Shutter speed is usually expressed in simple units like 60, 120, 240 etc. The numbers mean how many seconds the lens is open for light to pass. A 240 setting means it is open 1/240 of a second. The camera settings often go to 1000 or more as the fastest setting and down to about 60 as the slowest for a hand held camera. If you set up a camera to take a picture of something still, and mount it on a tripod, a 30 setting lets a lot of light through a small aperture and gives a sharp picture for things like a landscape where the whole thing will be in focus. If you have a very open aperture and a faster setting, you get just as much light to the sensor but things that are at the wrong distance are obviously out of focus. Getting the distance right becomes critical with an open lens and just needs to be sort of close with a pinpoint lens. The amount of the picture in sharp focus compared to all the objects in a picture is called depth of field. With a large depth of field,resulting from a small aperture, much more of the picture will be in a sharp focus.
The adjustment factors in a good camera are simple but the combinations are almost endless.
1. Aperture, the size of the hole that the light goes through. It is often measured in units called f-stops, another arcane system. This is where you affect the depth of field. Larger f-stops are smaller openings, backwards of course. If you want a large depth of field you use a larger number which means the opening in the lens is smaller.
2. Exposure, the amount of time the lens is open to pass light. This mainly affects how bright the image is when you get the picture. If it is not right, colors can fade badly from overexposure or objects can be hard to see in the dark picture of an underexposure.
3. Focus, the adjustment that you make, or is automatically made, to bring the image into a sharp focus on the sensor for a given distance from your subject. Be sure to focus on the main subject of the picture. Some camera automatic settings, including on my camera, will focus on the glass instead of the fish. That means manual focus only when I am shooting fish pictures.
Then you get into things like the lens number. A 50 mm lens is about a typical lens for a decent camera. The numbers go up as your lens goes into the telephoto region and it is a way of saying how big the image will be on the sensor for a given object. Bigger numbers are bigger images. We call a lens a telephoto if it magnifies the picture. We call it a wide angle lens if it makes the image seem smaller, that kind is good for capturing large objects from fairly close distances. I use a zoom lens so the magnification is yet another thing to fiddle with.
I use a rather nice digital SLR called a D-80 so my options are almost akin to those on a professional camera. I have been playing with SLR cameras for quite a long time so many of the things just seem to come easy now. Now my real focus when trying to improve my picture taking options comes down to choosing the right lens for what I want to do. Unfortunately the lenses can cost more than the camera.
you cannot treat aperture and shutter speed separately. they are two, inseparable, parts of the same equation. even considering blur (shutter speed) and depth of field (aperture) adjusting one, or the other, incorrectly, will have the same effect. there will be too much, or too little light to make a picture.
apertures setting are ALWAYS known a F stops, not usually. a Stop is simply, a 50% decrease in light, or a 100% increase, in same.
Exposure is not the amount of time a film/ccd is exposed for. exposure is the result of adjusting both aperture and shutter speed. in other words the total amount of light the film receives.
the aperture controls the amount of light reaching the CCD. the shutter speed controls the length of time that amount of light is given.
most of you will be aware that the 50mm lens is no longer the "standard lens, for many DSLR's. "Standard lens" denotes a lens with, roughley the same field of view of the human eye. in the days of 35mm. that was 50mm (well actually 38-40mm is the best match. but 50mm stuck). today lengths from 17-35mm are considered "standard". if you really want to look into it. a standard lens is, roughly, the same as the diagonal measurement of the ccd.
most of us are not printing pictures. so, MP ratings of over 7MP, are largely, irrelevant. (you will need to look at "selective" sections of an image differently). but a bigger CCD will offer better quality pictures at 7MP than a smaller CCD would at 12MP. This is an effect of noise (electronic interference between the pixels).
taking good pictures is, for the most part, down to practice. but a few tips and rules help:
get as much light into the tank as you can.
set a low ISO (100/200) it makes it harder to take pictures (you will need more light) but the pictures will be of better quality than if you use Auto ISO
avoid reflections by keeping curtains closed.
if you have the facility, set a manual white balance before you take pictures.
a bit of tissue paper over the flash. can reduce burn out, and the harshness of contrast. (you will use flash honest)
instead of a big tripod (still very useful). get yourself a mini tripod. you can use this to brace against the tank (extra stability)
get used to a program like Photoshop/Paintshop pro or Gnome. as in the past, many photos are made in the darkroom. things have not changed.
but, ultimately, its down to practice. spend time with your camera and read the instructions.
. I understand the basics, messing with the settings helps. Eventually you figure out what does what and how to use it.
) but i have macro mode which i use to shoot my fish....
