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I wrote:  I have a feeling you can observe the Sun with a bubble Kollsman without any power at all, but I might be wrong.  I couldn't check just now; my bubble seems to have temporarily gone walkies. 

Well I’ve found my Kollsman bubble.  It’s so long since I’d used it, I’d forgotten it hides in the three o’clock position.  Why don’t all bubbles hide in the ten thirty position like in the Smiths/Hughes/Kelvin models?  Yes, you don't need power for a Sun shot.  DaveP