How slow can you go and still be sharp?
Do I need a tripod any more?
My gut feeing was that I needed a shutter speed around 1/250 sec to ensure my images weren’t blurred by my hand and body motion when shooting hand-held, even when today’s cameras have image stabilization built into the body and/or lens.
I was trying to recreate a shot I took years ago that showed a person crossing the road under a long bridge. It was taken at a shutter speed of 1/30 sec. The person was blurry but the bridge was still sharp.
I tried to take the same shot again with my full frame Sony A7CR camera and found I could get down to 1/10 sec and still maintain sharpness. That got me thinking about how slow could I go before the images lost sharpness. So I did a super scientific test using my full frame camera and a Sony 90mm macro lens with its own image stabilization. I shot a ship docked at night. To get the most light I shot wide open at f/2.8 and, to keep it simple, AUTO ISO.
At 1/250 sec, the image was sharp but noisy. Since the ISO was 80K, I’d expect some noise. At 1/10 sec, the image was sharp and noise was minimal at ISO 3200. At 1 sec, the image was still sharp and the ISO was down to ISO 320. That was amazing performance.
I repeated the exercise with the Sony A6700 and the same lens. It had an upper limit of ISO 6400 for Auto ISO, so the image was under exposed at 1/250 sec. At 1/50 sec, the ISO was still stuck at 6400, but the image was pretty sharp and noise was easily dealt with in post. At 1/10 the image fell apart into a blurry mess. At 1 sec, the image looked like it had been taken by a drunk suffering the DT’s.
My preliminary conclusion is that I can use much lower shutter speeds on both cameras, but the A6700 shouldn’t be pushed slower than 1/50 sec while the A7CR can go down to 1 sec. For landscapes and cityscapes, knowing how low I can go will help me get sharper and cleaner images in poor light
I might do a few more tests to see why the A6700 fell off so abruptly. Maybe the lens stabilization doesn’t work with the A6700 or vice versa. I also might check the effect of focal length. A 500mm lens is going to magnify any movement 10 times more than a 50mm lens, or so I think.