Solar viewing ? filters

[peter brown]

Ihave bought a front solar filter for my LX200 10" SCT.
I guess it is a neutral filter. Can I use a H alpha filter in my eyepiece and get better views and pictures using the eyepiece filter.
Many thanks, in anticitation,

Peter B

[CoombellKid]

Originally Posted by peter brown

Ihave bought a front solar filter for my LX200 10" SCT.
I guess it is a neutral filter. Can I use a H alpha filter in my eyepiece and get better views and pictures using the eyepiece filter.
Many thanks, in anticitation,

Peter B

In the hope of seeing Prom's and surface filaments... in a word no. Your
EP H-Alpha filter works on a different set of emission lines to one that
can allow you to observe these features on the Sun. Bottom line is if
you wants to see prom's and such you need to get a PST or similar.

The front filter you have only allows you to observe sunspots and possibly
hints of surface granulation. Dont use you SCT on the sun unless you
have that front filter in place. And btw, if you ever see an EP filter
that's called a solar filter to be used on the Sun, steer well clear of
it. These are highly dangerous as they crack under the intense heat
(like putting glass under a powerful magnifying glass). This can blind
you in a second.

regards,CS

[Merlin66 (Ken)]

You're 100% right about Ha observing; to see surface granulations and proms you need either a PST or one of the Solarmax (sm40/60 plus blocking filter).
If you'd asked me a year ago - does a secondary Ha filter imrpove the visible surface detail I would have said no, but recently I've seen some excellent images which show significant surface detail when a narrowband Ha filter is used in conjunction with a front aperture solar filter ( Baader/ Sola screen etc) It seems to definately increase the contrast.....

[Popeye (Bert)]

Peter I used to have a Baader filter that I made by myself and I used it on a 90mm Meade ETX. It was great for seeing sun spots but very little else.
I sold the ETX long ago and now have a LX90 and was wondering aloud about how a new Baader film could be made on the LX90 and also wondering aloud about the benefit of a PST. My wonderful wife then got the message and bought me a PST! It is great for seeing some of the granulations and other solar features. However we are in a solar minimum and there is not a lot of activity up there. Nevertheless I enjoy a bit of time looking at prominences etc. But as of late there has been no sign of sunspots. On that note I would recommend that you stay with the solar filter that you have for sunspots as they are seen better with that type of filter. I've since bought another (2nd hand) 90mm ETX and bought a Thousand Oaks filter for it. (Bit of a rip-off as there are really only 999 Oaks! ) Just waiting for some sunspots now! )
So I would recommend a PST even though they are a bit pricey but the next step up is even more expensive.
Cheers!
Popeye

[caleb]

where can i buy safe film to use as both, a filter on my scope, and to look at the sun without a scope.
low price and shipping too.

[CoombellKid]

Originally Posted by caleb

where can i buy safe film to use as both, a filter on my scope, and to look at the sun without a scope.
low price and shipping too.

Most astro shops sell solar film. I brought an A4 size sheet for about $40.00
from Star Optics on the Gold Coast.

Also I dont quite agree with Popeye assumption solar film is better to observe
sun groups/spots. To a degree this might be true as it is cheaper with solar
film than a HA scope aperture for aperture. What Solar film wont show you
is the surface filaments and Plague associated with the sun group. Also
the granulations around the sun group is akin to swirling currents all
observable in a PST. You can watch it change over several hours and some
granulations changes over several minites. It's an awesome thing to
observe, especially sitting there feeling the very heat it's all creating. I
like to get out there with a good sun hat, a towel, and half a dozen beers
in an esky once you have seen the Sun in HA it's awe inspring and
even a touch scary, but certainly a crowd pleaser.

regards,CS

[casstony]

While a white light filter can't show features that a pst can, the sunspot itself is better defined in white light, paticularly the outer region (penumbra). I imagine the sunspot detail would be better through a double stacked pst but I haven't had the pleasure.

[Merlin66 (Ken)]

Although there haven't been to many spots to demonstrate the capabilities of the PST, there's no doubt looking at the surface features in Ha gives far more detail than white light. Single or double stacked. You can see the magnetic streamers around the spot in the penumbra region..

[caleb]

H-Alfah filter? is this nesesary to view solar flares.
is it some complex electronic thing or is it just a type of filter i can afford...

[casstony]

Originally Posted by Merlin66

there's no doubt looking at the surface features in Ha gives far more detail than white light. Single or double stacked. You can see the magnetic streamers around the spot in the penumbra region..

True, but the penumbral region of a sunspot still looks better in white light - much better contrast with the surrounds. The white light filter I used was baader solar film; perhaps baader film gives better contrast than other white light filters? Perhaps a difference in aperture influenced my opinion? Alternatively my memory is failing (quite possible).

[casstony]

Caleb, whereas a white light filter passes a tiny amount of light from the whole visual spectrum, a H-alpha filter passes light from a very narrow portion of the spectrum. The Coronado PST is the cheapest way to get into H-alpha viewing - about $800 from Bintel.

[Merlin66 (Ken)]

For solar Ha you need a special filter which only allows the light from the emmission wavelength of Hydrogen (6562.8 Angstrom) to get through.

These filters are VERY sensitive and expensive. The bandwidth of available filters can vary from 1A to the "best" at about 0.5A.
Lumicon make a prominance filter (1.2A) which can be used on scopes up to 100mm aperture ( But I'd still recommend using an energy rejection filter (ERF) up front), Coronado do a range of SolarMax filters starting at 40mm aperture up to 90mm. Daystar also have very good filters but these require a power source to heat and stabilise the bandwidth. Lunt have also started to sell solar filters and scopes. The cheapest is probably the Coronado PST, which is a 40mm scope fitted with a 0.7A etalon filter.

The "normal" Ha filters used for deep sky observering are not suitable for Ha solar work. The minimum bandwidth is usually 7nm (70A)

The cost of entry is pretty high. An 80mm ERF filter would cost about $300+, a PST about $600. The SM40 starts about $1200, SM60 $4000 etc

Observing the Sun can be dangerous, don't be tempted to use inappropriate filters.

[Merlin66 (Ken)]

Casstony,
I have the 1000 Oaks, Type 2, Baader and the JMB, Class A white light filters. The 1000 Oaks and the JMB both give a pinkish cast to the solar image whereas the Baader is white. The contrast is slightly better with the Baader, but not significantly so.
Unfortunately, when you've observed the Sun in Ha it's difficult to go back to white light! As mentioned a combination of the white light and a 7nm Ha filter seems to improve the contrast even more.....

[caleb]

so what can you see with baader?
and where can i buy a sheet, i realy only need half an A4.
plus, are glass of film better.
i need something to fit D=80mm but the outside of the tube is closer to 100mm.

[Merlin66 (Ken)]

With the Baader filter on a 80mm scope you'll see plenty of surface detail in and around the sunspots ( when the solar cycle allows!).
I have both the glass and film type; the film just requires a bit more care in handling, but should last a long time ( mine are almost 10 years old and still OK)

[caleb]

where can i get some with cheap shipping to aus.

[CoombellKid]

Originally Posted by casstony

While a white light filter can't show features that a pst can, the sunspot itself is better defined in white light, paticularly the outer region (penumbra). I imagine the sunspot detail would be better through a double stacked pst but I haven't had the pleasure.

Yeah but you have to remember your only using a 40mm scope with
the PST, solar film on my 200mm newt the resolution is 10 fold by
factor of aperture, if you have ever looked through a solar max 90 you'll
know what I mean. I find you can observe the penumbra quite easily
through a PST, if you de-tune the filter. But it's a whole lot cheaper
using solar film... one could only imagine the price of a 200mm solar
HA filter

When I'm doing solar observing I like to have both setup

regards,CS

[Popeye (Bert)]

As I mentioned a few posts ago I did use Baader film on my 90mm ETX and I made the fitting out of plastic water pipe, needing to use a lathe to get the part that fits over the objetive wide but snug enough to be safe.
This time I used the Thousand Oaks filter because I was just too idle to go through the rigmarole of making another filter and it fits very snugly and safely on the ETX. For solar viewing in that medium I tend to like the white light of the Baader film better that the glass of the Thousand Oaks. However, like the previous writer I too like to have both set up when solar viewing but lately it has been very quiet 'up there' and the glass filter only shows an orange ball while with the PST I can see prominences and granulation which is much more interesting. I use a bucket hat to keep the sunlight from spoiling my view in the EP.
Cheers!
Popeye

[AstralTraveller (David)]

You can improve your white-light views significantly fairly cheaply with a solar continuum filter (as sold by Andrews and presumably most other retailers). This is basically a green filter which passes the peak emission of the sun and blocks the red and blue ends of the spectrum. So the sun appears a pretty green (just like my posts!) In my 15cm refractor the improvement in contrast and detail is very noticeable.

Of course you won't see prominences and so is no replacement for a Ha setup. However it is cheap and you get the resolution of (in my case) a 15cm scope compared to a 4cm scope.