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Forum: Pentax SLR Lens Discussion
11-14-2014, 08:44 AM
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Yes but the internet DID invent (or at least enable) de-territorialized and de-temporal complaining about it...
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Forum: Pentax SLR Lens Discussion
11-13-2014, 07:58 PM
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Forum: Pentax SLR Lens Discussion
11-13-2014, 05:52 PM
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Well, for formats smaller than 135, lenses sound better than they are that way: "28-300mm (equivalent) f/2.8!!!"(example: Olympus Stylus 1, actually 6-64.3/2.8).
"93-186mm (equivalent) f/5.6!!!" on the other hand doesn't sound any more impressive than "150-300mm f/5.6" (example: Pentax-FA 645 150-300mm F5.6).
So even if medium format users were all complete morons, there would be no advantage.
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Forum: Pentax SLR Lens Discussion
11-13-2014, 04:34 PM
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Yes, the paper minus the cut-off edges will be lighter. (not that it matters much...).
Also:
Cutting off 1/3 of both dimensions of the sensor (5/9 of the area) and 1/3 of the lenses focal length while keeping the aperture diameter (absolute, not relative to focal length) constant
and increasing the pixel density of the sensor by 1/3 and the quantum efficiency of the sensor by 125% will get you the same arbitrary picture.
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Forum: Pentax SLR Lens Discussion
11-13-2014, 01:05 PM
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I don't get how equivalence is confusing anyone (it's just a bit of maths, ffs!)...
My
58mm f/1.2 lens[1] used on my Fuji X-E1 (exposing for 1/X seconds on a 23.6*15.6mm (28.29mm diagonal) sensor[2] with a sensitivity of ISO Y)
will make the same[3] picture that a
88.7mm f/1.84 lens[1] used on a 135 format camera (exposing for 1/X seconds on a 36*24mm (43.27mm diagonal) sensor[2] with a sensitivity of ISO Y*2.34)
would make when pointed from the same position in the same direction.
[1]: Assuming idealised lenses and that those specs are precise
[2]: Assuming equal quantum efficiency for both sensors and equal resolution
[3]: Same perspective, same perspective distortion, same field of view, same depth-of-field, same amount of motion blur and same image-level signal-to-noise ratio
That isn't confusing, is it?
It just mean:
A ~58/1.2 lens on APS-C can serve the same purpose a ~90/1.8 lens on 135. For roughly contemporary cameras, the APS-C camera will be roughly 1 stop worse in terms of image noise. |
