Remember that full-aperture metering operates with the lens at maximum (or full) aperture.

See how to set the film sensitivity speed on the meter here.

In the photograph to the right, the meter indicates a range of correct exposures (in a particular low-light environment):
1/125 sec at f/2.8, 1/60 sec at f/4, 1/30 sec at f/5.6, 1/15 sec at f/8, etc.  In that environment with that lighting, all of these combinations of aperture and shutter speed would expose your film to the right amount of light, but it does matter which one of these combinations you choose.

The camera in the picture to the right was obviously metering quite a dark area.  On a reasonably sunny day with 50ASA/18DIN film (ISO 50/18°), you are more likely to see a series of combinations rather like those in the following chart.  (Most film is faster than this, but for teaching purposes, this will give us a good range of usable apertures and shutter speeds.)

On most analogue cameras produced over the past 50+ years, a range of shutter speeds has been used in which each speed is half the time of the next speed on one side of it and twice the time of the next speed on the other side.

Thus, at 1/125 sec the shutter is open for half the time (approximately) of 1/60 sec, but for twice as long as 1/250 sec.

Likewise, during the past 50+ years, the aperture values on lenses for analogue cameras have used a range of settings, each of which lets through half the light of the setting on one side and twice the light of the setting on the other side.

Thus, f/8 lets through half the light of f/5.6 but twice the light of f/11.

So, if you halve the time that the shutter is open (say, by using 1/125 sec instead of 1/60 sec), you can compensate by doubling the amount of light coming through the lens (for instance, by using f/8 instead of f/11).  In both cases, the film will receive the same amount of light.

To know which combination to use, we need to answer a few questions.

1.  What lens are you using?

A general rule states that the slowest shutter speed at which you can safely hold the camera is the reciprocal of the focal length of the lens.  What does that mean?

If you are shooting with a 250mm lens, you should consider 1/250 sec the slowest speed at which you can safely hold the camera without risking blur in the image due to movement of the camera during the exposure.  Not all focal lengths correspond to a shutter speed, so if in doubt, choose the next higher speed.  Here are some examples:
 

Focal length of Lens	Recommended minimum hand-held shutter speed
30mm	1/30
50mm	1/60
80mm	1/125
120mm	1/125
180mm	1/250
250mm	1/250
500mm	1/500

You may know from experience that you can safely hold the camera absolutely still at a slower shutter speed, but if in doubt go for a higher shutter speed, to avoid any risk of blur, or use a tripod.

Other things that you can do in order to be able to use a slower speed can be:

• stand with your feet apart (at a comfortable distance from each other)
• tuck your elbows in as far as possible (dependent on the lens that you are using – with a longer lens, your left arm will obviously be further forward)
• brace your body (tighten your muscles)
• hold your breath
• squeeze the shutter gently.

2.  Is the subject moving? If you want to freeze movement, perhaps of a fast-moving subject, choose the highest-possible shutter speed, possibly even 1/1000, even if the lens that you are using is not that long.  If we use the example combinations given above, you would then need to set the aperture at f/2.8 to get the correct exposure. Alternatively, perhaps you want to reveal the movement.  An example might be to show the movement of water.  For that you will probably need the slowest-possible shutter speed – in the example above, that would be 1/8 sec, for which you would need an aperture of f/32.  If your lens doesn’t stop down that far, but has a smallest aperture of f/22, like the 80mm Biometar standard lens, you would need to use a shutter speed of 1/15 sec.  Needless to say, for either of these exposures, the camera would need to be on a tripod, and it would be preferable to use a cable release, and possibly mirror pre-release or MLU, if it is available. You can achieve slower speeds still (or larger apertures) by using a neutral-density filter – a colourless filter that will reduce the amount of light entering the lens.  These are available in various densities.  For instance, a ×2 ND filter halves the light, which means that you can double the exposure time, for instance, instead of using 1/15 sec you could use 1/8 sec.  A ×4 ND filter obviously reduces the light reaching your film to one quarter, enabling you to go, in the above example, from 1/15 sec to 1/4 sec. One of the great things about using a TTL metering prism (as opposed to a hand-held meter) is that the prism automatically compensates for the filter, so you don’t have to adjust the reading that you get from the meter, just choose the combination of shutter speed and aperture that you prefer.     Image to the right:  This waterfall was quite dark, being shaded by branches and foliage. The exposure was 8 seconds at f/22 to reveal the movement of the water. You can see more information on this picture here. (scroll down)

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3.  What depth of field do you want?

Do you want maximum depth of field?  This means, “Do you want everything from very near to the camera to very far away to be in focus?”
This can be great for much landscape photography.

Or do you want minimum depth of field?  This means, “Do you want just one part of the image to be sharp, with other parts of it that are nearer to the camera or farther from it to be out of focus?”
This can be great for many portraits, but also for other types of photography.

There is a detailed explanation of depth of field, differential focus and hyperfocal focussing here.

To see how the 80mm Biometar reproduces the out-of-focus parts of an image (so-called "bokeh"), see here.

You can learn more about the effects of different formats and lenses on depth of field here.

You are in charge!

By thinking through these options, you will be able to find the combination of exposure speed and lens aperture that are right for the lens that you are using and the type of picture that you wish to create.

In the above, I have mostly gone to the extremes of aperture and shutter speed, to explain the point as clearly as possible.  However, depending on your preferred type of photography, most of your exposures may not be at the extremes; they may well use a medium speed for the shutter (such as 1/125) and a medium aperture (such as f/8 or f/11).  Depending on the sensitivity of the film and the ambient lighting, such settings are likely to give you sharp images that are not blurred by movement nor by out-of-focus areas.

One of the great benefits of the Pentacon Six is that it gives you the choice.  As you increase your familiarity with the results of the different settings, you will be able to express your own creativity by selecting the combination that is best for the photograph that you wish to create.

• Keep notes of exposure (shutter speed and aperture, plus the name of the lens used, if you have more than one);
• Choose a film that you like and stick to it.  You will learn its characteristics and its lattitude to a range of exposures.