full frame and pixel pitch

Started Jan 4, 2013 | Discussions thread
Theodoros Fotometria Senior Member • Posts: 2,090
Re: It's all physics, unless it isn't.

Leo360 wrote:

moving_comfort wrote:

vbuhay wrote:

There is a very good article on NPhoto (Nov2012) issue regarding this issue. In essence the larger the Photo site (Pixel) the more Photons (light particles fall on it, the better the the signal to noise ratio), less noise at higher ISO and higher dynamic range (black or dark to white range), Like I say, its all Physics. FYI the Pentax 645D has a 44mm X 33mm sensor vs FX at 35.9mm X 24mm. The Pentax 645D body is about 10$K the D800 is 3$K. DXO has some indepth test on all these sensors - its all there for our comparison. Just my input. You can draw your own conclusion.

"It's all physics." Amazing how that statement can be applied to anything at any level of accuracy.

If a sensor held only one pixel, you'd want that pixel to be as large as possible in order to collect as much light as possible. Luckily we can put more than one pixel in the same area, collecting the same amount of aggregate light with even greater efficiency, at times, depending on those pixels' qualities, than less pixels could over the same sensor area.

What is being maximized is the amount of Shannon information the sensor collects. Smaller pixels do not hurt but at some point (depending on optical aberrations, diffraction etc) more pixels stop to improve on the information captured. I guess for any given optical system there is an optimal pixel pitch (aka sampling rate)


I believe this is correct...  Additionally I think that many people approach a sensor like if all the pixels of it perform the same, which is far from truth since photons hit the sensor at different angles and although micro lenses (most of the time) are there to ease the problem, they cannot make an edge pixel perform like if it was at the center... Basically, that is the reason why a maker can crop the image area of a larger sensor and create a smaller one, but the opposite, cannot be. That is exactly why in cameras, the more direct photons hit the sensor (which in all cases is relevant with smaller sensors), the more the pixel density... Thus having people that "dream" about 54mpx sensors and imagine of it being D3200 sensor ...grown to be a FF one, simply dream of making feasible the unfeasible... such a sensor would be much worst of the D800's 36mpx one.

That is not to say that 54mpx sensors won't be able to be made in the future... it's just to say that D3200's sensor (which is today's tech and made up to the limit for a DX camera) cannot be of "expansion use" for a FF camera.



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