The 50-53mp War

Sony has a ridiculously good sensor in the RX100, 20MP in a 1" sensor which would equate to 63MP at APS-C or 148MP in FF. The technology is there, but useless to us until they succeed in making an Airy Disk smaller.

Some clarification questions:
I understand the preference for an EFCS but the insistence on tethering raises a question for me. I see it as a Nice to have but not overly important. My camera transfers photos via blue tooth,wifi or NFC to my computer as I take the shots. My copy stand is up stairs and my Pc down stairs I simply take the photos.. then wander down stairs to do the editing( the camera stays where it is! I can control the camera via my lap top or my smart phone. But I prefer using the cameras LCD screen WHY is tethering that important? I suspect (don't know) that tethering software includes what comes automatically with my camera and other top end mirrorless offerings. Focus magnification, Focus peaking and Zebra. Focus magnification in manual focus mode I can zoom into an area of the image and adjust the focus extremely finely, I can even move the magnified area around the coin to ensure every thing is uniformly sharp. Focus peaking: when on it will highlight on the camera screen and EVF which parts of the image are in focus( using contrast detection) Zebra: often used in video it gives feed back on exposure. You preset the zebra to a preferred exposure level. When setting up the shot diagonal strips are shown where the exposure level matches the setting. I find it really useful with bellows and extension rings as it takes the guess work/calculations out of exposure compensation. I should add it was really useful now having used it for a long time I instinctively know how much to adjust the Exposure compensation dial

Next question: I have already budgeted to get the new A7r( the rumoured 50MP beast) in May this year. MY main interest is the EFCs and for outdoors photography the 5 axis IBIS. With all the comments on diffraction limiting the actual resolution would I be better going for the Sony A7s ( a see in the dark Camera?) It has EFCS and is a full frame 12mp camera. The sensor pixels are larger than standard making for very low noise photographs. The big failing of the A7s,for me, is the anti aliasing filter

I don't know about you, but it's a bit easier for me to focus a shot on a 27", 2560x1440 monitor than a 3" camera lcd. Not to mention workflow speed. You could conceivably do 100 coins per hour on a tether rig.

I'm not going back, that's for sure.

What sort of pixel pitch are we talking? I can't imagine being able to shoot a narrower aperture than f/5.6, and the sensor will expose the tiniest imperfections in the optics.

It's easy to calculate what the pitch will be.

FF sensors are 1:5:1 aspect ratio (36 x 24 mm). So assuming square pixels, TotalMP = Xpixels * Ypixels = 1.5*Ypixels * Ypixels = 1.5Ypixels^2

So for a 50MP sensor... 50e6 = 1.5Ypixels^2, or Ypixels = 5774 and Xpixels = 8660. The sensor will actually be some nicely-divisible number, perhaps 8832 x 5888. This actually calculates to 52MP and divides nicely by 2's down to 69x46. It also has LOTS of 8's so will be a hit with folks who love them!

So now we know what the sensor size will be, 8832 x 5888, for 52MP. What is the pixel size?

36mm / 8832 = 4.08um. This is a bit smaller pitch than my 18MP APS-C at 4.3um, but not enough to worry about diffraction problems being any worse. The DLA, which is just the onset of when diffraction can start to degrade the image, will be f/6.4, so not much of a problem for current lenses.

I really don't know why folks are making a big deal about 50MP FF. The technology is already in place and has been for years. Please explain what I am missing here.

Sony has a truly wonderful 1", 20MP sensor in the RX100 which would be 140 Megapixels in FF size. Only processing capability lags a 100MP+ dSLR; the sensor tech has existed for years.

Still useless to us until Airy Disks become smaller than 4 microns.

I disagree strongly you are both confusing the ability to produce a high pixel density in a small area with the ability to apply the same density on a large sensor. Its not just the pixels but the design and placement of the micro lenses. Using your arguments We could say the technology for going to the moon had been available for years before the apollo program. In actual fact the science had been available for years the application of that science ( technology took along time to follow)

If you guys are right why haven't we had 50mp sensors for years already. You are right in that the limits of the bayer sensor are being reached but as you both know other sensor types are being researched and patented. There is even work on a curved sensor there is a a cell phone with a curved sensor, that technology only allows use on small sensors for now there still has to be considerable development before it can be scaled up to larger camera sensors