[davidmanze]

Well, ok... let's see how this works in practice, I have doubts, to be honest.

Regarding non-extending lenses, I do disagree with your statement. Moving the inner lens groups moves air around, but only air that is in the lens already. So, in theory, there should not be any dust.

Practice shows: there is. But a lot less than in extending zooms.

I'm siding with BC here:

If the filter is of the "micro particle size" which is common theses days in the like of modern cars vacuum cleaners etc ......... there should be no problem with dust ....... I had been wondering why a filter had not been added before!

  ......... as for the Canon 70-200mm it's another masterstroke optic for sure ...... but it focus breathes and the Sigma 150mm F2.8 macro doesn't ......... (I've just checked) ........ so I'll use it being the lens I have ....... however, at portrait distances it has a max aperture of F3.2 ...... giving not exactly the shallowest DOF.

   ...... thxbb 12 ......... am I right in thinking you have now gone FF ...... if so which?

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Dunno about service in Europe, but here it should be a no issue, all lenses will need some maintenance over time, like camera shutter aperture and flex cables have a lifespan so I would be more worried about those, besides any lens with frequent use,  will need re-centering, cleaning is usually done for free with those services so I wouldn't worry too much, anyway depending on complexity of design elements cleaning at professional service isn't that expensive. I paid 30$ for for 17-55f2.8 IS, 20$ for 100mmf2.8  macro.

You get all that as part of the service from Canon in the Lebanon ....

  re-centering and all ......

   Wow !

Hey Dave,

I used to shoot FF back then, with a Nikon D800, but I sold it several years ago to go APS-C (Fuji) and MFT (Olympus + Panasonic).
I'm being realistic: for my style of shooting FF is not needed (APS-C with the right lenses is good enough in term of DOF control and the convenience of MFT cannot be matched with FF).

 OK, I  thought you had had a "very discrete" format change ........