Meade SN-10 AT Manual de instrucciones descargar pdf (Pagina 9)

First step is to rotate the OTA in the cradle with the fo-

cuser directly opposite the counterweight shaft (Assum-

ing youre using a SNT here).

Next step is to use the polar scope (assuming it is aligned)

to put Polaris dead center on the cross-hairs (which is NOT

the correct polar alignment position). Double check the

polar scope by rotating the scope on the RA to make sure

Polaris doesnt move. Do not make any further adjustments

that will move Polaris off the cross-hairs throughout the

rest of this procedure - this is very important.

Now - put a low power eyepiece in the scope and point the

counterweight shaft straight down. Move the scope on the

DEC axis until Polaris is centered as best you can - then

lock down the DEC. Loosen the RA and manually swing

the scope 90 degrees in each direction. If Polaris moves

side to side, use the hand controller to move Polaris left-

right (DEC only) to a position halfway between the two

points. When you have it right, you can swing the scope

through 180 degrees and Polaris will move very little from

side to side. (Once you get to this point, you shouldnt move

the scope in DEC anymore until the final step below is

completed).

Unfortunately, youve probably noticed that Polaris is also

moving up and down in the FOV as well :-( You now have

to adjust the screws on the bottom of the dovetail cradle in

order to eliminate this movement. Go 1/2 the distance you

think you need to go at a time, then swing the scope 180

degrees again to check your progress.

WARNING! Do not apply excessive force to the dovetail

adjustment screws! It is made from cheap cast aluminum

and the centers of the screws holes will break out (voice of

experience, here)!

Once the dovetail screws are properly adjusted, you should

be able to swing the scope through 180 degrees of motion

on the RA and Polaris should move very little. You are

done.

You can now proceed to tweak the polar alignment if you

want. Determine the current hour angle of Polaris and off-

set it the proper distance and direction from the cross-

hairs in the polar scope with the adjusters on the tripod. If

the counterweight shaft is pointing straight down, you are

in the polar home position and are ready to do the Autostar

alignment.

One little problem remains that can degrade the pointing

accuracy of the GEM mounted scopes vs. an Alt-Azimuth

mounted scope. The optical axis of the scope is sometimes

not exactly parallel with the mechanical axis of the tube.

This is mostly affected by the optical collimation of the

scope. Always make sure the collimation of the scope is

done accurately before attempting to do the adjustments

described above! If you dont, and you collimate the scope

last, youve just undone everything. Even when the scope

is collimated accurately, the optical axis and the mechani-

cal axis may be a little different. If this is true, then a

potential problem arises that is not so easily fixed...You

rotate the optical tube in order to move the focuser to a

more comfortable position. You have just misaligned the

optical axis and the mount again. (The only cure would be

to readjust the radial position of the mirrors within the

optical tube to make sure the two axes were perfectly par-

allel - not a job that most of use have the ability to tackle).

Scopes with a rotating star diagonal (including SCTs) and

most alt-azimuth mounts dont have (or need) rotating

tubes and thereby avoid this potential problem.

Courtesy of: Greg Granville

Mount & Tripod Hints

The following suggestions are listed in no particular order.

Most of them come from members of the Yahoo! LXD55 News-

group (with permission). Contributor information is given af-

ter their suggestion (or not) according to their wishes. You

may notice some redundancy, but we have found that some

things are well worth repeating. If you wish to contribute to

this, or any other database, send us an e-mail at

opt@optcorp.com, and put “Information Motherlode” in the

subject heading. We will certainly consider it. Thanks!

ADJUSTING THE RA / DEC LOCK LEVERS: I noticed someone

mentioned that they overtightened their DEC or RA lock

lever and it jammed up against the motor housing when

the scope slewed. Ive found that the axes locking levers

may require readjustment after a bit of use in order to

maintain a firm lock without hitting the plastic motor hous-

ings. Simply remove the phillips head screw from the lock-

ing lever, remove the handle and rotate it counterclock-

wise one or two notches, and then reinstall the screw. Prob-

lem solved.

TRIPOD HINTS: Several people have mentioned that the alu-

minum tripod is a bit more rigid if the tripod is not ex-

tended any more than necessary to level it. Another sig-

nificant portion of the flex occurs at the point where the

top of each tripod leg joins the tripod headpiece. The prob-

lem here is that the fit of the pivot bolt (the one with the

large wing-nut) is a little sloppy. However, this can be

largely overcome by taking each of these bolts completely

out, and removing the headpiece. There are a set of approx

2-3 thin teflon washers on either side of the top if each

tripod leg. Remove all these teflon washers and put the

headpiece back on and put the bolts back in. Now, when

you setup the tripod, make sure the legs are spread out

firmly against the spreader bar before tightening the wing

nuts on top (Pull outward on each leg as you tighten the

upper wing-nuts). Without the washers in place the top of

each tripod leg will have a much more secure grip and will

not pivot or shift at all as it would do when the teflon wash-

ers were in place. The tripod still has a few minor flex

points, but the stiffness seems substantially improved.

Courtesy of: Greg Granville

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Meade SN-10 AT Manual de instrucciones Pagina 9

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