Crop Factor, Low Light and Aperture with m4/3 lenses? Part 2

Started 4 months ago | Discussions thread
noirdesir
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Re: Crop Factor, Low Light and Aperture with m4/3 lenses? Part 2
In reply to Ulric, 4 months ago

Ulric wrote:

bobn2 wrote:

Ulric wrote:

The larger format lens does not have to resolve as many lines per millimeter on the image plane, thus it can be (but need not be) optically inferior to achieve the same output image quality compared to a smaller format lens. The reason is in the lesser need for enlargement from the image in the image plane to the output image of arbirtary size.

OTOH, what matters is not resolution per millimeter but per image, and the larger format lens has to perform over a larger image circle. It evens out.

In practice, no it doesn't - the advantage is to the larger image circle.

To even out means to become even or more even, and yes it does.

You mean all (D)SLR tele lenses automatically get a 50% higher centre resolution when used on a DX camera compared to be used on an FX camera? (Or is this just all lens manufacturers without exception refusing to release DX tele lenses?)

The problem is that we cannot fully test any hypothesis because so far with the exception of the Nokia 40+ MP phone cam, larger sensors come with higher pixel counts and we cannot verify whether a m43 lens in front of a 80 MP sensor would deliver the same resolution per picture height as MF lenses in front of a 80 MP back. We can compare a m43 lens in front of a 16 MP sensor with a MF lens in front of a 16 MP sensor (Phase One P20) but while we know that the MF lens has a lot of reserve resolution as visible when used in front of a 80 MP sensor, we cannot test whether the m43 lens would do equally well in front of 80 MP sensor because there is no such sensor.

The closest we can get is to compare 'equivalent' DX with FX lenses adapted to smaller-sensored (and thus higher pixel density) cameras. For example the Nikon 40 mm f/2.8 DX vs the Nikon 60 mm f/2.8 G FX or the Nikon 35 mm f/1.8 DX vs the Nikon 50 mm f/1.8 G FX tested on the 10 MP Nikon 1 V1 (as done by Photozone), the 10 MP correspond to a 32 MP DX sensor. We see that DX lenses have a somewhat higher resolution but nowhere 50% higher than they would need to deliver the same resolution when used on DX and FX with the same number of MP.

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