Lens equivalent

<p>Preliminary note: I'm a die-hard caveman, still mostly using fim cameras. So, please be patient with me and my silly question.<br>

If I use an adapter to put an old 18mm lens (Nikon F bayonet) on an EOS 70D, what angular aperture will I get? I seem to understand that, given the camera's 1.6 crop factor, the result will be the same as when using a 28mm lens on an old 35mm camera. Is this correct? Many thanks </p>

 

28.8MM effective angle view to be precise.

<p>Well, sorta. I'm not so sure that the precision of the stated "crop factors" (1.5 Nikon, 1.6 Canon) is so great that things can be stated as being in the tenths of millimeters precision.<br /> see http://photo.stackexchange.com/questions/5287/difference-between-a-canon-and-a-nikon-crop-sensor for examples from what I presume may be an engineer or two.<br /> But the stated ratios are "close enough for government work" as we used to say when I worked for the "Gummint".<br /> So yes, if the 18mm lens were really 18mm in focal length (a big assumption in the first place) then you could treat it as a "full-frame" 28+ mm focal length, that is also assuming that the "full frame" sensor was really exactly 24x36mm... You take my point, I guess.</p>

<p>While you're chipping away at your cave, realize that the magnification does not change. It's as if you took a picture with that lens on a full-frame body and then cropped the image to the proportional size of the crop-sensor vs. full-frame. </p>

<p>That said, the pixel-density of the two sensors will determine the number of pixels on the subject. In focal length limited shooting (trying to shoot a bird with a 300mm lens when you really need a 500mm lens to fill the frame with the subject) the sensor with the highest number of pixels per inch will put the most pixels on the subject and seem to have more "reach", for lack of a better term.</p>

<p>If that's confusing, then forget it. It only really matters in focal length limited shooting. It does have some impact on how large a print you can make. That's easy to understand because the more pixels on the subject, the higher the resolution and the larger the print you can make.</p>