Crop factor

Started May 5, 2012 | Discussions thread
Bruce McL
Senior MemberPosts: 1,092
Re: Crop factor
In reply to BILLY 0F THE NORTH, May 5, 2012

The focal length numbers on the lenses are real measurements. It is a number that can be measured without using a camera at all. That is what is stamped on the lens.

It's just that everybody is used to thinking about the focal length numbers in 35mm. So people use crop factor to help them compare lens numbers on cameras with different size sensors.


OK..let me see if a understand this. My Olympus E620 has a "crop factor" of 2x and I have a 70-300 lens and on the outside of the lens is stamped 140- 600 equivalent on a 35mm camera.

No, that is wrong. You have a 140-600 lens, period. When you put it on your camera, it looks like a 70-300 lens would look on a 35mm camera. But that's just for convenience.

Your lens also looks like a 190-810 lens on a Nikon V1 or a 56-240 lens on a Leica S2. If everybody used an S2 or a V1, our minds would be used to those focal length numbers, which seem unusual now. Then you would have a different crop factor to compare your camera to the S2 or V1 numbers. But the numbers stamped on the lenses of all cameras would not change.

So to say that a 300mm on a 4/3 format is still a 300 view of the I right or do I need more coaching?

Definitely not right. A better way of saying it is the 600mm focal length lens on your camera has the same angle of view as a 300mm focal length lens on a 35mm camera.

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