I see lots of photographers aiming for absolute pin sharp images, and that includes me, but is it really so important? Is content and “telling the story” not more important.
Well, yes and no. It all depends on what YOU want. When I photograph birds, for instance, sharpness is not negotiable, and thats why I use the best lens that Nikon has to offer, a beast of a 400mm f2.8 lens. Can you imagine shooting the most beautiful kingfisher and its not a sharp photo? Its not worth the effort, whereas, you can easily get away with slightly soft or OOF (out of focus) pictures when photographing people, I have to qualify though, that it does not mean you have to be sloppy, and I suggest a decent lens set, comprising some f2.8 zooms and then of course your superfast 50 and 85mm f1.4 lenses. So, to achieve acceptably sharp photos you need to look at, and adhere to a few rules.
- DOF, or depth of field, It makes no sense to shoot a couple at f2.8, one of them will be “smudgy, or out of critical sharpness” as rarely are they exactly in the same focus plain, so make sure you use adequate DOF to keep your subject sharp. You need to understand DOF and focal length, generally the shorter the focal length, the shallower you can keep your aperture to maintain crispness across the frame. The longer the focal length, the tighter your aperture needs to be to achieve crispness across the frame. Keep in mind though that wide angle lenses do not produce flattering people pictures.
- Shutter speed, A general rule of thumb is that your shutter speed needs to be at least the inverse of your focal length, plus a little more, handheld, off a tripod, you can of course slow down. So, for a 50mm lens you will need a minimum of 1/50 sec for static subjects, for moving subjects you will have to up the shutter speed to keep stuff sharp. With modern hi megapixel cameras, I would suggest you do 1.5 x FL (focal length) to achieve optimum sharpness, but some have steadier hands than others, so experiment and see what your personal limits are.
- ISO, Well, the interesting grainy part of the equation, and as you may know, the higher your ISO, the grainier your picture, and we all want ISO50 pictures, but in real world photography it does not work like that. To maintain adequate DOF (1) and shutter speed (2), you need to adjust your ISO to keep up, its all you have left. The only saving grace here is that technology has been good to us and with a full frame sensor you should get away with ISO3200 to ISO6400 reasonably easy, whereas on a cropped sensor I would say ISO1600 is roughly your limit, although with the advent of the D7200 and D500, I suspect it may be higher.
- Focus accuracy. Well my friends, best you get this right, best you focus fine tune your Nikon for absolute best results. I strongly suggest that you also use back button focus, (google it), a simple technique that will make your life so much easier, but you will need some time to get used to. Some consumer cameras may not have this function, so you will have to do with half pressing shutter button. For moving objects, use AF-C (autofocus continues), for static subject AF-S (autofocus single)
- Fill the frame, The more pixels you get into the frame, the more accurate your focus system, it does not help you fill only 30-50% of frame and crop afterwards. Its just a waste. To this end, I suggest you learn the focus and re-compose technique. By using the most accurate centre point, you grab focus, hold it, recompose and take the shot. Here back button focus comes into its own, although the shutter button also works.
My favourite kiddies pic, and honestly at 100% view its horrible, so as I said, content sometimes takes precedence over critical sharpness.
A 100% crop, showing more than adequate sharpness, this one shot at f5.6, you really need to be at f5.6 for couples.
My French Brittany, shot with a 85f1.4 lens at f2.8, ISO3200, 1/200sec, where everything just came together.
I hope you find this all helpful, and until next time good light