The TS-E 24L Mk I is actually a much better lens than it is made out to be. It did (does) things no other lenses can or could do, on Canon anyway, until the Mk II version.
Shifting this lens creates higher quality pictures than similar corrections in post-processing with a non-TS lens of roughly the same era, so its IQ is a bit of a moot point when you need shift (or tilt for that matter).
Furthermore, its bokeh is extremely good for a 24 mm, as unlike with other lenses, and especially WA lenses, sharp OOF edges, such as blades of grass, defocus very beautifully, both in foreground and in background, whereas other lenses will create double lines or blocky bokeh. And this lens creates this very good bokeh at all apertures, even at F/8, F/11, F/16 <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />. BTW, this is true for all of Canon's TS-E lenses.
Pictures taken with this lens also take well to sharpening - it does "see" a lot more detail than one would expect at first, at least IME. It does require a bit of work IOW, but the images it produces are really nice. I've actually used it a lot for (semi-) macro sessions on APS-C, and the neat thing is that with tilt it can focus a lot closer than the official MFD of 45 cm. You can get as close as half that distance without a problem, IME.
When I switched to FF, I started using this lens less, basically because it now became a proper 24 mm, and I used the TS-E 45 for the shots I used to use the TS-E 24 for on APS-C.
Eventually, I sold it, to partly fund a TS-E 17, as I was also looking for a high quality 17 mm. However, lately I find I am missing this lens again, so I am reconsidering, especially as I don't have the budget for a Mk II right now <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />. And the TS-E 24L Mk I seems to go for anything between 650 and 800 euros these days, so with a bit of luck you can find one at a good price.
As to PC only Canon lenses, that may have been some FD or FL glass, although I am sure the last 35 mm incarnation was a TS lens. They can be converted to EOS, BTW, with a bit of work. Due to the distance to the back element, this is not a problem, you just need to be a good technical handyman. This procedure is irreversible, however, if you want infinity focus.
The difference in design and quality between Mk I and II is optics, in the first place, the TS-E 24 Mk II is probably the best lens Canon currently produces, it is very sturdy, with clever independent tilt- and shift - setting options, whereas the Mk I is good for a 24 mm of its period, is no slouch in sturdiness either, even if the Mk II is better, and has TS settings either positioned at 90 degrees (standard setting), or in parallel. And the latter requires a (good quality precision) screwdriver and some careful disassembling and reassembling of the housing of the lens. Easy enough, though, I've done it a few times.
HTH, kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
