Over the days leading up to the 25th of December I’d like to give something to everyone who stops by my blog. So here is the first of my 50 photography tips. These tips cover camera settings and tricks, flash, lighting, software and gear. I’ll be providing a pair of tips each day for the next 25 days.
#1 – ISO safety shift
This custom function helps to keep your pictures correctly exposed when the light reduces while you’re shooting. For fast moving subject, or with longer lenses you need to use a fast shutter speed to avoid camera shake and limit subject movement. When the light level starts to drop, the camera opens the lens aperture, but there’s only a finite limit. When you hit that maximum aperture of your lens, then ISO safety shift will raise your ISO to ensure a good exposure. This works when you have selected a fixed ISO.
As an example, for this wildcat you might be using a 70-200mm f/2.8 lens and shutter priority at 1/320s to freeze movement in the whiskers and grass. If the cat is in bright light your selected ISO 200 will be fine, but as the light drops ISO safety shift will raise the ISO to maintain a correct exposure. For this shot ISO 500 was needed.
This setting also works with aperture priority, but it has less value as the camera can reduce the shutter speed quite a lot. Really old cameras only had safety shift that changed the selected shutter speed, but for most modern ones you can also choose ISO safety shift.
#2 – Turn Image Stabilizer off when using a tripod
Image Stabilizer is a great thing, but it can reduce the sharpness of your long exposure shots, and or shift your scene when shooting video on a tripod.
IS works by moving an element with the lens to reduce the effect of camera movement. However when the camera is not moving it should detect that too, and stop correcting – so called tripod detection. However your tripod may not be perfectly stable, and this can cause the IS to start correcting during a long exposure, which reduces sharpness.
Likewise for video, a camera on a tripod is not moving, but sometimes it looks like the camera was moving when you playback the footage. This is due to the IS correcting slight movements. If the background of your subject has no clear markings this is not usually a problem, but if it’s a scene with lots of visible elements near the edge of the frame you might see this.
Also make sure to turn IS back on when you finished working on a tripod.