Hi, I know many have already responded but allow me to share my plans for
viewing the eclipse in China with my AstroTrac. You can view the photos of my
setup in my album entitled "Tandem Setup for Eclipse". I've tested it out over
the last two weekends and now I get it good enough to be willing to share with
all of you.

To align during the daytime, I first made sure to level the tripod head this is
very important when adjusting for latitude as described later. Then I used a
compass, adjusted for the magnetic declination for my site to help find true
north. Then I used an inclinometer to set the angle of the AstroTrac arm equal
to my latitude. If the tripod isn't level in the north-south direction then
this angle will be incorrect. As recommended by AstroTrac, the Manfrotto geared
head is easily adjustablel for the small, precise movements needed to accurately
polar align.

To mount a small scope and camera simultaneously, I constructed a tandem bar
using a 1" x 3" length of Maple cut to one foot long. I drilled a hole in the
center to fit the mounting stud on the AstroTrac. The stud isn't long enough to
protrude above the wood so I bought a coupling which I cut so it's length is
just a little shorter than the depth of the wood. Then using a 3/8-16 cap head
screw and washer and allen wrench, I could tighten down the bar in any
orientation by screwing the screw into the coupling. On either end of the wood
bar, I drilled and countersunk holes to mount two more 3/8-16 bolts screwed into
T-nuts. To mount the telescope, I attached a Giotto Ball Head on one stud, and
I used a second Manfrotto Model 410 geared head to support my camera and 300mm
telephoto lens.

This setup provided amazingly accurate solar tracking and when occasional
adjustments had to be made to the camera, the second geared head allowed me to
make small precise movements quickly.

To get results like I got in my backyard today, there are several caveats: I
used the solar tracking rate instead of the sidereal tracking rate; level the
tripod before adjusting the altitude for your local latitude; adjust your
compass for magnetic declination to find true north.

I'll be viewing the eclipse a few hours to the south west of Shanghai. The
latitude there will be 30 degrees north and the magnetic declination is -5
degrees.

I hope this helps.


--- In astrotrac@yahoogroups.com, Leopoldo de Castro <leopoldo_de_castro@...>
wrote:
>
>
> Hi,
>
> I'm planing a trip to China to see the total solar eclipse in July.. The idea
is to bring my astrotrac with me. However, I'm not very experienced and I have
lots of questions.
> - one....how do I align the AT in daylight? How precise has to be the
alignment?
> - second...What kind of lenses would you recomend? I have a Canon EOS 400 and
a Canon 40D. Is there any difference in using a modified camera for
astrophotography?. I have already the baader astrosolar filter.
> -third....I have a remote controler (intervalometer) TC80N3....could it be of
any help for taking the pictures of the eclipse?
>
> any ideas/suggestions would be welcome.
>
> Thanks a lot
>
> Leo
>