Difference btwn "Existing Light" and regular cameras?

[Gabe Agoado]

I've seen the abbreviation "XL" thrown around a lot in regards to cameras, my question is this:

 

Given 2 cameras (super-8) of the same brand and model, with the same lenses, one being a "XL" version and the other a regular version, Does the increased shutter angle of the XL camera (like 220 degrees versus 150 degrees) really make all the difference when it comes down to low-light shooting, or would a fast lens (say f1.2) fully open, be able to adequately pick up enough light to get a good image even with the 150 degree shutter?

 

I'm also curious if the conditions are the same when it comes to digital shooting, like a Canon's GL2 versus the XL2. Would the difference between the 1/3 sec. shutter speed of the XL2 and the 1/8 sec. shutter speed of the GL2 really make or break a low-light shoot?

[Satsuki Murashige]

A shutter angle of 150 at 24fps gives a shutter speed of approx 1/60 (1/24 x 150/360). 220 shutter angle at 24fps is approx 1/40. So the difference in exposure is 2/3 stop.

 

A lot of these variable shutter super 8 cameras like the Canon 1014XL-S were taking into account that you were shooting 25-200ASA reversal film with a relatively slow fixed zoom lens, where you needed every little bit of extra exposure to even get something usable in a lot of existing light conditions. If you could combine that with a fast lens plus a little undercranking then that's what you did because you had no other choice.

 

1/3 sec is 1.3 stop more exposure than 1/8. But there's so much motion blur at that point that you would pretty much only use that for time lapse, a static still image, or a special effect.

[David Mullen ASC]

You can't actually have a per-frame exposure time longer than what max time the frame rate allows, in other words, if your video camera is taking 60 images per second as fields, each field cannot be exposed for longer than 1/60th of a second, unless Dr. Who built your camera as a time machine. So cameras like the Canon XL2 set to a 1/3 of a second shutter speed are actually lowering the frame rate to allow the longer times and then spreading out those fewer frames to fill 24 fps or 60i, whatever. This is why you get that steppy, blurry motion look.