The third part of taking control is the ISO part. In the old days you could buy film at ASA or ISO sensitivities of 64, 100, 200, 400, 800 and the like. 100 was the standard film. 800 was for low light photography. The difference was how much light the film gathered given the exposure of the same amount of light. In other words, shoot a shot at 1/100th of a second at an aperture of f/2.8 with film having an ISO rating of 100 and you might get a fairly dark image captured at sunset. Take that exact same shot on ISO 800 film and the image captured would be much brighter. The ISO film was much more sensitive to light…and captured more of it…than the ISO 100 film.
Todays digital cameras work the same way. Although they all have a huge range of ISO settings to choose from, we generally use ISO 100 to 400 for most photos. We use ISO settings of up to 2500 for long exposure Milky Way shots…but do our best to shoot lower than ISO 2500. I will get into why in a moment.
So…you know how to control the time or T….you know how to control the aperture or A…and the third control is ISO and now you know how to control it…just pick an ISO of from 100 to 400 for most shots other than Milky Way type shots. Yes, yes there are ways to let the camera choose ISO within a range you set…but forget that for the next couple of years. Learn how the different ISO settings effect your images.
By the way…shooting in Manual or M is nothing more than you manually selecting the T, the A and the ISO setting yourself rather than letting the camera figure out any of those settings. So when the time comes to start shooting in Manual…and I hope that is soon…that is all there is to it. You try different combinations until you find the combination that works for the situation you are in…and then you will be getting the absolute best shots your camera can produce.
ISO effects how your photo looks. If a photo looks grainy, the ISO was probably fairly high…like 800 or above. We call that grain…noise. You can deal with it with software, but learn to deal with it in your camera. Shoot 100 ISO when you can and slowly creep up. Suspect your photos will look pretty horrible once you get to 800 and above. The bigger you try to blow up a photo for your walls at home or to sell…the more that grain and noise will show up. Lower is mo betta, as we say in Hawaii.
Try this…go out at sunset and set your camera at 1/250th of a second and your aperture at f/16 and do this in that M or Manual setting. Take a photo…if it is too bright by a lot or two dark, adjust the speed up or down to get a decent shot…then leave it right there for your next ten shots. Next, do that same shot at ISO 100, the 200, then 400, then 800, then 1600. By now it may be too bright…probably is so slow the shutter speed down until you are getting a normal exposure again…then continue to shoot at ISO, 2500, 3200, 5000 and higher. Put those images into your computer later and look at them carefully…especially in the sky. You will see the grainy/noisy effect that higher ISO causes. Good to know.
That is really about all there is to it…learn to control the speed, the amount of light gathered by the lens or aperture and the sensitivity of the sensor or ISO…it is the combination of those three that create your image. You are really ready to shoot in Manual at this point…but master either T or A before you go full manual. I still shoot in T a lot…because I shoot birds in flight and moving waves across changing backgrounds. Good luck.
I am going to take a break now, but the next article will be on setting focus. Aloha.