Viewfinder OMD has same magnification

Started Feb 7, 2012 | Discussions thread
Michael J Davis
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Re: Forget Crop numbers and talk SENSE!!!
In reply to misolo, Feb 10, 2012

misolo wrote:

Michael J Davis wrote:

misolo wrote:

A 0.5x magnification viewfinder means that the image you see looking into it is one-fourth the area (relative to 1x magnification), and that things appear at 50% of their actual size with a 50mm lens. If you were to put a 100m lens on such a camera, looking into the viewfinder things would again appear unchanged in size relative to looking at them without the camera.

In 4/3 and MFT, because of the 2x crop factor, to get these numbers you have to divide the numbers given in the specs by 2.

I've looked through this thread and hardly understood all these numbers' 0.92' etc. I've looked through various standards and can't find a 'definition' of v/f magnification. (I'm sure there is one, and would be grateful for a pointer.)

So I'm forced to talk sense...

My old Leica M3 had a viewfinder that gave an image approximately 0.9x real life. That's because it was optical and independent of the lens. Easily measured and understood.

My G1 has a viewfinder that shows the whole of the image, and when fitted with a lens of 45mm focal length, gives me a 'real life' 'full sized' view. Indeed with both eyes open (as I normally shoot), I get a clear stereoscopic view, with my left eye showing the world around and the stereo image in the centre being the image I'm framing.

So all I want to know about the new camera's v/f is: "At what focal length do I get a full sized image?"

Isn't that it? And Pleeeese can someone tell me the answer?

Claiming to be the only one making sense is not the smartest way to ask for help about something you don't understand...


I wasn't claiming to be the only one!

On your G1, the focal length that gives you a 'real life image' is actually a 36mm (or, in terms of 35mm-format-equivalent field-of-view, 71mm). The calculation is: reference focal length divided by viewfinder magnification =50/1.4=36.

Yes, you are right! I shouldn't have shot my fingers off, without checking. 36mm is correct, of course!!

Your eyes and brain have the ability to adjust to a good bit of difference, which is why you can still merge the images at 45 (however, with a difference that large, it'll quickly become tiring).

On the E-M5 the focal length that gives you 1:1 is 50/1.15=43mm (or, in 35mm-equivalent, 87mm).

Thanks for that. A bit of sense, certainly.
(And why do we keep having to refer to '35-mm equivalents'?)

Mike
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Mike Davis
Photographing the public for over 50 years
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