Consequently, we rarely need anything greater than 40 lp/mm unless we are doing close up work.
Agreed! This is probably why a 1.4x converter on my 100-400 zoom focussed at infinity serves no purpose. There's nothing reaching the lens that's beyond the Nyquist limit of the sensor. Dust, water vapour and the general distortion of the atmosphere is filtering or blocking the very fine detail. However, train the lens on a test chart 20 or 30 metres away and the superior resolving power of the lens plus converter becomes very apparent.
I think that the SNR of the CMOS is so low that this provides a much higher contrast than Velvia at a slightly lower resolution and if we cannot see much more than 40 lp/mm (Erwin Puts), we sure can see the higher contrast and hence the picture appears to have a much higher detail. For example the MTF curve for Velvia shows a contrast of around 60% at 40 lp/mm and I think the percentage contrast transmission of the 1Ds CMOS must be in the high 80’s or 90’s, or maybe more.
Agreed again, but whether or not we see much more than 40 lp/mm depends on the size of the print, doesn't it? Erwin Puts would no doubt have laughed at the idea of making a 22"x33" print from 35mm, but that's the same degree of enlargement as a Super A3 size print from the D60's 22mmx15mm sensor.
I've recently been using my Canon 50mm F1.8 as a portrait lens (on the D60 it's 80mm). With a Speedlite 220EX in conjunction with a Metz 45 CL-1, I've been able to take fully exposed head and shoulder portraits at F8 and 180th sec, indoors. I'm amazed at the clarity of individual strands of hair on some of the 13"x19" enlargements on Epson Premium Gloss. In fact, I had an uncanny experience whilst gazing at one particular enlargement of a lady with flowing, platinum blonde hair. It appeared for a fleeting moment there was hair lying on the surface of the print, fallen from my own head or wherever. I reached out to brush it away and realised it was part of the image. (No, I definitely wasn't drunk.)
40 lp/mm on the sensor translates to less than 2 lp/mm on a 22x enlargement. These prints look a lot sharper than that. When I get back to my studio, I'll see if I can measure the width of some of these individual strands of hair. (I've never tried doing something like this before. I suppose the best way would be to make a much bigger enlargement from a small crop so I can take a ruler to it.)