Review of Baader Herschel wedge

[JohnW]

There is a new review of the 2" Baader Herschel wedge on the "Ice in Space" website under equipment reviews then accessories.
Cheers all.
Direct link is: http://www.iceinspace.com.au/47-722-0-0-1-0.html

[swisswalter]

Hi John

thank you, yes that is a fine write up

[marktownley]

Do you have a direct link John please?

[Merlin66]

Mark,
Try this one:
http://www.iceinspace.com.au/47-722-0-0-1-0.html

[MjrTom]

Very nice review
It is a great product.

Mark

[Derek Klepp]

Hey John great review I have the Lunt versions but purchased the Solar continuum filter and the view and DSLR pics are similar to those you obtained.

[Cschur]

That really is a great review of a world class product. Mine DOES get very hot with my 150mm refractor, but thats probably running it at its aperture limit anyway.

[Merlin66]

Chris,
The Herschel wedge has been used on 8"+ refractors in observatories in the past...it was very popular with Victorian astronomers.

[brianb11213]

The Herschel wedge has been used on 8"+ refractors in observatories in the past...
Yes but the old wedges had an open back ... the modern closed back type has a heat sink which absorbs the surplus energy & there is clearly an energy input level at which the heat sink will reach a temperature beyond its design limit. The aperture at which this will occur depends on the atmospheric transparency as well as the objective aperture, with the transmission efficiency of the objective as a secondary factor. Victorian objectives made with flint glass rather than modern synthetic fluorite and without anti-reflective coatings probably transmitted significantly less waste energy than modern objectives of the same size, due to reflection from the forward facing surfaces of the objective and absorbtion within the objective elements.

I've been wondering how long it will take someone to suggest liquid cooling the heatsink of a commercial Herschel wedge using the sort of plant used by CPU overclocking enthusiasts!

[trwinship]

Cshur, your Baader wedge gets very warm with a 150mm scope? On my 150mm scope this has never happened in two years of use, even with exposure time of several hours . I've had some correspondence with the Baader Planetarium people on this subject, and they report routinely using the wedge with apertures up to 200 mm with no problems. If this is happening with a Baader safety wedge I would strongly urge contacting the Baader people. These reports of product variability are of great concern to them and really need confirmation.

[mr40mm]

I've had some smoke coming from my baader P wedge before when used with my 152mm scope. I now use it with the Baader 160mm D-ERF. Heating problem solved.

[Cschur]

While aperture is a major factor, the focal ratio which enlarges the solar image to varous sizes no doubt also has a big impact on how hot your wedge gets. Summer and winter too I would assume. Mine produces an image on the back of the screen like 3/4 inch in diameter, and its burning hot. The good news is that in the cold winter mornings, the wedge body makes a great hand warmer...

[trwinship]

Focal ratio may be the answer--my 152 mm refractor is f/8, and the housing and ceramic plate (winter or summer) has never been more than slightly warm to the touch. Seriously, I'd contact Baader customer service about this---it's not supposed to happen. I've never read any restrictions from Baader on focal ratio. Although the solar disc on my ceramic plate is about 3/4", too. Oh, andf Ihave the visual version, not the photographic one.

[Merlin66]

Hmmm
I was using the Baader wedge on the TS102 f11 yesterday for a good couple of hours or so (trying to get the set-up ready for Ca filter tests)and the rear surface was warm but definately not "hot hot". That's in the bright Ozzie sunshine....
( I have hear of smoke from the wedge - but only in it's very first use - burning off the oil from the perforated screen? I never experienced that, nor has there been any smoke with mine)

[Bob Yoesle]

I've been wondering how long it will take someone to suggest liquid cooling the heatsink of a commercial Herschel wedge using the sort of plant used by CPU overclocking enthusiasts!

When I first wrote up the design of a vented but enclosed Herschel wedge using a CPU heatsink to dissipate heat (in 2005 -- where I believe first Lunt and then Baader learned of the idea and subsequently did the same for additional safety in their designs), I also incorporated the idea of using a TEC - thermal electric cooler. But with my ED 100 this turned out not to be necessary:

http://www.cloudynights.com/ubbarchive/ ... t/all/vc/1

Using a suitable TEC with additional heat-sinking and thermal compound would be a simpler way to solve the excess heat from a larger aperture without too much trouble, or the associated coolant and plumbing complexity... the Lunt 2" wedge would be the easier model to cool this way as the interface would be more straightforward.

Bob B)