Re: Pier height and counterweights for 900GTO

Joe Zeglinski

Hi Dirk,

If you are considering a "portable pier", as I am for my own AP-900, one thing not to forget is the height of the pier versus your own arm's reach. With the mount in "Park Position 2" (counterweight down, CWD, and saddle horizontal), you will have to lift he weight of your OTA up high enough to carefully drop it into the slots, and lock it in place. If the pier is too high, you are likely to strain your back, possibly seriously, or risk dropping the OTA. Same thing on take down - handling the OTA can become tricky, especially if you are standing on snow or ice. I suppose, if you still would like a slightly taller setting, you could use a step stool at the pier, to make the final lift - but that is really a high wire act.

I use a Losmandy G11 tripod, with the newly released "AP mating adapter" to the AP-900 (or Mach-1). Initially, I adjusted the legs in the house, and practiced lifting and attaching my (MAK) OTA. On the first test fit, I had to stand on my tippy toes, for that final gentle push into the saddle - with one hand (and chin) supporting the OTA, and the other locking the adapter plate in place. But it seems to end up at a quite reasonable height (for me), for my standing use. I will mark the leg extensions so it is repeatable in the field, or I might try cutting a dowel, or pencil, as a measuring stick for each collapsible leg extension, before lock down in the field, and attaching the OTA.

Of course, if you are using a fixed length pier, like the AP piers, you will have to get some advice from others here, based on the limiting non-adjustable optional two lengths. Or, you could simply test lift your OTA, to a comfortable upward reach, at home, and have someone measure the distance to the floor from it's adapter plate, accounting for the AP-900 height above its pier (see Howard's Dimensions Spreadsheet for this). That should give you some idea which pier post to choose, so it fits your needs.


----- Original Message -----
From: "Dirk Lammerts" <>
To: <>
Sent: Saturday, April 19, 2008 11:16 AM
Subject: [ap-gto] Pier height and counterweights for 900GTO

I am thinking about getting a 900GTO for my C11. I was hoping to get some advice on:

1. How much counterweight will I need (initially only visual, no CCD or heavy finder scope)?
Can I get away with just one 18lb weight?
2. What is a good all-purpose pier height (I usually observe standing). I am thinking about
the 48" A-P portable pier. Any thoughts on lower - higher - just right?



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