<<bangs head repeatedly against keyboard>> On Mon, Sep 8, 2014 at 11:33 AM, Bryan Jacoby <bryan.jac...@gmail.com> wrote: > The other side of the coin is that, to produce the same picture (same > depth of field and shutter speed), the full frame camera will only be > getting half as many photons per unit area, so has to shoot at 2x the > ISO of the crop camera. So the common wisdom that you get a stop > extra ISO out of a full frame camera is true but misleading, because > you _need_ a stop higher ISO on full frame to produce the same image > as you would with an APS-C camera. > > On Mon, Sep 8, 2014 at 12:27 PM, Bryan Jacoby <bryan.jac...@gmail.com> wrote: >> On Mon, Sep 8, 2014 at 10:11 AM, Darren Addy <pixelsmi...@gmail.com> wrote: >>> To try to find lenses that still give you that focal length and >>> maximum aperture becomes an expensive proposition, when it is possible >>> at all. >>> >>> Extreme example: DA* 200mm f2.8 can be bought for under $1K. (More >>> like $700, used) 300mm equiv. FOV on APS-C >>> Move to a full frame, now you need a 300mm f2.8 to replicate that FOV. >>> Price one of those lately? A Sigma is $3400. A more reasonable choice >>> would be a 300mm f4. You've replicated the FOV, but lost a full stop >>> of light. >> >> Not really (I mean about losing the stop of light). It's true that >> f/4 on full frame will only produce an image half as bright on the >> sensor compared to f/2.8 on APS-C, but that's half as bright in the >> sense of photons per second _per unit area_. The full frame sensor >> has a little over twice the area, so it will actually be collecting >> slightly more photons per second _over the whole image_, which is what >> actually matters (or, another way to think of it is they will both get >> the same number of photons per second per pixel if the two sensors >> have the same number of pixels). And a 300 f/4 on full frame would >> have about the depth of field as the 200 f/2.8 on APS-C. So these two >> scenarios are actually very comparable. > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions.
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