4/3 has no focal length advantage-correct him if he is wrong

Started Nov 15, 2008 | Discussions thread
PeterLeyssens Senior Member • Posts: 1,532
Re: 4/3 has no focal length advantage-correct him if he is wrong

What it comes down to is basically the same difference as between 6x6cm mid-format and 24x36 negatives "in the good old days" of film. The only difference between a full frame digital and 4/3, is the size of the sensor, which is identical to a different film size.

As an example, let's take a 300mm lens for standard film SLRs or full-frame sensors. On a standard 24x36 negative, you could almost use this lens for bird photography. For 6x6, the same 300mm lens is just a pretty long portrait lens. Nobody would dream of doing bird photography with a 6x6 camera, because they'd need a 500mm lens for the same angle of view, which is a horrendously big lens.

It becomes even more dramatic when you compare 4x5 inch to 24x36. To get the same angle of view as that 300mm, you need a 1000mm lens on a 4x5 camera. That kind of lens is close to a telescope: the Olympus OM 1000/f11 was 4kg and 66cm long. (A 4x5 1000mm lens would be even bigger, because it needs to give a 4x5 inch image, not a 24x36mm image like the Oly lens). Compare that to the Olympus OM 300/f4.5, which is first of all much faster, and weighs only 1kg at a length of 18cm. The same angle of view is clearly much more portable with a smaller film size.

Comparisons of 24x36 to 6x6 and 4x5: http://photo.net/equipment/medium-format/focal-length-conversion

So, back to your Nikon friend. If he has a full frame camera, he might want to use that 300mm. I found a Nikon 300/f2 lens at this site:


The lens weighs 7kg and is about 33cm long. For the same angle of view, i.e. the same field of view on your photo, you can buy the 150/f2 from Olympus. It's 14cm long and weighs less than a kilogram. Ask him which he wants to carry around.

The only difference left is the depth of field: Olympus lenses will show a wider range of distances in focus than the equivalent field-of-view lens for larger sensors. But that would be a bit too technical to discuss here. Impress him first with these comparisons, then see if he cares to argue further


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