Burning baffles in refractor

[davhei]

Hi everyone, first post here.

I have an 80 mm f6 apo triplet that I have done some white light solar with using a 1.25” Lunt solar wedge with ND3 filter and a baader continuum filter at the eyepiece. Got some very crisp views in august and early september with granulation effects (macrogranulation I suppose) and groups of sunspots and faculae during perhaps a dozen sessions. Great!

The scope is aluminium and the focuser is metal, something I took care to confirm prior to using it as a WL solar scope. The other day I started thinking about the baffles though, and the manufacturer confirmed they were plastic.

So. Stop or don’t stop.

What makes me uncertain is the fact that the heat sink on the wedge hasn’t gotten warm during my sessions so far, indicating that the beam at that spot anyway isn’t searing. And since the beam narrows to a point the closer you get to the focal plane it should be less concentrated further up the OTA towards the objective lenses.

What are your thoughts on this. Should I stop using the scope for solar with a wedge? Obviously don’t want to burn the baffles, but on the other hand, being overly cautious would prevent me from using the nice gear I have sitting around.

[AndiesHandyHandies]

Hi

If not a problem so far then I would continue.

Use an IR thermometer up the scope after a session?

A rubber washer in a 180mm where the Sun was 20mm in diameter survived.

Andrew.

[rsfoto]

Hi,

I do not think that the wall of the telescope tube will reach high temperatures. The main temperature development is at the wedge.

Look at the Sun and touch the telescope tube on diferent positions with the outer part of your fingers. If you have to take it off after 3 seconds then perhaps it is getting too warm but I really doubt it.

Rainer

[davhei]

Thanks!

Do you think this is valid off axis as well? For instance when the sun is just outside the fov of the eyepiece. I suppose this could happen while finding the sun at the start of session or if you let it drift outside the field of view.

[EGRAY_OBSERVATORY]

Never had a problem with the same set-up..

Best - when not using that set-up to actually view or image, to turn the tube well-away from the Sun and/or cover the objective-lens...

Terry

[marktownley]

Never ever known an issue with this over many years...

[davhei]

Thanks everyone! I feel more confident now.

[DeepSolar64]

The light cone should be inside the baffles and not even hit them. Otherwise they would stop the scope down in aperture. The baffles are only there to control scattered light outside of the focal plane.

You should be safe.

James