Coronado Solarmax 40 vs 60

On Mon, 23 Feb 2004 10:46:43 -0000, "Roger Hamlett"
wrote:


"Bill Dean" wrote in message
.. .
On Sat, 21 Feb 2004 17:57:44 -0000, "Roger Hamlett"
wrote:


"KC" wrote in message
. com...
I'm looking for some comments from Coronado Maxscope users. Which
would you prefer - a double-stacked 40mm or a single 60mm? Obviously
the image of the Sun in the 40mm will be dimmer but more detailed. But
would it be too dim for public viewing?

The double stacked 40mm is actually $600 cheaper than a 60mm and half
the cost of the double stacked 60mm. Would appreciate any comments on
this, thanks.
To photograph with a single SolarMax40, at 800mm focal length, I have to
add
another polarising filter to reduce the light (on the BF unit), even when
using 1/100th sec exposures, so there is still plenty of light...
The key is that aperture controls the fine detail visible. The image is
plenty bright enough through the 40mm filter. Double stacked, the image
will
be dimmer, and will be able to 'pick out' detail better (rather than
being
'more detailed' - the narrow band, allows you to more precisely pick
which
parts of the solar image are being shown, but the actual detail on these
parts will be limited by the aperture).
Remember it is the ratio of focal length to aperture, that gives the
'speed'
of the system. If you are intending to use the unit(s) (talking here
about
SolarMax filters, rather than the Maxscope), on something like a 400mm
focal
length scope, the result, is a f/10 system with the 40mm, and would be a
f/6.6 system with the 60mm. The latter will possibly be uncomfortably
'fast', and also because of the relatively steep angles presented by some
of
the light to the etalon, the bandpass will degrade. However if the units
are
instead being put on a 1200mm scope, the result will be a F/30 system
with
the 40mm etalon, and a f/20 system with the 60mm etalon. In either case,
the
larger image size will require a BF15 blocking filter if the full solar
disk
is to be viewed. The longer focal length system will give more detail,
and
the images will be 'finer' at this sort of focal length with the larger
etalon.
I think that the Maxscopes, are both f/10 systems, so the 60mm unit has a
longer focal length, and the brightness will be the same on both systems,
with the 60mm showing more magnification, and detail (this is why it
needs
the BF10, rather than the BF5 rejection filter fitted to the smaller
unit).
The solar image with the double etalon, should not be too dim, unless you
are running at very high focal lengths. In this case the lack of detail
with
the smaller unit will also show.
One comment, Coronado have just said to me, that you are far more
'likely'
to be able to stack a pair of 40mm units, without them carefully
selecting
the assemblies, than any of the larger units (the 'repeatability' on the
smaller units is better).
The image on a Maxscope 60, is then 50% larger than the image seen on a
Maxscope 40.

Best Wishes


Hi Roger-

Actually the focal ratio is a major consideration with our SolarMax
filter sets. The important consideration is focal length. Consider the
blocking filter as a field stop near the focal plane (blocking filters
are expensive, aperture is based solely on the focal length the filter
is used on for economic reasons) and you pretty much have everything
you need to determine which blocking filter should be used. It's
simply a question of image scale.

Fast, slow, and angles do not make much difference to our system as
the etalon is mounted afocally. The blocking filters aren't impacted
much at all by the cone with a configuration we would expect to see in
the real world. Internal etalons are fitted with afocalizing lenses
which are carefully integrated with existing designs.
I would agree entirely. However a 'fast' system will inherently (for a given
size etalon), imply a shorter focal length, so the image scale will reduce
and the potential angles at the etalon rise. I should have made it clear
that it was not the 'speed' of the system that mattered here, but the
resulting image scale, and potential incoming light angles.
Fortunately, because of the afocal mounting, the maximum angles that are
normally involved, are only something like +/- 0.3 degrees, (for a full
solar disk, with corona), so the effect in normal use is very small.

There should be no confusion with the stacking issue- we'll get it
done properly. We ask that existing customers send their etalon and
blocking filters to us when purchasing an additional etalon in order
to ensure the performance is as it should be. No if ands or buts. A 40
receives the same amount of attention in this process a 90 does. In
any event *we* are far more "likely" to ensure that a customer
receieves a properly matched set of etalons.
The thing that annoys me here, is you say 'we ask that existing customers
send their etalon and blocking filters to us when purchasing an additional
etalon'. This is not quite true...
I purchased a etalon and blocking filter a year ago, in the UK, from the
Coronado representative at AstroFest. There was no mention in the paperwork
with this, of this requirement. At Astrofest this year, I went and purchased
a second etalon on it's own, with no blocking filter, specifically for
stacking, yet the Coronado person on the stand made no mention of this
requirement then, happily selling me this etalon. Again no mention is made
of this need in anything with the filter. Afterwards, I happened to look on
your website, and there not exactly 'leaping out at you', is the reference
to having the system custom matched....
The comment about the 40mm, possibly not needing this, came from an email
from yourselves about this, where I received this statement: "The chances of
a successful random match are best with the 40mm filters because their size
ensures consistent uniformity in coating runs". This is not in any way
reflecting on more/less 'care' about the coatings, but you do obviously find
it easier to get good matches on the smaller filters. I am hoping that this
will be true in my case (waiting for the skies to clear).

Best Wishes


Hi Roger-

I wish you the best! But if the matching doesn't meet your
expectations we will be happy to take the etalons in and ensure that
you have a wonderful system.

This is getting a bit off-topic for the thread so feel free to contact
me at work should this service be required. Use bill at
coronadofilters dot com and I'll be happy to answer any questions you
may have.

Regards,
Bill Dean
Coronado Technology Group

snipped
The thing that annoys me here, is you say 'we ask that existing customers
send their etalon and blocking filters to us when purchasing an
additional
etalon'. This is not quite true...
I purchased a etalon and blocking filter a year ago, in the UK, from the
Coronado representative at AstroFest. There was no mention in the
paperwork
with this, of this requirement. At Astrofest this year, I went and
purchased
a second etalon on it's own, with no blocking filter, specifically for
stacking, yet the Coronado person on the stand made no mention of this
requirement then, happily selling me this etalon. Again no mention is
made
of this need in anything with the filter. Afterwards, I happened to look
on
your website, and there not exactly 'leaping out at you', is the
reference
to having the system custom matched....
The comment about the 40mm, possibly not needing this, came from an email
from yourselves about this, where I received this statement: "The chances
of
a successful random match are best with the 40mm filters because their
size
ensures consistent uniformity in coating runs". This is not in any way
reflecting on more/less 'care' about the coatings, but you do obviously
find
it easier to get good matches on the smaller filters. I am hoping that
this
will be true in my case (waiting for the skies to clear).

Best Wishes


Hi Roger-

I wish you the best! But if the matching doesn't meet your
expectations we will be happy to take the etalons in and ensure that
you have a wonderful system.

This is getting a bit off-topic for the thread so feel free to contact
me at work should this service be required. Use bill at
coronadofilters dot com and I'll be happy to answer any questions you
may have.

Regards,
Bill Dean
Coronado Technology Group
Thank you.
I'll come back once I know how they perform (snowing at the moment!...). It
was the comment that 'you ask that existing customers send their etalon and
blocking filters to us when purchasing an additional etalon', that slightly
'annoyed', since this did not happen to me. An oversight obviously.
I am slightly 'hopeful' at present, since some initial 'peer through' tests
to a white light source (a xenon discharge lamp), show that the bands do
appear to be adjusting in a fairly hopeful way.

Very Best Wishes

On Sun, 22 Feb 2004 06:02:16 -0700, Bill Dean
should have slept rather than
typed the following:


Actually the focal ratio is a major consideration with our SolarMax
filter sets. The important consideration is focal length. Consider the
blocking filter as a field stop near the focal plane (blocking filters
are expensive, aperture is based solely on the focal length the filter
is used on for economic reasons) and you pretty much have everything
you need to determine which blocking filter should be used. It's
simply a question of image scale.

Sorry, the first line should read:

"the focal ratio is NOT a major consideration"

WSP on my mind....

Regards,
Bill Dean

On Sat, 21 Feb 2004 17:57:44 -0000, "Roger Hamlett"
wrote:


"KC" wrote in message
. com...
I'm looking for some comments from Coronado Maxscope users. Which
would you prefer - a double-stacked 40mm or a single 60mm? Obviously
the image of the Sun in the 40mm will be dimmer but more detailed. But
would it be too dim for public viewing?

The double stacked 40mm is actually $600 cheaper than a 60mm and half
the cost of the double stacked 60mm. Would appreciate any comments on
this, thanks.
To photograph with a single SolarMax40, at 800mm focal length, I have to add
another polarising filter to reduce the light (on the BF unit), even when
using 1/100th sec exposures, so there is still plenty of light...
The key is that aperture controls the fine detail visible. The image is
plenty bright enough through the 40mm filter. Double stacked, the image will
be dimmer, and will be able to 'pick out' detail better (rather than being
'more detailed' - the narrow band, allows you to more precisely pick which
parts of the solar image are being shown, but the actual detail on these
parts will be limited by the aperture).
Remember it is the ratio of focal length to aperture, that gives the 'speed'
of the system. If you are intending to use the unit(s) (talking here about
SolarMax filters, rather than the Maxscope), on something like a 400mm focal
length scope, the result, is a f/10 system with the 40mm, and would be a
f/6.6 system with the 60mm. The latter will possibly be uncomfortably
'fast', and also because of the relatively steep angles presented by some of
the light to the etalon, the bandpass will degrade. However if the units are
instead being put on a 1200mm scope, the result will be a F/30 system with
the 40mm etalon, and a f/20 system with the 60mm etalon. In either case, the
larger image size will require a BF15 blocking filter if the full solar disk
is to be viewed. The longer focal length system will give more detail, and
the images will be 'finer' at this sort of focal length with the larger
etalon.
I think that the Maxscopes, are both f/10 systems, so the 60mm unit has a
longer focal length, and the brightness will be the same on both systems,
with the 60mm showing more magnification, and detail (this is why it needs
the BF10, rather than the BF5 rejection filter fitted to the smaller unit).
The solar image with the double etalon, should not be too dim, unless you
are running at very high focal lengths. In this case the lack of detail with
the smaller unit will also show.
One comment, Coronado have just said to me, that you are far more 'likely'
to be able to stack a pair of 40mm units, without them carefully selecting
the assemblies, than any of the larger units (the 'repeatability' on the
smaller units is better).
The image on a Maxscope 60, is then 50% larger than the image seen on a
Maxscope 40.

Best Wishes


Hi Roger-

Actually the focal ratio is a major consideration with our SolarMax
filter sets. The important consideration is focal length. Consider the
blocking filter as a field stop near the focal plane (blocking filters
are expensive, aperture is based solely on the focal length the filter
is used on for economic reasons) and you pretty much have everything
you need to determine which blocking filter should be used. It's
simply a question of image scale.

Fast, slow, and angles do not make much difference to our system as
the etalon is mounted afocally. The blocking filters aren't impacted
much at all by the cone with a configuration we would expect to see in
the real world. Internal etalons are fitted with afocalizing lenses
which are carefully integrated with existing designs.

There should be no confusion with the stacking issue- we'll get it
done properly. We ask that existing customers send their etalon and
blocking filters to us when purchasing an additional etalon in order
to ensure the performance is as it should be. No if ands or buts. A 40
receives the same amount of attention in this process a 90 does. In
any event *we* are far more "likely" to ensure that a customer
receieves a properly matched set of etalons.

Regards,
Bill Dean

"KC" wrote in message
om...
I'm looking for some comments from Coronado Maxscope users. Which
would you prefer - a double-stacked 40mm or a single 60mm? Obviously
the image of the Sun in the 40mm will be dimmer but more detailed. But
would it be too dim for public viewing?

The double stacked 40mm is actually $600 cheaper than a 60mm and half
the cost of the double stacked 60mm. Would appreciate any comments on
this, thanks.
To photograph with a single SolarMax40, at 800mm focal length, I have to add
another polarising filter to reduce the light (on the BF unit), even when
using 1/100th sec exposures, so there is still plenty of light...
The key is that aperture controls the fine detail visible. The image is
plenty bright enough through the 40mm filter. Double stacked, the image will
be dimmer, and will be able to 'pick out' detail better (rather than being
'more detailed' - the narrow band, allows you to more precisely pick which
parts of the solar image are being shown, but the actual detail on these
parts will be limited by the aperture).
Remember it is the ratio of focal length to aperture, that gives the 'speed'
of the system. If you are intending to use the unit(s) (talking here about
SolarMax filters, rather than the Maxscope), on something like a 400mm focal
length scope, the result, is a f/10 system with the 40mm, and would be a
f/6.6 system with the 60mm. The latter will possibly be uncomfortably
'fast', and also because of the relatively steep angles presented by some of
the light to the etalon, the bandpass will degrade. However if the units are
instead being put on a 1200mm scope, the result will be a F/30 system with
the 40mm etalon, and a f/20 system with the 60mm etalon. In either case, the
larger image size will require a BF15 blocking filter if the full solar disk
is to be viewed. The longer focal length system will give more detail, and
the images will be 'finer' at this sort of focal length with the larger
etalon.
I think that the Maxscopes, are both f/10 systems, so the 60mm unit has a
longer focal length, and the brightness will be the same on both systems,
with the 60mm showing more magnification, and detail (this is why it needs
the BF10, rather than the BF5 rejection filter fitted to the smaller unit).
The solar image with the double etalon, should not be too dim, unless you
are running at very high focal lengths. In this case the lack of detail with
the smaller unit will also show.
One comment, Coronado have just said to me, that you are far more 'likely'
to be able to stack a pair of 40mm units, without them carefully selecting
the assemblies, than any of the larger units (the 'repeatability' on the
smaller units is better).
The image on a Maxscope 60, is then 50% larger than the image seen on a
Maxscope 40.

Best Wishes

(KC) wrote in message . com...
I'm looking for some comments from Coronado Maxscope users. Which
would you prefer - a double-stacked 40mm or a single 60mm?


I have looked through stacked 40's mounted on a Pronto/Ranger and
single 60's and 90's at the Coronado exhibit at NEAF. Frankly I found
it more interesting to view through the stacked 40's than a single 90.
While the 90 gives better resolution, these old eyes found it easier
to see disc detail in the stacked 40's. Also the 40's can be
unstacked for prominence viewing.

So all in all, for plain old fun, I think the stacked 40's give the
best bang for the buck. And don't forget, you don't have to mount
them on a $3,000 apochromatic refractor, as the band pass is so small.
A coke bottle will probably do. OK, you may have trouble focusing a
coke bottle, but any Synta quality refractor will function quite well.