If you’ve shot through a long lens or tried macro photography you probably know about mirror shake (which I’ve also heard called mirror slap.) If you don’t know what I’m talking about, here’s the deal. Some cameras (usually SLRs) have a mirror that sends light coming in through the lens up through the diopter, or viewfinder, so you can see what you’re aiming at. When you press the button to take the picture, that mirror moves up and allows the incoming light to hit the sensor which records the picture. When the image has been recorded, the mirror snaps back down. That quick movement of the mirror slapping up and down is a large part of what makes the “Click-Click” sound when you snap a picture. In addition to making noise, this movement also causes your camera to vibrate (you can blame Newton for that I suppose) which keeps your images from being as sharp as they could be.
Now that you understand what’s happening, the solution is simple. Keep the camera from vibrating while the sensor is recording. There are a couple of ways to do this. Some camera have built in features like Mirror Delay mode which raises the mirror and then waits some amount of time before the sensor records in hopes that the camera will stop vibrating by then. A similar method is a Mirror Lock Up feature that allows you to raise the mirror and wait however long you choose before recording the image. These methods work, but not as well as you would hope. The best method I’ve found is to set your camera on something that will absorb the energy out of the camera when that mirror moves, like a bean bag. Prove it to yourself. Get out your longest lens and shoot from the tripod and then from the bag and compare the images to see which ones come out sharper.
I’ve seen specialty bags for sale and they all look like they’d work great, but I think they’re a bit pricy for what you’re buying. If you want the same result without spending much money, go to the grocery store and buy a bag of the black sunflower bird feed big enough for your camera and lens to rest on (an old pillow case makes a nice protective case too.) Plus, as an added bonus you’ll have something handy to bribe the birds, squirrels, and other little animals with so they’ll stand still for you!