Reason No. 3 Your Photos Aren’t Sharp: Vibrations from touching the camera
Just touching a camera mounted on a tripod can be enough to set it wobbling a little and this can make your images soft. Fortunately, it’s relatively easy to resolve the problem with a remote release.
Remote releases come in two forms, wired and wireless. As a general rule wireless remote releases are more expensive but more effective than wired ones.
A wired release has to be connected to the camera and any movement of the cable, perhaps as result of it blowing in the wind or you moving it, can transfer to the camera and soften the image, so take care how you handle it.
One downside with wireless remote releases is that they usually work via infrared light and this can make them trick to use in bright sunlight. They also usually need the trigger to be in the line of sight of the receiver/camera.
Remote releases are especially useful when you want very long bulb exposures because they avoid you having to press the camera’s shutter release button throughout the duration of the exposure.
Photography Basics: the No. 1 cheat sheet for metering and exposure
Expose to the right: the camera technique every landscape photographer must know
3 exposure techniques every beginner must know (and when you should use them)
Reason No. 4 Your Photos Aren’t Sharp: Mirror-slap
If don’t have a remote release to hand the camera’s self timer can be a good stand-in as it triggers the shutter to fire after the vibration from pressing the shutter release has died down.
However, DSLRs can actually create image softening vibration themselves because the action of the mirror flipping up to allow the exposure is enough to start things wobbling.
Mirror-slap is more of an issue with some cameras than others. Some have a more dampened mirror movement, which makes it less problematic, for example.
However, if you want to get the full benefit of all those pixels on high-resolution cameras like the Nikon D800 you need to go the extra mile and use mirror-lock up mode.
When mirror-lock up mode is selected the first press of the shutter release (on the camera or a remote release) lifts the mirror.
Then, when any vibration resulting from the mirror movement has died down you press the release again to trip the shutter and take the shot.