Variable aperture iris

[Leda]

Is there a variable aperture iris diaphragm for putting over a solar filter on a refractor available?

So far I have a cardboard circle I tape up over the filter when I want to stop it down but a variable one would be nice

[Merlin66]

Haven't seen one available.

An 80mm aperture seems to be "optimum" for the average seeing conditions in UK and Europe.

[Leda]

Yeah I cut my "cardboard" out to approximately 80mm aperture.

I also have a "loo roll" for my solar filter, it is very hard to buy a decent budget solar finder too.

[ollypenrice]

For a finder you just need a short tube (2 inches?) with a cap on the front in which you make a pinhole in the middle. On the back you need a screen of some kind. Mine is just an eyepiece cover in translucent plastic. A dot of light will be projected onto this from the pinhole. Line up on the sun and then mark the correct spot for the dot of light with a felt tip. (I copied this from Helen. Thanks, Helen!)

Your front aperture masks sound fine to me, better than ones closing into a not-quite-round shape.

Olly