Re: [APML] Drift alignment - a common misunderstanding

[KGKIRKLEY@aol.com]

In a message dated 9/17/01 1:45:51 PM, matt@starmatt.com writes:

>
>I always have to set up at a remote location to do AP. The A-P 600E QMD
>mount
>has no built-in level. I affixed a circular bubble level inside the mount
>(where
>it can be seen with some difficulty). The mount head has very little azimuth
>leeway, so you want to get the tripod or pier lined up very close to North
>before you attach the head. If you are setting up before sunset (which
>is Highly
>Desirable), it is helpful to have a magnetic compass and know the 
magnetic/true
>offset for your locale.
>
>I wish that any of my A-P/Losmandy tripods or A-P portable pier enabled
>a large
>degree of azimuth offset, but they have none. The A-P tripod has spiky
>feet that
>you sink into the ground for stability. But turning the tripod to change
>the
>azimuth means yanking it out of the ground (which is tricky with the head
>and
>scope on it) and replanting it; then it has to be releveled. With the A-P
>pier,
>you have to hope that the supporting pavement is level, because it has
>no
>provisions for leveling. Yes, you can turn the turnbuckles on the tension
>rods,
>but that can lead to some loss of stability.
>
>What does all of this mean? It means that it may not be trivial to ensure
>that a
>portable mount is precisely level before starting the alignment procedure.
>
>Also, with any portable mount, to have to evaluate how stable the surface
>and
>mount are. If they are not stable, you have very little confidence that
>the
>mount will stay aligned after you drift align it.
>
>I have accurately collimated my A-P polar bore scope. I have found that
>alignment with this bore scope is very accurate, and I only need to touch
>the
>azimuth and altitude the barest amounts to get a 15-min no-drift alignment.
>I
>have found that aligning with a good bore scope is much quicker than aligning
>with DSCs.
>--
>Matt BenDaniel
>http://starmatt.com

AMEN!!! I second the above!!!

As wonderful as AP equipment is, I wish (and don't know why?) that 
Astro-Physics would (had) put leveling devices on each of their pier legs. At 
the time of manufacture,this would be a simple and relatively cheap addition. 
After the fact, it's more difficult, unless you are a machinist and welder. 
All that is needed is a sturdy
 1/2"-1" x approx 6" threaded bolt with knob or handle and reciever at the 
end of each leg. This would allow leveling on uneven ground. I always sink 
three hard-fired bricks in the groud and place the legs on them. This spreads 
the weight out and prevents sinking and loss of polar alignment. 

Kent Kirkley

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