RustyBug
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 Re: M glass on Leica SL3 (or SL SL2) | |
1bwana1 wrote:
RustyBug wrote:
Yeah, that's like saying I don't get as much pepperoni on my pizza when you cut the pepperoni into smaller pieces.
The lens dictates dictates the maximum resolving capability of the optical projection. The sensor just subdivides it.
I mean, if I put 24 pepperoni slices on a 12 inch pizza ... and then cut it into 6, 12 or 24 slices ... does that change how much pepperoni I have in my belly when I eat the whole (or 1/2, etc.) thing? Now, if I cut it into 100 million slices, and only eat one pixel, I mean slice ...
Think about it. 
Well smarter people than me who are optical lens specialist have come up with math that works very differently than your pizza.
Here is Roger's math on the subject. He has thought about it, and done the testing to check the math.
"Lots of people think that will be ‘whichever is less of the camera and lens.’ For example, my camera can resolve 61 megapixels, but my lens can only resolve 30 megapixels, so all I can see is 30 megapixels.
That’s not how it works. How it does work is very simple math: System MTF = Camera MTF x Lens MTF. MTF maxes at 1.0 because 1.0 is perfect. So let’s say my camera MTF is 0.7, and my lens MTF is 0.7, then my system MTF is 0.49 (Lens MTF x Camera MTF). This is actually a pretty reasonable system.
Now, let’s say I get a much better camera with much higher resolution; the camera MTF is 0.9. The system MTF with the same lens also increases: 0.7 X 0.9 = 0.63. On the other hand, I could do the same thing if I bought a much better lens and kept it on the same camera. The camera basically never ‘out resolves the lens.’
You could kind of get that ‘perceptual megapixel’ thing if either the lens (or the camera) really sucks. Let say we were using a crappy kit zoom lens with an MTF of 0.3. With the old camera; 0.3 X 0.7 =.21. Let’s spend a fortune on the newer, better camera, and we get 0.3 X 0.9 = 0.27. So our overall system MTF only went up a bit (0.07) because the lens really sucked. But if it had been just an average lens or a better lens (let say the MTF was 0.6 or 0.8), we’d have gotten a pretty similar improvement."
Steve, you missed my point ... 100% of the pizza is still there (i.e. the 1.0 = perfect). The degradation begins from there. I'm very much +1 with Roger and the math. John Colwell has posted the (more complex) formula here at varying times, too.
If I've got a crappy lens with 0.3, then the max I can get is 0.3. If I've got a pizza with three slices of pepperoni, the max I can get is three slices, no matter how small I slice it. The max I can get from a 0.3 lens is 0.3 (theoretically).
OTOH, if I upgrade my 0.3 lens to 0.6, the max I can get is 0.6. How much pepperoni I lay down on the dough dictates the max I can get. How much I project onto the sensor dictates the max I can get ... even if different sensors are differently divided, the max I can ever get is 1.0X of the optical projection (theoretically). Granted, moving from a 0.7 to 0.8 or 0.9 sensor does "reduce less (from the 1.0 theoretical), thus gives more" ... but, it can never surpass the maximum possible from the optical projection. It just reduces, less ... while making finer transitions.
So, yeah, a finer resolving sensor cuts the image up into smaller pieces ... up to the limits of the lens. I think we're saying the same thing, just from different perspective. Some folks are saying it makes it better ... I'm saying it makes it less worse, but the combination of the system can never exceed the limits of the optical projection.
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