Herschel Wedges - Lunt or Baader

[cyborg421]

Hi All,

I am looking to but a solar wedge and am trying to decide on the Lunt or the Baader. The Baader being considerably more expensive. Apart from the fact that the Baader has a solar finder is there any reason to choose one over the other optically?

Also is there any advantage to a 2" as opposed to a 1.25" wedge?

Thanks

Simon

[michael.h.f.wilkinson]

I have the Lunt (1.25") and really like it. A 2" (like the Baader) is not really needed when you have a short focal length scope like the 80mm F/6 I use it on, as the image of the sun is a mere 5mm or so across in my case. A solar finder is also not much of an advantage. With the 24mm 68 deg as "finder EP" I have a 3.4 deg true FOV so finding the sun is fairly straightforward. A TeleVue Sol-Searcher would be much cheaper if finding the sun is the issue. Optically, the Baader is supposed to be very good indeed, but I find it hard to fault my little 1.25" Lunt.

[cyborg421]

Thanks Michael,

I have a 100mm f8 if that helps.

[michael.h.f.wilkinson]

Thus F=800 or roughly 8mm solar disk. Plenty of room in the 28mm clear aperture of a 1.25" wedge. Maximum FOV not as good, but putting a bit of solar film over the finder scope, or a Sol-Searcher would work as well (or better) as a finder. I use a Sol-Searcher on my LS35. This has only 400mm focal length, but even with the 4mm blocking filter (so clear aperture 4mm rather than 28mm) the Sol-Searcher got the sun centred in the sweet spot easily

[Pig]

Simon I have the Lunt 1.25, if you would like to try it message me and we can arrange something.

[Steve Ward]

There is also available the "Scopium" wedge from 365Astronomy .... http://www.365astronomy.com/scopium-white-light-herschel-wedge-solar-wedge-with-integrated-nd30-filter-blue-p-3533.html

Considerably cheaper than either the Baader or Lunts but works every bit as well , I know , I've got one ... 

[cyborg421]

Simon I have the Lunt 1.25, if you would like to try it message me and we can arrange something.

Thanks Shaun. Will do.

[Luke]

I have the Lunt 1.25 and the Baader 2 inch. Visually, there is not much between them for me (I have used both a fair bit in my F9 100mm scope). All in all I'd probably take the Lunt 1.25 (or similar, there seem to be a few cheaper clones?) for visual with my ED100, as it is super compact and lightweight.

[cyborg421]

There is also available the "Scopium" wedge from 365Astronomy .... http://www.365astronomy.com/scopium-white-light-herschel-wedge-solar-wedge-with-integrated-nd30-filter-blue-p-3533.html

Considerably cheaper than either the Baader or Lunts but works every bit as well , I know , I've got one ... 

Interesting, have you compared them side by side?

Simon

[cyborg421]

Thus F=800 or roughly 8mm solar disk. Plenty of room in the 28mm clear aperture of a 1.25" wedge. Maximum FOV not as good, but putting a bit of solar film over the finder scope, or a Sol-Searcher would work as well (or better) as a finder. I use a Sol-Searcher on my LS35. This has only 400mm focal length, but even with the 4mm blocking filter (so clear aperture 4mm rather than 28mm) the Sol-Searcher got the sun centred in the sweet spot easily

How do you attach the Sol-Searcher to your scope?

Simon

[IanWatkins]

Baader only really comes into its own when used for imaging, with the photo version mainly because a full system of filters and available adapters.

If just visual I doubt you would really see much difference but do consider a Baader Continum filter whichever one you go for. I feel it really helps contrast and detail.

Cheers

Ian

[Steve Ward]

Interesting, have you compared them side by side?

Simon

Certainly did .... £425.00 vs  £189.00 vs  £129.00 .... 

Have looked through the Baader as well as the Scopium and couldn't see a £300.00 difference .

The 2" would be better suited to DSLR photography but the 1-1/4" does work in this role , for webcam or planetary camera work the Scopium punches well above its price tag.

[hunterknox]

I switched from a Lunt 1.25" to a Baader 2" due to the vignetting I was getting with the former. The Baader seems a tad sharper. Both are only incrementally better than Baader film for most people so do keep that in mind. 

One thing I don't like about the Baader is the method of fixing the filters in place. You screw them into a threaded tube which in turn screws into the wedge. I don't think there's a safety stop before the actual prism, so you screw the tube down until it's at the internal prism. You then screw the eyepiece holder onto that. If the 2" Lunt used a better system it might sway my vote.

I do like the finder window with the Baader and as far as looking through it goes, I can't fault it at all.

[Merlin66]

I don't know why, but the Lunt website only recommends the 1.25" version up to a 100mm aperture......

[cyborg421]

Why is a 2" wedge better for DSLR work?

[Merlin66]

Larger chip size in the DSLR + larger prism in the wedge = less vignetting....

(IMHO DSLR's are handy cameras to have, but not ideal for solar. A mono video (DMK etc.) is the way to go - fast frame rate, and stacking for quality)

[michael.h.f.wilkinson]

I have used a DSLR for solar with my Lunt wedge and experienced no visible vignetting. The key reason for this is that I used a 2.5x Powermate to crank up the image scale.That is really the point: if the image circle of your wedge is big enough to show the entire sun with room to spare, your wedge is big enough. In your case the image of the sun is around 8mm, so to boost the image size on the camera chip, you might want to increase that a bit with a Barlow or PowerMate. That should always come after the wedge.

A 2" may well be more sturdy mechanically, and may be optically better

[Steve Ward]

Larger chip size in the DSLR + larger prism in the wedge = less vignetting....

(IMHO DSLR's are handy cameras to have, but not ideal for solar. A mono video (DMK etc.) is the way to go - fast frame rate, and stacking for quality)

Unless you want to capture the whole disc in one go for a daily record and don't want to spend forever doing a multi-pane mosaic that is ... 

For close-in detail I cannot argue with you , ( and I use a Mono chipped SPC900NC for the purpose ) but for capturing a full disc a DSLR with it's much larger chip is very good. 

[Luke]

I see they say the Lunt 1.25 wedge gives best results with scopes with a front aperture of 4 inches or less. For imaging with my 120mm scope and mono video camera (Grasshoppper 3), the Baader clearly gives a better image than the 1.25 Lunt. More contrast and more definition. I wondered if that was because the Baader was straight out a bit better, or whether it was because I was using the ND1.8 Baader filter (for imaging only! must not be used for visual) that comes with a few other ND filters in the Photographic version, versus the built-in ND3 with the Lunt. But perhaps it's at least in part because the Lunt is 1.25 inch and I should get better results with the 2 inch?   I haven't imaged as far as I recall with my 100mm yet, that might be an interesting shootout. The 120 is clearly a win for the Baader for imaging with my camera.

[michael.h.f.wilkinson]

Two aspects may well make the Baader 2" diameter diagonal better for bigger scopes. Many mirrors show slight degradation towards the edge, so a large mirror will have a larger centre area in which the surface is very good. The other issue is heat: a 120mm may heat up a 1.25" diagonal more, because the heat capacity is smaller compared to a large one. More heat may lead to distortion. The difference in ND filter should affect small scopes more, I would say, as they can less afford to waste photons. In my Lunt the ND filter can be swapped out easily for a lower density version

[IanWatkins]

Heat is always going to be an issue as Ken suggests.

I certainly wouldn't want to use a Lunt 1.25" in my 154mm f/8 after seeing what happened to my Baader 2" the first time I used it in strong summer sunlight. I had smoke pouring out of the back of the Baader the first couple of times I used it. Baader replied to my worried email by saying it would clear with use and was likely to just have been construction oil/grease from hands on the ceramic. (much like a car engine smokes at first after you have been working on it). Sure enough after a couple of uses it's been fine ever since. To be fair, that was a lot of energy.

If you are going to want to do serious imaging with big fracs, then the Baader is an obvious choice, especially the photo version as it comes with all the filters you'll need to maximise your shutter speeds on say a DMK or other mono high speed camera. Those filters on their own are not cheap. Depending on how you stack them, you can get into the sweet spot of exposure time for the particular camera you are using (around 1/8000th sec on my DMK41 mono). I used the various NDs to get to that spot, then the Continuum filter than an IR cut, then the DMK. Works really well.

Yes, you can use DSLRs as well, and that's how I started with the wedge once I had low profile adaptors, but that lasted about two days once I understood the importance of using a mono camera.

I guess the question is going to be this: Do you want a wedge to observe with smaller fracs and maybe the occasional snap with a DSLR? Or are you likely to start using bigger fracs and want to do serious imaging?

Cheers

Ian

[cyborg421]

Thanks for your replies. My only experience with Solar Observtion was back in the day. I had a Tasco scope with a diagonal and an attachment that fitted to the barrel of the focuser which had a white plate on it. I am not particularly interested in imaging, as I am a visual observer. The wedge is to use with an alt/az mount with out tracking so I guess the Lunt will be sufficient.

Simon