Understanding ISO Ratings and How to Use Them.

Tuesday, February 8th, 2011

What is an ISO rating?

Well, in a nutshell, it refers to how sensitive the camera’s film or sensor is to light.  If you look through your camera’s menu, you will most likely see options like 100, 200, 400, etc.  up to 3200 or perhaps 6400 and higher.  The rule of thumb is, the lower the number, the less sensitive to light the sensor will be.  This means that in order to produce a well exposed image, the shutter speed will have to reduce and/or the aperture will have to be opened wider in order to let in enough light.

Why Should I Use a Low ISO?

It is worth knowing that the lower the ISO you shoot with, the better the quality of the resulting photograph.  In both traditional film and digital photography, “noise” or the  graininess in the image increases when the ISO increases.  For landscape photography, for example, the camera can be mounted on a tripod and a slower shutter speed can be chosen as the subject is stationary.  A smaller aperture can also be selected which will afford you a lovely deep depth of field, keeping everything from the foreground to the background in focus.

This means that the ISO rating can be set low – as low as you can in order to achieve the best quality image possible from your camera.  As a guideline, a low ISO rating is in the region of 50-200.

Are There Benefits to Using a High ISO?

Absolutely!  What if you are shooting sports or nature – subjects that move faster than a mountain range?  Then a faster shutter speed is necessary to capture the action. In order to create a good exposure in the very short time the shutter is open, the sensor in your camera needs to be much more sensitive to the tiny amount of light hitting it.  If you raise the sensitivity by increasing the ISO rating, this will “balance out” the exposure, so to speak.  So, the higher the ISO rating you shoot with, the faster you can set your shutter speeds.  Faster shutter speeds also means that you can hand hold your camera without getting blur from camera shake, so no need for a tripod.

The added sensitivity to light with a higher ISO also gives you better results in low light situations.  But the advantage of being able to hand-hold a shot at dusk comes at a price – the noise in the photograph will become more noticeable.

“High” ISO’s are generally in the region of 500 and above.

The color reproduction, overall contrast and detail will be much better than the same scene shot at a much higher ISO.  Take a look at the 2 photos below to see what I mean.

The fine detail of ISO 100 is in stark contrast to that of 6400, which displays noticable grain as well as reduced contrast and color detail. The one benefit of the image shot at 6400 was I could hand hold the camera in the realatively low-light scene. The 100 ISO shot needed the camera on a tripod to avoid camera shake.

They were both shot at an aperture setting of 5.6.  The first one was set to ISO 100, meaning that the exposure time needed to be 1/3 second to achieve a well-exposed image. But the result is sharp, clear and with no real noticeable grain.

The second shot was again, 5.6, but this time I raised the ISO to 6400.  The added sensitivity meant that I could use a faster shutter speed of 1/160th second – but look at the horrible grain when viewed at 100%.

Which One Should I Use?

Well, with today’s advances in digital camera technology, the images produced at even relatively high ISO levels are becoming better and better.  In-camera processing can remove a lot of the noise produced at higher levels, so it is a matter of experimenting.  My experience has shown me that a good place to start for general, all-purpose photography is ISO 400.

So getting to know how ISO ratings, shutter speeds and exposure times affect each other is an invaluable step in becoming a better photographer.

Point and Shoot vs. DSLR

Thursday, January 28th, 2010

Digital cameras have improved dramatically in quality and price over the past few years, but what kind of camera should you buy?

Point and shoot cameras are small, cheap, and easy to use. If you don’t want to carry a camera bag or be bothered with fancy settings, a point in shoot is the way to go. A compact camera that takes nice photos that you always have with you can be much better than a fancy DSLR that is always left at home. However, there are some drawbacks. Many point and shoots take 10 mega-pixel photos or better, but mega-pixels don’t tell the whole story. A DSLR with 10 MP will take better looking photos than a point and shoot with 10 MP. The image sensor won’t be nearly as good, which reduces the quality of the image no matter how high the resolution, giving you grainier images than you’d see with a DSLR.

Cnet.com rates the Canon PowerShot S90IS ($399) as the best point and shoot and the Kodak Easyshare Z915 ($120) as the best budget point and shoot.

If you are an aspiring photographer, a point and shoot will not be good enough. My favorite thing about my DSLR (Digital Single Lens Reflex) is that there is no lag, it takes photos as I press the shutter button. It’s so much easier to capture the moment! The superior image sensor (up to 25 times better than that of a point and shoot) allows the camera to take photos at a higher shutter speed, reducing your chances for getting a grainy image. My second favorite thing about a DSLR is your ability to control depth of field. You know how professional photographs often have a blurry background? You can do that with a DSRL and impress your friends. As you develop as a photographer you will appreciate being able to adjust the settings for different situations and you can use different lenses (wide angle, long range, etc.) and different flashes.

Cnet.com rates Nikon D5000($665) as the best entry level DSLR, but you can’t go wrong with the Canon Digital Rebel ($559).

What Everyone Should Know About Cameras

Monday, December 28th, 2009

Great article from Gizmodo: What Everyone Should Know About Cameras