Zenit-EM

Zenit-EM (Зенит-EM) is a 35mm SLR camera made in the Soviet Union from 1972 to 1984. It was part of the long running series of SLR cameras by Zenit which were produced in huge quantities. The camera has an M42 lens mount which supports a large number of lenses. It was usually marketed with the Helios 44M 2/58 which is shown in this video. This lens is famous for the swirly bokeh it produces in open apertures.

Zenit-EM was an upgrade of Zenit-E. The basic new feature was that it had an automatic diaphragm step-down, when using the appropriate lenses. The compatible lenses have a switch that enables this feature. What it basically does is that whatever aperture you've chosen, it will stay completely open to facilitate composing and focusing through the viewfinder. But when you take the photo, the aperture will close to the chosen value. Mind that the auto lenses will not work properly on cameras that do not support this feature. So be careful when combining Zenit bodies with various lenses, or the aperture will remain in full open position.

Zenit-EM, like previous Zenit models, has a very basic light meter. Using selenium cells on the front it powers a needle which points to an exposure range. With the help of a dial, you choose the film's ISO and you rotate it until the needle meets the white line. When it does, the dial will show you all the possible aperture/speed combinations to take a photo with correct exposure. Mind that the selenium cells degrade over time, and the light meter might not be accurate. You'll need to test it first, either with an external light meter or with a modern digital camera metering.

The camera has a self-timer and can support accessories like electronic or bulb flash, cable release.

It is a very cheap SLR camera and like all the Zenit's very easy to find. The famous Helios 44 lens is also very cheap and of good quality. The swirly bokeh leads to interesting results which makes it popular (it can be used in other cameras too, even for video with an adapter). The camera is very heavy and solid, made from metal but problems with the shutter speeds and the shutter curtain are very common, so check carefully before buying, because often a repair might cost more than the camera itself.

Zenit cameras in general, because of their low prices and fairly good lenses, are very popular and a good starting point for those wanting to enter manual film photography with an SLR camera.

Important things to remember:
#1 Never attempt to turn the shutter speed dial between "B" and "500" or you will damage it. You'll need to go all the way around.
#2 Advance the film before choosing a shutter speed. Doing otherwise might damage the shutter and disorganize the speeds. Although not necessary in all Zenit models, better remember this rule, to make sure nothing happens.
#3 Always advance the film before activating the self-timer.