We all know that small apertures (f22 and beyond) give you a great depth of field. Returning from my recent trip to Cradle Mountain, I passed these crop fields near Forth. I took this scene with a zoom lens and wanted everything to be in focus, so dialled in f22.But small apertures have an unwanted side effect. The smaller the aperture the more light diffracts (bends) as it passes through, resulting in an image on your sensor that is not as sharp as you would expect. Knowing this, I took another photo at f13.
Compare the two images on the right – the top one is at f22 and the bottom one is at f13, both were taken with a tripod. The images are small, but hopefully you will see the difference. On my computer screen, the f13 image is much sharper. The general rule is that mid-range apertures (f8, f11, f16) are optimal for sharpness.
Can’t see the difference? I have blown up the centre bit of each photo, maybe you can now? If not, have a go yourself and compare the sharpness of your images at a mid-range aperture (say f8) and stopped down (say f22).
Leave a Reply