By Roger (7 Nov 2013)
While Mark is blogging about sharpness in post-processing, I thought this might be a good time to remind you about things you can do, before post-processing, to ensure your photos start at peak sharpness. We're not talking about poor focus or shallow depth of field – that is a different, if related, topic. We're talking about getting the best you can from your equipment. Rather than go into the science of lens and sensor resolution, I will concentrate on techniques to improve your results before you move into your software.
If you look at photography every day, one of the first things you notice is whether or not the photo is sharp. A non-photographer viewer may not consciously be aware of why one photo looks better than another, but, in a side-by-side comparison, they will almost always say the sharper photo is the “better” one. Too many photographers have loose standards on sharpness, and this degrades the quality and effectiveness of their photographs. Therefore, as a discriminator, sharpness can make your photos “better” than the norm.
Let's start with the easiest way to improve the sharpness in your photography – buy and use a good tripod. A tripod provides a stable base for your camera and eliminates the most common problem of camera shake. Monopods are useful when tripods are not practical or allowed (most museums, for example). There are a million reasons photographers don't follow this advice, but the fact remains that the tripod is a great tool for ensuring sharp images.
Please don't go out and buy a flimsy tripod that costs only $10. It won't properly hold your gear steady; you'll hate it; and you'll leave it behind. Short-sighted photographers will buy several tripods, in succession, each costing a little more than the last, before they surrender and buy a quality tripod. A good tripod costs more upfront but will never need to be replaced. I like the carbon fiber ones that are lighter; don't transmit cold or heat; and don't rust. When you use a tripod and cable/remote release, you're already doing more than most photographers to ensure your photos are sharp.
When you aren't using a tripod, use the proper camera holding technique. I first learned steady hold techniques in the military when "shooting" meant using a weapon. The basics are identical. You should grip with your right hand and support with your left, keeping your arms as close to your body as possible; this will keep you steady. I won't buy a compact camera without a viewfinder. Watch as most people try to compose their photo on the LCD panel, with their arms out in front of them, and you can see how unstable this process can be. Joe McNally has a great demonstration of the proper way to do this on YouTube (link).
Camera settings can also be helpful. The higher the speed, the more likely you are to achieve sharpness, especially when hand-holding the camera. There is simply less time for any camera shake to impact your sharpness. A good rule of thumb, when you are off the tripod, is to keep your shutter speed above 1/125. When you have a zoom lens, use the focal length as a guide for shutter speed. So, if you're using a 70-200mm zoom, set the shutter speed faster than 1/200 of a second. You should use manual mode or shutter priority if you know know you need to be at a certain shutter speed to freeze all motion.
Don't forget you can use a higher ISO setting to further increase the available shutter speed for your camera. Newer cameras don't even begin to show noise until you start pushing your ISO to 1600. As always, you have to make the compromises between shutter speed, lens aperture, and ISO. If your only decision is for sharpness, I'd make the adjustments in that order.
Finally, here is something that may be a little controversial to some folks. I never put protective filters on my lenses. Those UV or haze filters were pushed back in the film days to reduce a color cast on the film, and I never bought that story back then, either. With today's post-processing, you can eliminate any color cast in about two seconds. The only filters I will use are polarizing or neutral density filters, and those are removed right after I use them. The filters most people buy are poor quality glass, or, sometimes, plastic. Why would you want to put that on the front of your expensive lens? High quality filters, made of optical quality glass, cost well over $150. I've seen them priced as high as $300. Is that what you bought for your lens or did you pay less than $50 for a filter, based on the advice of a guy who profits greatly from its sale?
Yes, I know what that guy at the camera store said when you bought the lens, “It will protect your lens.” A lens hood will protect the front element just as well. In 35 years, I've never scratched a lens. Here is the sad tale of the only time my camera and lens hit the marble floor (link). A filter would not have protected the lens, and the elements weren't damaged. You decide for yourself, but filters – especially cheap ones – can interfere with the sharpness of your photos.
Of course, all this assumes your aim is to create photographs with the maximum sharpness. There are times that maximum sharpness may not be desired. You may want to depict speed with motion blur. Or, maybe, your goal is to create an ethereal world of esoteric blur for your art. OK, go for it. You should, still, understand all the factors to increase sharpness, but only you can determine which ones you'll use the next time you press the shutter.