Technical flaws, like the following:
- Chromatic Aberration
- Blown-Out Highlights
- Lens Flare
- Out Of Focus
- Motion Blur
These technical flaws can ruin your day, or at least your photo. Like the Black Plague, until you're aware of what's causing these flaws, they are likely to kill your best shoots. Each one of these issues are addressable and with the proper knowledge can be completely avoided, or minimized.
Exposure is the amount of light allowed to pass to the film, or image sensor. Thanks to digital cameras, LCD screens, and being armed with loads of information on each shot, getting exposure "correct" <--(correct is relative) has never been easier. Each camera is different, but the idea is the same. You have a few variables to adjust how much light passes through the shutter, shutter speed, aperture, and ISO or film speed. Getting the photo to turn out as you intended is what we deem as "correct".
An easy way to get things looking right is to take bracketed shots. To do this simply take a few shots at a low shutter speed, raise the speed between each shot. Also try adjusting aperture and ISO until you have the desired exposure.
Most cameras have an on-board histogram. The histogram is a fantastic tool, if you're not using it you either hate data, or you don't understand it. The histogram is just a graph that shows the amount or number of pixels in photo or image. The higher the mountain the more pixels, low valley = less pixels. Left is black, right is white, and grey is everything between. A good image often, but not always, has a histogram spread all over. In this example, you can see there are zero pixels in the white area of the graph. This histogram was from the underexposed pumpkin picture. One look at this graph and you'd see your settings need some adjustments.
Noise in your photo is typically undesirable. It's a by-product of the image capture that adds spurious and extraneous information. Always try and reduce noise with your camera settings by lowering your ISO, have adequate light, and use noise reduction on long exposures. But let's say you have a great shot with just a little noise, we have a tutorial on how it may be saved.
Chromatic aberration is a type of color distortion that manifests itself as "fringes" of color along edges that separate dark and bright parts of an image. This issue is usually fixable with a little post editing. See our tutorial.
Blown-out highlights are common with a bright light source and reflective surfaces. Break out the powder for your human subjects, and try shifting your position with uncontrollable surfaces.
Most often lens flares are not ideal, use a lens hood to prevent them. Sometimes it can be a nice effect, just be sure it's intentional.
Out of Focus
Being just slightly out of focus is never good, and will alway be rejected, this is not to be confused with purposefully defocused subjects. For example, defocused Christmas lights, everyone has at least one in their portfolio.
Most photos with motion blur will be rejected with the occasional passable photo where the blur is intentional and appropriate. This one was close, but too much blur.