Maximum exposure times for solar imaging?

[Poita]

I've been gazing at the sun via the PST a lot lately, and am interested in having a go at imaging through it.
How long can you capture the Sun for before the changes become too great for stacking?

[Merlin66]

I normally try to get around 1000 frames for stacking....
With my double stacked SM60 and x2.5 Powermate I need exposures of around 1/120s for the surface features...so this gives about 10sec in total; for the proms I need down to 1/11 sec exposure and this can cause problems with fast moving edges of the proms.
General answer.... a few seconds....

[Poita]

Thanks, I was hoping I had longer!

BTW, I have access to a 2nd PST with a rusted out objective, is it worth extracting the etalon to double stack the PST?

[Merlin66]

IMHO - no, not worth the effort!
I machined up a special adaptor to hold the two PST etalons and got it working...BUT trying to get a repeatable positioning of the etalons/ sweet spot was so sensitive - it was a real PITA!
I gave up....tooooo much effort for little return.
Having said that, there is a guy in Hong Kong who had more patience than me and did get it to work pretty well.
HTH

[Paul Haese]

You do have longer. I take video for 70 seconds and not much changes. I am sure you have seen my images. 60 seconds is pretty good as a rule though.

[Poita]

Thanks Paul, I was hoping you would chime in, I aspire to get somewhere in the ballpark of your images one day.

I'll settle in a 60 seconds and see how I go. Got to do the getting rid of the black box mod first!

Cheers

-Peter