Shashin
Well-known member
Now, why you are bring diffraction and diffraction limit into this?This all has been discussed in length - e.g. here:
Full Sized vs. Cropped Sensors
Oh, an article on LuLa. Well, I don't have time to debunk this either...
.....
1. The sensor size alone determines the maximum useful f-number (N); and, in fact, the maximum f-number for high-resolution photography is given by 0.5 times (sensor diagonal in mm).
Well, not quite. You also need to have the same pixel resolution, which means that the smaller sensor also has smaller pixels and so each pixel is collecting less light. But if the sensors have the same pixel pitch, then each pixel has the same number of photons and then you don't scale the ISO. But you see the trick here, while you are matching those three attributes, you are not matching shutter speed and so the image will not be identical.2. We can take an essentially identical photograph with any sensor size by scaling the focal length, the f-number, and the ISO sensitivity.
But so what? Photographers don't go shooting identical pictures of some abstract ideal. All of these things are variables--there are no correct value for any of these, there is no correct product. What you need to learn is the significance of these variables. Just because the function of multiple variable can intersect, does not mean the intersect is a new law in photography--correlation does not equal causation.
Sensor size is irrelevant in regards to total light intercepted. It is pixel size that determines light gathered. You cannot determine S/N by sensor size alone.3. The smallest sensor we considered (denoted 1/2.5”) achieves maximum useful DoF at an f-number of N=3.5 while the full frame 35 mm sensor requires N=21 for a factor of 36 difference in transmitted light. If the full frame sensor gives the same signal/noise ratio (S/N) at ISO sensitivity 1600 as the small sensor does at ISO 80, the small sensor can still use a higher shutter speed. A PS sensor that could give low noise at ISO 800 or 1600 would appear to have a real advantage over FF sensors.
You are simply cheery picking your variables to chose a winner. No one is disputing different optical qualities or performance. I am simply saying the presenter's equivalency scheme is just a whitewash of "factoids" to try to win an argument. The problem is that is it rubbish.4. If maximizing the DoF is not the aim, larger sensors clearly win because of their ISO sensitivity advantage. A fast lens (N=1.4) with a full frame detector is impossible to match with the small sensor. Probably N=1 is the maximum aperture we can expect with a small sensor, and no company at present even offers N=2. The take home lesson is that small sensors should be coupled with large aperture lenses, i.e. small N values. Also, small sensors that support large ISO sensitivities should be sought. The vendors are showing some interest in higher sensitivities, but larger lenses are in conflict with their drive to smaller cameras. Unfortunately, none of the available PS cameras offer very high quality lenses......
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I did not see the presenter state anything about an equal pixel resolution. He certainly does not discuss equal pixel pitch. Obviously, he is either ignorant or being purposefully deceptive. He certain does not understand ISO nor f-numbers.It is clear that a small sensor is not having the same signal to noise ratio like a larger one, both with the same resolution. the conclusions in the video are exactly stating that.
It might be clear to you, but the argument presented in the video is factually incorrect. No one is saying different systems don't give different results. But what the presenter is stating is simply wrong.there is another very good article
Do Sensors ?Outresolve? Lenses?
see
Figure 2. Graphic representation of the MTFs of two hypothetical lenses and a sensor of 100 lp/mm (5 microns). Wavelength of the light is 0,000555mm.
and:
"...The signal-to-noise ratio, however, imposes an inflexible limit to the effective resolution of the whole system, mostly due to photon shot noise.
."
Regards
Stefan
BTW, aren't you the guy that was bashing MFD digital because that smaller sensor D800 was "better"? So, I guess you don't believe the presenter either because 35mm does not gather more light than MFD, or so he claims...
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