just starting out, and dont want to get stuck on the auto, so im using manual, and the other priority modes. when i take a pic with a manual mode i will switch to auto and take the same pic, i compare the settings on the photos, and see how close i am to the auto mode, just to see if i am in the ball park. i guess my questions is how do i know when my "manual" shot is better than the "auto" shot if they both look "good/ok"
IMO, the "look" of the photo is, for several reasons, not all that important in this case. First, most student photographers have significant amounts to learn about simply looking at a photo and coming away with any useful information.
Second, what are you looking for? Exposure values? If you are only aping exposure values of an automatic camera, then using anything more than an automatic camera has wasted your money.
Third, the camera has no "creative" aims when it registers data to set exposure values. The objective set up of the camera as it comes from the manufacturer is most often to simply achieve a properly exposed image in terms of shadows and highlights.
To do this, the camera manipulates "the exposure triangle" by changing aperture, shutter speed and/or ISO values. The camera has no concept of, say, dynamic range, the spread in relative light values between the darkest shadow and the brightest highlight. Dynamic range is, in a sense, a subjective value which can be controlled by the user to maintain useful details in the shadow areas and to not blowout (over expose) highlights to the point they loose their shape and contours. Subjectively, the photographer's intent should be to create an image which invites the viewer to linger over the image and to look more deeply into the image. This is a function of the photographer's creative control over their tools, the camera and lens. The difference between the two is the difference between a work of art and the cheaply mass produced, stamped out by the thousands copies of that piece.
The camera is simply relying on objective data to achieve a final image which is not overly unattractive. As a photographer, your "mind's eye" can and should do a much better job. The problem for most students is how to get what's (possibly) in your head translated into what is in the camera's image.
Many students post here saying they really don't know what they're doing but they've been using the "M" mode for all their work. For the most part, my advice is to not fear the "A" modes. While most modern digital cameras have automatic back up systems in place for the student using "M" (in other words, you're seldom in fully manual control of most modern DSLR's), the automatic modes are, IMO, good learning tools for the student - if they pay attention to what the camera is telling them.
So use the automatic modes but pay attention to which settings the camera will select and learn why the camera would select such settings. Generally, this education can take place at your kitchen table with your camera and your owner's manual in hand.
If you have yet to sit down with your camera and your owner's manual, that should be your first next step. Learning to control the tool you are using is the first step towards knowing how to create something with that tool. For example, if you do not know what metering mode the camera defaults to when set to fully automatic, you don't know what metering mode you might use which would alter your result. Switching to the manual modes and using the same metering method achieves what on your part? As noted, it only gives your fingers a bit of exercise. If you set - or do not override - the exact same settings as the camera has used on full auto, then there should be no difference what so ever between the camera's shot and your shot. That should be simple logic.
Learning the rules of photography is essentially learning when to control the camera's operations, not simply recreating what the camera can do on its own.
Shooting in "portrait" mode means the camera will default to a specific group of options. Selecting "landscape" will mean another group of options are available to the camera's automatic settings. And so on with each selection of another automatic function which your camera offers. Each new mode you select will inform the camera as to which values of the exposure triangle it can manipulate. Yet, consider the fact, looking only at the exposure triangle, the camera will always retain the option to automatically increase the ISO value unless you use a manual mode which prohibits that action. And there are numerous reasons to want to prohibit the camera's tendency to increase ISO.
How do you know when your manual shot is better than the auto shot if they both look "good/ok"?
As I said, don't be afraid to use "AUTO" mode. It's simply another tool the camera's designer has provided for your use. Know what to take away as an education from using the AUTO mode.
The broad answer to your question though is you will know your shot
can be better once you have learned when not to simply follow what the camera has done. If all you want is a mostly well exposed photo, never take your camera off full auto mode. The "P/A/S/M" options are there to provide something other than what a $49 point and shoot camera would turn out.
Therefore, you'll know when your shot - taken in whatever mode - is "better" than the automatic shot when you fully understand
why you used something other than a fully automatic mode. Until you begin to think about how you can make a better shot (by changing what the camera defaults achieve), there will never be a better shot you can achieve. Until you can begin to control your results beyond the camera's defaults, there is nothing that will ever be better.
In the end, until your thought process and understanding of how to control the camera suggests to you that something other than the camera defaults are required/desired, there is nothing that will give you a truly better photo. If your shots continue to look like the camera's automatic shots, there's nothing particularly bad about your work. There's just nothing that will ever be better about your work.
Learning your camera's operations and how to control them is your first step. Yes, there's a good bit to learn in this hobby. Take it slowly, one thing at any one time and have a plan for how to proceed. We all began at the same level you are at right now.
