[peter]

I Used this on my Blog
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Okay.. I went to pra imaging today and enquired about a seminar they hold... and somehow the guy there ended up teaching us a whole lot about the basics of photoing... most of which suprisingly me and Adam had no idea about.

So I decided to write out the bits I can remmember him teaching... most of it is related to Portrait photography.

Okay .. Here goes...

One of the last things he discussed that I decided to put first is the Subject/Background Relationship. descriptions and examples are derived by the way I see what he said.

Here are 3 points he gave for the process of deciding the relationship.

1) SUBJECT/BACKGROUND Co Existence
-The Background Determines the mood and/or emotion of the photo, so the background must be suited to the message or style that is to be portrayed in the photo.
e.g. A girl in a glamourous dress would not fit in a run down urban scene, unless the contrasting was purposly set up that way, in fact a nice building or a nice nature strip would be much more suited.
-This leads to the photo bein in either a) Context or b) Conflict. Taking this into account is one of the most important parts or taking an effective portrait.

2) BACKGROUND Brightness Range Vs. SUBJECT Brightness Range.
-Although the background is very important, whats most important is that the subject of the photo is of correct lighting. Therefore, the closer the lighting range of the subject is to that of the background, the better the photo comes together. To create a good relationship between the subject and background, the difference between the lighting of both of them shouldn't really deviate more then one stop away.

3) YOU ARE IN CONTROL
-Once you have the first 2 points correct, then you can pretty much say you have control of the photo you are taking, and subsequently all thats left is composition. A good idea that was presented was to go through some magazines beforehand and prepare a set of poses that you want to do in the shoot if you do not have nmuch experience with posing.

And then we are READY TO SHOOT!

Okay, now its time to get onto some of the fundamentals of light metering and how it should be approached.

First I will explain what the F rating (apeture of the lens) really means. at first i thought they were just weird random numbers but there is more meaning to them.

First of all the stops are counted by the folowing set of numbers (and some more outside, youll usually see the numbers around your lens).
..., 32, 22, 16, 11, 8, 5.6, 4, 2.8, 2.0, 1.4 ...
The transition of one of these number to the one immedietely above or below it, is the transition of 1 stop. At first it seemed confusing to me, but ill explain the relevence of the randome numbers shortly.
For each stop that you go down (ie the F number gets smaller), you get twice the amount of light coming in. Going up, the amount of light would be halved.

Now explaining the numbers like 16 and 5.6 and 2.8 ... I have always asked myself, where in the world did these numbers come from. Well heres how it works...



As shown in the diagram above, the F number represents the amount of times the width of the apeture can be spanned along the focal length of the lens.
So say you have a F/4 apeture and a 50mm lens. Then the width of the apature would be 50 / 4 = 12.5mm. Using the formula of a circles area you can then do a mathematical proof that a shift of one stop is in fact double the area.

Okay, now that it is clear what exactly apature is, onto the subject of metering.



Above is a representation of light intensity.
As expected, white and black are on the ends of the span, and not 50%, but 18% grey is in the middle. Basically, with metering, the rule of thumb is that if possible, when using spot metering, you should always try to get a reading from a colour with the equivelent brightness of 18% grey. When metering, you should be given a F stop and a Sutter speed rating,

If there is no area of 18% grey, another technique is to meter the black, and then the white and halve the difference so that the reading is in between the white and black reading. This should generally give a good reading. A much better was it to get a light meter, and measure the incedent light.

So say you get a reading of a 30th of a second with an F16 apeture. It means that you can use that setting or any equivelent ones. So say you want to reduce the F stop by 1, you have to double the exposure time.
So you will get a set of corresponding F Stops and Shutter Speeds as below

F => SS
32 => 1/8
22 => 1/15
16 => 1/30
11 => 1/60
8 => 1/120
5.6 => 1/340
4 => 1/680

As a rule of thumb, you shouldn't really deviate more than 1 stop either way of the given reading. Following this will ensure the correct exposure of your photos.

A few more tips on lighting
Okay, just a few pointers here.
1) Always ensure that the background are within about 1 stop of each other (exception is a white or black background).
2) Always position the light sources so that the shadow from the nose does not go more than half way towards the top of the upper lip.
3) Ensure that if the lighting is from an angle, the shadow fro mthe nose does not extend more than the width of a 10c coin placed next to the nose.
4) Always account for the fact that skin tones are brighter than 18% grey.
5) Don't buy expensive books, steal poses from magazines and stuff.

Okay, thats about it for that.

Now for 2 diagrams.

1) Photographing a sunset.



As shown in the diagram, the sun will no doubt be over exposed. The best metering point is the orange sky which is about equivelent to 18% grey, if you follow this, you should generally get a good sunset.
However, you will also notice that a person in fron of the sunset will always be majorly underexposed. This should be corrected by using flash fill. The intensity of the flash incedent on the person should be winthin 1 stop of the metered light off the background. The only real way of metering a flash is with the detection of the incedent flash using a proper light meter. Or you can do some trial and error.

2) General portrait setup



Basically, there are 2 objects illuminated, the background, and the subject. there should be 1 or 2 lights shining on the background to illuminate it and to overwhelm any shadows from stray light. Generally a hair light is used to illuminate the hair, generally less intense for blonde hair and curly hair. There should be a beauty dish in the front as a main source of lighting, and another diffuse light source, such as a soft box to illuminate the other side of the face if needed. The 2 fns on the side are to prevent the lights in the front from creating shadows on the background.

Thats about it for my discussion/tutorial. Please contact me if I have said anything wrong or if you have any questions.
Peterbui (at) gmail.com