By Gordon Lubbers /
Working your way around the exposure triangle has inherent risks. Sometimes you go for a long shutter because you want “silky water” or you use the highest aperture setting possible to maximize the depth of field. In the Gold and Blue Hours, you may increase your ISO because of the low light conditions. Any of these actions may produce an unsatisfactory picture. The unasked question is “How do I ensure a good quality image?”
This may not be a concern for those who shoot in a studio …. but for those of us who work the Gold and Blue hours it certainly can be. It definitely is when you go long shutter – shutter speeds of a couple-few seconds or longer. All of the landscape photographers I follow allude to this in their “Exposure Triangle” vlogs, but never really address the question, much less give you an answer. What I hear is ….
I can increase my shutter speed from 1/8000th second to 30 seconds but eventually I introduce motion blur into my photos and need to use a tripod.
I can increase my ISO from 100 to 12800 or higher but eventually introduce unwanted digital noise into my photos.
I can increase my aperture from f/1.4 to f/22 or higher but eventually introduce a permanent blur into my photos because of the way light acts going through a narrow opening.
The questions are: “At what shutter speed do I need a tripod to produce a good quality image? What’s the highest ISO I can use and still get a good quality image, one without noise? What’s the highest f-stop I can use and still get an image without blur?”
It’s never discussed by the vloggers. I’ve looked into this, though, and have the answer.
The answer is, it depends.
It depends on the camera body and the lens you’re using. So while there’s no one-size-fits-all answer, the answer is there for you to discover. You need to test your gear. When you do these tests, you’ll have learned the operating parameters of your gear. Work within those parameters and you’ll always produce good quality images.
For the ISO and aperture tests I set my camera on a tripod and focused on the side of my house on a sunny day. I set my camera at ISO 100, f/8, and selected a shutter speed to give me an exposure balance of zero. Took an image and increased the ISO to 200, reset the shutter for a zero exposure balance. Took an image and increased the ISO to 400, reset the
shutter for a zero exposure balance …. you get the idea. In the end I had 8 images (I stopped at ISO 12800). I did the same for the aperture test, starting at f2.8, keeping the exposure balance at zero and increasing by full stops up to f/8 (f2.8, f/4, f/5.6, f/8), then by one third stops to f/22. I tested each lens this way at its minimum and maximum focal lengths.
At the laptop I opened the first (base) image of each series in one window, and scrolled through the rest in a second window, comparing each successive image to the base image. I noted on an index card the lens and at what f-stop I saw blur, and at what ISO I saw noise. I repeated the tests for the other lenses I use with that body.
I keep the index card in my camera bag and look at it each time I set up. Refreshing my memory on the operating parameters I’ve noted has helped consistently produce noise- and blur-free images. The effort was minimal, and well worth the time. Why not give it a try yourself?
Be well and stay safe.