For subjects much further away then focal length (much further usually means 10 x or more) the following applies Image size = subject size x focal length / distance for full length portraits, Read more at: http://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/75464-best-mm-full-body-portrait-shots.html#ixzz3GcP0qB9Z
The "chimney" for my aunt's propane fire place. Still me testing the adapter for my legacy lenses on my Nikon. This picture was taken using my Nikon with an adapter to my 1970's Pentax 80-200 zoom lens. Kyler L Photography.
This is not the most spectacular picture in the world, but it is interesting because of how I took it... I took this picture with my Nikon D3200 (F mount body) using a 80-200mm zoom lens that came with my Pentax K1000 (K mount). I do not have an adapter (yet) and so this was taken by removing my Nikkor lens and holding the zoom lens in front of the image sensor. Dangerous? Yes. Smart? Probably not. Awesome? Definitely.