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Keep us posted on your progress!

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also, i collect most of my images for dso with a 110mm WO refractor, or a 61mm WO refractor. the 12"SCT just happens to be the biggest scope i have, and i mainly use it for planetary, which is unguided. but i figured what the heck, lets try some?

Perfect, ive picked it up, and if we ever get a clear night, ill get to start testing this things limits, thanks again to Jim! great seller.

On Sat, Feb 15, 2025 at 12:14 PM, Michael Ben-Yehuda wrote:

Welcome to the group Francisco!?

Thanks for the rain! ?

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Chip,?

This problem for those with large aperture telescopes... gets limited sympathy ??

Just kidding of course.

Thanks for responding as I think the point you make catches many of those with aperture fever by surprise.

There definitely is a wall,? or maybe I should say a glass ceiling, that starts really being felt at around 12" where atmospherics becomes predominant.?

It is a mistake to blame the hardware when it's performance well exceeds the seeing.

Perhaps vendors might not be eager to educate??

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Anyway, I don't want to drift too far off topic, but it is an important consideration when sizing and making hardware choices.

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I've owned and observed with different sized optics from 50mm to 355mm as well as different types of telescopes over the years.? As far as what works visually IME the knee in the curve starts with a very good 100mm and maybe just past that bend a good 130mm refractor seems like a realistic visual point of diminishing returns for most folks not living out past Yenterville.? That's Bortle 1 skies for you who don't know it.? For two surface reflector telescopes these same points seem to be about 6" and 8" or so.? ?

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For a long time I thought the atmosphere so severely limited out ability to observe visually even in a dark sky area.? So why go nuts on the best possible optics good should be good enough.? Okay so I was wrong.??

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Over time (slow learner), I've discovered the advantage of having really good optics, while only really able to fully deliver under perfect conditions (including using the right high-end back half optics), can ha isve a huge impact on what you can see once you learn to live in between the turbulence.? Those admittedly short moments of clarity can be amazing and if you learn it soon enough almost make the cost worthwhile.??

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As an imager the advantages of using the best optics is obvious in the data and resulting images.? But for visual observation it is harder to objectively quantify unless you have seen it.? I've seen it and I'm not going back to mediocre optics.??

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Welcome to the group Francisco!?

Thanks for the rain! ?

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Chip,?

This problem for those with large aperture telescopes... gets limited sympathy ??

Just kidding of course.

Thanks for responding as I think the point you make catches many of those with aperture fever by surprise.

There definitely is a wall,? or maybe I should say a glass ceiling, that starts really being felt at around 12" where atmospherics becomes predominant.?

It is a mistake to blame the hardware when it's performance well exceeds the seeing.

Perhaps vendors might not be eager to educate??

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Anyway, I don't want to drift too far off topic, but it is an important consideration when sizing and making hardware choices.

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I sold my G11G w/ LW Tripod to Francisco.? Please welcome him and help him out when he has questions.

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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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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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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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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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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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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?

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

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Joe

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.

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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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

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 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

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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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.

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.

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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