June 2009: Removing the Blindfold from the dSLR
Seth:
The only thing missing was the downside of that technology, at least for now.
Carrying such a rig while the system is still on can really burn up some pixels as it bounces into full view of the sun, etc. The mirror protects that until the system powers down.
The other thing on an interchangeable lens camera is dust. Right now, although sensors get dirty, the mirror catches most of it. I know there is a filter and/or cover over the sensor, but the extra barrier is a blessing more often than not.
Until Nikon and Canon come up with a reliable way to clean a sensor in the camera, having that mirror there when changing lenses at football, NASCAR, Indy--even some landscapes--is a blessing.
admin:
Quote from: Seth on July 08, 2009, 01:22:00 PM
The only thing missing was the downside of that technology, at least for now.
Carrying such a rig while the system is still on can really burn up some pixels as it bounces into full view of the sun, etc. The mirror protects that until the system powers down.
The other thing on an interchangeable lens camera is dust. Right now, although sensors get dirty, the mirror catches most of it. I know there is a filter and/or cover over the sensor, but the extra barrier is a blessing more often than not.
Until Nikon and Canon come up with a reliable way to clean a sensor in the camera, having that mirror there when changing lenses at football, NASCAR, Indy--even some landscapes--is a blessing.
Interesting but I'm not convinced either of those is a significant down side. When I'm carrying the camera, it usually has the lens cap on and even if it was off, I'm not sure light is going to ruin pixels. The mirror being in the way of the sensor for dust is of less concern than something accidentally poking the sensor while the lens is off. Dust tends to fall around the mirror anyway and the mirror just makes it harder to clean the sensor in the long run. My main concern is if you change lenses in the field, a branch, screwdriver, etc. might accidentally scratch the exposed sensor.
Mike
Seth:
Quote from: Mike Chaney on July 08, 2009, 03:30:55 PM
When I'm carrying the camera, it usually has the lens cap on and even if it was off, I'm not sure light is going to ruin pixels.
What I meant is that focused beam on the sensor. I have seen it burn through shutters in the "old days." Dunno.
Quote
The mirror being in the way of the sensor for dust is of less concern than something accidentally poking the sensor while the lens is off. Dust tends to fall around the mirror anyway and the mirror just makes it harder to clean the sensor in the long run.
In PJ you just have no choice. You're even supposed to urn the camera off when changing; we just don't can't do that in a fast moving situation. I agree about the mirror, somewhat. Of curse the D300 has a sensor clean (some kind of oscillation) but the D3 does not. Go figure. I have always wondered about those cleanings though. Where the heck can the dust go except hang around to blow back on at some point !?!?! It's not like they have a waste tank like printers do <GGGG>.
Misirlou:
The vibration cleaning systems work very well. I had to clean the sensor in my previous DSLR all the time, but my Canon 40D has only needed a wet cleaning once in 2 years. In the newer Canons, there's a patch of sticky material somewhere in the mirror chamber where the dust is supposed to accumulate after it falls off the sensor (off the anti-aliasing filter in front of the sensor, to be precise). I don't see the dust ever overwhelming that system.
I'd like to see someone run a test on noise generated by these live-feed sensors. As long as the sensor is operating, it generates heat, which should produce more noise. I've seen people suggest anecdotally that the live view cameras spike up in noise quite a bit when live view is engaged for a long time, say 30 seconds or so. I haven't seen it in my DSLR yet, but I only use live view for focus confirmation and so forth. Full HD video has got to really put heat in a sensor. Maybe what's needed is an active cooling system, like the ones used on astro imaging equipment.
I'm one of those guys who might have a real problem with the sun-on-the-sensor deal. I hardly ever use lens caps in potential shooting situations, preferring to leave lens hoods on all the time to protect the glass. I could easily imagine letting the sun accidentally fry whatever was at the focal plane. [Some years ago, I was shooting a snow scene on top of a mountain near Albuquerque with a Rolleiflex. I set up a scene with the sun visible. The air was very dry and cold. The sun beating down on the shutter blades caused them to warm up, and when I tripped the shutter, I got a blast of static electricity between shutter and film that ruined several frames. You can see from the negative that it started where the sun was in the frame.] A minor point to be sure, but it is something to consider.
I'll be interested in where this idea goes. Something like a ruggedized G1 might be ideal for underwater photography. The water bath would draw heat away from the camera, eliminating sensor heat buildup. Contrast focus would probably be great in that situation too. You could switch on the LCD for easier viewing through a mask. Could be a real winner.
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