Eyepieces for solar projection.

[Xilman]

Any suggestions on what eyepieces are best for projecting a solar image from a Newtonian reflector?

I am very wary of using anything with cemented doublets or multiplets for fear of cracking the cement from differential expansion from the intense heat passing through.

A few decades ago it was possible to get Ramsdens or Huyghens but these days?

Or am I worrying needlessly?

[Zermelo]

1 hour ago, Xilman said:

Any suggestions on what eyepieces are best for projecting a solar image from a Newtonian reflector?

I am very wary of using anything with cemented doublets or multiplets for fear of cracking the cement from differential expansion from the intense heat passing through.

A few decades ago it was possible to get Ramsdens or Huyghens but these days?

Or am I worrying needlessly?

 

Did you see this:

 

 

[inFINNity Deck]

I do solar projection on a daily basis (weather permitting) with a 1490mm focal length f/50 Galilean type telescope and found most importantly that the eyepiece is made of metal. It may be useful to check the draw-tube of the focuser, best to have metal there as well. Being a Galilean type telescope I use a home-made plano-concave singlet eyepiece made of an off-the-shelf -75mm focal length, 24mm diameter lens, but have been projecting with Plössls and Kellners as well without issues (apart from the plastic parts melting away).

Be careful with demonstrating the projection method, people do tend to dive to the eyepiece to see what is happening there! A safe alternative is the projection funnel.

Nicolàs

 

[Franklin]

I had a 60mm Prinz back in the day and used it for solar projection, it was handy being able to draw the sunspots actually on the projection screen. Since then I've used front mounted solar filters of various types and still use them on my small Petzval refractor. However, the best views I've had of the Sun in whitelight have been by far using a Lunt solar wedge and Baader solar continuum filter, all with refractors though. 

[Carbon Brush]

I have only recently started using a Herschel wedge with a 102 objective refractor.
Excellent sunspot views and no worries about eyepiece damage.
HTH, David.