Perspective Control: The right lens for the right job.
I've been seeing submissions for port review that have problems with perspective control due to lens selection.
I understand some are using a crop sensor. A crop sensor does change the Angle of View. With a Canon I believe it's 1.6 crop factor (which a just another way to say angle of view) and 1.5 with Nikon. Angle of View is all that it changes. It does not affect any of the physical properties of the lens. Even though a 50mm lens has an angle of view of a 75mm on a Nikon crop sensor...that's all it has. It has none of the compression, bokeh or other attributes of a longer lens.
Here is a good artical : http://prophotocoalition.com/jpmorga...ls_perspective
Head and shoulder shots should really be 70mm and above. I prefer to use 85mm or greater. For a 3/4 or full length of a single person usually use no less than a 50mm. Think about. Crop sensor or not ... if you are using a 35mm or wider to fill the frame on a 3/4 shot your going to get perspective problems making the person shorter and dumpier than they are. There are exceptions. These are just general guidelines for making initial lens selections for common situations.
Hope it helps.