11 replies to this topic

[Olivier Biot]

New Baader Herschel Wedge Solar Prism

By Ted Wolfe

[Mark9473]

Nice report; I've been eyeing that Herschel Wedge myself for a while now. Interesting to know that it can be set up to work with a 1.25" click-lock clamp instead of the supplied 2" clamp.

Could you help me understand what combination of filters works best if I decide not to use the Solar Continuum filter but do go for a polarizer - in other words, which ND filter would I need to use together with the polarizer?

Alternatively, have you explored the use of the solar continuum filter together with a coloured filter to result in a more 'natural' colour of the Sun's disk?

[Daniel Mounsey]

Good to see a review on solar wedges. All my co-observers use Herschel wedges. After viewing planets all night long we'd start solar viewing early morning. Nothing beats a solar wedge. I had a 100mm mylar and my friend had his refractor stopped down to 90 aperture with a wedge. The wedge was night an day better.

[Jim7728]

Nice review.

Getting the itch, once again, to purchase a solar wedge.

[The Ardent]

Two weeks after I bought the older version, I saw the newer one on the Baader website. It was not available in the US for long time.

[Bryguy]

I would love to see how the Baader compares to the Lunt wedge. I'm still partial to Baader.

Bryon

[BYoesle]

I am delighted that APM, Baader, and Lunt are producing Herschel wedges that have a ventilated and enclosed light exit and offer the safest wedge viewing possible. However, Baader can not claim responsibility for developing the enclosed wedge design:

From Alpine Astro:

“This development takes the Herschel Wedge into the 21st Century, by rendering the output energy cool and diffused, while completely sealing the prism body! In all other herschel designs, the waste energy is simply deflected out of the rear face of the prism by an angled mirror, also leaving openings for accidental or prying fingers to discover... Thanks to Baader Planetarium, this concern has now been completely removed.”

This is then referred to in the recent CN review by Ted Wolfe:

“In the fall of 2009 I began to see descriptions of a new solar wedge from Baader Planetarium, which promised excellent visual and photographic detail of this intriguing region of the sun – along with greatly increased safety. White light observing with a typical Herschel wedge focuses an enormous amount of solar energy which exits the prism. This forms a diffused, but still potentially harmful beam behind the housing, especially after prolonged usage.

Baader had been studying this problem for 15 years. Their new approach involved the use of a “heat cage” (multi-layered perforated steel screen) with a heat absorbing ceramic tile in the back of the housing. Baader believes this combination results in the safest white light wedge on the market."

The invention, and proof of concept, of the enclosed and ventilated Herschel wedge – and the reasoning behind it -- was discussed right here on Cloudy Nights in June of 2005, long before the introduction of enclosed wedges by APM/Lunt and Baader:

The primary purpose of the "wedge absorber" is to block the intense beam of reflected sunlight coming out of the bottom of the wedge -- See the thread's first image. Secondarily, it will keep curious fingers from getting too near the exit beam or touching the rear of the prism (an advantage over the Baader wedge's diffuser design).

Full thread CN Archive web page

As can be seen in the above Cloudy Nights posting, I actually measured the heat that was contained inside the enclosed/ventilated wedge to show that it was completely safe, as well as practical to implement. While I chose not to patent this invention so that it would remain available to the amateur community, and have no trouble with Baader and APM/Lunt adapting this for their commercial use to allow for the absolutely safest wedges to be manufactured, I had hoped none would claim credit for the invention or the principle.

While to my knowledge APM/Lunt has not done this, it is disappointing to see that Baader has.

The original enclosed/ventilated Herschel wedge with temperature sensor, June 2005. It uses a vent opening with a CPU cooler, with holes which were later drilled in it to pull air through the wedge. The fan has proven to be unnecessary (though helpful), as convection results in more than adequate ventilation:

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[George N]

I would love to see how the Baader compares to the Lunt wedge. I'm still partial to Baader.

Bryon

I own neither, but I’ve used both. The view is the same, but I like the Baader’s physical structure better. That’s the one I’m going to get.

[ken hubal]

I owned an older version of the Baader wedge and took many fine phtographs with it and enjoyed many hours of visual observation as well. I have since moved away from solar imaging but enjoy looking back on the many years I engaged in this work along with the photos I obtained and the Baader was the best Herschel wedge I had owned and used. I'm sure the updated units will be even better. Enjoy!

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[Gerard]

I would like to buy one but can it be used on a 80mm ED or should I go for more aperture?

[ken hubal]

The unit I had employed a 2" format barrel. If your 80mm ED has a focuser that can accept 2" accessories, you'll be fine. With solar work, large apertures(100mm or 120mm) are nice, but not mandatory so your 80mm scope should be o.k. to start. Best wishes!

[George N]

I’ve heard concerns that the Wedge should not be used on 6-inch or larger refractors. Anyone know if this is true?