Below is a long version of what the face looks like with lenses from a 35MM full frame DSLR, 24x36mm chip, at various focal lengths accounting for framing with distance (moving closer or further to the subject) here you can see the images in a tile, two rows to better see the comparison TILEPAGE and here you can see some larger versions one by one to compare up close. THUMBNAILS Read below the image to get a feel for distance to face of a lens at various settings.
OK real world real numbers
all 35mm full frame
Lens tip to subject, not making allowance for background here.
Lens tip to subject 7 feet
average head from tip of head to chin 10 1/2 inches
1 inch above head to nipple line of average large (tall) woman,
average 6'2inch male, 18 1/2 inches
Now realize, if the background were behind them by several 3 1/2 feet the angle of view would mean if you gave 1 inch head clearance your image would have approximately 5 inches above the head in frame.
Look at my work and the close up face shots for some great examples of long lenses and the flattened face you all say is present and tell me if a bigger nose and further backset ears would be better for you.
By comparison a 50MM on the same 35MM format Full Frame gives the following realize that a full face as stated above from tip of the head to the chin is 10 1/2 inches you would need to be almost but not quite 1 foot from the subject just to fit the whole head in frame, and closer if you crop into the head at all
50mm ___24inches at 3 feet 36inches
50mm____17inches at 2 feet or 24inches
50mm ____9.5inches at 1 foot or 12inches
I suggest you try this at the next shoot. Take a len maybe a zoom is best, and shoot the same straight on face shot at the widest you can get (maybe 24mm) than again at say 35mm, than at 50mm than at 100mm than at the longest you can get maybe 200 or better 300mm and keep the framing of the head and face the same for all shots, that's important to see this easily. It does not take a lot of room really if you are shooting a face top to bottom, so you do not need a huge studio to try this. Important things to do is keep the same framing of the face for all shots and keep the lighting the same for all the shots, you may need an extension tube or close up step to keep the same framing on all shots with all the lenses as some may not allow you to focus as close as you would need too.
Next with the face in the same framing, look through the images one by one to see the face change dramatically. That will make you more aware of what to look for, and also determine what your preferences are. OR BETTER YET CHECK HERE OR EVEN HERE
Yes, moving in closer allows for you to cheat perspective at times, as there is no reference to go by, but in general if their is a reference like a nose, ears, eyes, forehead, there is perspective that alters and the viewer can see it, it may be what you want, or it may not, you choose how to use it and for what purpose. There is no right or wrong, only what you want to achieve and get across to the viewer.
©Stephen Eastwood 2008 www.StephenEastwood.com www.StephenEastwood.com/bio www.StephenEastwood.com/Tutorials