The E-10 and E-20 are unique in the digital world in using a prism to split the light coming through the lens to provide a TTL view through the eyepiece. This innovative solution has advantages and disadvantages. It means you got a larger, clearer view of the image exactly as the lens sees it, no parallax errors, better framing and (in theory) focus.
While the E-20's viewfinder is good (and considerably better than found on any consumer digital camera) it's still not perfect. I found the eyepiece itself difficult to see through without the rubber cup vignetting the view, this seemed to be associated with its horizontal size and the fact that it's round rather rectangular.
The second problem is that despite what was written in the E-20's press release I didn't find any evidence of a focusing screen (and even the cutaway diagram below looks no different than the E-10), thus the problem of your eye focus 'through' the lens is still here. This problem makes it very difficult to use the viewfinder for manual focus or even checking auto focus.
The viewfinders frame coverage was measured as 97% with the bottom edge of the viewfinder view aligned with the bottom edge of the captured image. The viewfinder has an eyepiece shutter (to seal the optical path for long exposures) and a dioptre adjustment ring.
Below you'll find a diagram of the information shown on the status line of the viewfinder.
On several occasions when 'out shooting' we found that our images were being 'washed out' and overexposed, it turned out that if you use the LCD monitor as a 'live view' viewfinder you MUST close the eyepiece shutter otherwise you're risking sunlight entering the optical system through the eyepiece lens.
Another thing that makes the E-10 and E-20 unique among digital SLR's is that it features a non-removable lens. This could be seen as a limitation but there is a fairly useful 35 mm - 140 mm (equiv.) range of focal lengths and a mechanical zoom ring. It's made of very high quality multicoated glass with the use of aspherical pieces. With an F2.0 - F2.4 aperture range it's also VERY fast and bright allowing lots of light in. Another important reason for implementing a non-removable lens is that it keeps the imaging chamber sealed and avoids the problem of dust on the sensor. The image on the right below shows the lens with the supplied lens hood attached.
Infrared Focus beam
The E-20 has a removable cartridge which is used to load batteries, this cartridge can take either two Olympus CR-V3 Lithium battery packs or four AA batteries (like a good set of NiMH rechargeable AA's). When you first put AA's in this cartridge you'll be forgiven for thinking there's a problem as the top contacts don't touch the batteries. Fear not, the entire top panel is spring loaded and is pushed down onto the batteries when they're loaded.
In the right rear of the hand grip you'll find the storage compartment door, it springs open with just a flip of the (self locking) door lever. Inside you'll find a SmartMedia (up to 128 MB) and Compact Flash Type I/II slot. You can use one or both slots at the same time and switch between them by pressing the CF/SM button on the top of the camera. This time around Olympus officially support the newer 1 GB IBM Microdrive.