Originally Posted by Four Thirds User editorial team
A second-generation and backwards compatible 'Micro' Four Thirds interchangeable lens system has been jointly announced by Olympus and Panasonic this morning. Both manufacturers stress they will continue to develop Mark 1 Four Thirds lenses and bodies, while both look forward to super-compact and lightweight Micro versions as well.
Here's the big news of the day! It's also what I spent a week in Japan during June being briefed on. I'll try to pre-empt some of your questions:
1. Does Micro Four Thirds replace the original Four Thirds? No. Both manufacturers have stated that they will continue to develop and support Four Thirds bodies and lenses.
2. Is the sensor size smaller? No. The sensor size (image circle) specification is the same as the original Four Thirds spec.
3. Is the lens mount different? Yes. You can't directly mount Micro FT lenses onto an original FT body or vice-versa. The mount flange - sensor plane distance has been halved. But a spacer adapter will be provided to enable original FT lenses to be used, with full electronic communication, with Micro FT bodies.
4. If the distance between the lens mount and the sensor has been halved and the sensor size remains the same, where does the reflex mirror go? Well, there won't be a mirror! Micro Four Thirds cameras will have interchangeable lenses, but they won't, technically, be DSLRs (digital single lens reflex).
5. How much smaller will Micro FT lenses be? Incredibly smaller. The shortening of the mount to sensor distance enables big changes to be made possible in the optical design of these lenses, resulting in smaller and lighter optics. Just compare the sizes of lenses for existing interchangeable lens rangefinder cameras, for example, which also benefit from a closer mount to lens distance. Expect a halving or more in size and weight of some existing examples with comparable lens focal lengths, while maintaining the same aperture brightness.
6. Will I be able to use Micro FT lenses on an original Four Thirds body? No. The lens will be too far away from the sensor.
7. If there is no reflex mirror, does that mean Micro Four Thirds cameras must have electronic viewfinders? Basically, yes. Luckily, we can expect a major step forward in EVF technology for still cameras.
8. Without a reflex mirror, will that mean autofocus must be operated through the slower contrast-detection system, using the main sensor, instead of using the typical faster DSLR phase detection method. As far as I'm aware, yes. However, contrast detection AF technology is being refined for faster performance.
9. Photokina is coming up at the end of September? Will we see some physical examples of Micro Four Thirds at the show? I can't say, though I feel that the timing of today's press release is significant.
10. When will we see the first Micro FT products on sale? This information isn't yet available, but what I would say is that it's not a long way off. Micro FT has been under development for longer than you might think.
I hope the above will answer most of the obvious questions. As luck would have it, I'm out of the office for much of today, but I will try to drop in to answer any more questions if I can...