How do I decide which shutter speed and aperture to use?
|If you choose the full-aperture metering option, the meter
dial on your Pentacon Six TTL prism will give you a range of
choices. Which ones should you use? That will
depend on various factors. Here I will give you some
guidance to help you decide.
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:
The camera in that picture 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.
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
1. What lens are
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:
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:
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?”
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?”
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.
What if the shutter speed and aperture numbers don't line up on the meter?
Above, I gave a list of equivalent exposure values with a range of shutter speeds and aperture values. But what if the shutter speed numbers and the aperture numbers don't line up neatly in the way that they do in the photo and the chart at the top of this page? Someone who viewed one of my videos asked this recently:
Hi, your tutorials on the Pentacon six have been a great help ... I'm new to vintage photography so when reading my light meter which is analogue what reading do I use if the reading falls in between numbers, example: f/11 falls between 30 & 15 shutter speed, can I use either 30 or 15?
Congratulations on getting this camera. You must of course use the actual shutter speeds on the camera and you can't set speeds between two numbers, so in the example you give you should use 1/30 sec. However, you can use lens aperture settings between the numbers that are printed on the lens, to compensate, so here I would suggest that you use the "half-stop" setting between f/11 and f/8. (This is usually called f/9.5)
In fact, 1/30 sec is rather a slow speed for a hand-held camera, and you would be better using 1/60 and f/6.3 (half way between f/8 and f/5.6) or even 1/125 and f/4.5 (half way between f/5.6 and f/4). For hand-held photography with the standard (80mm) lens, it is generally better not to use a slower shutter speed than 1/125, to ensure that the image is not blurred by camera or subject movement.
If you are shooting negative film, being "half a stop out" (e.g., using f/11 instead of f/9.5) is probably well within the exposure lattitude of the film and so will give you a satisfactory exposure. If you are using "slide" or reversal film, being "half a stop out" will show, and so you should aim for the most exact exposure possible.
In fact, as you gain experience with your camera and your light-meter (whether in a prism of with a hand-held meter), you will learn what gives the best exposure. I would advise two points:
To go back to the page that shows you how to use the metering prism, click here.
To return to the instructions front page, click here.
To contact me, click here.
© TRA December 2012 Latest revision: August 2016