ISO Rating for HPX300?

M

Mark Smith

Veteran
Has anyone taken the time to come up with an ISO rating for this camera. I took a look last night and it seems to be close to 800 with 1080 24PN High Gamma and 0 db under tungsten light.... Yeah I know.
 
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Huh? what was your methodology? Call me curious in NJ

I framed 18% grey card which was lit . Using y get and confirming with wfm function set iris to 42 ~43 IRE noted F stop on lens and then toggled light meter settings to come up with a ISO number for the combination stop & light level.

One thing I found surprising is that there is virtually no loss of stop with the stock lens ( at least at the center) when comparing wide to telephoto.
 
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You can do it that way but 50 seems a little high to me. In the digital cinema realm 42-43 IRE seems to be the place people put their 18% grey these days. In the olden days of video, caucasian skin tones were 65-70 IRE frequently. The way Panasonic cameras are designed, I like mine in the mid 40's with peaks of course higher.
 
A Panasonic engineer told me to expose 18% gray at 30 IRE with whites at 70 IRE when shooting in Film-Rec Gamma. He didn't mention what percentage of dynamic latitude--probably 500%, because it was regarding an HPX3000.

Of course, the 300 doesn't have Film-Rec, so 18% gray would need to be exposed higher, depending upon gamma.

My HPX2700 has an ISO of 640, but when adding 180 degree shutter and -3db gain, Film-Rec gamma, it's more like ISO 400. Resolution and frame rate affects the sensitivity as well, of course.
 
You can do it that way but 50 seems a little high to me. In the digital cinema realm 42-43 IRE seems to be the place people put their 18% grey these days
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But that depends on the gamma curve. If you're shooting with a flat curve (such as cinelike-D) then at proper exposure middle gray might hit at 42, yes. But in HD Norm (which is a video gamma) then you'd want middle gray to hit at 50, or you'd be really underexposing. And High gamma is even raised further; you'd probably want middle gray to hit at about 55 for proper exposure when using High.
 
I rarely use HD Norm. I think I'm going to back through the menu of gammas and see what's what as far as exposure. I think ISO 320 is def too low, and 800 might be high but I still think the ISO is at least 640....
 
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