Jack Flesher
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 Re: A smaller XF16-55 II? | |
curious80 wrote:
gdanmitchell wrote:
jakelindsay wrote:
gear-nut wrote:
DOF yes, light gathering capacity, no. So nothing/nobody bit here, and again there is a significant difference in size and weight between the two systems.
And next, the Nikon 24-70/4 kit lens is good, but nothing special; the current 16-55/2.8 Fuji is very good by comparison. Granted, the Nikon 24-70/2.8 is essentially as good as the primes it replaces, but again it is large and weighs over 800gms.
No I think a FF F2.8 also gathers more total light than an APSC F2.8. Not relative to the sensor size (those would be equivalent) so the exposure values would be similar but definitely more total light. Bigger lens = Bigger bucket, right?
This notion has, unfortunately been bloated into meaning something that it does not really mean.
Yes, more photons fall on a larger area than a small one when all else is equal. But you still shoot f/11 at the same shutter speed whether your sensor is small or large.
To illustrate the trickiness of these comparison, consider rainfall. Let’s say that it rains 1” in an hour. If you look at a 10’ x 10’ area, the rate of rainfall is no different than if you look at a 100’ x 100’ area — it is 1” per hour either way.
Likewise, there’s no more light on a given area of your sensor (let’s say 1mm x 1mm) if the sensor is larger.
Technically, once you get into things like the dimensions of individual photo sites you see that this can affect noise and dynamic range potentially. But that’s not a “more light” issue — it is a “sensor bucket size” issue.
Consequently, as I mentioned earlier, folks getting something like the 16-55mm f/2.8 lens are, by and large, treating it the same way they would treat a lens with a comparable angle of view range on full frame — which is (very) roughly a 24-70mm f/2.8 lens. They will use them in more or less the same circumstances and for similar kinds of photographs. If they’d choose f/2.8 on one in a given situation, they almost certainly would choose f/2.8 with the other in the same situation.
(There is one exception. Because the effect of diffraction blur becomes apparent almost one stop sooner as you stop down on APS-C by comparison to FF, they might be moe likely to avoid the smallest apertures on the smaller sensor system.)
At about this point you typically see some forum creature enter the scene and write: “But your f/2.8 APS-C lens is really a f/4 lens!” (I’ve noticed that these are typically people who don’t actually use such APS-C lens, yet are utterly confident of the power of their arguement! ;-) Sigh. )
When I go into the field with my 16-55 f/2.8, my 50-140 f/2.8 (or, heck, just about any APS-C lens), I basically never think Oh, no! I’m really only getting f/4! Horrors!” ;-)
I have in mind doing a little experiment with a pair of systems, FF and APS-C. Let’s see if I can find some time…
Well yes and no. From an exposure perspective f2.8 is f2.8 like you said, whether it is APS-C or FF. However the APS-C would have higher noise because there would be less total photons per pixel due to its smaller area.
Lets step back and think why we use a faster aperture. We use it for lower noise in low light conditions, or for faster shutter speed, or for shallower DOF. For shallower DOF we know that f2.8 on APS-C is similar to f4 on FF. For low light, due to one stop noise advantage of FF, you can use f4 on FF and use one stop higher ISO and get similar results as f2.8 on APS-C. Similarly for faster shutter speed again, you can use an f4 on FF and use one stop higher ISO and get similar results as f2.8 on APS-C.
So I think it is fairly reasonable to say that an f4 zoom on FF is equivalent to an f2.8 zoom on APS-C. As someone who owns and uses both APS-C and FF systems this also matches my actual experience.
Nope. Photons per pixel are identical if pixel size and design is identical, regardless of the number of them *within the lens’ IC.* As to smaller pixels being noisier when smaller has recently been debunked with associated improvements in sensor technology; the fuji 26 and 40 mp apsc sensors are essentially equivalent as re noise; the nikon Z8/9 are slightly better than the Z7 at the same net pixel counts.
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