ISO – How sensitive do you want it to be?

When you talk about exposure there are a couple of things important. Aperture, shutterspeed and ISO value. Compared to the analogue era we just came from the advantage of digital is that you can change every photo instead only after every 36 photos on an average filmroll.

Most people can remember the days when you had to buy film for a sunny country or or a not so sunny country. Did you go to Spain than the store would recommend you get a 100 ASA roll. Did you go to dark Africa than a 400 ASA would be a better idea. In those days you had asa and din. Those have later been combined and are now universally called ISO.

If you’re camera comes fresh out of the box the chance is big it is still on automatic iso. Not everyone is aware of this and happily continues shooting only to find out much later when it is too late. Ofcourse it is not a major disaster if you’re iso is on automatic and nothing really bad will happen but it is always a good thing to know WHY you use or should use a certain ISO value. What is the difference between a low or a high value and how and when do you change it?

To start with, like I said; there is no right or wrong here. I determine the iso based on the circumstances in which I am taking photos and will always try and keep it as low as possible, That is not to say I never go high. If I am shooting indoors in a restaurant or at an indoor market I will go as high as iso 5000 or 6400 if that gives me a high enough shutterspeed to shoot handheld. When I shoot with my compact I often use the automatic iso. Simply because I cannot be bothered to think about it.. 😉

Left taken with Canon 5D, middle with Canon Powershot G12 and right with the powershot D10

When do you use a high and when a low iso value?

To start with; a low iso (from iso 50/100 or 200) means your sensor has a low sensitivity to light. A high ISO (800 or higher) means your sensor is sensitive to light and you can take photos longer handheld or without using either a tripod or a flash. Are you taking photos of products that do not run away; cakes or food in general, than there is no reason to use a high iso. For the simple reason that a tripod in this case is a much better option than a high iso. If you look at the results above you can clearly see that not all high iso’s give the same results. I did not correct the photos in any way these are all straight from the camera. And I shot them all on jpg and did not use raw to keep the comparison equal. The left is taken with my slr 5D, left with the powershot G12 (a high end compact) and on the right with my underwater camera D10. The cheapest camera (in this case the powershot D10) give a much worse result on iso 1600 than the other two do on iso 3200. Ofcourse it is not entirely a fair comparison as you can assume the 5D would do a better job than the powershot. Thankfully it does! Keep in mind also that the older your camera is the more trouble it will have with higher iso’s.

100% enlarged

But if we take a closer look you can really see the effect that iso has.

See what happens to the lines in the photo? They become less defined and blurry. And not to mention the colors. With the D10 that effect is a lot worse than with the G12 who has more grains. Now it will not happen that often that you’re viewing your photos at 100% of the size. In websize the differences are there but will not be as dramatic as when you view it up close and personal. And certainly when you’re talking about mood images a high iso is not bad by definition.

A photo such as the one you see above cannot be taken with a low iso. Assuming that you do not travel with a tripod on vacation, because since nothing moves here you could make it with a tripod and long shutterspeed and low iso ofcourse. If you would zoom into this photo and enlarge it at 100% you will find there is a lot of digital noise, but in this case I do not find that an issue at all. I captured it because I liked the atmosphere and the mood and I think it works out in the photo. Most importantly when you’re working with iso settings, is understanding what the consequences are of a high iso vs a low iso. The pros and cons listed:

PROS OF HIGH ISO

• faster shutterspeeds
• less camera shake
• taking photos at night or indoors without flash
• when using a flash a better balance between flash and ambient light (more on that later)

CONS OF HIGH ISO

• Lots of noise
• Colors will be less crisp (they become faded and not vibrant quickly)
• Less defined edges

If you look at the list it would appear that there are more pros than cons.. 😉 But the most important question is to be aware of your subject. Learn how your own camera reacts in higher iso circumstances. Maybe it is very acceptable and you find it more important to shoot without your tripod. Ultimately the choice is yours! Good luck and if you have any questions; you know where to find me.

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