What color is the moon?

In article ,
Chris.B wrote:

I was shocked when I took Venus transit images with a new Canon Ixus
digital compact when the Sun came out as brown as hens eggs!

My relatively ancient Sony makes the Sun pink. In both cases I used
the same old, Baader foil, full aperture filter.

Even further off topic, is it true that you can get a colored glass
"hydrogen alpha" filter that does not cost thousands of dollars, but
has a wider FWHM that the serious ones? Where would I find one? When
I try to search for one, I just find fractional angstrom filters that
cost more than my car did new.

--
"Remember when teachers, public employees, Planned Parenthood, NPR and PBS
crashed the stock market, wiped out half of our 401Ks, took trillions in
TARP money, spilled oil in the Gulf of Mexico, gave themselves billions in
bonuses, and paid no taxes? Yeah, me neither."

In article ,
Paul Ciszek wrote:

In article ,
Chris.B wrote:

I was shocked when I took Venus transit images with a new Canon Ixus
digital compact when the Sun came out as brown as hens eggs!

My relatively ancient Sony makes the Sun pink. In both cases I used
the same old, Baader foil, full aperture filter.

Even further off topic, is it true that you can get a colored glass
"hydrogen alpha" filter that does not cost thousands of dollars, but
has a wider FWHM that the serious ones?

You can get something like
http://www.astronomik.com/en/photogr...cd-filter.html
which costs a few hundred dollars and has a 12nm bandpass; or 50% more
for a 6nm bandpass; they'll get you lovely pictures of hydrogen
emission in the Milky Way and the Local Group but are no use for solar
work. The cloudnights forum suggests that 1nm bandpass is absolutely
the bare minimum for visual solar work.

http://www.daystarfilters.com/Quantum.shtml are tunable etalon filters
with down to 0.03nm bandpass, but price is roughly inversely
proportional to bandpass.

Tom

In article ,
Thomas Womack wrote:
In article ,
Paul Ciszek wrote:

Even further off topic, is it true that you can get a colored glass
"hydrogen alpha" filter that does not cost thousands of dollars, but
has a wider FWHM that the serious ones?

You can get something like
http://www.astronomik.com/en/photogr...cd-filter.html
which costs a few hundred dollars and has a 12nm bandpass; or 50% more
for a 6nm bandpass; they'll get you lovely pictures of hydrogen
emission in the Milky Way and the Local Group but are no use for solar
work. The cloudnights forum suggests that 1nm bandpass is absolutely
the bare minimum for visual solar work.

Well, I was thinking that a colored glass filter plus a suitable neutral
density filter might get me more interesting results than just a mylar
"neutral density" filter alone. My earlier picture was taken with a
mylar filter, the green channel isolated to minimize chromatic aberration,
and the contrast blown way up to show sunspot structure and granularity.
If a 6nm BP filter can make the sunspots and granularity more noticable--
still requiring contrast enhancement, just not as much--that would be great.

--
"Remember when teachers, public employees, Planned Parenthood, NPR and PBS
crashed the stock market, wiped out half of our 401Ks, took trillions in
TARP money, spilled oil in the Gulf of Mexico, gave themselves billions in
bonuses, and paid no taxes? Yeah, me neither."

On 2012-09-26, Paul Ciszek wrote:

Even further off topic, is it true that you can get a colored glass
"hydrogen alpha" filter that does not cost thousands of dollars, but
has a wider FWHM that the serious ones? Where would I find one? When
I try to search for one, I just find fractional angstrom filters that
cost more than my car did new.


The problem there is that with a wider pass band the hydrogen
alpha filters will not work to show any detail at that wavelength.
You basically have just a deep red filter. The least expensive hydrogen
alpha viewers I know about are the small Coronado PST and Lunt LS35T
that cost about 600 US dollars.

Bud

On 2012-09-26, Paul Ciszek wrote:

Well, I was thinking that a colored glass filter plus a suitable neutral
density filter might get me more interesting results than just a mylar
"neutral density" filter alone. My earlier picture was taken with a
mylar filter, the green channel isolated to minimize chromatic aberration,
and the contrast blown way up to show sunspot structure and granularity.
If a 6nm BP filter can make the sunspots and granularity more noticable--
still requiring contrast enhancement, just not as much--that would be great.

The Baader Solar Continuum filter with a 10 nm pass band centered on
540 nm works pretty well to filter out of focus colors. The pass band
is located at the wavelength where most achromatic telescopes are best
corrected for spherical aberration. With one of those and a Herschel
wedge plus an ND3.8 neutral density filter I get a sharp view visually.
A Baader solar filter plus a Solar Continuum filter also works well
for photography. I can't focus an SLR with the Herschel wedge because
I don't have enough back focus.

Bud

Den torsdag den 27. september 2012 02.10.02 UTC+2 skrev William Hamblen:

The Baader Solar Continuum filter with a 10 nm pass band centered on

540 nm works pretty well to filter out of focus colors. The pass band

is located at the wavelength where most achromatic telescopes are best

corrected for spherical aberration. With one of those and a Herschel

wedge plus an ND3.8 neutral density filter I get a sharp view visually.

A Baader solar filter plus a Solar Continuum filter also works well

for photography. I can't focus an SLR with the Herschel wedge because

I don't have enough back focus.

I use a Baader "Fringe Killer" which (usually) produces white images when used with Baader solar foil.

Would a 2" Barlow, or an old fashioned (film camera) tele-extender, tolerate the heat before the wedge?

On 2012-09-27, Chris.B wrote:

I use a Baader "Fringe Killer" which (usually) produces white images when used with Baader solar foil.

Would a 2" Barlow, or an old fashioned (film camera) tele-extender, tolerate the heat before the wedge?

You might cook a barlow with cemented lens elements, so I wouldn't
recommend it. The same thing applies to a photo teleconverter. The photo
teleconverter is designed to be attached directly to the camera and
therefore might not work optically with the wide spacing in front of
the camera you'd get with the Herschel wedge. A telescope with more
focuser travel would work with an SLR. A compact digital camera with
manual shutter speed and aperture settings would work afocally with what
I have now, but I really don't need to buy another camera.

I also have a Baader Semi-APO filter that's nice for lunar viewing.
Performance is similar to the Fringe Killer filter. I need the additional
filter factor of the Solar Contunuum filter when viewing the Sun, which
is another reason I use Solar Continuum filter with the Herschel wedge.

Bud