noone

And yet if you look at the new Sony 135 1.8 lens, there are any number of anti-Sony people posting on THAT. Go figure.

Not sure what you mean by that? A M43 150mm 2.8 lens would be the same as using a MF 150 2.8 lens if both used on a GH5 for instance (assuming you could find such lenses). The difference would be the individual lens quirks but not how bright an image is or DOF. Using a focal reducer on the MF lens will change the lens effectively but then it would just be the same as another M43 lens (again, assuming there is one). The 15mm Body cap "lens" can be fun but it isn't something I would want to use very often. Better thought of as a body cap you can shoot with rather than any real lens. It was more fun for me using it with a FF Sony A7s with a bit of clear zoom to remove the vignetting (and no different using it since it is focus free - three positions plus off). Still they can be found really cheap after people have tried them and put the away. Not something I regret selling (unlike the GX7) though it was fun at times.

Of course there is Mattias. I just don't think you can say a lens is better (or worse) because it is made for one particular format. Some people will like using MF lenses on smaller formats but not BECAUSE they are MF lenses. I am getting to the point with all the hundreds of lenses I have owned over a few decades I could happily get by with just four to six or so. That would include a Canon 17 f4 TS-E, Sigma 150 2.8 (Canon mount) an ancient 300 2.8 manual focus lens adaptall (interchangeable mount) with the rest being less important but maybe used more often. There are actually some others I want to keep (FD 24 1.4 L for instance and Sony FE 55 1.8 but I can not use those right now). Adapting lenses WAS/IS fun (at least for me) but I have reached the point I am happy with the lenses I have (if not the cameras since my A7s died).

Didn't say don't do it. Again, it IS fun and you can find lenses you like for sure, I am sure some will prefer the look they get but that isn't BECAUSE they are medium format lenses but rather because they like those particular lenses. My point is that if you want a fast lens for instance, you have MUCH greater choice using FF lenses than you do using MF lenses (and even with a focal reducer). Tilt shift adapters ARE a valid reason for some people and some uses with MF and LF lenses on FF (as they are using FF lenses on APSC and M43). Still, nothing compares to a real tilt shift lens (I guess I have been spoilt by my Canon 17 TS-E and previous 24 3.5 L TS-E ii). Those Mamiya lenses of yours are not going to give something that isn't readily available with FF lenses (with or without a focal reducer) other than some tilt/shift (when using the FF lenses on a FF camera) though there are plenty of different TS lenses available now. It is simply there are far more lenses available for FF than larger formats and larger format exotic lenses have even more exotic prices than anything. For what it is worth I am now too poor to experiment much further but I have tried adapting just about anything. IE, many different lenses even on a Pentax Q (like a Canon FD 85 1.2 on a Q or 300 2.8 on a Q), or mounting Nikon lenses bare on Pentax cameras (do that at your own risk but if careful it does work for older lenses).

How do you pull focus?

While adapting and trying different lenses is fun, MF lenses generally don't have anything readily available and reasonably affordable that I would prefer over better FF lenses like Canon FD (especially L's) and some of the better Nikkors and others. Even after using a focal reducer. There ARE some super fast MF lenses I would love to try but I doubt I will ever see any in real life or ever be able to afford them (mostly made for aerial photography) and most others just are not going to be different (even with a focal reducer) to what can be readily found for FF. I do have a couple of Mamiya lenses for my old Polaroid that I would LIKE to try but they are slow. That they have their own shutters is what makes them interesting to me though not something I can use.

That 28 f2 Vivitar is a decent enough lens but to me it has two main issues. Firstly it has a lot more distortion than most 28mm lenses and secondly it often gets stuck blades. I had two and one did have the blades stuck together while the other was ok. I used it a fair bit but was not good with people close in due to the distortion.

Just go back a few years and see all the negative stuff about Sony and why Canon and Nikon were ever so much better. Now, the SAME things from Canon and Nikon are like, meh, so what. Nah, they are all as bad as each other. (Currently I do not have a working Sony camera and I have four working Canon cameras among others but I would still prefer a Sony for MY uses).

It costs more but the nicest fast lens I have had in the 50-60mm range was the FD 50 1.2 L which is different to almost all those fast lenses in having a hand ground aspheric element (the ultra expensive Noct Nikkor did as well). That could be converted I think.

Depends on what you mean by a high end lens and what they are designed for. I would not expect "character" in a higher level macro lens but in a portrait lens, sometimes yes sure. Sigma has come a long way in the last few years. I have had a few that were not so good (one was about the best built lens I have had but was worse than a coke bottle optically - some weird 200mm lens from decades ago), Sigma lenses had the same importer to Australia as Pentax so Sigma zooms were often Pentax kit lenses here. That said, even though it isn't an art lens, the 150 2.8 APO macro (mine is the older non stabilized version) is one of my favourites and I have liked using it on M43 Panasonic, FF Sony and for now I even use it on a Canon APSC (EF mount). An ancient 180 5.6 APO macro wasn't all that horrible either.

That is generally the case. Pentax did make a mirrorless with the K mount but that is probably one of the main reasons it flopped. An already small user base and at the time , little reason to use K mirrorless instead of a K mount DSLR. https://en.wikipedia.org/wiki/Flange_focal_distance

I would just caution that with many (most?) old lenses your individual copies can be light years different to someone else's exact same lens. Many things will be the same but with old lenses there can be all sorts of issues (let alone if some were not great copies to begin with). Still at least you get to find the lenses that YOU like.

Is it really lighter than the original A7/A7R? Does the weight include batteries and card? I have seen a couple of different weights mentioned (485 with battery and card which would put it a little more) but it will be close either way.

Both those seem to have a bit of a 3d thing going to me which is down to the subject having DOF covering the toy and the background being empty for quite a distance behind. There are other issues that make me not like either of those lenses wide open (from that anyway). Stopped down and they are both ok (and both fast enough and long enough to easily separate the subject from the background). I have had many lenses from 50 to 58 and they all had their for and against and all could make "3D" type images easily but most were not great wide open. The four best I had were/are the Sony Zeiss 55 1.8 (ended my desire for any other normal lens really), Canon FD 50 1.2 L (loved that lens and regret selling it) Both those use aspheric elements- then the Pentax 50 1.2 (I used it so much for so many years it literally fell to bits even though it was a solidly made lens) and the Nikon 50 1.8 AF non D made in Japan (the best cheapie). The worst but one of the most interesting was an ancient Zeiss Jenna Biotar 58 f2 that had 18 blades and was sharp but very low contrast. Other people would have preferred the old Biotar to the others I think- IE it is all subjective. I had an old 55 Tak and didn't think it was all that good (I threw it away from memory when it got stuck on some bellows).

I do think that alone is a major reason many are hating on it. I am too poor these days to afford anything but if I wanted a 4k camera, what Canon camera currently could I use this lens on to shoot 4k at 17mm FF angle of view? I can use other brands FF or even use sub FF cameras with focal reducers from lots of makers but from Canon? It will be some time before Canon has a full complement of RF lenses and even then many EF mount lenses will work just fine with adapters.

All I can suggest is taking note of photos and videos that YOU like and asking the photographer/videographer what they used. As for the 3d thing, well to me that is just subject separation and the lenses said to give 3d type results all just make it easier (and most will be faster and tend to be longer or if shorter, used in close). Even a kit lens can give a 3d look with enough space behind the subject though will be a lot harder to achieve than say a 85 1.2 or 300 2.8

Isn't that lens actually a Minolta design?

There is nothing wrong really using FF lenses on crop cameras. It is simply that you do not get the same angle of view. It can be an advantage sometimes even (when you want more "reach"). I just find it frustrating with wide angles sometimes though there are other lenses you can use on crop cameras to get the same angle of view as you would get with a 20mm on FF. Of course, DOF depends on distance to subject as well as focal length and aperture.

Alas, no. It is actually worse as Canon crop is 1.6x and not 1.5x as Pentax, Nikon, Fuji and Sony are. A spacer would just take away infinity focus. Best to use another mount camera that does have focal reducers available. I am using a cheap old Canon crop camera while my A7s is dead and it is frustrating with lenses like my 17 TS-E. I have found a very cheap A3500 that I might get just so I can get a focal reducer for my EF lenses.

Canon, third party lens maker for Sony!

Sure, it is on its way! You should wait next to your mailbox. didn't say it made sense, just that there (almost) is such a thing as an AF 50 0.95 lens or at least it IS possible. You can also AF those super fast lenses on various systems with some AF adapters.

You can always adapt the old Canon EF 50 f1 to M43 (that is less than a third of a stop slower than f0.95).

I can see them selling a few to a small group of pro sports and wildlife shooters who use Canon DSLRs and have some decent long and expensive Canon glass (more so if they have also previously used M43 and know the benefits and limitations). If you add a decent smart adapter (both focal reducer and non focal reducer), you get much more use out of your expensive lenses and can use them on FF, APSC and M43. For some people (wild life shooters with big bank accounts and very expensive lenses), $3000 is not such a big amount to add a large increase in range. For others, it doesn't make a lot of sense though there is a (slowly) growing number of professional photographers who are quite happy with M43. Olympus does tend to put in a lot of value into their gear compared to Canon and Nikon (as do most of the smaller players). Not for me. Not a turkey though?

Almost all recent cameras from everyone seem to have have their operating max temperature listed as 104 degrees F (40 degrees C). There has only been two days in the last seven here UNDER that officially (and in both cases was close enough that it would have been well over for most outdoor situations like roads, concrete yards and footpaths, the swimming pool that used to be my bed ETC). The good news is that there are only three days predicted this week of 40 or more and the rest will merely be 38. Who wants to use a camera in these temps? I am happy to take a camera on a morning walk still but not gonna use one during the day for now. It is funny that some cameras have the max temp you should use the camera in as 40 but the cameras themselves generate heat far above that (would using a camera in over 40 heat void a warranty?).

Fireworks used to be legal in the ACT until fairly recently (2009 or so) I think. Fireworks were legal in Qld when I was a kid but that changed long ago. Cracker night was fun but too many were getting hurt I think.