[aurele]

They should better spread DC motor in all their lenses first.

[Na Horuk]

Well we know how Pentax SDM has worked out.. also, I like that lenses have a very long life. I don't want them to have a machine in there that breaks, needs maintenance, batteries.. I think the in-body AF is a much more elegant solution, especially when considering legacy lenses. The only "problem" is that it tends to be loud..
But I'd rather have AF problems with a body and just replace that, than have to replace it in individual lenses all the time.

[aurele]

also, I like that lenses have a very long life.

That's all we all want : that our current lenses can live as long as the Takumar

[Mistral75]

That's all we all want : that our current lenses can live as long as the Takumar

Sweet dreams...

My father's 1973 SMC Takumars are functioning like on day one. I very much doubt the 2008 DA* 16-50 and 2009 DA* 50-135 will last as long...

[aurele]

My father's 1973 SMC Takumars are functioning like on day one.

lenses from my dad too !

I very much doubt the 2008 DA* 16-50 and 2009 DA* 50-135 will last as long...

i couldn't say it better. Same for DA*55 i think.

[Rorschach]

I have not bought a single Pentax SDM lens and likely never will. Quality control has to be better in that price range.

[ElJamoquio]

lenses from my dad too !

Ha! I didn't even know my dad EVER had a decent camera, and he pops out a lens that works on mine.

[Anvh]

I have not bought a single Pentax SDM lens and likely never will. Quality control has to be better in that price range.

Discrimination, the primes don't have a problem

[aurele]

I have not bought a single Pentax SDM lens and likely never will. Quality control has to be better in that price range.

the DA*55 feels quite good, and i'm less afraid about the SDM issue on it. That said, god, it's not fast !

[Anvh]

44mm, AFAIK. And I don't think the space between the back end of the mirror and the sensor (this space would include the shutter and some clearances needed for it and for the mirror mechanism) can be scaled, yet you included it. Also, there is the distance between the flange and the lens back element (it protrudes a little bit), which AFAIK is included in the registration distance and cannot be scaled.
What you can actually subtract from a FF mount is the difference between the frame heights, i.e. 24mm - 15.7 mm. So around 8mm.
Again: can you show me how those 8mm would bring such a tremendous advantage (compared even to allowing the lens to protrude 8mm further into the mount) that would offset losing all their customers?

P.S. Yes, Olympus was quite busy talking about "telecentric" lenses when they launched the 4/3... as if it couldn't easily be implemented on the "obsolete", "film" mounts. But after the 4/3 failure and the birth of m4/3 they forgot everything about it

Canon FD use 42mm that's FF so the mirror is 34mm long, heigh however you want to call it.
APS-C mirror is 22mm long so that's already 12mm difference, 50% more then you say and this only by looking at the mirror.
So cannon FD mount but instead of using 34mm mirror we use 22mm mirror, and all of a sudden we have 12mm room to move the register from 42mm to 30mm.
Any flaws in this that will account to more then 1mm differnce?

Again: can you show me how those 8mm would bring such a tremendous advantage (compared even to allowing the lens to protrude 8mm further into the mount) that would offset losing all their customers?
good luck to you to proofing that it doesn't and i never talk about customers, i only said it could be a possible other direction to take to compete with FF instead of getting a FF sensor.

[ElJamoquio]

Huh? That doesn't make any sense to me. Are you trying to minimize the mount diameter? The height of the mirror is the more-critical dimension for the register distance.

[Anvh]

I'm half pulling your leg (kidding) - but seriously, the oft-stated reason to shorten the register distance (beyond your arguments about aperture benefits using APSc sensors) is to make the camera thinner, lighter and smaller, IOW pocketable. Is there enough benefit to 10-15mm (which then won't compete with the thin MILC's) to make it worth it?

I quite simply cannot hold these small cameras stable and don't really understand how others do it. I compare my K-01 to an MX - M50/1.7 and it compares favorably, for me. There's enough area on the bottom to palm-cradle the camera by its base and enough mass to brace my arms against my sides and stabilize the camera.

Now if I really want a small, light, mirrorless, high-IQ camera with a shorter register distance I can get a Q - or one of the other brands.

I just can't get my head around why Pentax should invest the time, money, marketing and relationship risk in yet another new mount.

I doubt it will make much difference in actual use but on paper it could look more marketable.

And developing a FF camera with a new FF lens line is less risk then developing a APS-C camera with a new mount and a new lens line?
Both have their risk and i know that some say that APS-C has more future then FF with the advances we are seeing now.
So yeah what makes sense... make APS-C system that can compete with Canon and NIkon FF or get a FF camera.
Both have their advantages and disadvantages, i know i'm not the only one here that a new mount might be beneficial, if it's better then FF camera, i don't know do you?

No, they reach as far back as they can without hitting the mirror (on an FF camera in the Pentax case, which could be changed). Moving the mount backwards means the lens can not go as much behind the mount, the distance to the sensor is unaffected.

Depends on the lens and the aperture, if you want a large aperture with for example the 85mm then it will never fit inside the K-mount.
Not sure if 50mm lenses go into the mount or not.
Beside that with new technology you can make a mirror that doesn't move.
Think about SLT of sony but then DSLR and with mirror that can change his state.
Electrochromic mirror they are called, i'm not sure how fast they can switch at the moment but if it's the same as electrochromic glass then there might be something in it.

Beside that the shutter can be replaced with LCD shutter, they can't reach 1/8000 but 1/1000 so not real improvement in that sense but it eliminates 1 more moving and this is your new x-sync shutter speed.
This might be great for the next 645D maybe, eliminating the large shutter will reduce vibration a lot.

You need a wider mount for very fast lenses, but since Pentax makes no lenses that reach the limit of the current mount that hardly seems like something they consider a problem. (But per my argument above you don't need it closer to the sensor, but you may want it for other reasons, like thinner cameras.)

The 50mm f/1.2 does and the 85mm f/1.4 and most likely also the very long primes and zooms.
But those are FF lenses, now if you want a FF equivalent of those lenses on APS-C what must you do then?

Canon actually has a slightly larger minimum distance between the sensor and lens than Pentax, it's just the mount that is closer. (Lots of M42 lenses hit the mirror on the 5D, but do not on any Pentax cameras (including old FF film cameras).)

thanks for that info, what mount are you talking about?

[Anvh]

Huh? That doesn't make any sense to me. Are you trying to minimize the mount diameter? The height of the mirror is the more-critical dimension for the register distance.

huh?
Like you say the height of the mirror is the more-critical dimension for the register distance and i calculated that... well not the height but the length of the mirror inside the mount when it's up so that's the maximum clearing the mirror needs to function.

[Rorschach]

Discrimination, the primes don't have a problem

Maybe, but I've got the primes pretty well covered by older quality lenses already. The 16-50mm would have been perfect for me, without the qc problems of course.

[Rorschach]

the DA*55 feels quite good, and i'm less afraid about the SDM issue on it. That said, god, it's not fast !

Ok, but I already have the focal range covered pretty well :-)