Much of what you are doing is beyond me, Jim. My biggest scope is a 10"
Dob, so I don't worry about too much aperrure, alas!

I suspect light polution will not be an issue. My best looks at Mars so
far (in a 5" SCT) were around dawn and the sky was very stable (an
important factor I think); I was able to crank my 5" SCT up to 300x,
about as high as it can go.

The equatorial platform will be essential at the magnifications you will
want for Mars.

I'm no filter expert (all mine relate more to nebulae than planets), but
here is a good web site:

http://sciastro.net/portia/advice/filters.htm

Phil

Jim Cate wrote:
Hi,

I'm hoping to be able to view Mars with reasonable high magnification
and would appreciate advice and suggestions. It happens that Mars will
be closer to earth on my birthday next month than it has been in a long,
long time, so I want to at least give it a try. Here's the plan:


1) Using my 16-inch, 4.5/f Dob light bucket, I intend to use an off-axis
aperture mask, with an opening of about 6 inches, to enhance the viewing
at high magnifications.

2) I have a Tak LE 5 mm, and a Nagler 9-mm. I plan on trying both of
these, and, if seeing is unusually good, adding a 2X Barlow.

3) I plan on using an equatorial platform to assist in keeping the
planet in view for at least a few minutes, permitting family and friends
to see it before it's out of the fov.

4) I will try some filters, but really don't know what would be the best
choice.

From the above, I would appreciate advice and suggestions regarding the
planned approach and regarding changes, combinations, or modifications
that would improve the expected results. What magnifications might be
expected with this scope, and is the use of an aperture mask equivalent
to increasing the effective focal length, and magnification? If so, by
how much? Are good seeing and low levels of light pollution of
significant importance when viewing bright objects such as the planets?
(Should I plan to travel to a remote location?) What color filters, if
any, would be recommended, etc. (incidentally, I also have an f8 -inch
(Chinese) refractor that we might try also)

Thanks for any suggestions or comments.

Jim