Shutter speed = how quickly the “eye” of the camera closes to freeze the action. The faster the shutter = the better it freezes moving objects, but, the less light that gets in. Represented as 1/whateverths of a second. Eg., 1/500= one five-hundreth of a second.
As a general rule, my shutter speed is never slower than 1/400 second. This is something I will rarely compromise, in order to get more light. It just isn’t worth it to end up with a blurry/soft photo.
For action, it is at least 1/1000 – faster if I have enough light! Ideally 1250 or 1600!
I usually keep my shutter speed at 1/400 because even Loki, my perfect model, is a living, breathing, moving creature. 1/400 freezes his slight movements, while still letting in as much light as possible.
Interestingly, using my 135mm lens recently on my old Crop-Sensor camera… I had a LOT of motion blur, even at 1/400 second.
A too-slow shutter speed, of about 1/125 second, is the MAIN mistake I see beginners making when they’re wondering why their images aren’t very sharp.
Shot at 1/1250 sec, f/1.8, ISO 1600
This photo (click to enlarge), as well as having a lot else wrong with it, was probably taken at 1/125 second. Everything is slightly soft and blurry because of this slow shutter speed.
I will also – although more rarely – increase the shutter speed in high light conditions. E.g, if I was shooting in bright sunlight. This is because my aperture will almost always be at its widest – allowing in the most light but making sure I get a nice, soft background. Although I could change my aperture to allow in less light, it would mean more of the background would be in focus, which isn’t usually what I want – and my ISO will be at its lowest, so the only other setting I can change to get a photo at the correct exposure without compromising the look of the image, is shutter speed. If this doesn’t make sense yet, don’t worry! It will all come together as you learn how the other aspects of the “exposure triangle” work.
Having a too-fast shutter speed will rarely/never be a problem. Having a too-slow shutter speed will be!
This photo is a great example of the above. It was quite bright out (though not harsh sun). Usually I would take this kind of portrait on 1/500 second, f/1.8 and ISO whatever. However on this day, because of all the extra light, I was already on f/1.8 and ISO 100 (as low as it can go, so letting in the least amount of light), and it was still EXTREMELY bright. My options would have been to narrow the aperture – meaning there would have been a lot more detail in the foreground, and in that soft creamy background…. or to increase the shutter speed, which would just freeze any small motions Journey made even better.
As a result, the settings were: 1/1250 sec, f/1.8, ISO 100.