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Grumpy Martian

1 1/4 inch Lunt Herschel wedge with 4 1/2 inch refractor.

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Have I made a mistake? I have ordered an 1 1/4 inch Lunt Herschel wedge for Solar viewing. The telescope that I am planning on using it with is a 4 1/2 inch f7. 7 refractor. Will this size Herschel wedge be OK and safe to use with this size refractor? Any knowledge and advice would be great. 

Thanks. 

Edited by Grumpy Martian
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I've used my 1.25" Lunt HW with my ED120 refractor several times including at outreach events. It's worked fine and continues to do so.

 

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I've had no problems using one with my William Optics FLT110.

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I've had no problems with using mine with the ED100 or ED120. 

Gets hot in the 120 on a clear day but not so hot that you'd really burn yourself. 

I'm pretty sure on here have used it in up to 150mm OTA. 

There's a quote in this thread by Moonshane that's interesting. 

 

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Ok with a 120mm scope here! I’m not sure that I would leave it tracking for hours, but certainly fine for manual work.

Paul

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Dont worry Martin, it will be fine. I've used one on a 120ED too with no problem.

Which scope are you getting?

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17 minutes ago, Stu said:

Dont worry Martin, it will be fine. I've used one on a 120ED too with no problem.

Which scope are you getting?

I acquired a Vixen ED 115 s refractor. It's focal ratio is f7. 7.

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Short answer, yes, under UK skies it will be fine.

---

Other members will disagree with my opinion, but I think a 2" version is safer under lower latitude skies where the sun shines for a long time. This because it is much better at dissipating the heat, or in other words it accumulates less heat. My 1.25" Lunt was untouchable when used with just my TV60 in Italy in August few years ago. Did it work? Yes. Was I comfortable? With a 60mm refractor, so and so, but I would not have used it with my Tak 100 to be honest.

As I said, people will disagree. Lunt tests their equipment in Arizona, which is quite low latitude. Fine, but in the end of the day, it's my eye and refractor... As I said, under UK skies which are at North, fairly windy and cloudy, the 1.25" is okay. In southern and hotter locations, I would go for a 2" version with a 100mm refractor.

In addition, the 2" Baader wedge is super.

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I have used my Lunt 1.25" HW on my 220mm refractor without a problem. I don't stare at the Sun for more than a few minutes at a time and don't track the telescope for long periods. The f12.5 dissipates the heat over a wider focal point area than a short focus objective would.  😀 

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1 hour ago, Piero said:

Short answer, yes, under UK skies it will be fine.

---

Other members will disagree with my opinion, but I think a 2" version is safer under lower latitude skies where the sun shines for a long time. This because it is much better at dissipating the heat, or in other words it accumulates less heat. My 1.25" Lunt was untouchable when used with just my TV60 in Italy in August few years ago. Did it work? Yes. Was I comfortable? With a 60mm refractor, so and so, but I would not have used it with my Tak 100 to be honest.

As I said, people will disagree. Lunt tests their equipment in Arizona, which is quite low latitude. Fine, but in the end of the day, it's my eye and refractor... As I said, under UK skies which are at North, fairly windy and cloudy, the 1.25" is okay. In southern and hotter locations, I would go for a 2" version with a 100mm refractor.

In addition, the 2" Baader wedge is super.

It would help if Lunt was a little more specific about this.

With my ED120, the heat sink on my Lunt 1.25" HW has never been more than rather warm, ie: you could still touch it but perhaps not for a long period. I have not used this combination south of the SW UK though.

We have a rule in my society that a solar scope should never be left unattended. This is aimed at outreach events but I apply it at home as well, just to be on the safe side.

 

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if your worried about heat put a ir/uv filter in the end of the wedge what gos to the focuser  and it will act like a ERF keeping cooler. but ive never had a problem with heat with my lunt HW the biggist problem you get with it is clouds 😀 charl.

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Ultimately the heat sink on the Wedge is designed to get hot, and there is a warning on it that it can get hot so there is not really a problem if it does.

If you think about how hot the inside of a car gets on a sunny day, or any metal  or glass surface, that doesn't cause any damage so I don't see it as being any different for a Wedge which is designed to get hot.

Like others, if I generally observe for shortish periods of time throughout a day, and always put the lens cap on and often cover the binoviewer with a cloth just to give it a bit of protect. Probably unnecessary but no harm in being careful.

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17 minutes ago, Stu said:

Ultimately the heat sink on the Wedge is designed to get hot, and there is a warning on it that it can get hot so there is not really a problem if it does.

If you think about how hot the inside of a car gets on a sunny day, or any metal  or glass surface, that doesn't cause any damage so I don't see it as being any different for a Wedge which is designed to get hot.

Like others, if I generally observe for shortish periods of time throughout a day, and always put the lens cap on and often cover the binoviewer with a cloth just to give it a bit of protect. Probably unnecessary but no harm in being careful.

Thanks Stu. I can understand that heat will be dissipated to some area. 

My main concern was that the 1 1/4 inch wedge was listed as for refractors up to four inch. If I used an 1 1/4 wedge in a 4 1/4 inch refractor, would it in any way allow excessive rays and heat to cause damage to one's eye. Would the 1 1/4 inch be inadequate for larger scopes. The replies appear to indicate that using an 1 1/4 Herschel wedge in a slightly larger than four inch refractor would shield the eye from heat and solar ray injury. 

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A polaroid filter doesn't block the IR. A ND3 should be used with a wedge.

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4 hours ago, Grumpy Martian said:

I acquired a Vixen ED 115 s refractor. It's focal ratio is f7. 7.

Very nice! A good choice, sure you will be happy with that 👍👍

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3 hours ago, John said:

With my ED120, the heat sink on my Lunt 1.25" HW has never been more than rather warm, ie: you could still touch it but perhaps not for a long period. I have not used this combination south of the SW UK though.

I'm in Poole on the South Coast and can confirm that my experience is the same as yours John. 

I agonised for ages over the 1.25"/2" wedge issue and got a 2" Lacerta then a 1.25" and it's the 1.25" that gets most use, even with the ED120. 

Mind you that might change now that I have managed to acquire a new to me Baader Cool Ceramic wedge 😊

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