I went into the park later in the afternoon today [2-1] with a friend. The conditions this afternoon [2-1] were not necessarily ideal. It was windy, cold, cloudy and there was just not much light to work with. Plus, the only interesting subject that I found was a single bull elk near Alluvial Fan.
There is a fine balance to capturing a photo that is of decent quality as well as close to what the eye saw – including camera settings and composition. It is much more complicated than setting the camera to aperture priority, shutter priority, manual or automatic modes. One of the points that I made to my friend is that it may be necessary to intentionally overexpose or underexpose a photo to get closer to what the eye saw and/or highlight certain areas. Another alternative with digital photography and photo editing is a High Dynamic Range [HDR] photo which is an underexposed, correctly exposed and overexposed photo merged into one.
I intentionally and unintentionally broke some of the rules of photography to get more acquainted with my camera as well as to give a few examples to my friend. Every setting on the camera impacts another setting on the camera. The aperture being closed a half step reduces light to the sensor. Vice versa, opening the aperture a half step increases light to the sensor. F/2.8 allows the most light to reach the sensor, where as f/32 allows the least amount of light to reach the sensor [depending on the lens aperture settings – it could be f/4 to f/22 or whatever the lens design allows]. Increasing the shutter speed [faster] a few hundredths of a second reduces the amount of time that light has to reach the sensor. Vice Versa, decreasing the shutter speed [slower] a few hundredths of a second increases the amount of time that light has to reach the sensor. Decreasing the ISO a few settings decreases light sensitivity of the sensor. Vice Versa, increasing the ISO increases light sensitivity of the sensor.
Being that it was overcast and later in the day, the ISO setting became important. I started off shooting at ISO 400 and ended up shooting at ISO 1000. Had it been a bright sunny afternoon, there would have been more light to manage and I could have started off with an ISO of 100. In many ways, it is harder to get a decent photo with less light to manage. The camera has to be set up in a manor to allow the most light to reach the sensor. The physics involved basically means that less light decreases photo quality. This is also somewhat true with more light, although it is somewhat easier to manage more light. Basically, the camera cannot physically see the same thing as the human eye regardless of the situation. It is somewhat limited.
Another factor is the subject matter. Is it moving or stationary? Is the camera on a tripod or handheld? One of the pictures that I took was set to the ideal exposure setting at a specific aperture and shutter speed. When I snapped the photo, the shutter speed was too slow to reduce camera movement and subject movement – resulting in a blurred image that was exposed properly. In order to fix this, I bumped the shutter speed up a little bit and then ended up with a slightly underexposed image. Next thing, I bumped the ISO up.
How do I get more light into the camera while the light is fading away? Open the aperture, slow the shutter speed down, bump the ISO up. What will those changes do to the image? Reduce the depth of field, add more motion into the camera and/or the subject, reduce the image quality by introducing more noise… If I have plenty of light to work with, I can: close the aperture, increase shutter speed, decrease ISO. That will increase depth of field, decrease camera and/or subject motion, increase photo quality by reducing noise. All things to think about!
All of these things help manage the light so that the image that is captured comes out properly. Knowing what the setting on the camera will do to the image is important. That is the nice thing about getting instant feedback from a digital camera. It gives the ability to better manage the light!
Ah ha. ISO makes sense now, thanks to the creativeLIVE session. It’s not increasing the sensitivity to light; it’s boosting the signal that the sensor is recording…