Re: Advice please: Standard verus Rotating Pier Adapter

Joe Zeglinski

Thanks Jeff,

That reinforces my decision to stay with RPA's on both tripod and fixed pier.

Actually, I had also considered having a machinist (horizontally &
vertically) "notch out" the pier mounting holes in two of my Flat Surface
Adapter (FSA), - one on the post, the other on the tripod - and leave a
"single RPA" attached to the fork, along with partially screwed in, (6) thumb
screws, so I could easily drop and twist the fork/RPA into either "slotted
FSA", just like a Losmandy G11 does into it's pier adapter. Then I figured it
is "almost" as easy as fiddling with those four screw in knobs on the fork (if
I don't lose one on the ground/snow). Besides, the RPA is pretty heavy, and
that would just about be a deal breaker for carrying weight, which was one of
the major factors, when I decided to upgrade from my two week old G11.

Appreciate this,


----- Original Message -----
From: "Jeff" <jlc@...>
To: <ap-gto@...>
Sent: Tuesday, April 17, 2007 6:37 PM
Subject: RE: [ap-gto] Advice please: Standard verus Rotating Pier Adapter

I've used both the SPA and RPA.

SPA on a 900 and RPA on a 1200.

I had my concerns/lack-of-belief with the RPA, but now I see the RPA is a
big jump over the SPA.
It is such a "subtle" difference that is THE BIG difference.

I suspect the RPA _requires_ the heavy duty az adjuster. But I suspect it
will work with the old style az adjuster, but not practically.
So, this would be the "only" reason to go with the SPA... but then the az
adjuster can be upgraded.

The only minor problem w/ the SPA is simply that if you ever need to move
the mount in AZ, you need to loosen all those bolts and retighten them.
The RPA is "no fuss". And it is SOLID due to the beefy AZ adjuster.

With the RPA, the AZ adjuster keeps it "set" in AZ.

With the SPA, the mount bolts keep it "set" in AZ, and the AZ adjusters just
"help keep it set".

Even with a fixed pier, I suspect there may be a need from time-to-time to
touch up the alignment.
(I'm not a fixed pier person, but where I live a) the ground moves every few
years (san francisco - living near a fault), and b) the ground is like clay
and moves with the change of seasons.)


From: ap-gto@... [mailto:ap-gto@...] On Behalf Of
Joseph Zeglinski
Sent: Tuesday, April 17, 2007 10:47 AM
To: ap-gto@...
Subject: [ap-gto] Advice please: Standard verus Rotating Pier Adapter


I would appreciate some advice about using the SPA versus RPA. I recently
purchased the RPA with my new AP900, since it looked like a better, wiser,
choice. Now I am considering a second pier adapter, for an alternative
permanent fixed pier.

I see how my RPA works , but I wonder, what are the difficulties with
using the Standard pier adapter, which made the RPA a more desirable,
more expensive, option? I intend on transferring the AP900 between a field
tripod, and the permanent post in the yard, so the small inconvenience of
simply "loosening" the four hold down knobs for the Standard adapter fine
adjustment, may not justify the price difference, for me. There must be some

other aspect, or convenience, of using the RPA, I may have missed.

Much appreciated,

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