best filters ? for Mars

Hi..

With Mars looming bigger in our skies, what is the consenus of the group
for a range of filters one should have to view different markings on the
planet, and what is best to use with a CCD camera?

TIA..
Jimmy..

I cannot address the CCD issues, but FWIW, visually speaking,
below are my notes from my observing log various filters when viewing
Mars with a 8" F-6 Newt , ~ 350-500X....
Date: 2003.07.11 seeing conditions mediocre...
From best to worst...
#21 orange
#11 yellow-green (very pleasing, relatively neutral color)
#25A red
#23A light red
#56 light green
Note: the above are all very subtle filters, and the difference (visually)
between one another is not as much as people might think.
#58 green, nothing special...
#38A deep blue, VERY DARK, could only see S polar cap.
#47 violet, like #38A only worse...
I understand a Salmon filter is very good as well, and hard to find, don't
know the wratten# of it...
Cleardarkskies!
Orion





"Jim Barclay" wrote in message
...
Hi..

With Mars looming bigger in our skies, what is the consenus of the group
for a range of filters one should have to view different markings on the
planet, and what is best to use with a CCD camera?

TIA..
Jimmy..



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"Orion" wrote in message ...
I cannot address the CCD issues, but FWIW, visually speaking,
below are my notes from my observing log various filters when viewing
Mars with a 8" F-6 Newt , ~ 350-500X....
Date: 2003.07.11 seeing conditions mediocre...
From best to worst...
#21 orange
#11 yellow-green (very pleasing, relatively neutral color)
#25A red
#23A light red
#56 light green
Note: the above are all very subtle filters, and the difference (visually)
between one another is not as much as people might think.
#58 green, nothing special...
#38A deep blue, VERY DARK, could only see S polar cap.
#47 violet, like #38A only worse...
I understand a Salmon filter is very good as well, and hard to find, don't
know the wratten# of it...
Cleardarkskies!
Orion


Agreed. I am using an 8-inch dob at 240X and 310X; my viewing site is
alongside a local stream that provides lots of humidity so seeing is
bad. In fact, the humidity is so bad that 171X and 240X are better
than 310X, with 250X my best view so far.

I have had the same results you cite he

-- #21 orange shows the polar cap nicely as well as some surface
markings when humidity is lower
-- have not tried the #11 -- will try it tomorrow
-- #25A red shows the ice cap and shading, though it is darker than
#21
-- #232A, same a #25A but not as dark.
-- #56 never thought this would show anything but it makes the polar
cap stand out and shows some surface markings.

Wihtout a filter, I can't see a damn thing except a shiny ball.


SPQR






"Jim Barclay" wrote in message
...
Hi..

With Mars looming bigger in our skies, what is the consenus of the group
for a range of filters one should have to view different markings on the
planet, and what is best to use with a CCD camera?

TIA..
Jimmy..



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If you have a broadband filter, try it on Mars. You might be surprised what is
visible.



Jeff

If your score is 8" or larger, I would suggest a neutral density filter
(such as a moon filter), which cuts out a lot of the glare, and prevents the
planet from appearing washed out.

-- Zan

"Jim Barclay" wrote in message
...
Hi..

With Mars looming bigger in our skies, what is the consenus of the group
for a range of filters one should have to view different markings on the
planet, and what is best to use with a CCD camera?

TIA..
Jimmy..

Thanks mate! much appreciated!! Mars will be almost overhead in late
August.. G

Jim

Bill Greer wrote:
On Tue, 22 Jul 2003 18:43:01 +1000, Jim Barclay
wrote:


With Mars looming bigger in our skies, what is the consenus of the group
for a range of filters one should have to view different markings on the
planet, and what is best to use with a CCD camera?


Speaking only on the human eye side of the issue:

Orange to red are good for enhancing most of the dark markings.

A violet filter can be used to check for violet clearings.

Blue is useful for enhancing clouds

A polarizing (or variable polarizing) filter can be useful in subduing
the planet's brilliant light, making it easier on some eyes to see
features on the planet's surface without too drastically modifying the
planet's natural colors.

When a scope is used with a relatively small exit pupil a lighter
filter works best. For larger exit pupils darker filters would be
better.

I've been consistently using an exit pupil around 0.5mm this time
around. My former favorite filter (a 23A light red) has been replaced
by no filter; but last time out I was able to briefly try a polarizing
filter. I was quite pleased with the result and, weather permitting,
will give the polarizer a more thorough trial tonight.

IMO it's best to acquire a variety of filters and experiment on one's
own. Different optics, magnifications, and eyes may do better with
different filters.

Bill Greer