[Prev][Next][Index][Thread]
(meteorobs) Rotating shutters
>If you take 450+650 you will get 1150.
I think I've almost got it! You found the blade had a rotation rate of 1150 RPM.
But wouldn't that mean the strobe would show harmonics at 575 FPM (flashes per
minute), 383 FPM, 287 FPM, etc., etc.???
Harmonics at 650 FPM and (near) 450 FPM make the actual blade RPM sound more
like 1300... In other words, 1300 / 2 = 650, 1300 / 3 = 433, etc. (Sorry to
thrash this one out, but I HATE when I don't get stuff like this right off! :>)
Anyway, having just a rough idea (around 1200) is going to give enough accuracy
for any single-station uses of a rotating shutter, right? And if someone's doing
two-station work, they probably need either a digital readout or a feedback
system to regulate speed, so I guess the question probably doesn't matter much.
Speaking of digital readouts, has anyone on the list tried using an optical
encoder, like the ones used in Digital Setting Circles, to monitor their
rotating shutter setups? Seems like a nice secondary use for those expensive
doohickeys, but I wonder how you could safely attach the thing.
>This probably means nothing to anyone other than me... One happy note here. I
>now feel that I have been using a relatively ideal rotating shutter speed all
>along and wasn't aware of it...
Nope: I appreciate the info! In fact, it'll probably make me think again about
using your plans, George... Who did you say that fan's manufacturer was? :)
Lew
References: