Originally posted by Venturi As I understand things, the captured image at the sensor is of fixed resolution, based on pixel density of the sensor. And whether I make a print at 4x6 or 12x18 the optical characteristics of the image remain constant. Bokeh, DOF, etc all happens between the leading edge of the forward lens element and the trailing edge of the rear lens element (or teleconverter).
Take an image from a 10MP APS-C (15x23mm) sensor and an image from a 10MP FF (23x35mm) sensor cropped to APS-C size. The APS-C image would simply enlarge to 4"x6" better than the cropped FF image due to pixel density (the cropped FF image would be only 6.5MP).
Sure, but who said anything abut cropping a FF image? I was talking about printing the entire image from both cameras, not cropping it after the fact from the FF sensor. The point being, the one from the APS-C sensor would look more "magnified" in *exactly* - and I mean *exactly* the same way the image looks more magnified with a TC. That is, image from APS-C camera would show face only, image from FF camera would show head-and-shoulders. Stick a longer lens or TDC on the FF camera - or, indeed, crop it - and it too would show face only, and hence also look more "magnified" when printed, in *exactly* the same manner as the APS-C camera.
Quote: Teleconverters actually physically alter the optics and project back a magnified image of 'infinite' resolution. The teleconverter physically alters the DOF, bokeh, focal length and aperture characteristics of the "beamed" image itself.
True, but I'm not (mostly) talking about DOF or bokeh - just field the field of view. And this is going to *identical*.
Quote: Because of pixel density as I outlined above, wouldn't the same sized image (talking field of view here) from a FF image need to be enlarged more than a APS-C image of the same FOV?
Only if you crop the image before enlarging it. I was never talking about that. And when i spoke of "magnification", I meant this in the naive sense of how big a pictured object looks on screen, not any actual calculation involving pixel density. That is, if you use a telephoto lens on a FF camera to picture a distant object - a bird, say - than print that picture (*without* first cropping it) at a given size - say, 12x18" - that bird will look bigger than it does to the naked eye. Now take that same lens and put it on an APS-C camera. Print the resulting image at 12x18", and the bird will look physically bigger on the print - more "magnified". And the difference in apparent "magnification" will be *exactly* the same as if one had used a TC or a longer lens on the FF camera, or had cropped the image first (although bokeh and DOF may indeed differ)
Quote: Take 2 cameras with identical 50mm prime lenses; one camera is FF the other APC-S. Now take a picture with each of the same scene (the FF will capture have a wider FOV of course). Now crop the FF image to the same FOV as the APS-C shot. The FF sensor having fewer pixels per square inch would be lower resolution therefore would need to be stretched by 1.53x in order to make the same sized print.
Sure, but once again, we were not talking about taking an FF image and then cropping it.