Return to the Cloudy Nights Telescope Reviews home page


Observing >> Solar Observing and Imaging

Pages: 1 | 2 | (show all)
KJL
super member
*****

Reged: 06/07/12

Loc: Boston, MA
90mm APO + Herschel wedge vs C6 SCT + Baader film
      #5961830 - 07/09/13 08:41 AM

I've been debating whether to purchase a 1.25" Lunt Herschel wedge as an upgrade to the Baader solar film I already use with my 90mm f/7 APO (SVR90T). I want to see more granulation more clearly! Also I could use it between my other refractors (80mm and 50mm APO). The twist here is that I also own a C6 XLT SCT, but have not purchased Baader film for it yet.

Would a top-flight 90mm APO with Herschel wedge return superior overall results (contrast + resolution) over a C6 SCT with Baader film?

My money is on the C6 + Baader film, but I've never used a Herschel before. I hear they are swell, but find it hard to believe the difference could make up for the presumably great difference in resolution.


Post Extras: Print Post   Remind Me!   Notify Moderator  
brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: KJL]
      #5961992 - 07/09/13 10:52 AM

Quote:

Would a top-flight 90mm APO with Herschel wedge return superior overall results (contrast + resolution) over a C6 SCT with Baader film?



My guess is, yes it would, but mostly because the thermal design of the C6 tube really isn't adequate for an environment being pasted with strong sunshine. If you have a really effective insulation system for the tube, or a well ventilated slitted observatory & helpful terrain to the south, the C6 may work better.

With the same scope (mine is a WO FLT 110) the wedge is marginally better than Baader solar film for contrast, very marginally better for resolution when used visually. The big difference is for imaging - the wedge allows much better control of filtration, allowing shorter exposures which enables performance to be maintained into much worse seeing.

In terms of percentage improvemnt of wedge vs solar film, I'd say around 10% visually, maybe 50% for imaging.

If you can get your hands on a Zeiss glass solar filter to fit your C6, you may find it better than solar film, very nearly as good as the wedge, especially visually. But it will cost an enormous amount of money. The cheap commercial glass filters are unsatisfactory from the point of view of optical flatness, often grossly so.


Post Extras: Print Post   Remind Me!   Notify Moderator  
frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: brianb11213]
      #5962242 - 07/09/13 01:55 PM

The C6 with Baader film will beat the 90mm with Herschel wedge. I've personally seen this comparison done in real life. It isn't even close.

Post Extras: Print Post   Remind Me!   Notify Moderator  
KJL
super member
*****

Reged: 06/07/12

Loc: Boston, MA
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: frolinmod]
      #5962312 - 07/09/13 02:40 PM

Such great suggestions, thanks!

brianb11213: I know astronomy is a game of inches, but even I have to admit that if I'm just barely seeing granulation with the Baader film, 10% better contrast is unlikely to satisfy my craving to see more. However, 50% suddenly blows open my interest in taking pictures of the sun. Thanks for the recommendations.

frolinmod: The comparison you experienced between a C6 + Baader film vs 90mm + Herschel wedge: was the C6 adapted in any way for heat issues?

It's hard to argue against the convenience of a Herschel wedge in a small refractor, but if the views in a C6 with Baader film without further modification are that much better I guess the decision is easy for me. After all, if the views are obviously better, the picture-taking must be at least as good!


Post Extras: Print Post   Remind Me!   Notify Moderator  
frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: KJL]
      #5962362 - 07/09/13 03:10 PM

Quote:

The comparison you experienced between a C6 + Baader film vs 90mm + Herschel wedge: was the C6 adapted in any way for heat issues?



No and neither was the refractor which was an Explore Scientific 102mm triplet APO with a 2-inch Lunt Herschel wedge (both mine). The C6 with Baader film (not mine) was superior. Both the Baader film and the Lunt Herschel wedge were the visual type, not the photographic type. The comparison took place at a local solar outreach event in May 2012. I would not say that the imaging results will be the same. That would need to be tested.


Post Extras: Print Post   Remind Me!   Notify Moderator  
KJL
super member
*****

Reged: 06/07/12

Loc: Boston, MA
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: frolinmod]
      #5962377 - 07/09/13 03:22 PM

Quote:

No and neither was the refractor which was an Explore Scientific 102mm triplet APO with a 2-inch Lunt Herschel wedge (both mine). The C6 with Baader film (not mine) was superior. Both the Baader film and the Lunt Herschel wedge were the visual type, not the photographic type. The comparison took place at a local solar outreach event in May 2012. I would not say that the imaging results will be the same. That would need to be tested.



Thanks again. I've put in an order for a Kendrick filter for my C6. Given your convincing results, trying a C6 with Baader will at least give me an upper bound for what a Herschel wedge on my 90mm refractor can do.


Post Extras: Print Post   Remind Me!   Notify Moderator  
George9
sage


Reged: 12/11/04

Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: KJL]
      #5962555 - 07/09/13 04:56 PM

Along those lines, I saw a 6-inch f/15 refractor with a nice Herschel wedge (I think Baader) and continuum filter versus a 10-inch f/5 Newtonian with Baader solar film. They were both great, but the 10-inch did better even under just very good seeing. Under great seeing, I think the difference would be bigger. And the 10-inch was a portable scope.

Medium-sized mirror-based scopes paired with full-aperture Baader film can be really impressive for pure visual work, and I think they are undervalued.


Post Extras: Print Post   Remind Me!   Notify Moderator  
brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: George9]
      #5962678 - 07/09/13 05:48 PM

OK. As it happens I own both a good quality 110mm apo (WO FLT 110) and a C6 tube. I have Baader solar film filters for both.

The smaller refractor almost always outperforms the SCT - despite considerable trouble being taken to insulate the SCT tube, the tube currents are a real issue. Just occasionally when the sun is low in the morning & the seeing is unusually stable the two are about equal for visual work.

The wedge is always about 10% better than Baader solar film on the FLT 110 - for visual work. As I said above, the flexibility of the secondary filtering with the wedge allows a bigger improvement for imaging.


Post Extras: Print Post   Remind Me!   Notify Moderator  
brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: George9]
      #5962686 - 07/09/13 05:51 PM

Quote:

Medium-sized mirror-based scopes paired with full-aperture Baader film can be really impressive for pure visual work, and I think they are undervalued.



Only, I think, if you can really get the thermal issues sorted ... and have an exceptional site.

I'm a great advocate of aperture vs. central obstruction so far as night time work is concerned, but IMVHO a refractor around 4 inches aperture is about ideal for solar work ... maybe a bit bigger if you have an exceptionally good site.


Post Extras: Print Post   Remind Me!   Notify Moderator  
zippeee
sage


Reged: 12/27/10

Loc: Alberta, Canada
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: George9]
      #5962714 - 07/09/13 06:12 PM

I use full aperture film (CPC11) and a Herschel wedge for WL, both with solar continuum filters. Here's what I've noticed;

Contrast is way, way better through my raptor. The sky is darker and sunspots seem to pop out more (almost looking 3d). I can pick out penumbral detail better as well.

Aperture is the king of resolving detail though. I can typically resolve granularity better with my CPC, BUT (big but) the air has to be cooperating too. Otherwise, at any comparable magnification, they're fairly close.

If I had to pick just one WL instrument, it would be my Raptor and wedge. I like the high contrast, full disk views and don't have to worry about tube currents or collimation. This is generally the consensus at outreach events too. Most people are more comfortable looking through the refactor and I still hear a lot of "Wow, cool"'s (though not as many as I get with the Lunt!).

All that being said, if you don't already have a film filter for your C6, then definitely get one before investing in a wedge. You'll be happy.


Post Extras: Print Post   Remind Me!   Notify Moderator  
George9
sage


Reged: 12/11/04

Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: zippeee]
      #5962961 - 07/09/13 08:52 PM

Sorry if I am exaggerating. It was about three years ago when I compared. I guess seeing must have been excellent. I could see granulation, pores, and faculae in both very well.

I used the 10-inch Newtonian as my white light scope for a decade. I did eventually switch to a 5-inch refractor not for the view but because it was mounted for tracking and I could piggyback my H-alpha on it.

Let me just say this. If you own a high-quality 6- to 11-inch Newtonian or catadioptric, might as well invest in Baader film just in case you run into some great seeing.

George


Post Extras: Print Post   Remind Me!   Notify Moderator  
George9
sage


Reged: 12/11/04

Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: George9]
      #5962969 - 07/09/13 08:56 PM

(I seem to remember with the 10-inch on the best daytime seeing I ever had, seeing not just the fine zebra pattern of a sunspot's penumbra, but also detail within the umbra. Is that possible? George)

Post Extras: Print Post   Remind Me!   Notify Moderator  
KJL
super member
*****

Reged: 06/07/12

Loc: Boston, MA
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: zippeee]
      #5963994 - 07/10/13 12:36 PM

Quote:

I use full aperture film (CPC11) and a Herschel wedge for WL, both with solar continuum filters. Here's what I've noticed;

Contrast is way, way better through my raptor. The sky is darker and sunspots seem to pop out more (almost looking 3d). I can pick out penumbral detail better as well.

Aperture is the king of resolving detail though. I can typically resolve granularity better with my CPC, BUT (big but) the air has to be cooperating too. Otherwise, at any comparable magnification, they're fairly close.

If I had to pick just one WL instrument, it would be my Raptor and wedge. I like the high contrast, full disk views and don't have to worry about tube currents or collimation. This is generally the consensus at outreach events too. Most people are more comfortable looking through the refactor and I still hear a lot of "Wow, cool"'s (though not as many as I get with the Lunt!).

All that being said, if you don't already have a film filter for your C6, then definitely get one before investing in a wedge. You'll be happy.



Thanks for the perspective. (And thanks again to everyone for their input!) I've decided that my best bet is to get both a wedge for all my refractors as well as the Baader film for my C6. I understand the impact of seeing, and most of the time I can only be bothered to bring out a refractor anyway. But on some rare occasions the daytime seeing lifts and I can be bothered to wait for a few moments of great clarity: for those opportunities, I want to have the C6 + Baader film on hand.

Next question: I have refractors ranging from 50mm doublet to 90mm triplet, all APOs. The 50mm APO in particular cannot come to focus with a 2" diagonal, even with the thinnest T2 adapters, so I would prefer to get the 1.25" Lunt rather than the Baader Ceramic Herschel. Is there any danger with using the 1.25" Lunt wedge in my 90mm Raptor with a standard 2/1.25" adapter in the focuser? Is there enough heat at the end of the focuser to heat that little ring of metal?


Post Extras: Print Post   Remind Me!   Notify Moderator  
brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: KJL]
      #5964037 - 07/10/13 01:07 PM

Quote:

I would prefer to get the 1.25" Lunt rather than the Baader Ceramic Herschel. Is there any danger with using the 1.25" Lunt wedge in my 90mm Raptor with a standard 2/1.25" adapter in the focuser? Is there enough heat at the end of the focuser to heat that little ring of metal?



I think you'll be fine.


Post Extras: Print Post   Remind Me!   Notify Moderator  
KJL
super member
*****

Reged: 06/07/12

Loc: Boston, MA
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: brianb11213]
      #5964871 - 07/10/13 10:31 PM

Quote:

Quote:

Is there any danger with using the 1.25" Lunt wedge in my 90mm Raptor with a standard 2/1.25" adapter in the focuser? Is there enough heat at the end of the focuser to heat that little ring of metal?



I think you'll be fine.



And with that -- and Lunt themselves telling me their 1.25" wedge is good up to 4" scopes -- I've ordered the 1.25" Herschel as well. The Kendrick Baader film for the C6 is already en route.

Of course with recent Boston weather it is unlikely I get to use either for awhile yet. Figures, as we've haven't gotten a good clear night recently either ....

Thanks again for all your help. I'll be sure to update with my own impressions!


Post Extras: Print Post   Remind Me!   Notify Moderator  
KJL
super member
*****

Reged: 06/07/12

Loc: Boston, MA
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: KJL]
      #5993696 - 07/27/13 09:27 PM

Quote:

Thanks again for all your help. I'll be sure to update with my own impressions!



I'm back! I have to say thank you again to all the great advice given above. Now it's my turn to return the favor, or more accurately pay-it-forward to other newbie solar observers.

I actually received the Kendrik 6011-SF Baader solar filter for my C6 SCT over two weeks ago, before the Lunt 1.25" wedge arrived. BTW briefly about this particular Kendrick filter: it is compatible with the C6's standard dovetail plate and has the sunfinder built-in, and I love it! Because of the flexibility of the three tabs it doesn't quite the positive screw-in "lock" feel of a standard ring solar filter, but in fact it seems to hold even more securely than the Astrozap filter on my 90mm refractor. Go figure. Besides, if you haven't modded your C6 SCT like I have (with rings) you must buy this version anyway to fit around the dovetail plate, and then you get the built-in sunfinder "for free." I highly recommend it.

The view through the C6 + Baader film knocked my socks off, as they say. In terms of percentage improvement over my 90mm APO + Baader, the C6 + Baader seemed to have 1/5 the scatter and 2x the resolution (technically only 67% more of the latter). I instantly saw the granulation in the C6 that I had been struggling to see with the 90mm. Generally I could "see into" features with much greater ease. Frankly, the view of solar features was a revelation: I can see why so many of you are hooked on WL.

Now, none of this is a surprise to all the experienced observers here, but somehow I got in my head that solar observing was governed by different physics from nighttime observing, lol. In particular, I somehow assumed that I wouldn't be able to appreciate the greater exit pupil for the same magnification, and also that the extra resolution would be asymptotically limited by seeing, especially in my not-so-special Boston city location. And especially in the ridiculously hot weather we were having.

I couldn't be more wrong. I had been teetering over selling the C6 in preference of the 90mm APO + future C11, but in that moment the little SCT earned its place as a grab-and-go white light solar scope. It was THAT good. Just as with nighttime views in my city white zone, six inches seems the minimum aperture required to really get an interesting view of the skies, night or day.

I didn't report my impressions then because I wanted to compare it to the Lunt wedge, in due deference to the differing experiences kindly reported here. I received the Lunt a few days later, and had one golden day to compare it with the C6 + Baader, but I foolishly decided to stay indoors instead. Then Boston clouded over, the heat broke and it didn't stop raining until last night. (As a sort of consolation prize, last night's sunset was absolutely gorgeous, all manner of violets and reds glowing through shredded clouds of myriad textures. A reminder that you don't need a telescope to enjoy the skies ....)

So the Lunt wedge: it's also amazing on my refractors. On my 90mm APO I could immediate see how the contrast was superior to the Baader film on the same scope, but I didn't really appreciate how much better it was until at the last moment I decided to try the Baader film again. The scatter was so much worse than the wedge I felt like I was looking through a milky haze, or an entirely different atmosphere. No joke. My first thought was how I had wasted so much time with the Baader film on the refractor! In terms of contrast the wedge is say, oh, 10x better? Not 10% better: one thousand percent better. The main consequence is that all of a sudden I felt I could actually see the resolution my SVR90T had on offer, which is a nice feeling. Until now I had just assumed that the slightly hazy view was due to heat waves.

So for my 50mm and 90mm refractors, at least, Baader film is permanently retired in preference to the Herschel.

The Lunt wedge vs the C6 + Baader film is a more interesting comparison. My viewing was at 10 am, the temp was just under 80F, and I was on a covered, still fairly cool, porch. Consequently, I'm fairly certain the C6 SCT was operating optimally in terms of heat issues. Also, the Lunt wedge's brightness could be tuned with a polarizing filter, and at its brightest it was actually brighter than the C6 + Baader film. So the comparison comes down to the contrast of the wedge vs the theoretical resolution of the C6's much greater aperture.

In terms of contrast, my initial impression is that the difference is small: the Lunt wedge on the 90mm refractor had a sharper contrast difference at the edge of the sun, but whatever scatter the Baader film imparted to the C6 was more than offset by the SCT's larger aperture. The view was decidedly not milky through the Baader film on the C6, like it had been on the 90mm refractor. To be honest, I was expecting a noticeable improvement in contrast with the wedge, but I had to really think about it to see a difference. Maybe this is my lack of experience, but truthfully the difference in contrast to me was a fraction of the improvement of either the larger scope or the wedge over the 90mm + film.

In terms of resolution, the seeing dominated proceedings, but this actually indicates a winner. I brought out the C6 after the 90mm refractor and by then it was quite obvious the seeing was deteriorating before my very eyes. Therefore, the fact that the view in the C6 was still more detailed probably means the SCT, under simultaneous conditions, would have obviously greater resolution than the refractor. Certainly my socks weren't as knocked off with the 90mm + wedge as they had been that day I first looked through the C6 + Baader film.

So my first impressions are that I will be dragging the C6 + Baader film out to do WL viewing of the sun rather than the SVR90T + Lunt wedge. I admit the Baader film filter for the C6 is rather large and I have yet to find a suitable container for it. At this aperture it's nowhere near as convenient as sticking a 1.25" wedge into a refractor! So the equation changes dramatically when you figure in the fact that I have a very convenient setup for my 90mm refractor that fits entirely in an airplane carry-on backpack. How's that for grab-and-go? So I am very happy I ended up purchasing both the Herschel wedge and the Baader film filter for my C6 SCT. I will certainly enjoy both of them in a wide variety of conditions, and if my impressions change as I mature as a WL observer I'll kick them back here.

Thanks again for everyone's help. I've finally found my daytime astronomy groove!


Post Extras: Print Post   Remind Me!   Notify Moderator  
PJ Anway
Double-Star Observer
*****

Reged: 06/04/03

Loc: North Coast
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: brianb11213]
      #5993909 - 07/27/13 11:36 PM

Quote:

If you can get your hands on a Zeiss glass solar filter to fit your C6, you may find it better than solar film, very nearly as good as the wedge, especially visually. But it will cost an enormous amount of money. The cheap commercial glass filters are unsatisfactory from the point of view of optical flatness, often grossly so.




I would agree. I actually enjoy the Zeiss glass filters over a Herschel wedge. I've compared the two on more than one occasion and preferred the Zeiss, but it's probably more a subjective preference (like the yellow tint more) than a performance advantage. They're very close.


Post Extras: Print Post   Remind Me!   Notify Moderator  
George9
sage


Reged: 12/11/04

Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: PJ Anway]
      #5998424 - 07/30/13 01:12 PM

KJ, I wonder if there is something wrong with your 90mm Baader filter, perhaps stretched or folded or dirty. It sounds like too big a difference from the 90mm film to the wedge on the 90mm scope. I know it is a moot point for you because you have a nice wedge now, but I mean if other readers are considering a purchase. It sounds like your 6" Baader filter is performing well.

Yesterday I was comparing Baader film versus a 2" Lunt solar wedge on a 5" apo, and it wasn't a huge difference. Perhaps on a day with better seeing and less haze, it will be bigger. I also compared the 10" Newtonian with Baader film to the 5" with the wedge. They were both good. The finest detail in a complex sunspot seemed better in the 5"+wedge, and the faculae and mottled network seemed better in the 10"+film. But I'll try again.

George


Post Extras: Print Post   Remind Me!   Notify Moderator  
frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: George9]
      #5998774 - 07/30/13 04:53 PM

I think a 5-inch APO with a wedge will always beat the same 5-inch APO with Baader film. It might even beat the 6-inch SCT with Baader film. In order for the film to win, you need to use a larger aperture with the film and a smaller aperture with the wedge.

Post Extras: Print Post   Remind Me!   Notify Moderator  
brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: 90mm APO + Herschel wedge vs C6 SCT + Baader film new [Re: frolinmod]
      #5998889 - 07/30/13 06:16 PM

Quote:

I think a 5-inch APO with a wedge will always beat the same 5-inch APO with Baader film. It might even beat the 6-inch SCT with Baader film. In order for the film to win, you need to use a larger aperture with the film and a smaller aperture with the wedge.



Ummm ... given equal optical quality I'd estimate the wedge advantage over Baader visual solar film at 10% for visual work i.e. to equal a 5 inch with a wedge you'd need about 5.5 inches with the film. The wedge advantage for imaging is a lot more than it is visually because of the flexibility in the density of the filters used with the wedge allowing very short exposures to beat the seeing. The visual ( ND 5.0 ) solar film is waaaay too dense for satisfactory imaging, the photo ( ND 3.8 ) solar film is better but usually too thick too (bear in mind that you will almost certainly be wanting to use some extra filtration like the solar continuum to gain contrast). For imaging I've found that - even after insulating the tube - a C6 with photo film is not quite equal to my WO FLT 110 with a wedge, though it can get quite close when the seeing is unusually stable.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
7 registered and 13 anonymous users are browsing this forum.

Moderator:  Scott in NC, Phillip Creed 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1364

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics