When will the law of diminishing returns kick in?

I am just wondering. The MP counts will be increasing steadily.

Assuming the 35 mm sensor will dominate the market. When will we have a point that increasing MP won't produce an increase in quality.

I did a really simple calculation and approximated it to be somewhere between 50 and 90 mp. Are there any articles on this? I'm just curious.

What is the "final quality"? It depends on output media, right?

Overall quality of the image. Detail I guess.

There will be a point when increasing MP count will actually decrease the quality because the sensors are too small.

That would the diffraction limit.

With Rayleigh's resolution limit for a 35mm sensor, I estimated the following:
f-number pixel count
1 2.2Gp
4 140Mp
8 35Mp
11 11Mp
That's assuming the lens is perfect, i.e. no spherical aberration, no coma, no chromatic aberration. But I wouldn't hold my breath waiting for a f/1 lens with no SA and CA to appear any time soon.

Ken

Cool, I was close to your calculation.

HUH?

The limit is the wavelength of light. Just off the top of my head, I think the wavelength of red light is 0.7 microns. I'm not sure if the efficiency of a photosite deteriorates as this limit is approached, but smaller than this limit would seem to be less efficient. In fact, if it's possible to make an analogy with radio reception, efficiency might increase dramatically as the photosite size approaches the wavelength of light. Current small P&S cameras have around 3 micron photosites, so there's a way to go.

The other side of the equation is lens quality. It seems to be a truism that components in a controlled environment (sort of laboratory conditions), develop more rapidly than components that have to interface with the real world. For example, computer chips, camera sensors, hi fi amplifiers, factory robots, to name a few, develop more rapidly than computer monitors, loudspeakers, camera lenses and automobiles.

All lenses are limited ultimately by diffraction, until someone discovers a way of beating this limitation. But not all lenses are diffraction limited at every F stop. It's very difficult to prodice a 35mm lens that's diffraction limited at f8; even more difficult at f5.6 and well nigh impossible at smaller f stops (but perhaps not with an unlimited budget - I stand to be corrected ).

With increasing application of nanotechnology and new materials, it might eventually be possible to produce a lens that is truly diffraction limited at f2. Those 1 micron photosites (a guesstimate of the practical limit) might well become a reality.

One should also bear in mind that the Rayleigh's limit is at an MTF of around 9% (ie. the image has lost 91% of its original contrast). Current digital sensors are incapable of picking up such faint signals. I wonder if a photodetector tuned to the frequency of light would be able to.

We need some clever Physicists to answer such questions.

Read up on diffraction.It's an interesting subject in the way it relates to perfecting lenses.

Diffraction is something that can't be fixed or corrected for so is pretty much the upper limit in resolution

who is driving the need for greater image sizes?

Professional photographers - probably not as current sizes satisfy their needs for magazine/newspapers for the most part.

Advanced amateurs - possibly on a "ive got more pixels that you" basis but lets face it most of us print out no bigger than A3 for which 10mp is ample. For web based pics (which is the growing media for distribution), 10mp is too many and we downsize them!

I would say therefore that the thing that will limit mp growth is diminishing consumer demand. Development costs for new sensors is huge and the likes of Canon will increasingly find it is difficult to justify R&D costs from sales. I would think this point will be reached long before the laws of physics kick in.

The fight for more megapixels will go on and on for a while yet. Why? Marketing. "More megapixels = better", yeah?

It's the same as "digital zoom" on camcorders. I've got one that claims "1000x digital zoom" or something like that. It's as much use as a chocolate teapot, you get a couple of very large pixels on screen and that's about it... but it's a number that the public can compare. I can look down on the chap next to me who only has 300x digital zoom

I dearly hope for -instead of the same dreary increasing pixel count-
that they will make genuine improvements in brightness range and also in-body image stabilization.
Sadly canon and nikon seem to be officially not very interested in the latter

Competition between the manufacturers.
Progress...

Where's the market on film and the diffraction limit? As much as film might be further improved over time, isn't the resoltion achievable by all the non-specialist emulsions considered adequate, even by photographers using the most expensive 35mm film bodies & lenses?

If 35mm film resolution *is* less than the diffraction limit, I guess *that* resolution will be enough for digital too. We may find the maket migrates to other "mine's bigger than yours" metrics like max FPS, min shutter lag, max shutter speed, etc, etc, which could all approach minimum real usefulness pretty quickly.

With bodies into £1000's in the UK, many would say we're already well into the general law of diminishing returns... You spend a LOT more to get a little extra. It's just a case of what that little extra is worth to you and your work or hobby.

W

Phallometry...

I can't find the dictionary definition for some reason.

I'm really surprised that people are still in a megapixel war. As we have seen very clearly with cameras like the D1x and D2H, megapixels aren't the sole element in resolution quality. There are lots of pros producing stunning images with less megapixels. The manufacturers should be competing on the sensors and their ability to capture data in the best way to maximize the efficiencies of the rest of the gear, like the great optics.

Unfortunately, they are probably finding it easier to market to the public based on the megapixel myth - the higher, the better.
Very few understand the sensor technology to make purchasing decisions based on that criteria.

Lou