How To Master Your DSLR Camera Pt.1

A guide to getting the most out of your camera.


In part one of this series addressing the DSLR, we’ll take a look at your camera and what sets your DSLR apart from all other cameras, later we will learn about the camera’s controls and how to effectively use them. 


The accompanying illustration aptly demonstrates why a Digital Single Lens Reflex camera is known as a DSLR. In formative years before the introduction of the SLR photographs were generally taken with a Twin Lens Reflex Camera that would view through one lens and then the photograph was taken through another. When an image is formed through a lens it is captured on the sensor inverted and laterally opposed. (Upside down and the wrong way round) Our eyes work in exactly the same way but the brain turns everything around for us. In order for the image to be displayed correctly, the mirror directs it up and away from the sensor and turns it upright  (reflex) while the prism orientates it correctly. One of the biggest problems with this construction that it needs quite a bit of space within the camera’s housing

Being somewhat facetious in producing these two illustrations that succinctly describes the major difference between the construction of a DSLR and a Mirrorless camera. Mirrorless cameras are a technological feat and deserve all the accolades that these cameras deserve.

Below; a cutaway section of one of Nikon’s Z series mirrorless cameras so that you can have an understanding and appreciation of just how complex and sophisticated a mirrorless camera really is. The Nikon is fitted with a complex lens that has many elements within its construction however the image is produced in exactly the same way on the sensor as per the illustration, hower we view it with the aid of the also very sophisticated electronic viewfinder.


Most of the tutorials that are available, in my mind, take the position that you have an understanding as to what you need to do in order to take an acceptable photograph. All the tutorials that I have come across always start by saying that there are three essential settings or pillars describing each one of these separately that you will have to set in order to do this. Fundamentally this statement is not incorrect in itself and most of you are aware that there is a triangle as stated by other tutorials that comprise the ISO setting, the shutter speed and the aperture and there is a direct correlation between all three that has to be taken into account. We can’t ignore this fact, however, I am going to stand back and look at each one of these settings individually as the background information is not only interesting but once you have grasped this your photography will take on a whole new meaning.


In the first part of the tutorial, I am going to go back to basics and to explain to you what ISO is and how it came about as the sensitivity setting on your digital camera. Before digital even existed the standard had been established that ensured a film that you bought was manufactured in a very precise way. In reality, film has an ISO value whereas a digital sensor has a sensitivity setting and no native ISO but the term was kept, as it was advantageous to do so.


Included is an illustration that briefly explains how a film is constructed but will spend some time on the light-sensitive emulsion of film.

Photographic film is made up of millions of light-sensitive silver halide crystals that were commonly referred to as grain. The lower the film speed, the finer the grain; the higher the film speed, the courser the grain. The manufacturers of film discovered that if they used large silver halide crystals it would make that specific film far more sensitive to light so a larger number was ascribed to that film. The system that was adopted to identify the sensitivity of a particular film to light was called the ISO value ‘film speed.’ ISO that was followed by a low number i.e. 25 indicated that that particular film was not very sensitive to light. Higher ISO numbers (e.g., 400) indicated a greater sensitivity to light. The emulsion speed sensitivity was determined by the standards of the International Standards Organization (ISO), which is how the term ISO came to be used in this regard.

It was very important that you understood that setting the ISO value via a dial on your camera enabled your camera to set the correct combination of shutter speed and aperture for that given lighting situation. If you did not change this setting when loading a new film of a different ISO value you would invariably have over or underexposed that particular film. This is where fine-tuning the balance between f-stop (the aperture setting), ISO, and shutter speed comes in to achieve the desired result.  When you looked at a manual camera, you saw the dial with all of the film speed settings starting from 25 up to 6400 (depending on make/model). When you set this dial it only affected the light meter and had no effect on your exposures at all. After setting the ISO value of the film the light meter was used to achieve the correct shutter speed for every aperture that you set or visa versa. All being equal the correct balanced setting ensured that you would achieve the correct exposure for the scene or image that you were busy photographing. Left on the manual setting on your camera the light meter indicated the correct balance between f-stop (aperture setting) and shutter speed for the given ISO value of the film that you loaded in your camera.


Later film cameras and film cassettes were manufactured with a sensor in the camera and special canisters that would automatically set the films ISO value. However, this largely depended on the camera manufacturers themselves. As film became more popular the ISO standard also ensured that film being manufactured in different countries complied with the necessary requirement that ensured that all film with a given ISO value responded to light in exactly the same way. Adjusting for exposure is one of the most critical settings that today are generally undertaken by the ‘automatic’ camera itself, it is that important.

It was common practice that some countries adopted the same standard but named it differently. America adopted the ASA standard, which was exactly the same as ISO however Germany adopted the DIN standard. (º represented the DIN value that was also printed on the film box.) A film with an ISO/ASA value of 25 was 15º 50 ISO. 18º a 100 ISO, 21º. The German Standards Organisation that was based on a logarithmic scale. A change in +3º in rating indicated a doubling of film speed. We, therefore, can see that a 21º-film speed was twice as fast as a 18º. It is also interesting to note that the Russians had their own similar arithmetical increase system to ISO/ASA, called GOST.

A brief recap and summary of what I have just told you. Larger silver halide crystals have more light sensitivity than smaller ones, so a film with a higher ISO will be more sensitive to light than a lower one. An ISO of 50 or 100 is not very sensitive and requires brighter light, which means that if your camera’s largest f-stop is 4 or higher, you would not have enough light to shoot indoors without having to use a tripod or supplementing the light with a flash. An ISO of 3200 is extremely light sensitive, but the grain is also very pronounced, in digital photography the grain is generally referred to as noise. The ISO ratings of film are separated by a light value. I.e. we now understand that a 50 ISO film is far less sensitive than the next ISO value of 100 and the difference in the required amount of light to obtain the correct exposure was exactly a half or doubled if we went the other way and so on. The term that we use is that there is a stop difference between the set ISO values it would require half the amount of light between each full ISO value as the ISO values increased or decreased, therefore, a 100 ISO film only requires 50% of the light needed by a 50 ISO film.


We would achieve this by changing the aperture or the shutter speed settings on our camera or take other necessary steps that would be required in order to achieve the correct exposure or mood in our pictures. Notice how film was deliberately manufactured and I am including this to aid your understanding. Slow 50, 100, medium 200, fast 400, very fast 3200 ISO etc. There are slight deviations from these values that depended on the film manufacturer themselves. We have now hopefully come to understand that a 100 ISO film needs only ½ the amount of light that a 200 ISO film required and a 400 ISO required only a ¼ of the light than its predecessor and so on and so on. You would also have noticed how the ISO value doubled until you got to 400.

The explanation is technical especially when we discuss the 3200 ISO film and not at all necessary for what we are discussing at this stage. In digital cameras, the image sensor has a fixed sensitivity or response to light, but the term ISO is still used in a similar manner as with film. When changing the ISO on a digital camera, the gain is changed rather than the sensitivity of the image sensor. Increasing the gain increases the signal amplification from the sensor making it appear to be more sensitive and increasing gain increases the apparent brightness of an image at a given exposure. We were able to change the characteristics of an image by simply changing the film but we are not able to change the characteristics of an imaging sensor in a digital camera. There have been so many notable strides and advances in digital sensors that noise has now almost been eliminated when the sensitivity of the sensor has been boosted almost all the way up. 

There was notable competition from the various film manufactures as to how the light-sensitive emulsion layers were formulated; colour clarity and sharpness were always of primary concern. There were many countries that used to manufacturer film but by far some of the most notable were Kodak, American, Ilford, (black and white only) British, Agfa, German, FujiFilm, Japanese and Konica also Japanese. I am aware there were many other film brands that were manufactured in various countries but this should give you an idea as to how popular film really was.

You should have a better understanding now concerning what the ISO setting on your camera is all about. If you move over to the magazine section in this issue you will find a tutorial on depth of field and in the next edition I will discuss how changing the aperture and shutter speed settings can affect the overall look and feel of our photographs. Please feel free to contact us if you have any questions.