99 replies to this topic

[mpsteidle]

Hey Guys.  There are several archived threads on these old devices, but we can't exactly post to those so I'm starting this new one.

Today I received a package from Japan, containing what was listed as "Vixen Sun Zenith Mirror".  Now I'm not sure how they identified it as Vixen, but it is absolutely a vintage sun prism (Herschel Wedge) and that's good enough for me.  For $30 I might as well try it out.

I'm impressed with this little thing!  It gives me a safe way to use the old sun filter (Screwed into the eyepiece​. This is required!  Don't use the sun filter without the wedge, and vice-versa!) that came with my 7TE , and once I got over the green tint I was impressed with the level of surface detail that was revealed.  The sharpness is a significant improvement over my thousand oaks glass filter and Solar Projection.

This thing does have one glaring quirk - there's a laser beam coming out the back.  Of course this is an exaggeration, as long as you're more than about 6 inches from the rear of the diagonal it wont affect your body at all, as the beam defocuses.  You must remain aware of it though and its probably best not to use it around kids.

Enjoy these pictures of the wedge in use, along with a crappy out of focus snap with my cellphone.  Is anyone else using these still?

Edited by mpsteidle, 13 November 2023 - 02:57 PM.

[jgraham]

I have a couple of these vintage Herschel wedges and they do work very well. I use mine with a grade 3 ND filter and a polarizer to adjust the intensity, though I have heard of people using the old solar filters as well. As far as the beam exiting the back of the wedge you can make a simple shield with a small piece of aluminum sheet such as aluminum flashing to deflect/scatter the beam downward. The reflectivity is high enough that the shield shouldn't get hot. Unitron wedges came with such a deflector built-in.

Enjoy!

[Couder]

I complained about the light coming out from a Herschel wedge at one of the star parties I was at, and the guy told me off. I said you can defend it all you want to, but it's still a hazard to someone not expecting it.

 

I have several Herschel wedges, none have the light coming out like that. You can make something like in this picture on my Gaertner Herschel Wedge pretty easily.

Attached Thumbnails

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[gstrumol]

OK, I'm going to be brutal here. Keep the wedge as a museum piece and don't use it again. Take a hammer to that EP screw-on "sun filter", make sure the glass is completely destroyed, and toss it in the garbage.

 

If you want to get clean, white solar images of the sun get an AstroZap Baader solar film filter for the front of your scope. Glass filters are terrible, and solar projection is great for outreach efforts or when you don't want anyone (kids) to touch your scope. You can get something like a Lunt wedge, but it will be pricy and, quite frankly, you'd be hard pressed to tell the difference from the Baader film. The advantage of the wedge is in its longevity; it will last forever whereas the film will eventually develop pinpoint holes.

 

The Lacerta wedge (which is designed at a Brewster angle) has an open side, but it's at the bottom, so the light is directed away from the observer. This one has the light coming directly in line with the scope, and hence, the observer's head. Do you really want someone looking through this and, for whatever reason, moves his/her head downward into the beam? Seriously?

 

Having that horrible screw on filter may seem cool, but what if you or someone else forgets and replaces EPs for a different magnification. Instant blindness. The sun through a telescope is unforgiving, and it doesn't give you a second chance.

 

I know it's cool to have gotten it for $30 but for your sake, and any others who would look at the sun through this, cough it up as a learning lesson and don't use either of them again. Get either the Baader film or a proper Herschel wedge with a built-in ND3 filter.

[mpsteidle]

OK, I'm going to be brutal here. Keep the wedge as a museum piece and don't use it again. Take a hammer to that EP screw-on "sun filter", make sure the glass is completely destroyed, and toss it in the garbage.

 

If you want to get clean, white solar images of the sun get an AstroZap Baader solar film filter for the front of your scope. Glass filters are terrible, and solar projection is great for outreach efforts or when you don't want anyone (kids) to touch your scope. You can get something like a Lunt wedge, but it will be pricy and, quite frankly, you'd be hard pressed to tell the difference from the Baader film. The advantage of the wedge is in its longevity; it will last forever whereas the film will eventually develop pinpoint holes.

 

The Lacerta wedge (which is designed at a Brewster angle) has an open side, but it's at the bottom, so the light is directed away from the observer. This one has the light coming directly in line with the scope, and hence, the observer's head. Do you really want someone looking through this and, for whatever reason, moves his/her head downward into the beam? Seriously?

 

Having that horrible screw on filter may seem cool, but what if you or someone else forgets and replaces EPs for a different magnification. Instant blindness. The sun through a telescope is unforgiving, and it doesn't give you a second chance.

 

I know it's cool to have gotten it for $30 but for your sake, and any others who would look at the sun through this, cough it up as a learning lesson and don't use either of them again. Get either the Baader film or a proper Herschel wedge with a built-in ND3 filter.

I'm going to disagree here.

Obviously never use the sun filter by itself, but it + the herschel wedge are really no different than modern wedges + ND3 filters.

There's always risk with viewing the sun, but to me, the risk of me forgetting the sun filter is no more than an aperture filter falling off the front of the scope (which I have seen happen).

This isn't an outreach tool, its for my personal use.  Like I said, do not bring it around kids because the beam in the back. Not quite sure how a user would accidently get their eye way down there.  Besides, a simple foil screen or reflector fixes that issue.

 

Treat it with respect you should be fine, just use the same cautions you should always use when observing the sun.  Double check everything.

Edited by mpsteidle, 13 November 2023 - 04:14 PM.

[Bomber Bob]

I complained about the light coming out from a Herschel wedge at one of the star parties I was at, and the guy told me off. I said you can defend it all you want to, but it's still a hazard to someone not expecting it.

 

I have several Herschel wedges, none have the light coming out like that. You can make something like in this picture on my Gaertner Herschel Wedge pretty easily.

Nice!  Looks a lot like one of the old GOTO versions.

[deSitter]

Hey Guys.  There are several archived threads on these old devices, but we can't exactly post to those so I'm starting this new one.

Today I received a package from Japan, containing what was listed as "Vixen Sun Zenith Mirror".  Now I'm not sure how they identified it as Vixen, but it is absolutely a vintage sun prism (Herschel Wedge) and that's good enough for me.  For $30 I might as well try it out.

I'm impressed with this little thing!  It gives me a safe way to use the old sun filter (Screwed into the eyepiece​. This is required!  Don't use the sun filter without the wedge, and vice-versa!) that came with my 7TE , and once I got over the green tint I was impressed with the level of surface detail that was revealed.  The sharpness is a significant improvement over my thousand oaks glass filter and Solar Projection.

This thing does have one glaring quirk - there's a laser beam coming out the back.  Of course this is an exaggeration, as long as you're more than about 6 inches from the rear of the diagonal it wont affect your body at all, as the beam defocuses.  You must remain aware of it though and its probably best not to use it around kids.

Enjoy these pictures of the wedge in use, along with a crappy out of focus snap with my cellphone.  Is anyone else using these still?

Been looking for one forever. Not gonna spend $200 on a modern one.

 

-drl

[Ian King]

Been looking for one forever. Not gonna spend $200 on a modern one.

 

-drl

Modern ones like the Lunt Wedge are expensive, I have one though, and it has been such a great purchase. The views through my classics are excellent and it can easily be swopped to different scopes which is not so easy with a full aperture filter.

[AllanDystrup]

Classic Zeiss Herschel Wedge

 

 

     Here's my classic Zeiss Herschel Wedge, from before Zeiss closed shop and the service was overtaken by Baader; The precision of the prism is very high, and the view of the solar photosphere is ultra sharp, -- even a bit more crisp than in the modern Baader Cool Ceramic HW (with prism made to the Zeiss specs).

 

     I use it with T2 and 2" eyepiece adapters (for size comparison I've included a standard CZJ H-25mm 0.965 eyepiece). Note the "light trap" at the rear end of the HW to prevent burning holes in your trousers (or retina); Not as safe as the Baader CC HW version, so still not recommended for use by children.

 

 

     -- Allan

[mpsteidle]

 

Classic Zeiss Herschel Wedge

 

 

     Here's my classic Zeiss Herschel Wedge, from before Zeiss closed shop and the service was overtaken by Baader; The precision of the prism is very high, and the view of the solar photosphere is ultra sharp, -- even a bit more crisp than in the modern Baader Cool Ceramic HW (with prism made to the Zeiss specs).

 

     I use it with T2 and 2" eyepiece adapters (for size comparison I've included a standard CZJ H-25mm 0.965 eyepiece). Note the "light trap" at the rear end of the HW to prevent burning holes in your trousers (or retina); Not as safe as the Baader CC HW version, so still not recommended for use by children.

 

ZHW.jpg

 

     -- Allan

 

That's an awesome little piece.  Does it have an Nd3 filter built in?  If not which one are you using?

[deSitter]

Modern ones like the Lunt Wedge are expensive, I have one though, and it has been such a great purchase. The views through my classics are excellent and it can easily be swopped to different scopes which is not so easy with a full aperture filter.

The only scopes I ever use for the Sun are the ones perfectly made for it, the classics, so I just need a 24.5mm example. Always thinking about how to convert a standard diagonal. The unknowns of Zen keeps me out of that market. I still don't understand how it works or the costs.

 

-drl

[Terra Nova]

Yes, that will work or it seems to anyway. (I’ve done it a few times with some trepidation.) At least my old Japanese 0.965” solar diagonal did come with a ‘tailgate’ AKA necktie saver. My biggest problem with using those old solar filters is that they are completely non-spec and non-uniform. They seem to be as dark as an ND3 but you don’t know that and also you have no way of knowing what the IR and UV shutoffs are (and remember, both IR and UV are invisible to the human eye and you have no way of knowing what if any cumulative damage is being done. You also have to be **** sure that the thread-in filter was inserted before you or anyone else looks through it because, since it’s inside, it’s internal and not visible. My old one was a Unitron and it used the external solar eyepiece cap. I only used it a couple of times and that was enough for me. I did have an Intes wedge, but it also came with speced secondary filters (an ND3 and a Polarizer. I used it much more frequently, and the last time, I really scared myself because I changed eyepieces and forgot to make sure the ND3 was inserted. It wasn’t, just the polarizer! Thankfully my guardian angel told me to double check and I did. That was enough for me! I’ve been using a Lunt wedge ever since. It’s idiot-proof and has the build in ND3 filter so if you forget to use a secondary filter (continuum, deep yellow bandpass, polarizing, etc.) you only get an uncomfortably bright image. And you’re assured of no invisible SW or LW bleed through. I’ve had my Lunt for a dozen years now. Sure it cost a couple of hundred bucks but my eyes are worth a whole lot more to me! And it’s more than paid for itself. So yeah, the classic wedges are cool but use them at your own risk. I think most folks in the solar forum where I used to hang out a lot will tell you the same thing!

 

PS, the Lunt wedge also has the heat dissipater build in! That secondary beam of light coming out of the bottom of yours will blind you, (kids, dogs, cats, etc.), just as quickly as looking down the barrel of your telescope directly at the sun will.

Edited by Terra Nova, 14 November 2023 - 10:35 AM.

[mpsteidle]

My biggest problem with using those old solar filters is that they are completely non-spec and non-uniform.

I agree with this, it's my one real concern.

It turns out that the thread on the sun filter isn't even compatible with my new .965 Orthos anyways, so I can't use them for solar.  I think i'm just going to buy a new ND3 filter and permanently mount it inside the wedge, that way I can use whatever eyepiece I want and I don't have to worry about the filter.

Perhaps the 25mm Variant of this Hoya filter would fit the bill? https://www.edmundop...-filters/12305/

I will also say that I observed with this setup for about half an hour yesterday and the view was extremely comfortable, for whatever that's worth.

Edited by mpsteidle, 14 November 2023 - 11:14 AM.

[DAVIDG]

  With a wedge you need an additional 1000 to reduction so that requires a filter with an Optical Density of 3 not a neutral density of 3.  Optical density is the log of amount of reduction ie Log (1000) = 3. Neutral density of 3  mean a reduction of 3 photographic F-stops . Neutral density and optical density are many times confused so just be sure your getting the right amount of reduction.

    I have a number of Herschel wedges and very much enjoys the views they provide. I use a polarizer and a Baader OD 3 filter with mine 

  

https://agenaastro.c...-1-2458346.html

 

               - Dave 

[Terra Nova]

  With a wedge you need an additional 1000 to reduction so that requires a filter with an Optical Density of 3 not a neutral density of 3.  Optical density is the log of amount of reduction ie Log (1000) = 3. Neutral density of 3  mean a reduction of 3 photographic F-stops . Neutral density and optical density are many times confused so just be sure your getting the right amount of reduction.

    I have a number of Herschel wedges and very much enjoys the views they provide. I use a polarizer and a Baader OD 3 filter with mine 

  

https://agenaastro.c...-1-2458346.html

 

               - Dave 

That’s an important point. This is the same ND3 filter that I have and have used in the past. It’s speced as Neutral Density with a transmission of 0.1% that is 1/1000 or 10^-3.

[DAVIDG]

 Here is a chart that shows the spec's on Welder's glass. Note the difference between the Optical density on the Photographic F-stop which is neutral density.  

 

                    - Dave 

 

[mpsteidle]

Thanks David, that's a great reference.

I'm going to see if there's room in the diagonal for me to embed this filter (https://www.edmundop...nd-filter/8294/).

Edited by mpsteidle, 14 November 2023 - 01:15 PM.

[jgraham]

I just checked. My Baader ND 3.0 transmits 0.1% of the incident radiation, so I’m good. What I really like about using a neutral density/polarizer with a Herschel wedge is that you get a true color image. I was surprised to find that the natural color of the sun is a beautiful white! I have heard that astronauts have commented how white the sun is when viewed from above the atmosphere. The amount of fine detail visible with a wedge is wonderful.

 

Enjoy!

[mpsteidle]

There is one thing I am worried about if I make this modification.

Currently, with the old sun filter, the brightness of the image is very pleasant.  I feel no need to dim the image further, nor do i wish it was any brighter.

I wonder how much brighter the image will be through a standard ND3 filter, as I've always heard you need a polarizer to fine tune the brightness.  I dont think Variable Polarizers are readily available for .965 eyepieces.

[jgraham]

This is my standard Herschel Wedge kite;

 

 

Unitron Herschel Wedge, 0.965" to 1.25" adapter, ND3 filter, polarizer, 20mm Meade RG.

[jgraham]

My Herschel Wedge kit in operation on my Unitron 128...

 

 

Fun stuff!

[deSitter]

My Herschel Wedge kit in operation on my Unitron 128...

 

Unitron 128 Solar (11-3-2023)-2.jpg

 

Fun stuff!

I want one! wedge

 

-drl

[AllanDystrup]

That's an awesome little piece.  Does it have an Nd3 filter built in?  If not which one are you using?

 

Hi Mason; -- Oh yes, for visual I use my Zeiss HW most often with a ND3 + Baader Solar Continuum filter, but for other purposes (such as photography), I can easily switch to other standard 2" ND filters with higher transmission.

 

     -- Allan

 

PS: I've described the options for solar observation with my small model 128 Unitron in this post:

     https://www.cloudynights.com/topic/743322-all-this-telescope/?p=10709078

 

     And here some options for my small Zeiss refractors (Telementor, Teleminor):
     https://www.cloudynights.com/topic/743322-all-this-telescope/?p=11551143
 

Edited by AllanDystrup, 15 November 2023 - 08:38 AM.

[mpsteidle]

Hey again everybody.  I took delivery of something special today that brought this classic wedge truly back to life.  

 

A purpose made Vixen ND filter for use with un-filtered Hershel Wedges.

 

This is similar to the common "Sun Glass" we're familiar and often warned of, though it is less optically dense (More akin to the modern ND3's that are built into today's wedges).  It threads into any Vixen-style .965 eyepiece and allows safe use of unfiltered hershel wedges.

I used it in my C80 with "ScopeTown" orthos, which paired wonderfully and produced a comfortable and extremely sharp image.  The picture below is slightly less sharp than what it looked like through the eyepiece.

 

Edited by mpsteidle, 21 May 2024 - 06:39 PM.

[deSitter]

Hey again everybody.  I took delivery of something special today that brought this classic wedge truly back to life.  

 

A purpose made Vixen ND filter for use with un-filtered Hershel Wedges.

 

This is similar to the common "Sun Glass" we're familiar and often warned of, though it is less optically dense (More akin to the modern ND3's that are built into today's wedges).  It threads into any Vixen-style .965 eyepiece and allows safe use of unfiltered hershel wedges.

I used it in my C80 with "ScopeTown" orthos, which paired wonderfully and produced a comfortable and extremely sharp image.  The picture below is slightly less sharp than what it looked like through the eyepiece.

 

This brings back happy memories of using my eye-killer Sun glass on my Sears 6344. I didn't know it was dangerous. Fortunately I was not much interested in the Sun at the time! But the view was WAY better than full-aperture white light filters. I found the green very pleasant.

 

-drl