Martin Frey wrote in
:

Paul Lawler wrote:

... I was assuming that the fact that the sun
is difficult for non-observers to "position" in the eyepiece without it
blacking out was a result of the small aperture.

That's not really a "fact" - personally I find it quite easy to point
any telescope at the Sun. I just wish finding stuff in the night sky
was even 1/10th as easy!

The shadow of a telescope on the ground usually gets the Sun in the
eyepiece without reference to any kind of finder - but the sol finder
on the PST is nice too.

Yes, I agree that it's easy to position the tube of the PST, that is not
what I meant. In my experience, many non-observers have trouble finding
the sun in the eyepiece. If you don't position yourself at the precisely
correct distance (i.e., your eye is too close to, or too far from the
eyepiece) the solar image is not readily visible. Children especially seem
to have problems.

Maybe I am just spoiled by 2" wide field eyepieces where you can't miss.

As the PST filter is well inside the PST tube, what actually happens
to the heat that has passed through the objective?

Not much heat makes it through. That objective is highly reflective.