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PostPosted: Wed Feb 27, 2008 1:58 pm 
I was reading the review of the Zuiko Digital 35-100 f/2.0 in Digital Camera Magazine and realised that once you take the crop factor into account, this lens competes with the Canon, Nikon and Sigma 70-200 f/2.8. But this lens is an f/2.0!!!!

The Zuiko lenses (and all other 4/3rds lenses) seem to have an edge over the other lenses because of the shorter focal length required to achieve the same 35mm equivalent focal length.

For example:

Aperture Diameter = Focal length/F-number

So the Zuiko only needs an entrance pupil of 50mm to achieve f/2.0 at 100mm(100/2 = 50), while the others need approx. 71mm.

So I was wondering if this means that the the 4/3rds lenses have an advantage over the other lenses by Canon, Nikon etc. because of the fewer physical constraints involved in making a faster/brighter lens.

OR

Does the decreased noise performance of the 4/3rds sensor mean that the other lenses can make it up by increasing the ISO speed by 1 stop? The 4/3rds lenses also have a larger depth of field. So the depth of field on a 4/3rds camera at f/2.0 could be the same as a 1.6/1.5x crop camera at f/2.8.

What do you think?


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PostPosted: Wed Feb 27, 2008 9:42 pm 
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Hi Graham, there's pros and cons to every system - this is one of the pros of the 4/3 system, but there's lots to weigh up when working out which is best for you.

The shorter focal lengths do have differences in depth of field and perspective which you might prefer or dislike.


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PostPosted: Wed Feb 27, 2008 9:49 pm 
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It is correct that the 4/3-lenses can be of shorter focal length to achieve the same images. But that's not to say that it's easier to make equally good lenses for such a system. Remember: 10MPix on a 4/3 system just have a much higher pixel density than 10MPix on a APS-C or FF/FX_sensor. So this is much more stressfull to the lens. It needs a higher resolution and better CA to achieve the same IQ in the image :!: :idea: :shock:

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PostPosted: Thu Feb 28, 2008 8:30 am 
So I suppose it is about equal to the competition then, depending on what you like. I think their commitment to weather-sealing and compact lenses is commendable but I have no intention of switching camps! :)


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