On 2011-01-16 18:08, ADavidhazy wrote:
I will try to comment on some other points later but I will pick one that has been of long time interest to me. Increasing "sharpness" by reducing focal length or increasing subject distance. Detail is not increased as magnification is decreased in my opinion. So: 18. If a subject is moving at 100 feet per second appears blurred in an image made of it at 1/1,000 second (which is the top speed of the camera) changing to a shorter focal length lens will make the image detail sharper. TRUE or FALSE Circle choice and explain: My "stance" on this is that this is FALSE because the distance that the subject can move during a given time (the exposure time) is fixed and thus the ratio of "blur" to subject size remains constant. Blur (in relation to subject size) is magnification independent. Thoughts on this?
If you get a 1mm blur with a 50mm lens, changing to a 25mm lens will give you a .5mm blur, yes? This means, I think, that the image will "look sharper" to observers.
To take this to a limit, there exists a pair of focal lengths, differing by a factor of 2, where the amount of blur through the wider one is smaller than the circle of confusion suitable for the print made from the neg, and the amount of blur through the longer one is not.
Of course, the subject, that thing that's blurring, will be half as large also. In terms of useful image detail I'm not prepared to argue there's any improvement.
But I think, as a matter of human perception, the shot with the wider lens will be interpreted as sharper or less blurred by essentially all viewers.
-- David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info
