FX-DX FOV confusion

tom beard · Oct 11, 2009

I love the 28mm fixed focus lens on my old Canon F-1 full frame slr. I'm planning to get a dx dslr with a kit 18/105mm zoom as I would like to go even wider than the 28mm. The APS equivalent on the 18/105 (on the wide end) is 27mm. If I shot two test photos of the same thing (cameras side by side) with the old 28mm and the 18/105 dx would the field of view be about the same as the 28mm, or actually appear to be wider (18mm) in the DX format? If you know, or could guide me to a comparison chart of some kind between FX and DX fov, it would sure help. I've asked similar questions before but forgot to inquire about actual field of view. I looked at my old posts and I think the answer is 27mm on the dx. If that's right, I can always upgrade later.

Thanks, Tom Beard

fokker · Oct 11, 2009

As far I'm aware, the field of view will be approximately the same, however you will notice a difference in perspective - things close to the camera will be disproportionally large in comparison to things far away with the 18mm on the dx sensor. Kind of like the fisheye effect of a person's face close-up but less extreme.

At least, that is my undertanding - someone more experienced please flame me if I'm wrong.

Derrel · Oct 11, 2009

Here is a very handy on-line field of view calculator.

Field of View - Rectilinear and Fisheye Lenses

tom beard · Oct 11, 2009

I noticed a slight fisheye effect on the 28mm if you get really close in the center. TB

NateWagner · Oct 11, 2009

well, assuming that when you shot them on cameras side by side, and the full frame SLR had the 28, and the 18-105 DX lens on for example a XSI at 18mm the field of view would be very similar at the same distance to subject. Of course, DOF would be different but that's besides the point.

Now, if you were able to put both lenses on the same camera, they would both have different field of views based on the "crop factor" thus, even though the "full frame lens" is a 28mm lens, and the DX is an 18 if they were on the same camera they would appear different at their widest settings.