Baader Solar Continuum filter

[Stardust]

Has anyone had any experience with this filter, worth shelling out for or not?

Cheers

DAve :sunny:

[Kaptain Klevtsov]

I have one of these, so I'll chip in.

For imaging, it does what it says on the tin, to some extent. It is not in the PST league when it comes to detail resolution as the bandwidth is relatively wide (well I think that's why) but for sunspots it does help a lot.

Visually it sharpens up the image and makes the contrast between the background and sunspots much greater.

I have not been able to see (image) any solar flares, prominences or any of that exciting stuff that you see on solar pictures. It could be that I'm not doing it right (has been known) or that I've not yet got lucky.

HTH

Captain Chaos

[Stardust]

Thanks for chipping in, It also says that it enhances surface granulation, is this so?

I'll have to find some one with a PST to have a look through, they sound superb.

thanks

DAve

[The Warthog]

Apparently you see the really exciting stuff through an H-alpha filter. The solar films and filters are good for sunspots. I have had a look through a PST. It was neat, with granulation, flares, prominences and all that. Didn't make me want to run out and buy one, though. Looking through one a couple times a year will do me.

[Kaptain Klevtsov]

Thanks for chipping in, It also says that it enhances surface granulation, is this so?

I'll have to find some one with a PST to have a look through, they sound superb.

thanks

DAve

The surface granulation shows up more on the webcam (standard or SC3), I've yet to see any visually, though I mostly use the EP to line up the target and don't spend a long time looking down it. The image certainly looks improved with the solar continuum filter on making the aiming easier, the sunspots definitely stand out more and have more detail.

WRT H-alpha filters, the deep sky type will not show the detail that the Coronado type will. If you browse the solar images posted you can compare the results. These (mine anyway) are software enhanced to show the detail as I haven't actually looked through the Ha filter. Certainly my standard webcam is not sensitive enough to give an image with this filter so it might be too dark for visual use. I'll try to have a peep this afternoon after work if the clouds stay away and report back.

To finish with the usual (should have done this before - my bad) don't try solar without the correct blocking filter. All my images use Baader solar film on the front of the 'scope as well as the smaller filters on the webcam adapter.

CAptain Chaos

[Kaptain Klevtsov]

Managed to have a look through the Ha filter this afternoon at the sun. It looks like a dimmer redder version of the solar continuum filter version. I couldn't see any more detail, if anything there was less as the image was much dimmer.

WRT the PST, I'm very tempted myself in that direction. I've been toying with the idea of selling the Mak. to fund it as well.

Captain Chaos

[Stardust]

OK Thanks guys

something to ponder over

[Astroman]

For imaging, it does what it says on the tin, to some extent. It is not in the PST league when it comes to detail resolution as the bandwidth is relatively wide (well I think that's why) but for sunspots it does help a lot.

Visually it sharpens up the image and makes the contrast between the background and sunspots much greater.

I have not been able to see (image) any solar flares, prominences or any of that exciting stuff that you see on solar pictures. It could be that I'm not doing it right (has been known) or that I've not yet got lucky.

HTH

Captain Chaos

The SCF (Solar Continuum Filter) has a center at 540nm which is in the green range and slightly longer than the Magnesium line. This corresponds to the most sensitive band of the human eye. It's designed to filter out extraneous wavelengths and using the most sensitive area. This, in theory, increases the contrast and brings out more detail. I've never seen through one myself, but I'm not too sure the principal is sound. As I've said many times, different features are visible at different wavelengths, depending on the temperatures involved. You may actually do better to view a wider band for more detail. I couldn't find anywhere what the actual bandwidth of this filter is, so it's hard to say.

The PST is centered at 656.3nm, right on the H-Alpha wavelength. CC is right-that's a whole other smoke. The granularity visible at 540nm will be the regular, white light convection cells right at the "surface" of the Sun. Granularity visible with a PST or other H-A filter will more likely be Supergranularity. Granules visible in white light are much smaller, on the order of a few hundred miles across, while supergranules are on average 10 times larger. That's the main reason they're easier to see in H-A. Seeing granulation is a matter of training the eye and seeing conditions, especially in white light of any wavelength.

CC: You won't see any prominences, flares or filaments in white light. They're visible in H-A or CaK (Calcium K, which is violet). So cheer up, you're not doing it wrong. 8)

Apparently you see the really exciting stuff through an H-alpha filter. The solar films and filters are good for sunspots. I have had a look through a PST. It was neat, with granulation, flares, prominences and all that. Didn't make me want to run out and buy one, though. Looking through one a couple times a year will do me.

There's actually quite a lot to see in white light, just not at the moment. The Sun is "ramping down" in activity level, heading for solar minimum around 2010. The next cycle up is predicted to be a doozie, though. Stay tuned! You can check out some of my input on what to look for in the Solar section here under, "Do you do/like solar observing?" http://stargazerslounge.co.uk/index.php?topic=1940.msg19647#msg19647

[Kaptain Klevtsov]

Glad you told us that Astroman, I was thinking of buying a PST but if the sun is ramping down for a few years they might get cheaper very quickly.

When you say I won't see any prominences in white light I think I didn't make myself clear in the earlier post. I can fit the Ha filter on the webcam and not pick anything up. Do I need even more kit to get a flare or might the DSO type of Ha filter do the business?

TIA

Captain Chaos (filming clouds in time lapse today as its not dark and it IS cloudy)

[GazOC]

Glad you told us that Astroman, I was thinking of buying a PST but if the sun is ramping down for a few years they might get cheaper very quickly.

I think Astroman mean the sun spots (ie white light) were ramping down?

[Astroman]

CC: Your experience with the DSO HA filter is one I'd very much like to try with my solar scope setup described in the talk I just gave/uploaded. I do believe it's the same effect as the etalon type required for the PST and Coronado filter set. I could be wrong though. If I am, it won't work because the DSO HA filter isn't sufficiently narrow band pass to isolate just the "good stuff", as WH puts it. 8) The DSO HA is most likely centered on or near the 656.3 nm line, but my not be narrow enough, to put it another way. I'm not too sure either way. OTOH, if it is narrow enough, the Baader full aperture filter should let that band through, to be isolated by the DSO HA. The problem then would be that the contrast between the prominences along the limb and space is much lower than that between sunspots and the surface. Prominences are very faint by comparison and hard to isolate. Same with filaments and such on the surface.

On your other economic point, I'm not sure te prices will come down just because of the lack of activity, unless you're talking about the used market. Since someone will buy one and see nothing, the market could well get flooded artificially. Hmmm, good point...

Gaz: Yes, the sunspots are ramping down. But then, so is the overall activity. I once explained that prominences are more of a surface phenomenon while sunspots go deeper. There can be no spot visible, yet a prominence can be huge along the limb, with lots of activity simply for this reason. I wish I had a dollar for every time I've seen this. Unfortunately, prominence activity will also slow down as we reach solar minimum. IMHO though, it's still worth investing in devices to observe the Sun. It's a fascinating object, full of suprises, and lots to see. It is, after all, the closest star to us and therefore much deserving of our close attention.

[Astroman]

Just to be sure I'm clear, viewing prominences is a learned observing technique-you have to train yourself to see them, the same as with granulation, just as averted vision is learned, or delving deep into globulars is.

[GazOC]

AM,

You mentioned before that the next 11 year maximum is supposed to be a good one, how do they (you!! ) know that? What signs give it away?

[Astroman]

It's prediicted to be a good one based on the sum data collected during this cycle. Since the Sun runs on magnetism, and magnetism's properties are fairly well known, even on this scale, it's not too tough to predict how it will bounce back based on how it subsided. It's kind of tough to explain, but give me a minute and I'll get there.

The magnitude of the Sun's magnetic field is very well studied. Each solar cycle, it expands, twists, collapses, switches polarity and rebounds in a relatively predictable way. Think of the elastic properties of rubber balls of different densities and compounds. Highly elastic balls when dropped will bounce back up to a given height. Denser, harder compound balls will also bounce back, but not as high. Something similar can be said about the magnetic field of the Sun. The way it subsides and rebounds tells us a lot about the next cycle. You can picture it as a bouncing ball that changes certain properties each time it bounces.

I hope that helps. If not, ask again and I'll try to do better. 8)

[GazOC]

Thats an excellent explanation AM. Cheers!

[Astroman]

Ok, from what I can find out about Lumicon's HA deep sky filter, it is too wideband to see specific prominences on the Sun. It's designed to enhance the HA line and below. Here's an image of the response curve:

Anything above the blue line is rejected. Below and to the right is passed. A Coronado filter's curve is a very sharp "notch" around the dotted line on the right, indicating H-alpha.

[Kaptain Klevtsov]

Mine's one of these

(if its any use).

BTW The solar continuum is like this

Captain Chaos

[Astroman]

Ah, that's excellent, CC. At the scale of your chart, the bandpass for HA is roughly 15nm. To isolate the HA line, Coronado's bandpass is 0.1nm. While yours is better than the Lumicon, it's still insufficient to isolate the HA with the needed precision to view prominences, and so on. The bandpass needed would just about mirror the actual green line representing HA.

The solar continuum filter looks very much like the "V" photometric filter I use, maybe a little narrower. The numbers on the left are violet in color while the other side is red. If this filter does what it says, according to this curve, it may indeed improve contrast. I'll have to try my V filter with the baader film on a scope to find out for myself. I'll let you know.