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Author Topic: Photography FAQ Part 1 - updated 18/06/06  (Read 12030 times)

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PhotoJames

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Photography FAQ Part 1 - updated 18/06/06
« on: Jun 18, 2006, 10:14 »
Right, as so many people seem to ask the same thing most of the time, I thought I'd group all our collective knowledge into an FAQ. Those who know feel free to correct my mistakes

Q. What's shutter speed and how will it affect my picture?

The shutter covers the sensor/frame of of your camera (The bit that actually records the image). When you press the shutter release button, the shutter moves to expose the sensor to the light and then moves back to cover it up again. The time that the sensor is exposed for is determined by the value of the shutter speed you (or the camera) selects.

On an SLR, the shutter speed may vary from 1/16000th of a second, right down to 30 seconds. Most SLRs also have a BULB option. This will keep the shutter open for as long as the button is depressed. Faster shutter speeds will freeze motion, whereas slower speeds will allow you to capture motion (in the form of image blur).

Faster shutter speeds are obviously more suited for capturing fast moving objects, as you're less likely to get image blur. As a rough guide, when shooting handheld (i.e. no tripod or support) your MINIMUM shutter speed should be the reciprocal of the focal length of the lens you're using. For example, if you're shooting with a 50mm lens, then your shutter speed should be no less than 1/50th second. If the subject is moving, double that number. If you are moving, triple the number, and select the closest value you can.

Q. What is aperture then?

Between the shutter and the lens opening, you will find the iris. The iris is an opening of variable size controlled by the user or by the camera. The size of the opening in the iris, is referred to as the aperture. The two main things the aperture does are:

1) Controls the amount of light that falls on the sensor (when the shutter is open)
2) and thereby varies depth of field (DOF)

A larger aperture will allow more light to pass, but result in a shallower depth of field. Decrease the aperture and the reverse is true.

The aperture is measured in f-stops. Generally ranging from f/1 right up to f/32 and beyond, depending on the lens. A smaller number indicated a larger aperture.

Q. So where does this ISO thing come into it?

 
You can vary how sensitive the sensor is to the light that falls upon it. You can increase the ISO when the light levels are low in order to get a correct exposure. However, with a higher ISO comes grain/noise which can be undesirable. Better camera sensors (i.e. more expensive) are less prone to noise at higher ISO settings, and some cameras may incorporate a noise reduction feature to help get around this problem.

Q. Great, so I know all about Shutter Speed, Aperture and ISO, now what?

The key to a good photograph is getting a correct exposure [ed - not always ;)]. This means setting up your shot to get the correct amount of light to fall on the sensor for whatever picture you happen to want to take. Use these three things in conjunction to get the exposure right.

All digital cameras (SLR and Point & Shoot) will have automatic settings. This is where the camera meters the available light and then sets everything for you. If you are happy doing that then everything you just read will be irrelevant to you! The real fun with photography is when you take over and set everything up in manual or semi-automatic modes.

Q. That's fantastic, but i still don't know what SLR stands for, so rather than use www.google.com i'm going to continually ask at random points through other threads

Single Lens Reflex, my good man.

Q. My spanky new dSLR has a mode dial on the top...but what do all these letters mean?

Most dSLR and film SLR cameras have a dial on the top/back/somewhere to allow you to select what control you have over the camera. I shall speak in terms of Canon in this answer, and find the correct letters Nikon use when I can.

I shall ignore the automatic picture modes, because if you have to use these then why on earth did you buy an SLR?

Av (A) = Aperture Priority - you select the aperture, and the camera chooses the appropriate shutter speed to obtain a correct exposure

Tv (S) = Shutter Priority - you choose the shutter speed and the camera chooses the appropriate aperture to obtain a correct exposure

M = Manual - you choose aperture and shutter speed and try not to c*ck up the exposure

P = Program mode - This is on the border of fully automatic, it allows you to change some settings that otherwise might be locked out in the full automatic modes. But the camera chooses most things for you.

There are a couple of other settings in the semi-automatic area, but these are the important ones.

Also to note, with most semi-automatic modes, and fully manual, you will have to choose the ISO value. As mentioned above, the exposure isn't just controlled by aperture and shutter speed.

Q. What is Jpeg and what is RAW?

http://digital-photography-school.com/blog/raw-vs-jpeg/
« Last Edit: Jan 20, 2008, 18:12 by [Cookie Monster] »
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Re: Photography FAQ Part 1 - updated 18/06/06
« Reply #1 on: Jun 20, 2006, 18:19 »
We're adding bits to this as we go along. So to keep it in it's original format, i'm locking it. Cheers! :)


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