Hi. Questions. So many questions. But first, Story goes : I have the chance to buy a used Satellite hood (~$18). I'm told it has a dark spot in the lens. Waiting till after this bunny egg holiday weekend to get photos. But in the meantime i'm scheming schemes of what i might do to use this helmet if...

Electrons jump to and from things a LOT better when the things are hot. It takes a lot more to heat up a big chunk of tungsten than a little one. So it takes longer to heat up to useful temp (hence starts being an issue), and may battle to get there if the heat sink effect is large enough (a minute ...