Four Thirds lenses do start decreasing in resolution after f/5.6, but they are not "diffraction-limited" by f/5.6, not if by that you mean "they perform at the diffraction limit there and beyond" (although maybe diffraction is the main cause of decreased performance). I actually calculated some data on his from dpreview's tests of the Olympus Zuiko Digital 50/2 macro lens, which I own (I had to convert their numbers to lp/mm, of which here are the results):

Olympus Zuiko Digital Macro 50mm f/2
f/stop (4x5 equiv) -- resolution -- theoretical diffraction limit -- % Diffraction Limit
f/2 (f/14.2) -- 92 lp/mm -- 750 lp/mm -- 12%
f/2.8 (f/20) -- 112 lp/mm -- 536 lp/mm -- 21%
f/3.3 (f/23) -- 119 lp/mm -- 455 lp/mm -- 26%
f/5.6 (f/40) -- 116 lp/mm -- 268 lp/mm -- 43%
f/8 (f/57) -- 105 lp/mm -- 188 lp/mm -- 56%
f/9 (f/64) -- 96 lp/mm -- 167 lp/mm -- 57%
f/11 (f/78) -- 87 lp/mm -- 136 lp/mm -- 64%
f/16 (f/114) -- 72 lp/mm -- 94 lp/mm -- 77%
f/22 (f/156) -- 54 lp/mm -- 68 lp/mm -- 79%

some similar large format lenses for which there is data (I've averaged the results for center, middle, and midline): http://www.hevanet.com/cperez/testing.html/

Schneider G-Claron 305mm f/9 (equivalent to 43mm f/1.3 in 4/3rds for AOV and DOF)
f/stop (4/3rds equiv) -- resolution -- theoretical diffraction limit -- % Diffraction Limit
f/16 (f/2.3) -- 63 lp/mm -- 94 lp/mm -- 67%
f/22 (f/3.1) -- 55 lp/mm -- 68 lp/mm -- 81%

Fuji C-Series 450mm f/12.5 (equivalent to 63mm f/1.8 in 4/3rds for AOV and DOF)
f/stop (4/3rds equiv) -- resolution -- theoretical diffraction limit -- % Diffraction Limit
f/12.5 (f/1.8) -- 40 lp/mm -- 120 lp/mm -- 33%
f/16 (f/2.3) -- 43 lp/mm -- 94 lp/mm -- 46%
f/22 (f/3.1) -- 43 lp/mm -- 68 lp/mm -- 63%
f/32 (f/4.5) -- 41 lp/mm -- 47 lp/mm -- 87%

Some interesting things worth nothing:

(1) By f/22, 4x5 lenses can perform as well as 4/3rds lenses at f/22. Look at other lenses in the link I provided, some of them are getting around 50-55 lp/mm at f/22.

(2) However, at f/22, large-format lenses that may be performing at 63-81% of the theoretic diffraction limit are equivalent to f/3.1 on 4/3rds in terms of DOF. Around there, 4/3rds lenses are getting 21-26% of the theoretical diffraction limit (actually, not all 4/3rds lenses...the Oly 50/2 is one of the sharpest lenses ever made).

(3) For portraiture work at f/2 on Olympus and assuming 5 lp/mm is desired for final print sharpness, the Olympus 50/2 can produce an enlargement of 92/5 = 18.4x enlargement over the 17.3 x 13.0 mm sensor size, for final prints of 9.4 x 12.5 inches. This is about on par with my experience of what Olympus can produce.

(4) For portraiture work at f/16, which has equivalent DOF using the same composition as f/2 in 4/3rds, using say the 305/9 G-Claron, you can produce an enlargement of 63/5 = 12.6x over the 3.75 x 4.75 in film area (the edges are unusable due to the loading notches) for final prints of 47 x 60 inches! Now, granted, you'd need a lot accessory light for this. Also, most people don't blow portraits up that large, but even if not, you'd still have a much greater tonality and smoothness. (and if the pictures were too sharp, you'd have plenty of room to do some blurring to eliminate unwanted facial detail and provide a smoother image instead).

(5) If you want to shoot with less intense light, there are the Xenotar 150/2.8 and 135/3.5. The Voightlander Apo Lanthar 300/4.5 has a longer focal length and some may prefer it for portraiture -- but its $5,900 on eBay right now (and it covers up to 8x10, so may not be sharp enough for 4x5)! In any event, assuming my Xenotar 135/3.5 for portraiture work wide open, it gets 20 lp/mm at the center wide open and 10 lp/mm at the edge for 15 on average. That's an enlargement of 3x over 4x5 for final print sizes of 12x15. Somewhat larger than 4/3rds and much much narrower depth of field (equivalent to f/0.5 on 4/3rds), along with much much greater tonality and smoothness. By f/8 (equivalent to f/1.1 on 4/3rds) the 135/3.5 is already getting 45 lp/mm and you can make 34 x 43 in prints!

(6) For landscape work, unfortunately 4x5 lenses don't stop down below f/64. You won't be able to match the extreme DOF you'd get with 4/3rds at f/22, although by then you could think about pinholes or putting a pinhole aperture in front of a 4x5 lens. In any event, because 4x5 has the ability to tilt the standards, I've often achieved f/32 or even f/22 for landscape work (f/11 for some architectural work). But even in the worst case, at f/64, 4x5 still excels. I haven't seen tests, but from graphs I've plotted of resolution of 4x5 lenses vs. f-stop, I'm pretty sure 4x5 is going to resolve just about at the diffraction limit at f/64 (heck, according to Kerry Thalman and Mike McDonald, 4x5 lenses are already performing at or nearly at the diffraction limit at f/32 and the data backs that up; see my link and the link to discussion).

Anyhow, at f/64, the diffraction limit is 23 lp/mm. If 4x5 lenses perform near there, that's a 4.6x enlargement over 4x5 for 22 x 17 in prints. How large a print can we make from 4/3rds at f/9, equivalent to f/64 on 4x5? The Oly 50/2 gets 96 lp/mm, so that is a 19.2x enlargement for a 13 x 10 in print.

(7) All this is just a really complicated way of saying that at any given f-stop on 4/3rds, the equivalent f-stop on 4x5 for DOF in the same composition (AOV, framing) is going to be far closer to performing at the diffraction limit. The difference in the size of enlargements at equivalent f-stops is equal to the fold-difference in the % of theoretical diffraction limit achieved.

And when you can benefit from tilting or swinging the standards on 4x5 -- or when you want narrow DOF -- then you can really bang out incredibly sharp negatives of transparencies capable of enlargement to enormous sizes.

"As for the OP's intended use? Sounds pretty stupid to me... A good way to get into trouble."

I have no idea what you are talking about. An early poster mentioned something inappropriate about spying on other people; nothing like that was implied by my rather straightforward summary of the innovation.

I intend to use it for large format photography (e.g., landscapes), if it ever becomes affordable.

This isn't actually true, that when you're DOF limited, any format can produce the same image. At a crop factor of 6.64, f/28.4 on 4x5 (f/53 on 8x8) is about equal to f/8 on 35mm. However, large format lenses are a lot closer to the diffraction limit at f/28 (because it is a lower number) than are 35mm cameras to their diffraction limit at f/8. Furthermore, because the resolution of say ISO 100 film outstrips that of the lens by so much, you're basically getting the full aerial resolution on film (this has to do with MTF).

To make it clear:

Assuming both lenses perform at the diffraction limit, f/28.4 at ISO 100 on 100 lp/mm film will get you the same exposure, depth of field, and image quality as f/8 at ISO 6.7 (the area of 4x5 is 14.9x larger than 36x24) on 355 lp/mm film. By same image quality, I mean the quality of the final print. The reason for the disparity is of course the much greater area and diagonal of 4x5 film. Breaking that down:

* The equivalent f-stops and film resolutions are determined by the crop factor from 35mm to 4x5 (3.55x). Performance at the diffraction limit for f/28.4 is about 1500/28.4 = 53 lp/mm. Performance at the diffraction limit for f/8 is 187.5 lp/mm. For final 4x5 resolution, accounting for film resolution, 1 / (1/53 + 1/100) = 34.6 lp/mm. Assuming 10 lp/mm is acceptable for final print, that gets you a 3.46x enlargement over the 6.4in diagonal of the film: final print diagonal = 22in. For final 35mm resolution, accounting for film resolution, 1 / (1/187.5 + 1/355) = 122.7 lp/mm. Assuming 10 lp/mm is acceptable for final print, that gets you a 12.2x enlargement over the 1.7in diagonal of the film: final print diagonal = 21 in. The difference is in rounding error.

That is all hypothetical though. In reality, neither lens performs at the diffraction limit, but 4x5 lenses perform a lot closer to the diffraction limit at say f/32 than do 35mm lenses at f/8. Some good large format lenses get around 40 lp/mm or more at f/32, 85% of the diffraction limit of 47 lp/mm. The Olympus 50/2, a very sharp 4/3rds macro lens, gets 105 lp/mm at f/8...don't expect 35mm lenses to outperform that. That would be 56% of the diffraction limit of 187.5 lp/mm. So you're going to be able to make a print ~1.3x as large from 4x5 vs. 35mm...assuming you use 355 lp/mm film with 35mm.

* The equivalent ISO for image quality is determined by the fold difference in area between 4x5 and 35mm film: about 14.9x more area on 4x5 film. Hence, it can have an ISO 14.9x as high: ISO 100 on 4x5 has the same image quality (tonality, grain in final print) as ISO 6.7 on 35mm film. The problem here is, you really aren't going to find ISO 6.7 film. The lowest I've heard of for a TLR is ISO10. Actually, there is Efke IR820 Infared ISO 3. However, it is IR film. However, this is available for 4x5 too. If you want to talk about color film, for the most part, the lowest ISO of 4x5 and 35mm is the same -- ISO 100 or ISO 50 (for Velvia).

The same thing would be true for digital. If you're getting ISO 100 on say a hypothetical 4x5 digital sensor, you'd need ISO 6.7 to get the same image quality from a 35mm sensor.

I'm not sure I'd say the list prices are "cheap". They're around the price that I bought some of my Olympus 4/3rds lenses for (50/2 Macro, 14-54).

But they're incredible values, because of what the can produce. The lenses won't be as "sharp" as say 4/3rds lenses in measured lp/mm, but they don't need to be anywhere near that sharp, because the film is so much larger.

For landscapes, there is always a tradeoff between resolution and depth of field. There is actually a formula that determines optimum f-stop that balances defocus and diffraction, given what you want to have in focus in your image: http://www.largeformatphotography.info/fstop.html/. There are a few things that result in 4x5 cameras producing much higher image-quality than 35mm cameras or DSLRs: (1) At equivalent f-stops for DOF, large format lenses perform much closer to the diffraction limit, thus you can have have larger prints; (2) The film is so much larger, so if you have a film with the same resolution/sensitivity, the effects of 1/Rf = 1/(1/Rl + 1/Rf) aren't as degrading. You will capture far closer to the aerial resolution than you would with 35mm or DSLR.

If you're into portraiture, 4x5 and 8x10 is great. For 4x5, many use portrait lengths of 135, 150, or 220mm (slightly shorter than normal to slightly longer than normal). Some good ones are the 135/3.5 Xenotar or 135/3.5 Carl Zeiss Planar. I got my 135/3.5 Xenotar for around $600. There is a 150/2.8 Xenotar on eBay right now for $5000 (ridiculously overpriced, as I've seen one sell for $1500 before). Yes, 135mm on 4x5 is "equivalent" to around 38mm on 35mm, if you consider the diagonal of 3.75x4.75in, a far cry normal portrait length. The rules for 35mm cameras shouldn't be blindly applied to 4x5; but if you really insist on longer lenses, there is an $5,900 Voigtlander Apo Lanthar 300/4.5 for $5,900 on eBay. However, with large format, many have found that you can get closer to the subject without having unpleasing results.

It is worth noting that because of the incredible detail 4x5's get, a lot of 4x5 portraiture is full body shots. You can crop to H&S and still get far more detail than from even full-frame cameras. For full-body portraiture, 135 or 150 mm works (even 90mm, depending on what else you want in the shot).

I'm working on a T8-based DIY set of softboxes to produce ~40,000 lumens total. This would allow relatively easy focus with a 305/9 lens indoors even.

Those prices in the link I provided are probably too high, except if buying new from B&H Photo. I bought my 4x5 Linhof monorail (which came with a 150/5.6 lens) for $600. Kodak Ektar 203/7.7 $120. Nikon SW 90/4.5 wide-angle lens ~$600. Schneider Xenotar 135/3.5 ~$600. Schneider G-Claron 305/9 ~$410. I sold the 150/5.6 and 203/7.7, and now only have 3 lenses: wide-angle (90/4.5), portrait (135/3.5), and longer focal length (305/9).

An excellent 4x5 system can be had for less than the cost of a DSLR. But you'll also need the darkslides (Lisco slides ~$10/ea for 4x5), shutter release cables, and a solid tripod and tripod head.

Maybe the sensor will have larger photosites than others, maybe not. It could have 10 micron sized sites.

I think that in many years, it might be "affordable". When 50 megapixel medium format backs cost what DSLRs now cost, look for an 8x8in sensor to cost $50k. An 8x8in sensor is almost 10 times the area of a digital medium format back...look for it to cost at least 10 times the price, or around $500,000, at least (probably more, due to wafer errors).

I think that in many years, large format photographers (I shoot 4x5) will be interested in this, when prices are reasonable.

So...it has the size of a medium format or even large-format camera...but the resolution of a DSLR that is 5 years out of date. Doesn't seem too impressive to me.

There is nothing wrong with comparing different formats. There are things that you can do with a large-format 4x5 that you still can't even get close to doing with a full-frame DSLR, nor even really with a medium-format digital camera. But of course there are advantages for digital too.

There is really no direct comparison between 4x5 film and a scanner-back. The scanner back requires a much longer exposure, it is not a sensor. For something very static, it would work fine.

A 4x5in piece of film, assuming that 3.75x4.75in of it is usable, has 17.8125 sqin of area. A 36x24mm (1.42x0.94in) digital sensor has 1.3392 sqin of area. That's 13.3x the area and 3.55x the diagonal.

Many lenses for 4x5 will resolve close to the diffraction-limit (1600/32 = 50 lp/mm) at f/32*, maybe they'll resolve ~46 lp/mm, or 92% of the theoretical diffraction limit). f/32 on 4x5 is equivalent to f/9 on 35mm film (in terms of DoF at an equivalent angle of view & distance from subject, i.e., same framing). To match the resolution of 4x5, you'd need to have to come achieve 92% of the diffraction limit of 178 lp/mm at f/9: 164 lp/mm.

My Olympus ZD 50/2 macro lens, one of the sharpest lenses ever made, resolves "only" 123 lp/mm at f/4 (31% of the maximum theoretical diffraction limit). At f/9, it resolves 96 lp/mm (54% of the theoretical diffraction limit). Good luck finding a lens that resolves 164 lp/mm at f/9 and that is suitable for general-purpose use.

*http://www.hevanet.com/cperez/testing.html/

PS: That 600 lp/mm 28 mm f/1.8 Ultra-Micro-Nikkor lens I mentioned has an image circle of just 8mm and is optimized for 1:10 magnification (e.g., it resolves an 80mm subject size on an 8mm sensor or piece of film). Reversed, it would be optimized for 10:1, but would only produce 60 lp/mm (600 lp/mm are still "resolved" on the 8mm object side (4800 lp total), but this is all that can be produced on the image side (4800 lp / 80mm = 60lp/mm).

So this is a very limited application lens to get that kind of resolution.

The APS-H sensor is 28.7 x 19 mm. To resolve 13,280 pixels along the length of the sensor, you'd need a lens that could resolve 463 lines per mm (232 lp/mm). According to the laws of diffraction, this is impossible for f-stops greater than approximately f/3.24. (1500/463 = 3.24). That doesn't give you a lot of depth of field to work with, if you want to resolve all of those pixels. And you don't have a bellows design capable of tilts and shifts, as do 4x5 large-format cameras, so that compounds the problem.

The practical problem right now is that there just aren't any lenses that resolve 232 lp/mm for normal photographic use. There are some very specialized lenses that deliver many hundreds of lp/mm. e.g., the 28 mm f/1.8 Ultra-Micro-Nikkor resolves about 600 line-pairs per mm or 1200 lines/mm: http://www.naturfotograf.com/lens_spec.html/. The conditions under which the lens resolves that many lp/mm are very limited, however (macro only, at a very specific magnification).

It just requires that everyone have a flash plugin or browser capable of using flash. Too bad the iPad doesn't support Flash (well, one good thing about Apple).

This is silly and overly dramatic. The market has tended to favor moves towards open web standards.

and what CMS would you recommend that has been security tested by an outside firm? One that is as general-purpose as CMSMS?