crop factor on older lenses

Started Jun 6, 2014 | Questions thread
hindesite Veteran Member • Posts: 3,790
Re: crop factor on older lenses

mbower wrote:

Ok, my next question -

I understand crop factor and that my 45mm lens is equivalent to a 90mm lens in the 35mm world.

That is correct. But why is it of interest, really? If you are using m4/3 as your system, you only need to know what the focal length means as it applies to the system, ie 14mm is wide angle, 45 is good for portraits, etc.

It is a little like moving to the metric system; there is no need to convert back to imperial to grasp what a dimension means, if you get used to thinking in metric.

I don't think people used to think about crop factors when they used large format cameras and SLRs together, (I know I didn't) they just built up an understanding of what each lens did for them on each format.

But how do I calculate the crop factor for an older lens? I have the adaptor that lets me attach my Nikon 35mm prime to my M43s body.

My own personal opinion, is that crop factor is irrelevant. That lens generally behaves like any lens of its focal length, if its focal length is actually 35mm, on m4/3 it corresponds to the longer end of most kit lenses; to think how it looks on m4/3 just set a kit lens to the same focal length.

What is the general crop factor that should be applied when one uses older lenses?

It is 2x for 35mm (most SLR) cameras.

But I never think wow, I'm using a (600mm FF equivalent) when I'm using my 100-300 zoom. I never think that I'm using a 18-36mm FFE lens when using my ultrawide angle Olympus.

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