Herschel wedge and objective coating damage?

[Carl Au]

Just a quick question from someone who had only used Baader solar film (other than the sun filters we were given with our refractors in 1975). Are you happy for the full face of the sun to enter your telescope into a Herschel wedge. I must be missing someting here, but that can't be good for your anti reflective lens coatings? Is that nor going to bleach them out. I was thinking about buying one, perhaps a 1000 Oaks filter be safer? 

Edited March 6, 2021 by Carl Au

[John]

I use the Lunt 1.25 inch Herschel Wedge with my Takahashi, Vixen and Skywatcher ED refractors. No problems at all and no effect on the coatings.

The heat is concentrated well away from the surfaces of the objective lens, where the Sun's rays are bought to focus by the objective so, in my case, 663mm or 900mm away.

 

 

Edited March 6, 2021 by John

[RobertI]

45 minutes ago, Carl Au said:

Just a quick question from someone who had only used Baader solar film (other than the sun filters we were given with our refractors in 1975). Are you happy for the full face of the sun to enter your telescope into a Herschel wedge. I must be missing someting here, but that can't be good for your anti reflective lens coatings? Is that nor going to bleach them out. I was thinking about buying one, perhaps a 1000 Oaks filter be safer? 

Hi Carl, I asked the same question recently and was reassured by the responses I received from experienced members like John, so I went ahead and tried the 102ED-R with my Herschel wedge and binoviewers. The results were astounding, with exquisite detail of the only sunspot group at 170x.  Prior to this I had only used the Herschel Wedge with smaller short FL refractors and understood that it was rarely worth going above 60x magnification - how wrong I was! Let us know how you get on.

Edited March 6, 2021 by RobertI

[Carl Au]

1 minute ago, RobertI said:

Hi Carl, I asked the same question recently and was reassured by the responses I received from experienced members like John, so I went ahead and tried the 102ED-R with my Herschel wedge and binoviewers. The results were really surprising, with exquisite detail of the only sunspot group at 170x.  Prior to this I had only used the Herschel Wedge with smaller short FL refractors and understood that it was rarely worth going above 60x magnification - how wrong I was! Let us know how you get on.

Oh that is interesting. I am new convert to Baader Zoom Barlow's. I am struggling now to understand why I was so sniffy about them in the past (barlows that is). I must have read some bad stuff about them in my youth (I can still remember word for word the contents of my Obsevers book of astronomy) and hung onto it. A wedge and zoom sounds like a good idea all of a sudden. 

[hunterknox]

Think about it like this: how much do you worry about your windows with all that intense sunlight bearing down on their massive surface area?

Assuming you’ve got a standard refractor with the lenses at the front then the light and heat that hits the first lens is no more concentrated than it is on a window and on the second (or third) lens it’s slightly more so but not a big deal. As John implies: things aren’t getting too intense until closer to the eyepiece end and the Herschel wedge is designed to deal with the concentrated heat and excess light. The former doesn’t go round corners well and the latter is effectively filtered out using basic darkening (neutral density) filters once the heat’s been sapped away. 

Refractors with lenses at the back as well as the front (such as Petzval or Steinheil designs) might be more problematic but your Starwave should be just fine. Nice scope, by the way.

[Merlin66]

11 hours ago, hunterknox said:

Refractors with lenses at the back as well as the front (such as Petzval or Steinheil designs)

This is an Urban Myth!

All the suppliers who manufactured Petzval designed refractors ( TV, Takahashi, Williams Optics) have all replied in print that their refractors are 100% safe to use with a Herschel Wedge.

I use a TV Genesis (100/500 Petzval design) with a Herschel wedge for all my white light imaging. Never had any issue in the past ten years.

 

Edited March 7, 2021 by Merlin66
spelling

[Louis D]

I could see how exposing the objective lenses to direct sunlight could help to keep fungus growth at bay.

[hunterknox]

6 hours ago, Merlin66 said:

This is an Urban Myth!

All the suppliers who manufactured Petzval designed refractors ( TV, Takahashi, Williams Optics) have all replied in print that their refractors are 100% safe to use with a Herschel Wedge.

I use a TV Genesis (100/500 Petzval design) with a Herschel wedge of all my white light imaging. Never had any issue in the past ten years.

 

I happily stand corrected!

[RobertI]

2 hours ago, hunterknox said:

I happily stand corrected

....said the man in the orthopaedic shoes. (sorry)

Edited March 7, 2021 by RobertI

[RT65CB-SWL]

18 hours ago, Carl Au said:

Just a quick question from someone who had only used Baader solar film (other than the sun filters we were given with our refractors in 1975). Are you happy for the full face of the sun to enter your telescope into a Herschel wedge. I must be missing someting here, but that can't be good for your anti reflective lens coatings? Is that nor going to bleach them out. I was thinking about buying one, perhaps a 1000 Oaks filter be safer? 

Having used a Thousand Oaks type 2+ glass full aperture solar filter since 1998/99, it has a few pin-pricks and is no longer in use.

Since 2018/19, I now use a Lunt Herschel wedge and polarising & solar continuum filters with my TeleVue Ranger. 

I also make a habit to check all items before each and every use for defects.

[LDW1]

On 06/03/2021 at 14:30, John said:

I use the Lunt 1.25 inch Herschel Wedge with my Takahashi, Vixen and Skywatcher ED refractors. No problems at all and no effect on the coatings.

The heat is concentrated well away from the surfaces of the objective lens, where the Sun's rays are bought to focus by the objective so, in my case, 663mm or 900mm away.

 

 

I second your post, twice !

[Stephenstargazer]

I worried a little when I put a Barlow/OCS in front of the Herschel wedge to use a binoviewer, (well recommended!) kept checking the temperature by hand and it never got warm at all. 

Tip, wedge is also a good solar finder by looking underneath 😎