44 replies to this topic

[Spectrum222]

Okay! The sun is out and skies are pretty stable... so far

 

Running my ST120 f/5 w/APM Wedge and using initially 9mm NT6 EP (67X) with Baader Swan filter(s). I have two, started with one initially. 

 

First light has this showing a significant amount of granulation on the disk, on par I estimate, or slightly BETTER than my NB Na-I filters. Still in work, more to come, and will also experiment with double-stacking them. But so far - impressive, and IMO I like the view better than the Continuum view. 

 

Darren

[Spectrum222]

Okay: here's the 60 minute quick evaluation - sun was out VERY nicely for 40 minutes, then a huge cloud bank (figures!) occulted the sun. To add to the cacophony, the Ready-mix truck about 80' away was getting ready to do its thing to repair one of our complex suites - so I'd be dealing with vibration. Pulled scope in for now until they are done and back comes the sun (hopefully within a 90 minute timeline!)

 

Condo living has its challenges. I miss my house in Winnipeg sometimes!  

 

Okay - enough of that... What did the testing find out?

 

1. These are brighter and easier to use in the ST120 w/APM wedge than the Na-I filters, mainly due to brightness (expected somewhat).
2. Slightly, but not much lower (say less than maybe 5-8% - estimated) brightness level than the Continuum filter. Plenty of room for brightness adjusting in the wedges. No worries there!
3. Initial testing of each during best seeing at 67X (Nagler Type 6 - 9mm) showed pretty close performance. One of the filters SEEMS to be a bit better for pulling out subtle shading, but more work comparing need be done.
4. looks to definitely pass the b2 line - shading on the disk (and limb) exceptionally well seen - granulation is consistent with a "sort of" blend of CF and Na-I - in other words, I can see a sort of "hybrid" detail, with more shading easier to see in some ways (likely portion of visual spectrum) than the Na-Is, but that is still preliminary. 
5. During best seeing at both 67X and ~86X (7mm NT6), excellent rendition of penumbral detail, including pores and smaller spots. Disk details seemed in some ways a bit easier to see - I could make out plage as a brighter area, similar to the WLC (540nm) or Na filtering, but my first impressions were that this showed at least as well as the sodium, and so did granular structure. More evaluation warranted, but I was VERY impressed so far!
6. Stacking: At 67X I tried stacking both - had PLENTY of room in the APM wedge housing for this! Expected focal shift due to extra filter element, and details held well, but I will have to do more there. IMO, it seemed as if some of the more subtle details were less presented - I think the stacked pair MAY cut off a portion of the b2-line due to steeper cutting and narrowing. As I surmised, these as single pass as edge filters with the b2 line passing well, but JUST. More work to be done to confirm this. 
7. I actually like the "teal" tint of these - a soft, but very nice contrasting, view, similar to the "warm, and comfortable tinted" views in the sodium filters. The tint is (to me) more... smooth(?) in appearance? A bit less harsh, if I can use that term, to the more bright lime-green tint of the WLC 540nm filtering. They all work well, but I find the teal REALLY nice. I guess since its close to the O-III band, it reminds me of that pleasant tint.

So, to sum up first light, I think these have potential for sure. IMO, I prefer these so far, even just using them barely 1h so far, to the WLC (540nm) view, and the added brightness vs the sodium line is a boon to those wanting a bit more of a "hybrid" view; more work to be done on these to be sure, including a run on my venerable 152RFT solar scope, and a trial in the Lacerta wedge as well. 

 

I might be stepping on a limb here, and certainly don't want anyone to flatten their wallets, but I THINK these would do VERY well in a photographic application. Both on monochrome and combined using creative RGB mixing, if available for some. I am not sure whether running a dual stack yet is advantageous, more to come there. Single filtering is fine so far from what I have seen. Results might vary with BW and CWL differences between filters. (Baader QC). 

 

*Final Note for now:

 

When seeing was near ideal, for a very brief 5 minute window, I was able to make out plage channeling in the mid-disk; It was not just jumping out, but FAR easiest in any of the filters I have used to date. Further, granulation and what I have termed "shadings" in the past were REALLY easy to make out here, as well as very fine pores, similar to the sodium filtering. Again, more work to be done, but I have to call this a very successful (albeit truncated) test. 

 

Darren

[Spectrum222]

Well...

 

 

For those that understand that genre... lol!

 

Cloud left, but dust galore so glad I had scope back inside during that (!). Then, they left for lunch and overcast. 

 

Well, there's always tomorrow! Too windy now anyway.

 

A good first light test though. I thought. Happy I had at least 5-10 minutes of really good testing. 

 

And... now... SNOW?! What a country! 

 

Darren

Edited by Spectrum222, 24 October 2024 - 03:48 PM.

[LarryAlvarez]

I'm interested to hear if your 120 works with your Lacerta wedge.  It sounds like it did fine with the APM wedge. 

[Spectrum222]

Hi Larry, 

 

Oh it (my ST120) does work with the Lac-2S - I have used it on Na, WL, etc. no worries. Mine is modified to have a bit more clearance in it, for filters, etc. and my "stock" Lacerta ND3.0 was replaced with a Baader ND3.0, inserted into a 4mm M48f-M54m ZWO adapter ring that fits at the base of a 15mm extension tube, which has my Baader 2" CL on it:

 

 

I can add M48 extensions to my 1.25" CL insert, and then mount the 2" polarizer on it, OR stack 1.25" polarizer on the 1.25" filter. Just enough clearance. The reason I can run this modified wedge, which has about 10mm extra in-focus on the scope vs an APM, etc., is that I replaced the stock focuser with a TS Optics Monorail unit. It has more inward travel, and it is a decent focuser, but a bit finicky at times... I think I may look at adapting a FT or maybe a Diamond track on it. I REALLY like this scope for some applications, when I don't need an APO, or bigger scope like my 152RFT, or 165mm Mak. But more than $500-600 seems not worth it for such an inexpensive scope, and it IS working as is so... ?

 

You likely saw this on other posts, but just in case: So, basically, the Lacerta mod I did to the wedge, is:

 

1. Replacement of M54 stock insert, with a M54 x 15mm extension tube (I got mine from TS Optics, which has clearance for a 48mm filter, or other 2" accessory).
2. 2" M54a X 0.75 Baader Click Lock, which threads onto the 15mm top section.
3. M54m to M48f x 4mm filter adapter ring (ZWO), which allows the ND3.0 to fit inside the M54 x 15mm tube base, and provides a M48 "stop" for things going to the base of the extension. Won't stop 1.25" filters form hitting, but see #4 below. 
4. Then I use 1.25" CL inserts when not using 2" format EPs, and if I wish to make sure I do not hit the 48mm ND3.0 in the bottom by using various M48 extension tubes as needed for whatever I am doing.

 

Collectively it sounds like a lot of extra "stuff", and I guess it is, but the small investment from the stock system makes this whole Lacerta modified 2S wedge a real powerhouse and highly versatile. Probably part of the reason it works so well for me. 

 

2-3 years ago, I cleaned my Baader prism surface, and when I did these Lacerta mods, did so on the wedge window top and bottom. Came out clean, and dust/sleek/scratch free. I DO prefer clean optics, but I'm not <quite> a nut yet on that front. But occasional, careful, cleaning is a good thing - esp. for a first surface getting raw, focused solar radiation slamming onto it!

 

Darren

Edited by Spectrum222, 24 October 2024 - 09:59 PM.

[Spectrum222]

So Larry, with your modified Orion 100mm scope, now that you've got an additional 25mm of in-focus, you likely can use a Lacerta either stock or modified like mine to work with "other" medium-narrowband filters also!

 

If it focuses with the WLC (solar continuum) filter, it'll work with these too. 

 

Darren

[spicerack0]

the baader diamond track is a nice focuser and can be adapter modified to support lots of things, but its way too heavy for what it does. Stay away from it unless you have a real need for it-

 

 

Edited by spicerack0, 24 October 2024 - 04:54 PM.

[Spectrum222]

We had some "sun-flurries" today - wind came up as a squall, blew dust and debris around, then very light sleet mixed with wet light snow. Good thing I brought my stuff in well before that occurred!

 

Tomorrow looks pretty good - so I may play withe the Lacerta for Larry.

 

Saturday looks even better - so then, out will come the RFT with Lac-2s for a real trial!!! 

 

D

[Spectrum222]

the baader diamond track is a nice focuser, but its way too heavy for what it does. Stay away from it-

Thanks Spice - yeah - I don't think the DT focuser is an ideal add-on in my case. The TS MonoRail works well and is almost ideal for the ST120, only thing I do not like is that the roller on the track is pressed with what looks like graphite, and the single speed side spindle moves ~1-1.5mm when racking in and out. Annoying. It does not have a good bearing on that side. May look into replacing the graphite block with delrin or high density nylon. And, I may get our machine shop to do up a shim for that side. 

 

They usually get VERY busy into near-Christmas with late-year industrial orders, but we will see. If I can retrofit that to improve it, it'd be awesome. 

 

Darren

[Spectrum222]

So tomorrow for fun and adventure, instead of my ST120, I will run my SV/TMB105 APO, w/Lacerta Wedge and SWAN filter. 

 

Already verified that my B+W 48mm polarizer has plenty of clearance for the UWA/NT6 EPs w/SWAN Band/Mg-b2-4 filter!

 

Should be fun, and a good test for those with a 100mm scope. Also, this APO is very, VERY superb optically, and I would like to see how the Mg-b filtering does. Saturday will be the 152RFT run unless weather goes awry, which it is not looking to, currently. 

 

BTW, Larry A, the Lacerta DOES focus even with these filters in all my current scopes - APOs and the Achromats (ST120, TS152RFT). In fact, the added NB filters usually pull back focus ~1.0-1.5mm from when just using standard WL setups sans NB filter - FYI. 

 

The SV/TMB 105 is a f/6.2 (650mm f.l.) Apo. (actually, when I asked about this optic when chatting with Tom Back, the designer, he said this was one of the (technically) super-apochromatic designs he had done up.) Regardless, its been awhile playing with the "Deuce" (I call it that because it is serial #0222) and it does supebr on the sun also. 

 

Darren

Edited by Spectrum222, 24 October 2024 - 10:07 PM.

[Spectrum222]

I wanted to address these "shadings" I have been seeing, in WL, but especially in Mg-b2 and Na-D:

 

 

While these kind of features can be seen in some photographs, IMO, the brighter/short shutter times to reduce seeing I think reduces this subtle contrasting feature set that is visually detectable, esp. in really good seeing. It is often seen more regularly closer to small concentrations of smaller spots, or pore concentrations, but DOES also show a bit off from the edges of some plage or bright borders surrounding AR spots also. (off the penumbral border, where some more active spots have facular plage bordering the penumbrae, but these regions have deeper granulation (from the perspective of brightness/temperature). 

 

In this WL shot, you'll notice that there is VARIANCE in the brightness of the granulation around some of these described areas - some locations have darker appearance and some lighter. While taken at higher power and larger image scales than I am doing visually, I think (?) this helps illustrate the effect a bit better (?).

 

For those with H_a systems, you'll note that either visually or when observing a live view during a shoot, as you TUNE the filter, things get more contrasty and then BAM! there's the detail! Well, these narrow band filters, esp. near an absorption edge, act as a "partially-tuned" filter in a way, with continuum spillage adding to the signal in the passband. But visually, for sure, when the focus and brightness/contrast levels are "just right" (think tuning in the H_a case), the detail just "pops" out a lot more prominently. No, not like a Quark or dedicated line filter exactly, but definitely more details visible than without these NB filters being used. 

 

One thing that I only got a taste of today during my way-too-short session, was the granulation depth and plage contrast in the more mid-disk areas. It was really noticeable today in the SWAN when esp. single stacked - at least on the first short tries... I am hoping that this shows better tomorrow. 

 

Can one catch this stuff photographically? I think so. I think that the trick will be adjusting the brightness/contrast levels in shooting slightly dimmer than usual, and maybe the curves will show with mild adjustments these types of things when shooting through filters of this type. 

 

Hope that clarifies this a bit. 

 

darren

[LarryAlvarez]

The new modified 100 works good with the Lacerta wedge but I have yet to try it out with just regular imaging.  My main goal for it was to use it for my Sol'Ex with the Lacerta wedge attached as an erf.  I get maybe a good 20 min to shoot with it when I get home before the Sun goes behind the house.  It's a mad rush to get setup, tune in the Sol'Ex and start shooting.  It's like the Flight of the Bumble Bee.  I'm noticing that I am really liking scopes about the 600mm focal length.  I'm not sure quite why but that range +/- 50mm seems to work with everything well.  I've been thinking of putting some kind of filter drawer on my sol'ex for use with filters like you mentioned.  I still get lost in the barcode spectrum lines and I think some narrow band filters may be what I need to isolate the areas I'd like to explore.  I like that mod on your Lacerta wedge.  The stock 2" eyepiece holder on my wedge is a bit bigger than a standard 24mm and I like the way the Baader click lock works.  I might have to borrow that idea for my wedge, it looks like a good one. 

[Spectrum222]

I was happy to "re-share" this information, Larry - since you have one of these really neat wedges also, I thought that you'd like to hear ways to improve the unit. When I got mine, it was the immediate thing I first thought of. When I am executing a system, I think about what I will be using it for, and then find ways (if needed, as I think in this case) to improve the utility and performance of the accessory or system. 

 

You and I think a lot alike, methinks! We like our stuff to be both highly functional and look good doing it! That refit of your Orion 100 was superb! I am so glad that it is coming along the way you intended! 

 

You are also bang on with the "sweet spot" focal length of ~600mm for the 90-120mm aperture range - my 3 Apos sit right in this regime: 80mm f/7 (ED), 90mm Triplet f/7, and the 105mm I mentioned, which is 650mm (f/6.2). Also my ST120 of course does at f/5 The only scope longer than these is, of course, my 152RFT at 900mm. 

 

I think part of my "fun" as of late is exploring more novel bands not usually used for amateur study; it is interesting the details that show visually (for me) that present differently than the usual 538/540nm (continuum filtered) views, which also are designed NOT to hit any major spectral bands, which totally explains why some of my observed features don't show on photos using those filters. As we have seen on many fine contributors' shots and movies, different details present at different wavelengths, and it is well known that we look into different levels of the solar "atmosphere" with these various wavelengths. 

 

Now, with your Sol'ex, I think your approach isolating spectral RANGES in a narrower way will really "tune" your system to the region of interest at the time. Great idea, esp. in the 480-530nm portion of the spectrum which has a lot of lines in it! Some of the metal lines have particularly narrow widths, and in the case of Mg b-lines, these are highly influenced by solar magnetic fields, and Zeeman splitting of these have interesting magnetic features which differ, from what I have found to a limited extent, in the literature. Not as much done at that spectral area, but more studies are underway, not unlike the g-band stuff happening with DKIST and some amateur groups like the French pro-am investigations that Christian V's group has been doing with their special reflectors!

 

I am 95% certain that the SWAN allows isolation of the full Mg-b line suite, but in case you're very interested, I also found this filter which would also work to isolate the full Mg-b lines and also cuts one of the Fe lines, E₂, 527nm. I have added an approx. SWAN passband with the Alluxa filter for reference:

 

 

Here's that filter in case you're interested: 

https://alluxa.com/o...andpass-filter/

 

The issue with those is they come in a 25mm OD cell with 21mm open aperture, and these do not mate with standard 1.25" astro-filter accessories without some novel work to mate them.

 

I think there is enough on the SWAN for band edge to cover the primary b2 line, which is usually the broadest and deepest one from what I understand. 

 

Darren

 

 

 

 

 

[Spectrum222]

And Larry, for your information surrounding the Mg-b lines: 515-520nm hi-res spectrum. I marked it up with some info on the key lines. 

 

 

The GOLD line is ~0.4A, just for scale. Not sure how fine your Sol'Ex goes, but likely close

 

I added an approximate "unknown" roll off around 518nm for the Baader SWAN, but the main band of interest is the b2 line. 

 

Even with the rest of that "bar-code", you'll KNOW when you hit it with the pre-filter in there - it is a very DEEP line. IMO, I think the SWAN should be a good pre-filter to try, as it will JUST pass the Mg-b2 line, which is what you want for the most part, and reasonably priced. If you DO get the b1 line just past 518.3nm then, also-great!

 

One good thing with this approach is your start a bit "red", or longwave, and then slowly tune blueward until max resolution - when you hit Mg-b2, it is VERY obvious, apparently. 

 

Darren

Edited by Spectrum222, 25 October 2024 - 04:44 PM.

[LarryAlvarez]

I got outside today and got some WL with my Baader continuum filter normally (no Sol'Ex) and then put a Celestron UHC filter on my Sol'Ex.   It says celestron but is actually in a Baader cell.  I think Baader made the filter and Celestron just rebranded it.  Now that I'm looking at your image I think I was there but shot the b1 line.  I believe it was one of the lines included in the UHC filters pass.  Unfortunately I was pressed for time and clouds rolled in just before the Sun went behind the house. Attached are some very raw images from the Sol'Ex including the last one I got that I think might be b1. 

 

Attached Thumbnails

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• 
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[Spectrum222]

Hey Larry - that's awesome! A "triband" pre-filter - H_a, H_b, and possibly Mg_b2!!!

 

Wow! It LOOKS like the Mg_b2 line there, Larry! 

 

Here's a shot (reduced size to fit in CN) from a Hungarian Amateur through his Sol'Ex at Mg b2 - look familiar?

 

 

And yours - just below this colored one - hope okay to have proximally located!!

 

VERY close to your greyscale last shot! The middle looks to be H_b, correct? 

 

Looking forward to your next trials - I think you were fortunate! BTW, another option, should the b line be right at edge... the Astronomik UHC-E...

 

 

https://www.astronom...c-e-filter.html

 

I have these for my Canon 15x50IS binos and they work SUPERBLY for comets in 2" format.

 

I also have them for my big binoculars, and can use them in my scopes also. However, my SWAN Baader choice was strictly primarily for solar service, since i have the pair of UHC-E filters for comets. But who knows?

 

The UHC-E has a wide enough pass band to cover all three primary bands - and definitely covers b2 for sure! 

 

What vintage of Celestron filter was this? I know there are several variants, and if you know the timeline of production there may be a curve to verify how wide it is into the 520nm regime... But that last shot LOOKS very close to me to what I see in Mg-b2 shots so far! I am surprised a UHC actually covers this - the Astronomik was specifically designed for this wider curve. Hmm. 

 

Regardless, the beauty of your approach is all three key wavelengths can be had in one go! NICE!!!

 

Here's a higher res Mg-Quark shot off FLO's site on their Rotarion multi-wavelength Quark system - would be totally heavy as heck, but mucho-cool factor!

 

https://www.firstlig...kit_photo_2.jpg

 

 

Darren

Edited by Spectrum222, 25 October 2024 - 09:44 PM.

[Spectrum222]

SV105 Lacerta SWAN filter test update:

 

Well, I was out from ~16:40UT to just past 19:20UT today, on and off between work calls and such.

 

Ran the SV/TMB105 f/6.2 Apo with Lacerta Wedge and Baader SWAN/Mg-b filter with my TV 9mm NT6 (72X).

 

Initial run was SUPERB!!! seeing was about 7-8/10 for about 15 minutes, then periods of variable seeing, then it got much worse, like playing "whack-a-mole", trying to get a window of calm. It's been some time since I have seen THAT bad of seeing in a stretch! After 1800 UT - it was truly hit and miss... Maybe these SWAN filters don't like the sun? 

 

Well, during the best phase of seeing, I had to be vigilant; First to be checked were light bridges in the following ARs: 13868, 13869 and 13873. The Split spot, and then the two west of them, all had some brightening within their respective umbrae. VERY nice indeed! 

 

The real treat during best seeing - and I worked quickly (!) - were the pores and small spots dotted all over the place! The two best regions that REALLY popped in Mg-b2 edge filtering was the especially the northern-central group in between AR 13863 and 13874 spot pair near the NW middle to limb. There was also a nice lone spot easy pickings in Mg-b light. Would have been visible regardless, but the "treat" in this region was the plage network extending through AR13863 to the other side THROUGH the disk! The other superbly shown "shading" and pore/small spot development area was from AR 13866 through to AR 13863. The latter had a very neat "horseshoe" configuration, with "shading", perhaps initial penumbral or similar development, between these and surrounding these. If seeing had held better, I could have gone to 86X or so and had a real treat, but alas, once seeing dropped severely (like to 2-3/10 on the Pickering scale and sometimes went as bad almost as a 1 (!)), I was done. Even dropping back to 59X (11NT6) didn't help the cause when it went to "heck", seeing-wise. 

 

Now - to be honest, it does NOT show as good as Larry's 3rd shot for today - when doing b2 line views, he has (or should have) MUCH more fine contrast. I estimate my "depth" to be MAYBE... max ~1/3 (?) of his showing there. Still highly visible, but not blazing like his. Shows as a brighter region, for sure, and pretty nicely defined, and considering the aperture and filter used, not at all disappointing. Could have been seeing variances too, because yesterday's first light had a lot to show, for plage depth for some time, until we clouded out. I didn't really get to dig much yesterday. 

 

The plage on the limb edges was also superb - when seeing was steady, the eastern limb plage structures around 13873 were DEEP - I mean bright - All around the active core of this whole complex - very easy to see when seeing held... Also nice dotted plage between 13873 and the newer 13874 AR as well. 

 

Western Plage was also superb up through the 13860 region. 

 

Lastly - I did have a nice 15s period of superbly steady (9/10) seeing around 18:00 UT, and during that brief but glorious period, Penumbral structure within AR 13868, and also the nicely positioned pores, and even the extra small spots and pores extending westward towards Ar 13866.. REALLY finely spaced and SMALL pore-like spots, dotted all over the region. 

 

Considering my challenges today - WOW. I have to say I had a hoot, and I am truly elated to see Larry's apparent grab of the spectral region. He has more fine tuning on his shot than I get in my edge filter (Baader "Mg" I am calling it henceforth), and once he gets his technique, we are all in for a true treat with alpha/beta H, and Mg-b2 shots. 

 

Forecast yesterday was for clear skies, now a mix, but hopefully better seeing. Mg likely more sensitive to seeing than Na. TBD. If decent, out will come my 152RFT and will have a run with the Mg filters. Hopefully... 

 

Darren

Edited by Spectrum222, 25 October 2024 - 11:06 PM.

[Spectrum222]

Some filter investigations, and analysis:

 

Okay - first off - Larry's filter. If it was indeed a Baader UHC-s and rebranded, then it should pass Mg b-lines, and cutoff right near the 520nm regime. So it should be fine, and so far Larry's shots suggest that this is the case:

 

 

Shows Mg lines just before cutting out.

 

If the unit is a the older Celestron re-mounted, that original LPR filter also looks to be wide enough to just pass the b-lines:

 

 

Either way - I think that you did it nicely, Larry! 

 

Now I have asked Baader directly to give more detailed info on the SWAN filter(s), but likely will not see an answer until Monday earliest, if they do at all. Here's hoping!

 

Baader SWAN filter analysis:

 

In my investigations, these filters (interference ones in general) all have, depending upon the BW and cutoff needed, a fairly predictable formula for their line filter curves. My Baader pair of SWAN filters is listed on the box at 514nm w/15nm FWHM. I have seen literature stating 512, 513, and <15nm FWHM since these have been offered. 

 

I will assume that 513nm is the center WL for now with these, with FWHM is 15nm, as stated. We KNOW for sure that the 501nm line is omitted in the passband (at least the intent of this filter), so given the published "cartoony curve" (hate those!)...

 

 

Above is what is known as a "5 cavity filter"; this is a Fabry-Perot type of interference filter with 5 resonant cavities to "tune" the filter's response to the wanted band pass. Nice thing for me is I am also an advanced radio Amateur ("Ham" - callsign VE6QY), and this is similar in behavior to a multi-pole RF filter, which I am also familiar with, and the principal is similar, though in the optical case, the filtering is done by dielectric layers forming a "sandwich"; these layers cause internal interference by photon reflections. Small phase differences between the layers creates a narrow wavelength range that passes the light, and anything outside this range is destructively interfered with, effectively absorbing the light. (Taken of Andover website on passband filters)

 

Okay - since I have to do some assumptions for this analysis, here we go - here's what we KNOW, assuming Baader is up front and accurate:

 

1. Central wavelength is 513nm +/- ~1nm. 513 would sit mid-range in the passband 0.5*(505+520) = 512.5nm ~513nm
2. Passband for FWHM is rated a <15nm (or less than or equal); FWHM is the 50%T point, and it is stated as 505-520nm
3. The passband includes 511 and 514nm, stated in specs. 
4. Claims that O-III is "blocked", according to spec., so that would be 501nm. Since we want to "block" it, we should have no more than 0.1% (OD3.0) to prevent a camera from really having to deal with this signal. I think that's a fair assumption. 
5. In order to get anywhere close to this steep a curve, the assumption of a "5 cavity" (5-C) curve is warranted in this case. 
6. Assuming a fairly symmetrical passband response, then, OD3 will likely be also on the "red side", around 525nm (513+12). 
7. At f/5 or larger, the filter, being around 15nm FWHM will not shift by more than ~0.5nm max. to the blue side. Probably less, but let's use that. 

Okay! With me so far? The reason for all this is to verify (at least on "electronic" paper) the likelihood of the Mg-b2 band being passed with this filter, which I am 99% certain it is. Maybe right close the the filter edge, but passing...

 

So - assuming book specifications:

 

CWL = 513. A 5-C filter will have peak plateau around 0.85 of FWHM, at it's 90%T(+) range. So, assuming a FWHM of 15nm, I get 0.85*15nm = 12.8nm. I rounded up for simplifying math for now. So, we have a +/- 6.4nm "width" at 90% or more, over the "window" of this filter at the peak. That range is from 506.6 to 519.4nm. So, things look to be in great shape here. Even if a bit variable on spec, we have at least 2nm to the edge of the b2 line at 517.3nm. 

 

If Baader optimized for 514nm now, and still has their FWHM around 14-15nm, then we still have a little room here. Very highly probable that Mg_b2 is passing with some SMALL room to spare! 

 

I hope that this was not too boring for the gang here, and admittedly, only Baader's QC department knows their variance - which may be rather loose given only wanting the 514/511nm lines. I hope that Baader will reply in a timely fashion. these CCD-optimized filters though for this kind of application are likely a bit tighter due to the primary use of these in AP applications. Less room for error or else the cameras would "catch" it.

 

Now onto my 152RFT test this morning - Will post in a separate one. 

 

Darren

Edited by Spectrum222, 26 October 2024 - 03:15 PM.

[spicerack0]

I got outside today and got some WL with my Baader continuum filter normally (no Sol'Ex) and then put a Celestron UHC filter on my Sol'Ex.   It says celestron but is actually in a Baader cell.  I think Baader made the filter and Celestron just rebranded it.  Now that I'm looking at your image I think I was there but shot the b1 line.  I believe it was one of the lines included in the UHC filters pass.  Unfortunately I was pressed for time and clouds rolled in just before the Sun went behind the house. Attached are some very raw images from the Sol'Ex including the last one I got that I think might be b1. 

CONGRATULATIONS LARRY, YOU CAPTURED SOMETHING NOBODY ELSE ON CLOUDYNIGHTS FORUM HAS!!!!

 

Behold, a Magnesium prominence that you captured!!!!! Thank you so much for posting this, you just changed the entire field of solar astronomy forever.

 

Seriously dude, mountains of kudos to you for going above and beyond with your imaging skills-

 

[Spectrum222]

HEY!!! That is interesting!!! Hmm. That IS new! Great catch, Spice! (don't know your name, so have to use the CN moniker. )

 

...and people wonder WHY I try this non-standard stuff!!! You JUST NEVER know what you can do/see/shoot!

 

Great work, Larry! Truly! Orion 100mm vintage modified/upgraded achromat at f/6 and a Lacerta Wedge+Sol'Ex!!! Yipee! The solar crowd goes wild! Woo hoo... (Alex, I'll take famous Texan Solar Photographers for the win! lol)

 

D

Edited by Spectrum222, 26 October 2024 - 06:29 PM.

[Spectrum222]

Congratulations again LA! Mark that position on the Sol'ex! More work to play for there!!!! 

 

What time yesterday did you shoot that run?! We can correlate it with a H-a photo, and check that AR too!

 

D

Edited by Spectrum222, 26 October 2024 - 06:36 PM.

[RichA]

HEY!!! That is interesting!!! Hmm. That IS new! Great catch, Spice! (don't know your name, so have to use the CN moniker. )

 

...and people wonder WHY I try this non-standard stuff!!! You JUST NEVER know what you can do/see/shoot!

 

Great work, Larry! Truly! Orion 100mm vintage modified/upgraded achromat at f/6 and a Lacerta Wedge+Sol'Ex!!! Yipee! The solar crowd goes wild! Woo hoo... (Alex, I'll take famous Texan Solar Photographers for the win! lol)

 

D

These filters are pretty horrible, optically, (I've played around with them on planets, etc) but if it allows a documentarian imaging of such an event, it's a breakthrough. 

[Spectrum222]

Well - I'll let Larry talk more on his end. I assume you're referring to the Celestron (or Baader?) UHC filter that Larry used in his testing? He'll have ot explain his version, but I think I know of this one - I have seen a similar one used for DSP hunting by one of our club members at the RASC in Winnipeg when I was living there. 

 

My experience is that UHC or broadband sky glow filters tend to be a bit finicky if you try them on planetary observing/imaging. Not because they are optically poor necessarily, though QC may be a factor, but also source - a no-name or budget filter of this type likely could be a dud. Maybe a "second" that failed the supplier's QC for their customer, and then offer them up to other resellers. 

 

In my ~43+ years working with filters, the ones I avoid are the Wratten ones unless made by a higher end manufacturer like Hoya, B+W/Schneider-Kreuznach, or similar. Budget Wrattens are garbage and I will not get into that here, I still am amazed they get used by some for planetary. I personally avoid them except for a small few that are useful. 

 

But we digress: Most good-to-v.good quality nebula filters are decent quality, or else shots through them would show in spades. My guess is your experience (MAY) have been trying to get prime focus on passbands that are wide and far apart from each other. Scope f-ratio, type and quality may play into it too. Results vary a lot there. 

 

Anyway - THESE Solar results speak volumes. Larry may have bagged the b1 line - which is okay too, Larry - it is the redder of the three - at 518.3nm. If SO, then your filter DOES pass the b2 line as well. The b4 line is Mg, b3 is Fe. They are at 516.7/516.9nm - the blue side of b2. 

 

Either way - this is superbly intriguing. To have a prominence remnant on the limb in green Mg light is a totally new thing! As Spice mentioned, first time for this kind of thing! If you DID bag Mg-b1, Larry, maybe it is more "active" or perhaps some minor doppler effect brought this into the passband from b2? That would be a large shift though - I'll have to do the Doppler math later.

 

Darren

[eblanken]

Hi Darren & All,

 

I am following with interest this thread and in general your work Darren.

 

Best,

 

Ed

[Spectrum222]

Hey Thanks Ed!

 

Appreciate the kind comments. To be honest, I do indeed view this as a collaborative effort here, and quite a few have added very good suggestions and comments also, despite my prolific posting.

 

I have to also tip my hat to Senor Alvarez, who has done some really neat work with his Sol'Ex lately, and this whole effort is a true hoot. I think we are stumbling upon some new interesting things here, lately. It will be interesting to see how this all goes here. I wish my skies have had been more cooperative as they were back a few months ago - here in W. Central Canada the fall season can be usually a bit variable, as we transition to northern early winter, but I am hoping that skies settle to be more amenable to a longer series of tests in my case. 

 

Hopefully, Larry and others in the US will have more luck with their skies. Good news is the sun will be out and should stay busy during this cycle's peak, so we should be in for some fine shows in the next months into 2025...

 

Cheers, and please feel free to pipe in if you have some suggestions, discoveries, or even corrections where applicable!

 

Darren