What is ISO? Get your camera off Auto!

I hope you have all had a good week.  I thought in this blog we would get back onto our photography tuition mission. So after my little update lets get back to it and take a look at ISO.

Wedding Showcase at Rockingham Forest Hotel in Corby

If you got engaged over Christmas and are looking for a wedding venue or other suppliers why don’t you come down to Rockingham Forest Hotel in Corby on the 8th February. I will be there with my wedding albums to discuss your wedding photography along with other local suppliers. The venue has recently undergone some major renovation so it is well worth a look around. For details of the event click the link HERE or come and find them on FACEBOOK.

Valentines Day Photography Gift:

I am still selling my Valentines Day photography vouchers.

So anyone who has yet to buy a gift for their loved one there is still time. £125 includes a portrait session and one of my new Bamboo Panel Desk blocks.  This is a saving of £55. Just contact me if you would like more information.

Introduction to ISO

Recap on our last tutorial about Exposure:

So in my last tutorial we looked at ‘Exposure’ in general. Just to recap, there are three adjustable elements in photography: ISO, Aperture, Shutter Speed. These three controls all combine to give an exposure value, called EV. if you change any one of these three settings there will be a measurable difference on how the other two elements react to expose the image sensor, and ultimately change how the final image looks. If you want a recap on the whole blog, you can find it HERE.

I think beginners don’t give much thought to ISO, when you look at your new camera and the manual the focus (excuse the pun) is all on shutter speed and aperture but I think ISO really is the best place to start. Understanding ISO will give you flexibility and many more options in how you shoot in a variety of lighting conditions without expensive flash equipment.

Understanding ISO

In the old film days you may remember buying film that was 100ASA or 400ASA. This is a good way to understand ISO as film is more tangible than image sensors. In the old days of film, if you were shooting in low light you would buy film stock with a higher ASA. The film was and is much more sensitive to light. The difference in terminology between ASA and ISO is really just terminology. ASA is a scale created by the American Standards Association and ISO by the International Organisation for Standardisation – do we need to know this.. no 🙂 ISO is the same as ASA, it is the level of sensitivity your camera is to available light. As in film days, a low ISO (100/200 ISO) means your camera’s sensor is less sensitive to light than a high ISO (500/3000 ISO).  A higher sensitivity has a downside, as you increase your ISO you also increase film grain or digital ‘noise’ to your shot. Over the years improvements in digital camera technology has meant high-end professional cameras can shoot at very high ISO with very little noise, further work can be done in post-production to further clean the grain. With entry level DSLR’s however it is something that you need to be aware of. If you want to crop or enlarge an image shot with a very high ISO it will have a lot of digital noise and this can look very ugly. For want of a better subject meet Holly, my cat, possibly not the best of examples, also my camera can shoot very high ISO with very little noise, but you get the idea!

ISO 100
ISO 100
ISO 100 Detail
ISO 100 Detail
ISO 6400
ISO 6400
ISO 6400 Detail
ISO 6400 Detail

If you can grasp how to use ISO it gives you a greater range of options available to you to achieve the creative shots you want with your aperture and exposure.

In summary then, changing the ISO on your camera changes you camera’s sensitivity to light.

Every camera has something called ‘Base ISO’ which is the lowest ISO number of the sensor that can produce the highest quality image without adding noise to the picture. This used to be ISO 100 but these days it is common to be ISO 200. You should try to stick to the lowest ISO possible to achieve the best image quality but sometimes it is a trade off with creativity. In low light situations the high ISO settings will give you much more options for creative photography without the use of expensive flashes, than if you try to shoot  everything at ISO 200.

ISO Sensitivity

Typically ISO numbers start from 100/200 then increment by the power of two, each step between the numbers effectively doubles the sensitivity of the sensor. So ISO 200 is twice more sensitive than ISO 100, while ISO 400 is twice more sensitive than ISO 200 and so on. So when a sensor is sixteen times more sensitive to light it means it will need sixteen times LESS time to capture an image, this has great implications on how you then proceed to set your shutter and aperture.

Adjust your ISO

So before I give you something to practice with over the next few weeks take a few minutes to find how you adjust your ISO on your camera. You may have to get your dreaded manual out 😉 Just skip everything else and find the chapter on ISO. If you take your camera off Auto you will be able to manually adjust your ISO. Have a play and look at the range of ISO settings your camera is capable of, maximum ISO will vary camera to camera depending on it’s capability.

An Experiment

So have a go at this to help with your understanding of ISO. It needs to be a cloudy day! (I am trying to predict your lighting conditions) still have a go if it is blazing sunshine but your results may vary.

Take you camera off Auto and set your camera aperture to f5.6 – you will have to look in your manual to adjust this setting it is easy, just a dial and a number, don’t get bogged down with aperture we will look at this later.

Now set your shutter speed to 1/100 sec. (Again, don’t worry about shutter speed just manually change the setting)

Set your ISO to 100 and take a picture. Chances are you have an exposed photograph.

Now keeping your aperture and shutter speed settings the same change your ISO to 400 and take a picture, increment your ISO up and take an image every time and see how your image changes. It will gradually become more and more overexposed, ending with a completely blown out white frame. Zoom in the shot taken at 100 ISO on your camera’s viewfinder, you should be able to do this, then do the same on the shot taken at the highest ISO and look at the difference in digital noise. Excuse my poor examples of my garden plant, it’s pouring with rain and blowing a gail outside and it is the best I can do without getting drenched… but you get the idea 🙂

ISO6400
ISO6400
ISO 2500
ISO 2500
ISO 800
ISO 800
ISO 100
ISO 100

So you can see from this little experiment, if you keep your other settings the same and adjust your ISO your camera becomes more or less sensitive to light. This has great implications for how you use you camera creatively. For example if you need one second to capture a scene at ISO 100, possibly a bird in flight, simply by switching your ISO to 800 you can capture the same scene at 1/8 second or 125 milliseconds – you will freeze the action in the photograph by the speed of the shutter. We will come to this later. For both of the photographs shown below it was really important to capture a little of the room mood and ambience, the lights of the First Dance and the beautifully decorated room at The Belmont Hotel for a recent Christening were just as important to photograph as the event. I do use off-camera flash for my first dance photography as I try to keep my ISO down to reduce noise, but increasing the ISO along with a reduced shutter speed means I can capture a lot of ambient mood lighting in my first dance images.

IMG_0905188-MeeMacow

Have a play around with your ISO settings and let me know how you get on. Come and find me on FACEBOOK and Twitter @firetreephotos it is always nice to have feedback!

Kyra x