Herschel wedge

[Gary085]

Hi i was looking to start doing some solar observing but the HA scopes are too expensive for me at the moment so I have been looking at herschel wedges. I'm just wondering what length of time would be ok to view the sun without damaging my scope with it getting too hot, I have a skywatcher 120 evo. having to let it cool for periods is kind of putting me off it to be honest.

[Pig]

The heat is not a factor you have to worry about when using Hershel wedges, they have a built in ND3 filter that takes care of problem by directing the heat out through a disc on the rear of wedge. I hear the back can get hot but I have never experienced this 

A word of caution though is they must only be used in refractor telescopes.

I would also stick to a brand make should you decide to get one, you only get one set of eyes and it simply is not worth risking them over a few quid.

Here are a couple of links to help you. If you not sure ask the retailer before you buy one.

http://www.firstlightoptics.com/solar-filters/baader-coolceramic-herschel-wedge-solar-diagonal.html

http://www.firstlightoptics.com/lunt-solar-white-light-systems/lunt-white-light-herschelsolar-wedge.html

[Luke]

FLO answered a similar question a while back re: the Baader Herschel Wedge:

"The magnesium body houses a very effective 'heat cage' which includes a special heat-absorbing ceramic tile. Like on a space shuttle the ceramic tile traps the radiant energy without overheating its surroundings. Also the heat cage is separate from the prism body (attached using only four screws) so there is very little heat transmitted to the prism, so there is no restriction on how long you can observe or image using the Baader Herschel Wedge."

The thread is here:

http://stargazerslounge.com/topic/190059-baader-2-coolceramic-herschel-solar-wedge/

I use the Baader with my Equinox 120mm.

[Gary085]

Thank you for both of your replies. The Lunt solar wedge from FLO is the one I was looking at already so I might go for that one.

[Pig]

Thank you for both of your replies. The Lunt solar wedge from FLO is the one I was looking at already so I might go for that one.

I have the Lunt 1.25" and I find it to be excellent   a very good choice.

[Stu]

Thank you for both of your replies. The Lunt solar wedge from FLO is the one I was looking at already so I might go for that one.

Go for it Gary, you won't regret it, they are excellent!

Just remember you need either a polarizing or continuum filter in the eyepiece too to reduce the brightness for visual observing. FLO will be able to advise.

Stu

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[Joseki]

the (baader) continuum filter is definitely worth having - not just to reduce brightness but it enhances the view.  I have the lunt 1.25 wedge and continuum filter plus a polarizing filter,  which is a good combination (in my 90mm frac).  I'd quite like to try that setup in a bigger scope myself though (the lunt is rated up to 150mm).

I guess you've done your sums but a wedge + continuum filter isn't cheap and would be a big chunk of the cost of a used PST.  Even if you upgrade straight away it might be worth getting some solar film and making a cheap filter - which would still give very good results and you could see how you like it. 

[Gary085]

Hi and thanks again for your help. I bought the wedge but haven't had chance to use it yet.

I got the 1.25" Lunt wedge, I will be using it on my 120mm (4.75") refractor but wondering if this would be okay to use on a 6"?

FLO website says 1.25" wedge is best with 4" and below and 2" wedge is best with 6" scopes and below.  Would it get too hot with the bigger aperture or would it just be better visually?

It will be getting used at a public event using scopes at the observatory so I'm just making sure what is safe....safe for my wedge as much as the public

[Merlin66]

I don't have a Lunt wedge, so can't comment.

The Baader 2" Herschel wedge can be used on ANY sized refractor - well beyond 6" aperture.....

[Gary085]

I already have 1.25" eyepieces and cmos camera so getting the 2" would have been too costly for me replacing those also. I have heard the Baader is the best one, I'll just be happy to see the sun properly for the first time. I was given some Baader solar filter today so I can turn my finderscope into a sol searcher too  

[Stu]

The information I have seen is that the 1.25" Lunt Wedge is suitable to use in scopes up to 150mm so you should be fine. If you are at all concerned, you could easily create an aperture mask down to 4" to reduce the light and heat entering the scope but I don't believe this is necessary.

Stu

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[Gary085]

Thanks Stu, just used it for the first time on my 120mm and it does only get hot on the 'caution' plate as expected  and cooled pretty quickly so I think you are right about that

[Stu]

Good stuff Gary.

I've not used mine on anything bigger than 4" but am sure you will be fine. If I'm using mine all day, I just make sure it is capped and pointing away from the sun when I'm not using it so the heat doesn't build up. That's more of a problem with a tracking mount, I just use manual alt-as so no problem.

Enjoy!

[Gary085]

Didn't realise I've had this solar wedge for 2 and half years now until I just came across this post again. It was definitely worth purchasing

[Stu]

Very nice!!