| | |  Vallarta Living | Art Talk | June 2009 
Photo Tip of the Week: ISO Basics - Part 2
 Larry and Linda Bennett - PVNN
| | Photo Tips of the Week are written by Larry Bennett, a professional photographer living in Puerto Vallarta. For more photo tips click HERE. To view more of his work, visit LarryBennettPhotography.com. | |
Hope your week is off to a good start. This week we are continuing our discussion of ISO, and I will also get around to telling you about the noise in your images and how to get rid of it. If it’s been a while since you've read ISO Basics Part 1, let me recommend that you re-read that article before starting this week's article.
Lighting, ISO, Noise/Grain
Digital photography is easy - when you have plenty of light and the conditions are ideal. But, as you may know, lighting conditions in digital photography aren’t always as we would like them. In digital photography it’s essential that we work with light as much as humanly possible otherwise disappointing results may occur.
One of my friends asked me how he could take digital photos at his friend's wedding. Let me explain his question a little bit more, he did not want to use a flash because it would be very distracting to the bride and groom while they were saying their vows.
What he was asking me was how to get better digital photos in low light conditions without using a flash. This is a very good digital photography question. Well guess what, good news, it can be done. But like everything else in photography there are advantages and disadvantages.
Using a flash is the biggest solution to low light digital photography. However, the problem with this statement is that not all situations can benefit from using a flash. Using a flash not only interferes with your "moment" socially and artistically, but it can flatten out your digital images. This is especially true for a built-in flash on digital cameras.
The built-in flash (and a flash in general) has the effect of lighting your subject on the front only, which compresses the depth in your digital photos. Compressed depth can really decrease the beauty of your subject in your digital photography.
This can be avoided to a certain degree, depending on your subject and by watching how your light falls in any given situation. To be a good photographer, you will need to be able to judge in each situation, how the light will fall on your subject(s) and surroundings; as with anything, practice makes perfect - your mind will become adept at knowing what works and what doesn't with the flash.
Really, a good way to deal with the problem of low light can most times be accomplished by using a higher ISO. Your ISO simply means the amount of sensitivity of light falling on your sensor. For a moment, let's look at traditional photography. In traditional photography the ISO was your film sensitivity. (ISO in traditional terms works with film speed as well.) We have come a long ways with digital photography since then.
The only set back in digital photography ISO is noise. What is noise? The noise in a photograph is the grain in the picture. If your ISO is perfect for the photo and there is a significant increase in noise, software can be used to sharpen up your digital photo. There are two good noise reduction software programs called "Noise Ninja" or "Neat Image." There are also noise reduction layers in Photoshop, Coral Pro, etc.
If you don't set the ISO higher you may find your problem to be an image with camera shake (if a tripod is not used.) By adjusting the ISO you will find that a problem with noise is better than a problem with camera shake. Most times an image with noise can be fixed.
How can you fix an image that is blurred because of camera shake? In digital photography noise will always be something you will need to deal with.
In digital photography, a higher ISO allows you to take photos in low light situations. In traditional photography you'd have to change your roll of film. In digital photography ISO gives you the opportunity to adjust a setting, rather than fiddle with changing a roll of film. This is advantageous if the subject is not going to stay around, or you yourself are unable to stay for an extended length of time.
Let's take for example a situation where you are taking some digital shots indoors... Maybe someone is speaking or playing an instrument in a concert and perhaps the flash is not appropriate in either of these situations.
In either of these situations (which happen a lot in digital photography) you would simply adjust the ISO to a higher setting. If you set the camera on "ISO Auto" your digital camera will then detect that a higher ISO is necessary. Alternatively you can also set the ISO yourself. This higher sensitivity can give you the opportunity of gaining the right exposure for the shot.
If you find that's still not right, because your digital photo now has camera shake (you don't have a tripod,) you can in fact decide on the next stop ISO which will then enable you to select a faster shutter speed.
For me, when I'm absolutely desperate for light without a flash, I use this technique:
1. Crank ISO as high as I need to go to get the shot;
2. Shoot RAW if possible;
3. Use aperture-priority with the lowest f-stop on the fastest lens you have;
4. If that still causes my shutter speeds to be too low to hand-hold, then I might even set exposure compensation down a stop, which will increase the speed a little, and then I'll push the exposure in post processing (preferably in RAW); and
5. Lastly, I'll use various forms of noise reduction software to help on the grain/noise.
Why Not Just Use a Higher ISO All the Time?
While using a higher ISO setting, which is often needed to capture images with reduced blur in lower light, it also increases the noise level of the image. (In film this is often referred to as "grain".) A lower ISO setting is preferred whenever possible since it helps to reduce this noise or grain.
ISO settings can also be used to help control the shutter speed of a camera while in automatic mode. In order to "freeze" motion in a scene, a camera needs to be able to use a higher shutter speed. By selecting a higher ISO you are allowing the camera to gather more light, this automatically forces the camera to select a higher (faster) shutter speed, which helps to reduce motion blur.
With film, the ISO rating is considered a "speed" rating. ISO 100 would be considered a slow film, while ISO 400 would be considered a faster film. Digital cameras obviously don't use film thus the ISO number corresponds to the image sensor's light sensitivity.
ISO 100:
Great for bright sunny days, at the beach or on the snow. Produces clean images that are great for enlargements.
ISO 200:
Great for overcast daylight pictures (noise levels may increase, but in most cases not noticeably)
ISO 400:
Great for lower lighting conditions (indoors, night time) or when you need to capture faster moving subjects in lower lighting conditions. In many consumer cameras, ISO 400 can make photos look very noisy in dark areas of the picture. The reason a higher speed ISO helps you capture fast moving subjects is because a higher ISO makes the image sensor of the camera more light sensitive. This forces the camera to use a higher shutter speed to compensate for the extra brightness, which in turn helps to "freeze" movement in the captured frame.
Until next time, remember, it's just another day in Paradise and F8 and be there!
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 Photo Tips of the week are written by Larry Bennett, a professional photographer living in Puerto Vallarta. These tips are to be just tips, refer to your cameras owner's manual for specifics on your camera. Readers are welcome to enjoy Larry's website at LarryBennettPhotography.com.
Click HERE for more Photo Tips from Larry Bennett. |
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