Rodolfo Paiz wrote: gdsf2 wrote:
How is a DX sensor better for long-focal-length needs than just cropping on a full frame camera?
2. Potential for more reach. If what you want is the narrowest FOV possible (\"greatest reach\") then you can use your longest FX lens, and get the FOV that you\'d get from a lens with a 50% greater focal length... with no loss of light. Your 600/4 becomes a 900/4, which is impossible to do on FX.
Great points, but I have to stop you at this one.
A 600/4 does not magically become a 900/4. Aperture is a relative number and directly depends on the focal length, and the focal length is a physical measurement. The more accurate statement would be that a 600 F4 becomes a 900 F6. You have to multiply not only the FL, but also the f-stop when making these conversions for them to have any meaning.
In other words, a 600/4 on crop sensor is still a 600/4, but with a 900 FOV. Bokeh and compression characteristics remain the same, just with a narrower FOV.
If we accepted the rampant multiplication of FL and not aperture, we\'d have to accept that superzoom cameras touting a 1000mm F2.8 lens is a thing, when in reality, it is patently absurd. Can you imagine a 1000mm F2.8 lens? It\'d be the size of a truck.
Jan 05, 2016 at 07:15 PM
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