They say to err is human. In that case, photography often reminds us how human we are. The process leading up to the point where you press the shutter release is frought with opportunity for oversight and mistake. Others may not appreciate it, seeing only the final image, but to get to that point a photographer usually has to be mindful of many things and juggle them all successfully - aperture, shutter speed, ISO, composition, right down to making sure the battery has enough charge or that there's enough space on the memory card.
What follows are oversights on my part that I feel are not common things photographers think about but can surely foul a picture up if not corrected.
Turn Off Image Stabilization When Using A Tripod
This almost seems counter-intuitive. After all, a tripod, like optical vibration correction, is meant to stabilize the camera, too. Shouldn't those two things working together make the camera more stable than either by itself?
When the camera engages the image stabilization motors it cause the image to jump, if for a brief moment. Left engaged, the image stabilization system often times will jump randomly as it attempts to correct for movement it thinks should be happening. Some newer lenses employ tripod sensing algorithms that shut down the stabilization motors when the lens detects no movement, assuming that the camera must be on a tripod. However, best practice is to just turn the image stabilization off when the camera is tripod mounted to avoid any shot killing hiccups.
If you've ever used a tripod and inexplicably ended up with an image that isn't as sharp as you think it should be, check that the image stabilization is turned off.
Be Careful When Using Polarizers On Ultra-Wide Images
Perhaps the single most important filter in any photographer's bag is a quality circular polarizer. I use Singh-Ray, B+W, and Lee for the different polarizers I like to use - warming, multi-coated, and 4x4 square, respectively. In my opinion, these filters are the pinnacle of performance and quality. However, like all circular polarizers they are at the mercy of physics. Polarizers work best when the sun is at 90 degrees from the subject, that is if you point at the subject with your index finger ideally you want your extended thumb to be pointing at the sun. This limitation means that for wide angle lenses, or any lens wider than 28mm, only part of the image can be polarized at a time.
This effect can become even more pronounced if you take a long exposure with a moving sky, as above. This particular artifact could not be seen in the viewfinder, but the dark banding could. (The "dark banding" refers to the darkened of part of the sky, the part that is actively being filtered by the polarizer.) However, as the clouds moved at the extreme edge of the image it became possible to see the polarizer's foil structure. Do you notice the concentric circles most evident on the right side of the image? This artifact can be a real bear to correct in Photoshop!
Micro Focus Adjust Your Lenses or Have Them Professionally Calibrated
If your camera is from within the last 6 years or so and is above consumer grade chances are it has the ability to individually adjust the focus of your lenses. This is especially critical for lenses with large maximum apertures since if the focus is off by even a little it can dramatically alter the shallow plane of focus, and thus the sharpness of your subject.
The above was shot with a Canon EF 85mm f1.8 at f2.5. This means that I was working with a very narrow depth of field. As is standard when taking portraits, focus was placed on the nearest eye but if you look closely, you may notice that it's the farthest eye that is more sharp.
Looking at the above image on the back of the camera, without zooming (also a no-no for checking critical focus - always zoom into an image!), you may not notice that focus was missed. In fact, this image was meant for web-sized display on a company's internet site, so anyone would be hard pressed to see that the left eye isn't tack sharp.
But, what if this were meant for print? What if it was going up on the company's lobby wall? Suddenly, it's not good enough and should be considered a missed or wasted shot.
It turns out the lens was indeed back focusing. Back focusing is when the lens is returning a positive focus lock at a point when in fact the lens is optically focused behind that point, or farther from the viewer. (Front focusing is the opposite.) Using a LensAlign Pro I determined that the lens needed -18 adjustment on my Canon 5D Mark III camera. (This number is arbitrary and would differ from camera model to camera model and certainly maker to maker.) A correction that great is something more than I care to correct for in camera (most corrections are within the single digits) and this lens will be sent to Canon for some permanent adjustment.
Hopefully this will give you, faithful reader, some food for thought and perhaps you'll have more keepers for it.