Quote Originally Posted by sarvi
Hi
In search of a portrain lens for my Nikon D70 SLR. I have generally heard that lens between 80mm and 105 mm fixed focal length lens is good for portraits, and is supposed to give the photo a "tight perspective" as my friend called it. He was refering to his N80 and so was talking 35mm photography.

Nikon D70 is a smaller CCD and hence the lens seems to have 1.5(approx) multipcation factor.

So the 50mm lens would be 75mm on D70
and the 85mm lens would be around 125mm on the D70.

Does the "perspective get affected by the CCD size, i.e. should i use the multiplication factor when picking the right sized lens.

I have so far narrowed it down to the 50mm(f/1.4 and f/1.8) and the 85mm(f/1.8), based on the multiplication factor, which makes them 75mm and 125mm for the D70, close to the 85 or 105 that my friend recommended.

Questions:
1. Should I take into consideration the multiplication factor, or should I just be looking for an 85mm and a 105mm lens ignoring the mutliplication factor. Does the mutiplication factor affect "perspective"?
2. Between the 50mm(f/1.4 and f/1.8) and the 85mm(f/1.8), what would you recommend?
3. Does the multiploication factor affect working distance from the subject?
The perspective and DOF of a lens is based on it's real focal length, not a "35mm equivalent" calculation. A 90mm lens will still be 90mm, the sensor merely crops the sides off just as you could do in PS. What changes is the angle of view.

If you want a 90mm portrait, use a 90mm lens and just stand back further. If you go to a 50mm lens, you will get the same effect as a 50mm on a film camera, again with the sides cropped off
.