diffraction blur. I have owned all sensor cams so far. And even 10.000$ bodies or more had some noise.



Oh, I see what you mean! I think I can (I hope I may?) correct /clarify a few things here if you are interested (and I hope my english is good enough that you understand what I mean hehe).Well, of course every ISO setting (with every sensor/camera combination) has some kind of grain/noise (you have different sensor sizes like crop, full frame or medium format and so on and also different algorithms that are in the software to reduce the noise) ...it's a term like ASA on film (or at least almost). So noise can be different from model to model and brand to brand.You can usually recognize it the most in homogenous areas like the sky and in the shadows). Some cams start with ISO 50, while others start with ISO 200 and can still provide the same quality! (It's just a result of technicals specifications and software...and money).The aperture ( for example f2,8-f22) does never have an influence on your noise- never.The lens does also never have an influence). It's just the amount of light that hits your sensor or film (that is what they mean in your article/link).Altough (!) at the same time you have an increased amount of noise (that is a fact and you are right but not because of the aperture!) if you take a photo with a longer exposure!Usually you can only see that in the night or on very long exposures (I don't mean 1/20s or so....I'm rather talking of several seconds or minutes -the sensor gets hot and other things happen that increase the noise). The smaller the sensor, the worse it is.This is not a result of the aperture but the time you need to expose your photo. A photo with f2,8 1/1600s and f22 1/160s with bright sunlight at 12 o'clock will have the same amount of noise (basically). The time is just too short that you would be able to see a difference (in 99% of the photos).If for example f2,8 needs 1 second to expose your photo then f22 might need 6 seconds. Of course you will then see more noise on the 2nd photo but that is not a result of the the aperture...it's a result of the time (1 second vs 6 seconds). This is btw why some people if they want to take photos with a very long exposure ( like 10 hours) - they take analog cams/films....they have a specific amount of noise that doesn't change during the exposure (time) ...anyway how long the exposure is...in other words 'only analog cams can provide a decent image quality when we talk about of exposure times of several hours'. While digital sensors always produce more and more noise, the longer the exposure is. Second to second, minute to minute.What you are now basically doing (with your photos) is a technique known from stellar photography. In our present the most people have digital cameras and equipment. If you want to take a photo of dark objects (like the milky way/ space and so on) you need to have the ISO (sensivity) very high to shorten the exposure time (it would get blurred if you wouldn't do that). They have very very grainy/noisy images.Noise on your sensor and in the result on your photo does never have the same position (it's basically random- I'm not talking about dead pixels here-> dark frame). The position of the noise/pixels changes with every image. For example you got a 'bad pixel' in the top left, one in the top right and one in the lower left....if you combine those 3 images of the same thing then you are able to filter those 3 'bad pixels'. That is actually what you do. At the same time you sacrifice image quality because of the blending (and the different moments). Some people do also take a series of 10 images (for example) then cover the lens and do another photo with the protection hood on it....then they combine the 10 photos and then subtract the plain dark photo (that has actually only noise)...like a dark frame.Btw (just as an additional info) the sweet spot of your lense is somewhere (depending on the body) between f8 and f13 or so....only medium format (in 99% of the case) can have a good image quality at f22. This is called