#63610

All:

I mounted my meter-long Mak-Newt OTA on my GM811G, and while it doesn't hit the HD tripod leg as I slew, it comes perilously close (and did hit a dew heater control I had attached with a Velcro strip to the tripod leg).

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So, to avoid this in the future and to give me a margin of error, I figure I need either a pier extension OR an RA extension kit.?

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Any advice on this?? I do NOT plan on getting a longer OTA (famous last words).? My sole interest here is AP--if I want to do visual, I have a perfectly nice Dob.??

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Also, if a pier extension is the way to go, any thoughts on the 8" extension vs the 12" extension?

Thanks

#63620

The RA extension worked out for me, but this was with a different OTA. But this is what it is intended for, to give some extra clearance. Going higher vertically may not help the clearance in the same way. But what I especially like is being able to break the RA into two pieces with the thumbscrews, which splits the mount into 2 sections for lower weight and smaller sizes, for set-up, tear down and transportation.?

John Bridgman

#63621

I guess the question is how much additional clearance you need/want. The RA extension is only going to give you a couple of inches at best, while a pier extension will give you 8 or 12 inches depending on model.?

In terms of pier extension size I would go with 12" for visual (I'm 6'5) but for AP I would go with the 8" unless there is some other reason for extra height (seeing over the sides of your hypothetical future observatory is a good one :)).

#63622

开云体育

I think John pretty much netted it out.

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You could do it either way. The RA extension is quite a bit less, but you have the added benefit of being able to break apart RA and DEC

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The pier extension would give you more clearance, but it would still be a single piece, so maybe better for permanent installs or less travel?

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I just realize I have a 12” extension I experimented with but I’m not using, if you’re interested in picking one up used.

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Thanks

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Brian

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portfolio https://www.brianvalentephotography.com/

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Show quoted text

From: [email protected] [mailto:[email protected]] On Behalf Of John Bridgman
Sent: Thursday, September 5, 2019 9:27 AM
To: [email protected]
Subject: Re: [Losmandy_users_io] GM811G--pier extension or RA extension?

?

I guess the question is how much additional clearance you need/want. The RA extension is only going to give you a couple of inches at best, while a pier extension will give you 8 or 12 inches depending on model.?

In terms of pier extension size I would go with 12" for visual (I'm 6'5) but for AP I would go with the 8" unless there is some other reason for extra height (seeing over the sides of your hypothetical future observatory is a good one :)).

#63625

开云体育

I am WAAAY behind, and as such have not read the responses to this query.. But there is a third option, as you said (roughly) “hit the tripod leg”.. i.e. there is no problem clearing the motors..

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For my Stellarvue 130mm Triplet Refractor, which is Carbon Fibre and seriously nose heavy, I added some serious counterweight near the FeatherTouch focuser so the scope was pushed much farther forward in the G11 saddle.. And yes, I love the RA Extension, which has the added benefit of splitting the mount in half, making transport much easier..

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:-))

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Derek

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Show quoted text

From: [email protected] [mailto:[email protected]] On Behalf Of jmyers1951@...
Sent: Wednesday, September 04, 2019 8:05 AM
To: [email protected]
Subject: [Losmandy_users_io] GM811G--pier extension or RA extension?

?

All:

I mounted my meter-long Mak-Newt OTA on my GM811G, and while it doesn't hit the HD tripod leg as I slew, it comes perilously close (and did hit a dew heater control I had attached with a Velcro strip to the tripod leg).

?

So, to avoid this in the future and to give me a margin of error, I figure I need either a pier extension OR an RA extension kit.?

?

Any advice on this?? I do NOT plan on getting a longer OTA (famous last words).? My sole interest here is AP--if I want to do visual, I have a perfectly nice Dob.??

?

Also, if a pier extension is the way to go, any thoughts on the 8" extension vs the 12" extension?

Thanks

?

Virus-free.

#63664

Jmyers1951,

These two parts were designed to do different things. The RA extension was designed to let the saddle clamp clear the servo motors when used with the newer tucked motor configuration and to extend the time before needing to do a meridian flip. If you have a tucked motor mount the RA extension allows 360 degrees of rotation on RA and DEC.?

A pier extension is designed to raise the mount for better placement for standing or tall visual observers and to increase the time available before needing to flip and reduce the chances of a tripod leg strike by a telescope with long overhangs.?

For best results you will find you need both upgrades to maximize the time shooting through the meridian and to reduce the chances of a let strike. When used in combination with the safety limts set specifically for your longer tube you can maximize you time on target before meridian flip and totally eliminate leg strikes.?

Of course you also may want to consider the need to tuck the motors for the absolute maximum freedom of movement of the G11 head. The improvement is significant but maybe you don't need or want it.

--

Chip Louie - Chief Daydreamer Imagination Hardware