Ever look through an Oly E-10/20? My first thought when I picked one up in the store and looked through it was "UGH! How dim!"...
Here's how Oly can do what they do-
1. They use a beam splitter. Sounds good on paper. In reality, only about half the light gets to the viewfinder, the other half gets to the CCD. That's how the CCD can be constantly exposed while you see an image in the optical viewfinder. This results in two problems-
a) Dim viewfinder, as it gets much less light than it would if it was using a reflex mirror.
b) Slow ISO ratings on the sensor since it is only getting half the light it would get if it was using a reflex mirror (the reflex mirror will move out of the way upon exposure allow ALL the light to hit the sensor).
Now let's say that some Canon engineer starts smoking crack and decides that a new Canon SLR needs to come out with a beam splitter for live preview. One more sacrafice has to be made for that to happen:
2. Consumer cams with live preview use an interleaved CCD that is constantly discharging its output one row at a time. They have serial registers at every row between the pixels. This results in a constantly updated pixel, but also means that less of the CCD's total area is being used for actual light collecting. Wasted space.
With real SLR cameras, we have sensors that do not have these registers between each pixel. The sensor outputs the entire image at one time after exposure. This means the image cannot be updated live, but also means that much more of the sensor is doing what it should be doing: light collecting. With this arrangment, you can have larger photo cells which collect more light, which results in a larger sample of data to process, which results in a higher S/N ratio, which ultimately manifests itself as a cleaner image with more dynamic range.
Give all that up to be able to use my LCD as a viewfinder or have some crappy EVF screen in my viewfinder? Sorry Charlie. If it happens, I'd seriously suspect someone at Canon bumped his head a little too hard.
Joe
Hi Jonathan,
I think your statement is valid.
SLR does not have to be like 1D.
I know it is technically very hard and Olympus already have this
feature.
But it would be a perfect SLR camera if it shows the moment of
shooting without sacrificing the quality of the optical viewfinder
Paul J.
