy started making their own tripod. I bought my used G11 in that configuration. The more modern Meade giant field tripod (LX200GPS) are ok for visual/planetary What was better was an older Giant FT from the LX200 classic. 3"+ dia legs and taller (if you are a really tall person or have a long refractor.) I bought a used Losmandy original non folding HD tripod. It's an absolute rock. I'm sure others can advise about the Folding HD tripod.

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OT, PM plz if you still have the Meade fork mount?

I have a couple of projects needing parts.

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Michael?

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Hello Francisco,

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Do not get me wrong, I firmly believe at the under $5000 budget Losmandy makes the best mounts in their class.? I owned a G11T for a year.? I thought I wanted two rigs,? it was for my C14.? It moved the C14 around, I used it for visual and it was very good.? However, I also owned two refractors at the time, that C14 was noticeably heavier to push across the grass. I donated the C14 to my local middle school for their astronomy program, the mount went to my neighbor.?

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As Michael above pointed out,? there are a lot of things that affect pointing and tracking when doing DSO imaging.? I know you said you are just trying it out and not really going to do it. That is great.?

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Image scale is what you need to track under.? Your periodic error has to be less than your image scale you are shooting at.? With a 2600 camera that has 3.76 micron pixels, you need to guide under .4, that is a 12 LX200 OTA with a .63 reducer.? With a 2400 camera you are at .64, more manageable but still kind of tough to do.? My opinion.? Reason,? you have a 14" barrel that is over 24" long with a dew shield on top of that mount. A 6" RA and Dec gears driving it. ?

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My opinion, ? a mount with a 10" RA gear and 8" minimum Dec gear.? If you get serious about DSO imaging with a 12" SCT.? If it were me, and I know this is a Losmandy group, but with a 12"SCT for DSO imaging successfully an AP1600GTO, 10 Micron 2000GPS,? a Planewave or ASA mount .

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At 50 pounds you are approaching the weight limit,? physical size you are probably over the limit, focal length you are past the limit.? The least little thing and you are done. No room for error. A gentle breeze of wind, someone walking around.

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Planetary, visual yes. EAA yes.? DSO, I'm going with no.? Final answer.

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Joe

On Mon, Feb 10, 2025 at 12:48 PM, Jim Waters wrote:

Francisco

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With any luck it will be clear enough tonight to do a PHD2 guiding run.? I adjusted the RA worm to ring gear spacing and I want to make sure I didn't mess things up.? I also found some loose grub screws.? I will contact you Tuesday PM.

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

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Use a drop of low torque thread adhesive on those darned Oldham grub screws.? Loose grub screws are one of the most common issues and cause a lot of grief to the uninitialized.? If you are having issues with your drivetrain those grub screws are right up there with worm axis endplay.? ? ?

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At one time I used Blue Loctite on the grub screws and quickly regretted it.? It wicked onto the shafts.? It took me an entire weekend to clean stuff up.?

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Several years ago I replaced the grub screws on the two aluminum 1-to-1 transfer gears with 4-40 x 1/4 cap screws. Theses work much better than the original grub screws but occasionally they work loose too.?

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

What is a grub screw??? Is it like a set screw??

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Joe

Yeah Joe, a set screw.??

As you say, there are bigger mounts to be had and at bigger price points.

Tracking/Guiding is a discussion all of its own!.

If DSO at native FL were the primary purpose I might think differently, but IMO there's a long way to go before the mount would become the limiting factor.

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Michael?

On Tue, Feb 11, 2025 at 07:08 PM, joe kuhl wrote:

Hello Francisco,

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<<SNIPPED>>

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Image scale is what you need to track under.? Your periodic error has to be less than your image scale you are shooting at.? With a 2600 camera that has 3.76 micron pixels, you need to guide under .4, that is a 12 LX200 OTA with a .63 reducer.? With a 2400 camera you are at .64, more manageable but still kind of tough to do.? My opinion.? Reason,? you have a 14" barrel that is over 24" long with a dew shield on top of that mount. A 6" RA and Dec gears driving it. ?

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<<SNIPPED>>

Joe

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I'd like to hear how you calculated these numbers.? What is the method and why?? ? ?

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Joe

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Same question as Chip.? Walk us through the math.? Yes, an AP mount or above would be better.

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

On Tue, Feb 11, 2025 at 07:08 PM, joe kuhl wrote:

Hello Francisco,

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<< SNIPPED >>

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Image scale is what you need to track under.? Your periodic error has to be less than your image scale you are shooting at.? With a 2600 camera that has 3.76 micron pixels, you need to guide under .4, that is a 12 LX200 OTA with a .63 reducer.? With a 2400 camera you are at .64, more manageable but still kind of tough to do.? My opinion.? Reason,? you have a 14" barrel that is over 24" long with a dew shield on top of that mount. A 6" RA and Dec gears driving it. ?

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<< SNIPPED >>

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Joe

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I don't understand how you came up with this.? Regardless of optical resolution or camera seconds per pixel image scale or how well the mount tracks the rate limiting factor when imaging from the surface of the Earth is the quality of the air column between the sensor and the object.??

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