Originally posted by Mystix
ic... perhaps u could explain a little bit more bout the 3 parameters for choosing the focal length? ie if subject is half body and small type which one should i choose...the 85mm?
I'm talking in the scope of general portraiture (documentary style), not art-portraiture. True that there is no limitation on focal-length in use, that's why there's no 'best focal-length'.
In general portraiture, we should know who will see and 'judge' the picture, is it ourself or our client. If it is the client, then we shall produce a picture which satisfy them regardless of whether we like it or not. Our client may not a photo-savvy, nor an art conscious person, but they can see and sense whether the picture resemble the mood and character he/she want.
The duty of the photographer is to create the picture they want, using all the "tools" he can imagine of (lighting, pose, location, props, make-up, etc.), including selection of focal-length.
Most of the time the focal length would be around 80-135mm, which considered as "safe" for most presentation. Only at certain occasion a photographer will use different focal-length.
So if you're saying that you want to take portrait of a small-size person in half-body, then there're still another parameters to consider: e.g: face-type, pose, mood to achieve, etc.
a brief example: my subject is small-size pointy-type, and I want to make her looks not that small & pointy, so I choose a focal length 135mm or longer to flatten, with frontal diffuse lighting and direct-to-camera pose, with minimum shadows.
Another example: if my subject has a flat-face and fat, then I will choose shorter than 100mm lens, angled shot with a bit shadows, to create a sense of slim person.
Pls note: all of those are general guidelines for presentation to client who mostly want to get their picture looks "better than reality". But most of experienced documentary portrait photographer will talk and understand their client's character & personality to be portrayed, not merely just based on his own taste and style.