Tuesday, 18 March 2008

Shutter Speed | Macro Photography | ISO

Shutter Speed
In my recent posts I have explained aperture and depth of field. Now we will get to grips with shutter speed. In my first post I suggested that beginners use aperture priority mode for macro photography. This is good advice but there will be times this mode is not adequate. This means you might have to use full manual mode. In this mode you can enter the aperture and shutter speed settings yourself. It sounds quite scary but once you understand how to use the shutter speed settings it will be a piece of cake. This is a good introductory tutorial because it is based on general photography techniques. In other words this will benefit your general photography skills. Knowing how to select and use the correct shutter speed will make a lot of difference to you photographs. Firstly the shutter itself is just a mechanism that opens and closes when you take the picture. The button you press on the camera to take a photograph actually operates the shutter. On many cameras you will hear a distinctive click as the shutter opens and closes. Some cameras allow you to add or change the shutter’s sound effect. The shutter allows light to enter the camera when it is open and is used along side the aperture to get a good exposure. Fast shutter speed is measured in fractions of seconds. Slow shutter speeds are measured in decimals of seconds or whole seconds.

The Horrible Mathematical Bits!
Shutter Speed can be confusing to the mathematically challenged such as me, because anything that involves numbers makes my brain ache. What is worse is that shutter speed is expressed in fractions of seconds. Different makes of camera display the shutter speeds differently, which adds to the confusion. When shutter speeds are written in a list on a sheet of paper they are quite easy to understand. This is because you can retain their proper format. Fast shutter speeds that are measured in fractions of seconds are displayed as 4000 (1/4000) which is one four thousandth of a second. Slower shutter speeds are measured in whole seconds. The fastest shutter speed on my camera is 1/4000 of a second. The slowest setting is 30 seconds, although I can set it to “bulb” and hold the shutter open for longer if required. In general day to day macro photography you will only use the range of more moderate shutter speed rather than the extremes. There has to be a huge amount of light available to use the very fast shutter speeds. The very slow speeds can be used to take photographs in low light conditions.

One of the great innovation of a modern digital camera is that it measures the light available. This is not always accurate but you can use the figures the camera displays in auto mode to work from. If the image is under exposed the shutter speed is too fast and therefore not enough light is entering the camera. If the image is too light with areas that are bright white the shutter speed is too slow and therefore allowing too much light is entering the camera. Adjust the shutter speed and recompose and take the photograph again. If you find it difficult to tell if the photograph is correctly exposed using the cameras LCD screen try using the histogram feature on your camera this is the best way to check the exposure. I plan to cover exposure in more detail in a subsequent post.

There are a total of 55 shutter speed settings on my camera listed here from fastest to slowest. 1/4000 (4000), 1/3200 (3200), 1/2500 (2500), 1/2000 (2000), 1/1600 (1600), 1/1250 (1250), 1/1000 (1000), 1/800 (800), 1/640 (640), 1/500 (500), 1/400 (400), 1/320 (320), 1/250 (250) 1/200 (200), 1/125 (125), 1/100 (100), 1/80 (80), 1/60 (60), 1/50 (50), 1/40 (40), 1/30 (30), 1/25 (25), 1/20 (20), 1/15 (15), 1/13 (13), 1/10 (10), 1/8 (8), 1/6 (6), 1/5 (5), 1/4 (4), 0.3 (0”3), 0.4 (0”4), 0.5 (0”5), 0.6 (0”5), 0.6 (0”6), 0.8 (0”8), 1 (1), 1.3 (1”3), 1.6 (1”6), 2, (2), 2.5 (2”5), 3.2 (3”2), 4 (4), 5 (5), 6 (6), 8 (8), 10 (10), 13 (13), 15 (15), 20 (20), 25 (25), 30 (30) - bulb

Figure 1. Illustration of Shutter Speeds (Click to Enlarge)

ISO Speed
ISO is a standard set by the International Organisation for Standardization and is used to measure the sensitivity of camera film. Digital cameras inherited the term ISO and it is used to measure the sensitivity of the camera sensor. This is quite a big advantage in digital macro photography because you can select a different ISO easily between shots. In a film camera this would mean having to stop to change the roll of film! This allows the photographer to use a faster shutter speed in low light situations with or without using a flash. There is one draw back with using higher ISO settings. When the sensor is made more sensitive to light it has a tendency to create noise (speckles) on the picture. This is more noticeable at very high settings of 1600 and 3200. The use of higher ISO speed can be used to overcome lighting problems in macro photography. This in turn is a useful way to reduce camera shake, which will ruin your shots by making them blurred. The low and moderate ISO speeds do not create as much noticeable noise. Always use the lowest ISO number possible to retain the highest quality image. Increase the ISO as a last resort so that a faster shutter speed can be used without altering the aperture. I hope to cover this subject in more detail at a later date.

Controlling the Exposure with Shutter Speed
Shutter speed is the amount of time that the shutter remains open during an exposure. Using the correct shutter speed and aperture will result in a good exposure. This is what all photographers are aiming for when they take a photograph. A good composition with the subject in sharp focus and an overall good exposure is the recipe for a great shot. The shutter speed can be entered manually on most cameras. In shutter priority mode (marked as TV or S on most cameras) this will select the appropriate aperture on your behalf. I have had some fairly mixed result using this mode and much prefer to use full manual mode as it offers much better control of the camera. If you set the shutter speed too fast not enough light will be able to enter the camera and your image will be too dark (under exposed). Setting the shutter speed too slow will allow too much light to enter the camera causing the image to be too light (over exposed). It can be difficult to see whether the exposure is good or not using the LCD screen on the back of the camera. I suggest using the histogram feature if your camera has one. This is the best way to quickly check that your image is exposed correctly. Make adjustments to the shutter speed to correct under and over exposure problems. If the image is under exposed use a slower shutter speed to allow more light to reach the sensor or film. If the image is over exposed use a faster shutter speed to allow less light to reach cameras sensor or film.

Creative Uses of Shutter Speed
Shutter speeds can also be used to add creative and artistic flare to your photographs. When taking photographs of moving objects you can freeze or blur the action to suit your preference. Use fast shutter speeds to freeze the action in a shot or slow shutter speeds to add motion blur. In macro photography these techniques can be applied to insects to freeze or capture wing movements. This is can be very effective with large insects such as Dragonflies, Bees and Hoverflies.

What we have learnt so far about Shutter Speed
In this introductory tutorial we have learnt that fast shutter speeds can be used to freeze action. Slow shutter speeds can be used to add motion blur giving the impression of movement in the photograph. In macro photography this can be used to get impressive shots of insects. My personal preference is to freeze the action as this makes identification easier. Some insects have very intricate detail in their wings that will be lost if you use slow shutter speeds when the wings are moving. In addition any unwanted movement will be captured and could ruin the shot. If your subject is around long enough it might be possible to get both types of shot. As a photographer you have to make the decision of what type of shots you want to take. This tutorial has also briefly looked at ISO speed. Increasing the ISO setting will make the camera more sensitive to light. This can be really useful in terms of macro photography when finding enough available light can be a problem.

Hopefully this tutorial has been a good introduction to shutter speeds and has opened your eyes on this subject. Knowing how to set the correct shutter speed is guaranteed to improve your photography skills. This will enable you to overcome exposure problems with your images. Never be afraid to take a lot of shots of the same subject using different settings to get the best overall image. This is one of the advantages of using a digital camera. If it is helpful you are welcome to print my illustration to shutter speeds.

Coming Next…

In my next post I will be writing a much less formal post about some of the perils of macro photography. I do not want to give away too much about my next my article but it will be a good way to take a break from all this very technical information. It will be still be a useful source of information.

Thank you for visiting my Macro for Beginners Website. I hope you found the information that you were looking for. I will be adding new and interesting articles to this website regularly. If you have any questions, queries, comments or suggestions please leave a comment or contact me by email: marvin.africa@yahoo.com

Free photography tips and advice – what more could you ask for?

Read about the Physical Challenge of Macro Photography in my next post.

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