first dSLR with live preview
After one year of more or less successful sale of Olympus E-300,on PMA show 2006 Olympus presented successor, new E-330 EVOLT. E-330 is first dSLR camera which is capable to provide live-preview taking pictures using LCD display on back side of the camera like all prosumers-consumers digital cameras, differs from all others SLR cameras where you have to use viewfinder. SLR cameras lack these feature because their construction, they have mirror, used to project picture in viewfinder, tween sensor and objective, as a result there is no light on the sensor while you look at viewfinder. Another problem is that big sensors used in dSLR cameras do not support video playback – which live preview actually is for camera.
Olympus decide to overcome technical short-comings of SLR technology, by using additional optical sensor just to project image on the LCD display. So new E-330 have no one, but two optical sensors built-in one 4/3 Type ‘Live MOS’ (NMOS) with 7.5Mpix used for taking pictures. And other one small Full time live preview CCD sensor only used to give full time preview on LCD. Olympus new E-330 provides two modes of live preview, first A mode Full time live view, main mirror stays in its place allows to use viewfinder, and small CCD sensor is used to provide live picture on display. In other B mode Macro Live View, shown in upper left picture, mirrors goes up, shutter opens and live preview picture is produced by large LiveMOS sensor.
On this diagram we see demonstration of A mod and placement of additional mirrors and additional CCD sensor. There are some significant differences between the two modes, also a few lacks.
In A mode, you can use LCD for composing a shoot either viewfinder, but if you use LCD light metering can be imprecise because the light which is entering through viewfinder. Using viewfinder cap solves this problem. Frame coverage is like through viewfinder about 92% of frame. Another lack appears, because of difference in size tween two sensor DOF – dept of field is not presented right. B mode offers fixes for most A mode problems but create few new, like lack of live light metering – because metering sensor is located in viewfinder chamber, No auto focus! and shutter delay about 1 second – mirror have to come down to alow light metering and go up to make a shoot. Advantages of this mode is absolute precision in DOF, 100% frame coverage and even live view 10x magnification.
To explore maximum from live-preview feature, E-330 was given excellent 2.5” LCD monitor already seen on older brother E-500. Its Crystal clear, bright, and with wide viewing angle. Its mounted on flip-out mechanism, which is quite different from what I used to see on cameras. LCD is protected by Plexiglas’s screen which have an anti-reflective layer to improve visibility under all light conditions.
In my opinion, Olympus chose to make pioneer step forward, so we have first dSLR with live-preview and removable display. This is not the perfect product but it clearly point the way of development for other manufacturers. I won’t be surprised if in year or two every entry level dSLR camera have live-preview features like this Olympus.