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Lacerta 2" Herschel Wedge


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Lacerta Brewster-angle 2" Herschel Wedge - First Light

My new Herschel wedge arrived the other day and got it set-up with my Orion 120mm f/5 frac.

Impressed with the sheer quality of the wedge. Very, very solidly made and has the feel of a big hefty piece of industrial equipment. This wedge has a Brewster angle of 56.6 degress instead of the standard 90 degree angle. This allows for better polarization and gives a wider range of adjustment.

Although this design has an open bottom for better heat dissapation it's not to be confused with the old style Intes wedge that had an open bottom that let a potentialy dangerous beam of light shine out. This is a very dfferent design that doesn't allow any stray light to escape. You can actually look stright up into the open bottom of the wedge with no danger. See the two relevant pics.

The angle of the prism is also adjustable. Mine didn't need adjusting but it's nice to know I could adjust it f I needed to.

Manufacturers blurb:
"Most commercially available Herschel wedges (like INTES, Lunt, Scopium, Baader...) come in a 90-degree variant.
The Lacerta Herschel-wedge features a significant, 56.6-degree angle, so called Brewster-angle that provides a special benefit when compared with other 90-degree Herschel wedges.
This befenit is coming from the fact that nearly 100% of light is polarised under this angle; this means that the Lacerta Herschel wedge offers continuous or even complete dimming with the mandatory ND=3.0 filter and an additional (optional) polarising filter. In reality a dimming range between ND=4.07 and 6.37 or even more can be achieved.

Without the polarising filter the Herschel prism operates at ND 4.07 that is very good for photography. The 90° "traditional" Herschel prisms can achieve ND=4.24 to 5.00."

First Light:
Although there's nothing to be seen worth mentioning at the moment it did show good surface granulation and the image was nice and sharp. I used a Baader Solar Continuum filter and a single polarizing filer. Haven't tried the IR cut filter yet. I used to have a Baader Cool Wedge a while ago and initial impressions are the Lacerta seems to be every bit as good. Also have used a Lunt wedge and would have to say the Lacerta was a bit better.

Conclusions:
A worthy competitor to the Baader Cool Wedge and cheaper as well and has potential advantages over the Baader for photographic use. Does require a fair bit of infocus and I found with the Orion 120mm f/5 focus was just about achieved at full infocus travel with the zoom eyepiece I was using. I have trimmed 20mm off the OTA tube to allow for extra infocus travel which won't be a problem with usng the scope for other that white light solar as the new focuser has 20mm more travel than the stock one.

        John

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Edited by johninderby
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Lacerta Brewster-angle 2" Herschel Wedge - First Light My new Herschel wedge arrived the other day and got it set-up with my Orion 120mm f/5 frac. Impressed with the sheer quality of the wed

Like Stu and John, I've frequently used my 1.25" Lunt with my ED120  and whilst the red spot on the back gets hot, that's what it's supposed to do. I got the 2" Lacerta because I was worried abou

Cheers both, you really don't realise how glad I am you've both said that.  1.25" It is 😀😀😀😀.  Thank you 👌👍

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It hasn't been out that long and not yet common in the UK but I think it will become popular once word gets around.. About half the price of the Baader too. Built like the proverbial tank. Check out the thickness of the metal housing. Lacerta seems to be an Austrian brand and quite popular in Austria and Germany.

          John

Edited by johninderby
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Very interesting report John. Never heard of this filter but will do a bit of research on it. I was thinking of getting the Baader filter,  but you have given me food for thought. Thanks for the post.

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What is the open mirror/lens part in your second last image?. I'm guessing it is to allow solar projection?.

*edit*

Sorry, i see it is part of the heat dump system.

Edited by LukeSkywatcher
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  • 3 months later...

I'm very interest in one of these especially at the price difference between the Lacerta and Lunt / Baader 2" version I realise the 1.25 Lunt is a decent price but I have  a 6" scope and the recommendation is for the 2".  

 

How does the Lacerta handle heat over long observing periods ? (I know it's unlikely in the UK). Does anyone know if it would handle a few hours of outreach solar observing with a big (150 x 1200mm Evostar) refractor.

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Not a problem in the UK at least with my 5" refractor. Does seem to handle heat better than the Baader Cool Wedge I used to have. Did use the Badder with a 6" refractor and that did get very hot after a while. The Baader was fully enclosed and so didn't get rid of heat very well with the 6". The Lacerta with it's open bottom design has much better cooling so should handle the 6" OK.

            John

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On 21/07/2017 at 10:58, johninderby said:

Not a problem in the UK at least with my 5" refractor. Does seem to handle heat better than the Baader Cool Wedge I used to have. Did use the Badder with a 6" refractor and that did get very hot after a while. The Baader was fully enclosed and so didn't get rid of heat very well with the 6". The Lacerta with it's open bottom design has much better cooling so should handle the 6" OK.

            John

Great John, thanks for the update

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John,

I've been trying to decide between the 1.25" and 2" versions but was wondering whether or not you could confirm whether the ND filter is fitted internally or whether it needs to be attached to the end of the eyepiece.

From the manufacturers blurb it sounds like it's internal, but on the 1.25” version the filter has to be attached to the filter thread of the eyepiece.

I'm keen to minimise the potential for forgetting anything to a minimum and so if the filter is internal it can just stay there permanently.  As I'm intending to use a polariser and  a #58 green filter I don't want any chance of missing the ND.

I also have another question regarding whether an extra ND is needed to make viewing more comfortable in addition to the mandatory ND and a polariser.

Hope you don't mind me asking, but my finger is poised over the buy button and I want to be sure.

Ade

 

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Hi

On the 2" the built in ND filter is mounted in the bottom of the screw in base for the eyepiece holder so it can't be forgotten as it's an integral part of the wedge. 

The single polarising can darken it right down to the point that it's too dark so no additional ND filter needed.

Buy it and feel sorry for those Baader Cool Wedge owners who paid through the nose for something that's nearly as good as the Lacerta. :evil4:

            John

 

IMG_1347.jpg

Edited by johninderby
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John,

Thanks for confirming so quickly, I was hoping this was the case.

I'm also glad to hear that I don't need an additional ND filter.

I'm pretty hopeful that I should have no probs reaching focus as the OTA is a ST102, albeit with an ED80 dual speed focuser, but that is pretty much identical in length to the original so hopefully no issues, and as I use a Skywatcher 2" diagonal anyway it shouldn't add too much length to the light path.

Off to place an order now ?

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45 minutes ago, johninderby said:

Buy it and feel sorry for those Baader Cool Wedge owners who paid through the nose for something that's nearly as good as the Lacerta.

Nice one John. I will remember that as I next look at individual granulation cells at x200, thinking about what might have been.... :headbang:

Slightly more seriously, it looks like a nice and interesting piece of kit. Ade, I hope you have some great views with it; I look forward to the reports :)

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Having had a Cool Wedge I'm very impressed with how the Lacerta compares. Amazing value for money. Who knows might make Baader bring out an improved Cool Wedge or heaven forbid cut the price. Not much in it for visual but the Lacerta's Brewster angle does give it a more evenly illuminated image which will help with imaging.

When someone new brings out a great bit of kit at a great price it can only be good for the hobby.  The old names in the hobby will have to sharpen up their game to stay competitive..

       John

Edited by johninderby
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I have this 2" version of this Lacerta Wedge that I bought about a month ago and it's very good, the contrast performance is great. Only one drawback that I can find is the angle of the eyepiece holder, which makes me have to nearly sit on the floor to see the Sun when it's high up.

Regards,

AG

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@Live_Steam_Mad thanks for the info about the angle of the diagonal, I had thought that this might be the case.  

I'm glad that you're pleased with yours and I'm looking forward to receiving mine.

I use one of the Mey Observing Chairs (https://www.firstlightoptics.com/misc/mey-observing-chair.html) which I've modified so that the lowest position is only about 150mm off the floor, so hopefully it won't prove too uncomfortable.

Thanks for the warning though.

 

Edited by AdeKing
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Interesting review John and it sure does look a well built piece of kit. I still think if given the choice I'd go with the cool wedge as I have never heard any comments on people feeling the need to chop the ota to leave room for focus. Also I have to wonder.... I appreciate you know what you are doing and say it is ok to look at the underside of the diagonal and that no heat is emitted but as we all know the main dangers of looking at the sun are ones that are hidden and that don't expose themselves for several hours after exposure. These being UV & IR. I have to wonder how much of these invisible hazards would make it out the bottom on to your summer shorts exposed leg ??? 

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It was the eyepiece I was using. Also fitted a new focuser that was longer than stock meaning the scope has less infocus than stock. Wouldn't' have been a problem with the stock focuser.  With current eyepiece has plenty of infocus travel. Had the same problem with the Cool Wedge I used to have as certain eyepieces wouldn't focus.

There is absolutely zero,light emissions of any type from the bottom of the wedge. The bottom is open purely for cooling. Tried  my old Cool Wedge on a six inch scope and it got hot enough to burn you if you touched the back of it. A not so Cool Wedge. Fine on a four inch but the design can overheat on a bigger scope.

          John

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On 30/07/2017 at 21:32, johninderby said:

Having had a Cool Wedge I'm very impressed with how the Lacerta compares. Amazing value for money. Who knows might make Baader bring out an improved Cool Wedge or heaven forbid cut the price. Not much in it for visual but the Lacerta's Brewster angle does give it a more evenly illuminated image which will help with imaging.

When someone new brings out a great bit of kit at a great price it can only be good for the hobby.  The old names in the hobby will have to sharpen up their game to stay competitive..

       John

This seems to happen quite frequently in astronomy. You push the boat out to get the top dog at that time then something else comes out which is a little better and sometimes even a little less expensive.

I guess the options are to either keep chasing to keep on top of "having the best" or to step off the "kit roundabout" and get on with using what you have, which has not got any worse of course :icon_biggrin:

I was thinking this the other day re-reading this thread on diagonals (non-solar):

https://stargazerslounge.com/topic/291658-the-baader-bbhs-sitall-silver-diagonal-is-it-really-that-good/

While it's nice to have the best in class I suspect that it's ultimately a mugs game constantly trying to maintain that :rolleyes2:

It's nice to hear about new products though, all the same :smiley:

 

 

Edited by John
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Agreed. Just because a piece of kit may be old doesn't mean it's still not as good as ever.

Case in point. Big Red the Carton 100 f/13 frac that I built years ago. Very nice for planetary observing.

              John

 

IMG_1359.JPG

Edited by johninderby
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16 minutes ago, johninderby said:

Agreed. Just because a piece of kit may be old doesn't mean it's still not as good as ever.

Case in point. Big Red the Carton 100 f/13 frac that I built years ago. Will still see off most APOs in planetary observing.

              John

 

IMG_1359.JPG

Very nice John but you could have just said that it's very nice to observe the planets with it rather that to inject that note of competition ? :smiley:

 

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