Thursday, March 12, 2015

More on Ursa

The awesome Libby Csulik turned us on to which is where it looks like we'll rent the Ursa camera.
Shane Hurlibut says the Ursa wants to shoot at an ISO of 400. He says that whackity-doo* things happen to the image at both 200 and 800 ISO.
The fact he has a football strapped to his kit is all kinds of awesome.

The trick is to use infrared resistant ND filters for out there in the sunshine. Whether we feel the infrared pollution on the image is a good or bad thing may be up for debate, but we're GOING to need some ND. This morning I measured an f45 out in the daylight at 400 ISO at 24fps and a 180 shutter (I still have my Sekonic light meter from Pandora Machine). That's right, an f 45.

Obviously that will have to be knocked down a couple stops. The IR ND filters are delightfully expensive. Delightful!

This is information I frequently need:

Neutral Density Factors

• 2x = ND.3 (exposure adjustment = 1 stop, reduces ISO 1/2)
• 4x = ND.6 (exposure adjustment = 2 stops, reduces ISO 1/4)
• 8x = ND.9 (exposure adjustment = 3 stops, reduces ISO 1/8)

*My words, not his.

Update: a complete explanation of f-stops!


Kangas said...

Might have to look into renting a sweet zeiss lens for a week rather than paying for a decent-yet-not-zeiss lens for my upcoming short...

And why don't you just up the shutter speed drastically to reduce the amount of light coming in?

Andrew Bellware said...

I don't want to rely on faster shutters just because I don't want the movie to look too video-y. Or to lose motion blur (even though that seemed to work for Pitch Black).