GL2 Shutter for Still Pictures?

[Steve McDonald]

I've been trying to answer someone's question about the GL2's still-picture mode and I can't find the information on Canon's website, nor here or anywhere else. Does the GL2 have the same type of mechanical, progressive shutter for the still mode as found on many Sony camcorders? Or, does it just use the same electronic shutter as it does for video shooting? The Sony models with this feature need more light when this mechanical shutter mode is used, as it is very fast. I'm trying to determine if this is a cause for still pictures from a GL2 being dimmer than video footage when shot in limited light levels.

[Andre De Clercq]

Steve, what makes you think that IT CCD used in camcorders have (need) a mechanical progressive(?) shutter? As far as I know, only full frame (FF) and frame transfer(FT) (sometimes) need mechanical shutters.

[Steve McDonald]

dre, when in still-picture mode for J-PEG storage, the Sony MegaPixel camcorders use a mechanical shutter, that exposes both pixel fields at the same time. They are then scanned as two interlaced fields. The 2nd field's acquisition is retained on the CCD until its scanning turn comes. Then, they are combined into a frame for storage that is the same as if it was progressvely scanned. When you click the button for a J-PEG picture, you can hear the shutter work, just like on a film camera.
This mechanical shutter is not used
in video mode.

[Andre De Clercq]

Thanks Steve, I am not so familiar with the photomode concepts used in camcorders. The shutter seems to be there for other reasons than the technology based reasons. I thought they solved the memory buffer problem just by doubling the buffer memory size togheter with a progressive readout.(like in real progressieve camcorder systems) Apparently the missing half is taken from a retarded CCD storage, and the readout is kept as interlaced. On yr original question now. If you have a calibrated scope available, set the scanspeed at say 10 ms/div take a couple of pictures and verify the number of divisions the spot is lighted up. From there it's easy to calculate the shuttertime. For short exp times (</= 1/60) you can also point yr cam to a crt TV and estimate the shuttertimes based on the hight of the visual image part.(band)

[Don Palomaki]

Which model Sony?

FWIW, my Minolta digital still camera has a mechanical shutter sound one can turn on or off - its for folks who like the comforting sound of a shutter rather thatn a beep or silence when the CCD is read.

[Jeff Donald]

I haven't fully researched the reasons for a mechanical shutter on a digital camcorder. It may have to do with flash synronization. I've heard Nikon D1 users and Canon D series users say the mechanical shutter gives a different look.

Jeff

[Andre De Clercq]

Digital photocamera's use a mechanical shutter because they have FT or FF CCD technology. In order to avoid readout blurr they need a mechanical shutter. I was not aware of the "trick" used in camcorders with IT CCD's. Steve, is this readout strategy for still pictures on Sony's camcorders explained somewhere?

[Steve McDonald]

dre, this old page from Canon is the only one I could find today about mechanical, progressive shutters in camcorders. I've read more detailed descriptions of it in the past, but the manufacturer's aren't including as much information about such features on their websites nowadays.

http://www.canondv.com/optura100mc/f_progressive_photo.html

I know there is now a way to make links clickable on this forum, but couldn't find the directions to do it. It'd be nice if this was included on the F.A.Q. page.

[Andre De Clercq]

Thanks Steve. Also about the shutter see http://www.camcorderinfo.com/content/progressive_video_ntsc.htm