Based on angle of view I've built a little chart

Normal Lens Comparison using the closest focal lengths available in K mount as you can see
this is a more complicated answer than simply, "Oh yeah use a 43 LTD", partly due to the different
aspect ratios between APS and 35mm.


The chart works as follows on the left we have an accepted "Normal" Focal length lens for 35mm
followed by their angle view vertically horizontally and diagonally. This is followed by the
APS equivalent that matches the AOV diagonally. I've also included the lenses that match either
horizontally or vertically and noted which lens each is closest in which dimension.


Focal                        Focal                           Closest
Length        35mm           Length               APS        Match
MM     V       H      D      MM       V       H       D      35mm


28 33.21� 56.67� 63.29� (v 40) 30 31.11� 53.44� 59.81� (v 43) 40 33.40� 48.46� 56.81� 31 30.15� 51.94� 58.20� (d 40)

43   31.19� 45.43�  53.41�   35     26.84�  46.67�  52.49� (v 50, h40, d 43)
50   26.99� 39.60�  46.79�   40     23.58�  41.36�  46.67� (v 55, d 50)
55   24.62� 36.24�  42.94�   43     21.98�  38.70�  43.73� (h 50, d 55)

If you use the current standard of 50mm then the closest diagonal match is the M 40 F2.8.


At 08:52 PM 9/29/03 -0700, you wrote:
There was a discussion in the last few weeks about "standard" lenses,
which came to the conclusion that the 55mm focal length matched the
magnification of the spotmatics and K series viewfinders, while the 50mm
focal length matched the M and later series cameras. Would someone who
has bought an *ist-D care to relate what the "standard" focal length is
for it? By matching I mean that what you see in the viewfinder is the
same magnification as the outside world, so that if you keep you're left
eye open while looking thorough the viewfinder with the right it all
looks the same. Just put a 28-70 on it and change the focal length till
it looks right! I would prefer to have a fast prime to a slow wide zoom,
so I would like to know whether to look for a 28/2, 31/1.8 or 35/2. I've
got a 24/2, but it will probably be just a little too big to keep on the
camera normally.

Thanks,

Paul Ewins
Melbourne, Australia

I drink to make other people interesting.
-- George Jean Nathan





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