H Alpha scopes with variable polariser?

[paulastro]

Like many other's I've spoken to, when visually observing the sun in HA, I've noticed when some thin cloud goes across the surface detail can be greatly enhanced.

Does anyone out there use a varible polarising filter to produce this effect, has anyone tried it? I'd try it myself, but I don't have such a filter! Best regards, Paul

[Peter Drew]

Hello Paul.

I tried a variable polariser unit on my 80mm Ha scope on Tenerife last week. I found that this, and any other filtering that I have so far tried at the eyepiece end seems to have little effect other than just dimming the image. A couple of days had a noticeable atmospheric haze which dimmed the image externally producing similar but consistant enhancement of surface details to that when thin cloud passes. On these occasions the view was very comparable to a double stack filter. I'm disappointed that this effect seems to be achieveable to order only by high expence.

[paulastro]

Welcome home Peter! Many thanks for that, I should have know you would have tried most things HA by now . Presumably there is some technical reason polarised light does not have the same affect as haze or thin cloud. Perhaps I ought to come up to TAC and light a fire down wind of your solar scope and see if that works as the smoke drifts over .

See you soon Peter, and thanks again.

[arbacia]

Paul,

At least in the Coronado Solarmax filters, beside the tunning wheel, to get the best contrast with extreme care rotate the front filter until contrast is better.

Try a single polarizer instead a variable one (which is a stack of two crossing PL).

Patricio

[markt]

IMHO all adding a polariser does is dim the image. These often have poor transmission at ha wavelengths... Not something worth bothering with if you ask me...