Lunt Herschel Prism

[Teal Rain]

Morning all.

Pardon my ignorance of the subject but.... with Herschel prisms does the energy that would normally be reflected by a front mounted glass or film filter have any detrimental effect on the optics of the scope used? I'm thinking of getting the Lunt 1/25" prism from TS (149 euros) to use with the FS102 so I'm a little bit nervous!

Cheers

Mark

[Merlin66]

The objective should handle the incident energy OK, and if the Herschel wedge does its job properly the emerging beam will be 100% safe. You may need additional ND filters to tone down the brightness.

[johninderby]

I've been using Herschel wedges (prisms) for nearly 10 years with no detrimental effect on any refractor I've used.

BTW a 3" to 4" aperture is ideal for using a Hershel wedge.

Here's my solar setup.

Lunt 60HA and a TS 80/480 triplet APO with 2" Herschel wedge and Skytee 2 mount.

John

[A McEwan]

John, that's a great looking dual solr setup. I was thinking along the same lines for my Lunt LS60THaPT and 90mm/600 Triplt Apo with wedge. How do you find the motions on the Skytee 2 with those relatively lightweight tube assemblies? I've read that the mount needs some weighty tubes on it to perform at its smoothest...

Ant

[brianb]

The "emergent beam" of the Lunt wedge doesn't emerge ... it hits a heat sink at the back which gets midly warm to the touch with my WO FLT 110. Older wedges often allow the waste beam to escape the diagonal where it has been known to ignite ties. But no danger to optics.

[Merlin66]

Brian,

A mis communication....you are correct for the deviated beam.

I was thinking of the brightness of the visual beam.....

[brianb]

I was thinking of the brightness of the visual beam.....

Yes, well, of course that's safe too, once the (supplied) ND 3.0 filter is installed on the output side of the wedge. You'll probably want some more filtering to be comfortable, the Baader Solar Continuum filter is very good, an ordinary green or deep yellow filter is nearly as good & a lot cheaper. Deep red (Wratten 29) is excellent for imaging with a monochrome camera.

[Teal Rain]

Afternoon all.

John, Brian, Merlin

Many thanks for the information - have taken the plunge and ordered the 2" Solarvue 2 from Astro Engineering! Seemed a bit of a no-brainer really to go for this one rather than the 1.25" Lunt.

Now all I need to do is take the plunge with a Lunt 60 B1200! - maybe next month as car tax also calls this time.

Cheers

Mark

[johninderby]

John, that's a great looking dual solr setup. I was thinking along the same lines for my Lunt LS60THaPT and 90mm/600 Triplt Apo with wedge. How do you find the motions on the Skytee 2 with those relatively lightweight tube assemblies? I've read that the mount needs some weighty tubes on it to perform at its smoothest...

Ant

Hi

The Skytee 2 is very smooth even with only a light load. Rather than hijack this thread I've started a new one. I've posted some more pics in the new thread.

"Show us your solar observing set-up"

http://stargazerslounge.com/equipment-discussion/138014-show-us-your-solar-observing-set-up.html

John

[ollypenrice]

Older wedges often allow the waste beam to escape the diagonal where it has been known to ignite ties.

Chortle!! A blazing tie is one thing but worse scenarios than that come to mind!!!

Olly

[Teal Rain]

Just a follow on question..

The WO 80 Ann. edition has a plastic baffle - I take it using this with the wedge would be bad??!

Mark