You may stop thinking about resolution and start thinking about sharpness. These terms are loosely related. The reason is that what human eye and brain perceive as sharpness is the difference in dark and light on tiny details. A good measure for that is MTF. It seems that much research suggest that an MTF of around 50% is pretty relevant of for our perception of sharpness.
Now, according to data from Fuji and others Fujichrome Velvia (which happens to be the sharpest slide film for common use ever made) achieves about 50 lp/mm at 50% MTF, this is pretty close to the 40 lp/mm you mention. Now, multiply this with MTF for the lens. Leica has a design target 50% MTF at 50 lp/mm. If we multiply 50% with 50% we get just 25%. So we could suggest that a well designed Leica lens achieves at least 25% MTF at 50 lp/mm, because MTF drops rapidly with increasing lp/mm we may assume that a Leica lens may achieve 50% MTF at 40 lp/mm. So if you take the best lenses, designed for 135 and the best slide film you may get to 40lp/mm. A medium format lens designed for film may not get even close!
Sorry this is simple math.
You may check Norman Koren's website for more information, it's really excellent: http://www.normankoren.com/Tutorials/MTF.html
The situation may be somewhat different with print film or black and white. Especially T-MAX 100 has excellent MTF characteristics and T-MAX 100 with the very best lenses may achieve phnatastic sharpness. But this comparison is Velvia on a Pentax 67 agains full format digital.
Now, that awful scan will probably enlarge just fine to something at 70x100 cm, I know because I have done it. It's good enough to impress professionals who have worked with every format from 135 to 8x12". (I have two good friends who have worked at two of Swedens top professional photo labs and they are impressed). The print I made were printed on Durst Lambda at 200 LPI, which the lab recommends above A3 size prints.
The scanner I use is known for a bit harsh reproduction characteristics. There is a special adapter made to make it softer.
Regarding 3180 lines I don't know. If you are looking at resolution charts they can have something called false resolution, or contrast inversion wich give to high values. This is related to aliasing. If a program like Imatest is used it may indicate that MTF is above 50% at the Nyquist limit. the figures I have achieved are:
Sony Alpha 900, with SONY SAL 24-70/2.8 ZA at f/8 and 100 ISO: 2890 LW/PH at 50% MTF
Pentax 67 with Pentax 90/2.8 at f/8 on Velvia with Vuescan and sharpening: 2127 at 50% MTF
Based on film characteristics and MTF data on MF lenses it seems that the 67 figure is in the ballpark. That calculation ignores MTF in scanner and shrapening, however.
Here are my complete findings: http://188.8.131.52/ekr/index.php/photoa...-sony-alpha-900
Please note that the above are based on a different shot with Velvia 100.
Never had a Pentax 67, but these 6x7-scans look awful and I don't think they do the mdium film justice! A 6x7-slide/negative has to resolve only about 40lp/mm to match a 24MP-DSLR!
This one looks better: http://www.rockgarden.net/download/60MP_from_6x7/
"...the D3X captured an off-the-charts Excellent 3180 lines. The only DSLR to beat it: Sony's own Alpha 900, whose 24.6MP sensor tested at 3230 lines...an average of 3,397 LW/PH..."
What are they measuring here?
P.S. The theoretical (unreachable) max. resolution of the D3X/A900 is 3024 linepairs!!!