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Have an APM/Lunt Hershel Wedge: Need Filters.

LukeSkywatcher

By LukeSkywatcher
in Observing - Solar

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nicoscy

nicoscy

Posted
Posted

Luke,

I have the same wedge. It comes with a built in ND3 filter which is sufficient to keep you from getting blinded if you accidentally forget to add another filter *but by itself is not sufficient*.

A second filter is required for solar viewing, typically a polarising filter (single filter as the prism in the wedge polarises light once) which you screw on the eyepiece and rotate the eyepiece to the brightness you are comfortable, or a solar continuum filter for maximum contrast.

Do NOT use any other kind of filter, just pick one of the two above (or both as I have done and use according to your mood) and have fun observing!

Note: if your wedge came without the built in ND3 filter, ask APM to send it to you free of charge as the built in ND3 filter comes as standard with the wedge and is included in the price.

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nicoscy

nicoscy

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Mine didn't come with one installed but they did supply three filters with it. I have to screw them all on each time.

APM offer various packages including one with no filters like Paul's but at a cheaper price.

That... is not even remotely acceptable and is really scary. Viewing the sun is an inherently dangerous sport. At the very least the built in ND3 filter should be ... well... built in!

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Moonshane

Moonshane

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I actually prefer not having the filters fitted as I can more easily clean them, I can use the wedge for lunar observation and also it cleans up Venus impressively.

That said, I agree that you must have good processes for any form of solar observing to ensure safety.

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Piero

Piero

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Okay, Luke.

I've just taken some photos of my Lunt Wedge. Hopefully, they will go some way in giving you a hand to check over your own wedge and again, hopefully they will offer you a little piece of mind:

The Wedge

attachicon.gifLunt 1.JPG

Bird's eye view down the eyepiece-end of the wedge. The tinted blue glass is the ND 3.0 filter.

attachicon.gifLunt 3.JPG

The Wedge with the scope-end barrel unscrewed

attachicon.gifLunt 2.JPG

Inside the Wedge. To the left you can see the ND 3.0 filter screwed in place. To the right is the wedge's mirror. If you don't have that filter to the left, you need to buy it!

attachicon.gifLunt 4.JPG

Needless to say, before using the wedge for the first time, I rang Lunt and double checked that what I was seeing was really the ND 3 filter. Better safe than sorry. 

Hope this helps :grin:

My ND 3.0 filter is tinted green, instead of blue. Or at least at my eyes it is green... !

Just curious to know why..   :confused:  Different material? Any ideas? Thanks in advance! 

In any case, as Rob said, you can see it by looking inside the eyepiece-end barrel very clearly.

Thanks Rob for posting your pics!  :smiley:

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spaceboy

spaceboy

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That... is not even remotely acceptable and is really scary. Viewing the sun is an inherently dangerous sport. At the very least the built in ND3 filter should be ... well... built in!

From what I gather there are the two options because one is for imaging and the other is for visual. The visual one has a ND3.0 filter which has been Loctite in place to avoid any miss haps. This is obviously no good for those who intend to do imaging as the more light to the sensor the better. The advantage is that you can image as well as purchase filters to visually observe. The down side to that is a longer optical train and not all eyepieces will have sufficient inward travel.

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nicoscy

nicoscy

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I actually prefer not having the filters fitted as I can more easily clean them, I can use the wedge for lunar observation and also it cleans up Venus impressively.

That said, I agree that you must have good processes for any form of solar observing to ensure safety.

Learned something new. As a prism diagonal, it should shine on Venus.  :grin:

From what I gather there are the two options because one is for imaging and the other is for visual. The visual one has a ND3.0 filter which has been Loctite in place to avoid any miss haps. This is obviously no good for those who intend to do imaging as the more light to the sensor the better. The advantage is that you can image as well as purchase filters to visually observe. The down side to that is a longer optical train and not all eyepieces will have sufficient inward travel.

And again, more knowledge gained.  :laugh:

Thank you both for these titbits!

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Stu

Stu

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Mine came with the ND3.0 pre-fitted but it is not loctited in place, it unscrews quite easily for cleaning if needed.

I think the most dangerous thing is the inconsistency of product that is being marketed, and perhaps poor descriptions. There should be clearly labelled imaging and visual packages which have what you need already included. To be fair, I bought a package which did have the ND3.0 fitted and included what was called a 'top polarising filter'. I also added a Continuum filter which is now what I use instead of the polarising filter.

Shane's is another variant with no capability to install the ND3.0 internally. That's not something I would like, but young Master Shane seems to deal with it perfectly well.

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spaceboy

spaceboy

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Mine came with the ND3.0 pre-fitted but it is not loctited in place, it unscrews quite easily for cleaning if needed.

That's interesting Stu. When I looked in to imaging with mine I came across this video https://www.youtube.com/watch?v=Kft2yxQ85sY which suggested the ND filter was fixed and a looking inside mine confirm that. I can only assume there has been some changes made to prevent people removing the filter but it now appears there is a mix of all variants out there.

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jetstream

jetstream

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Paul,

How come it cost about 200 quid? Teleskop Service sells the 1.25" Lunt Hershel Wedge (which I gather is what you got since you are after 1.25" filters) for EUR 175 + EUR 20 shipping, well below GBP 200 and this includes the ND3 filter (this is what I got).

Something's not right here mate... Did APM overcharge?

I don't think Paul bought the wedge from APM.

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Pig

Pig

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In my opinion they should make it law to have the ND3 fitted to a Herschel wedge, especially so as anyone using it will expect to be able to look at the sun through it.

Crazy people !!! some of the retailers in this business really need to get to grips with the damage that can be done rather than making something appear cheaper just for the sake of sales figures.

There are quite a few experienced solar observers within this thread and all are pretty sceptical in answering for fear of blinding the original poster

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Piero

Piero

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In my opinion they should make it law to have the ND3 fitted to a Herschel wedge, especially so as anyone using it will expect to be able to look at the sun through it.

Crazy people !!! some of the retailers in this business really need to get to grips with the damage that can be done rather than making something appear cheaper just for the sake of sales figures.

There are quite a few experienced solar observers within this thread and all are pretty sceptical in answering for fear of blinding the original poster

I agree with Shaun completely. The ND3 should be fitted in and mandatory by law.

There should be the possibility for unscrew it (so that people interested in AP are happy too.. I am ignorant on this.. they don't need it, do they?), and every user should receive a clear description about how it works, which are the components, and what must not be removed for visual. 

I received mine this week from FLO (excellent service and at the best price out there. I thank them very much!).  :smiley:  :smiley:  :smiley:

After reading this thread, I still wonder why my ND3 has a green tint instead of blue. I am sure this is safe, but if this is a new model, I think Lunt should have specified something about it. 

Unfortunately, I have had the opportunity to try it as it is a solar and not a rain filter :sad:, but I am looking forward to it!  :smiley:

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Qualia

Qualia

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There are quite a few experienced solar observers within this thread and all are pretty sceptical in answering for fear of blinding the original poster

Aye, great observation, Shaun. A litlle nerve racking it is but bit by bit, I think we're getting somewhere now :smiley:. It would help if Luke could post up some pics. It's a bit like inching our way through the dark without being able to 'see' his set up.

I still wonder why my ND3 has a green tint instead of blue. I am sure this is safe, but if this is a new model, I think Lunt should have specified something about it. 

I find Lunt to be a friendly place, so if there's any problem or measure for concern, drop them a line, Piero. They will respond. Other than that, post up some pics (we love looking at astro-gear :grin:) and we can do some comparing of filters etc.

Looking at my ND3.0 filter in daylight, it's more or less the same colour as in Stu's photos. It's a kind of burgundy deep wine colour. I indicated to Luke the 'blue' filter because in the photos I took the other night, I think the reflection of the flash made it come out blue.

Sadly, I can't get to the filter and pull it out to take a more detailed photo, for it seems to be glued directly into the Wedge. That's no bad thing for dumb old me though. One doesn't want to take too many risks with an individual who sometimes forgets how old he is :p

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LukeSkywatcher

LukeSkywatcher

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I didnt buy direct from APM. I bought from Astroshop.eu (155 euros incl 7 euros p+p). They are based in Germany. The wedge itself is a Lunt/APM wedge. There is no ND 3.0 filter in the wedge anywhere. The wedge prism itself does polarize the view. There is another package on the same site for the same wedge that includes the ND3.0 filter for an extra 20 euros. I didnt see it when i was buying. Not to worry. 

My filters should arrive on Thursday. Thanks to Shane and others i am confident that i have bought the correct filters. I was going to leave buying them til end of March but with a solar eclipse on 20th March i decided it was too good a chance to miss by waiting a few days longer.

Murphy's Law dictates that the 20th March will be cloudy.

Thanks to everyone here for their input and glad i brought it up as a few people are now doubting their own solar setup and the whole topic of these wedges being sold without an ND filter is crazy. Also it doesnt help when descriptions are bad, or lost in translation. I have a whole 3 pages of instructions for my wedge and where the filters go in the optical train...........which are all in German. The single diagram helps though.

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LukeSkywatcher

LukeSkywatcher

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Here's mine. Note I can see my lounge blinds through it.

Just curious Shane about your image there. Is that showing your wedge with or without the ND filter?. Anyways..............i'm all done now with buying wedges and filters. Next thing is to learn where they all go. The diagram i have shows them all being stacked together in a certain sequence just below the EP. Cant say which order. I'll have to have another look. Pretty sure the ND filter goes onto the EP first, then i think it is the continuum and finally the polarizing filter, but dont quote me on this. 

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Stu

Stu

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Paul, the ND3.0 must be the first filter the sun's light hits after passing through the wedge ie closest to the wedge/furthest from the eyepiece. The other two come after this (closer to your eye), and I don't think the order they are in makes any difference.

So, the ND3.0 (which reduces the light by a factor of 1000), is in the optical train ahead of the others and ensures the brightness is reduced before going through the continuum and/or polariser.

Stu

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LukeSkywatcher

LukeSkywatcher

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Paul, the ND3.0 must be the first filter the sun's light hits after passing through the wedge ie closest to the wedge/furthest from the eyepiece. The other two come after this (closer to your eye), and I don't think the order they are in makes any difference.

So, the ND3.0 (which reduces the light by a factor of 1000), is in the optical train ahead of the others and ensures the brightness is reduced before going through the continuum and/or polariser.

Stu

Gotcha. Yes that makes more sense. My diagram most likely shows this and me being me got it wrong (as per usual).

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