EX 50mm f/1.8. Also have a 35mm f3.5.
Battery: M20, PX-13 or 625 mercury cell. Today, use an Wein EPX-625. It will function without a battery without metering.
Originally launched in October 1969. Replaced by EX AUTO in February 1972.
This camera had unusual features such as shutter speed-priority AE, maximum-aperture TTL metering and AE, a bright aerial image viewfinder, and focal-plane shutter. The front lens element was also interchangeable.
Apertures are set automatically or manually by a dial on the top plate; the only indication is in the viewfinder.
The light meter seems to overexpose in bright light. If you're shooting a high contrast photo, be sure to meter off the shadows. (You generally should be doing this anyway if you're shooting black and white.) If it's just bright outside, you might want to consider stopping down 1/3 or 2/3.
At 1/60 or lower, blur from camera shake starts to become an issue, especially at low apertures. I find focusing hit or miss at 1/60 and just about impossible below.
For lenses other than 50mm f/1.8, need to set maximum aperture manually on film speed setting.
For the benefit of the TTL meter, the maximum aperture of the lens fitted (f1.8 for the 50mm, a slow f3.5 for the others) has to be set manually on the film speed setting. Otherwise, shots will be 2/3 stop overexposed. (This flaw was corrected in the later EX Auto model). I don't quite understand how this works, but experimenting with it now.
Other Lenses Available
The rear half of the lens is permanently attached to the EX AUTO body, while front sections interchange. This has the advantage of making for less expensive accessory lenses, since you only have to buy the front half, and that the camera is never open to dust and dirt while changing lenses.
The camera had a built-in rear lens consisting of 3 elements in 2 groups. Besides the normal EX 50mm f/1.8 lens, three other interchangeable front lens elements were available: EX 35mm f/3.5, EX 95mm f/3.5, and EX 125mm f/3.5. Centerweighted averaging metering was incorporated for easy operation.
Both the 50mm and 35mm lenses have a 48mm filter size.
This Flickr page contains more useful information about the lenses.
August 14, 2019
Acquired EX 35mm f/3.5.