If I carry out the test you outline, I must measure the diameter of the first camera's aperture blade's opening, and set the second camera to that opening diameter, NOT the f-stop?
Is that what you're saying?
This is cropping in the camera while recording the image, yes?
What will that give me?
Let's say I take my 105 mm lens and my 24 mm lens, set both cameras at a 20 foot focal distance, for example, and make both lens openings the same, and you're saying the photos I record will be the same, except for magnification of the grain?
What will be the same? The area covered? Certainly not.
The image sizes will not be the same. A person's head in the 24 mm lens shot will end up being smaller on the film frame than it will on the 105 mm lens image.
Taking that a step further, if I took a 100mm lens shot, and after changing lenses (to the 24 mm), walked up to the subject and had their head image size match the first shot, the image might be the same, but the perspective will certainly and most noticeably change.
What will "be the same," Tom?
keith whaley
graywolf wrote:
Well, the question was about portraiture, as I recall. In actuallity any lens can be used for any photo as long as it is not too long to get the subject into the frame from the distance you have to work in.
As for portraits, I love how our English/American cultural biases dictate subject distance. We tend to be comfortable holding conversations at about a five-foot distance. So we like portraits to show faces from about that distance. Then we try to impose that upon people who come from cultures where the norm is to get right up close. For them 2-3 feet is comfortable.
We reason our discomfort away with silly statements about perspective. But that is really displacement on our part. As an example we are usually quite comfortable with portraits from about 3 feet, if we know that person intimately. Humans are such strange animals.
An aside about cropping wide angles v. short tels: Distance, and aperture being the same, the only difference in the photos will be grain magification. Note I said aperture, not f-stop. That experiment will I show something about DOF that I have tried to explain here before.
