[Ole]

Rumor had it that Pentax would create compact lenses specifically designed to work with the mirrorless K-01. Pentax has released an image which illustrates this new design where the rear elements stick into what used to be the mirror box!

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[Docrwm]

Perhaps this is why there was so much initial confusion regarding the 40XS and its fit on dSLRs? Do we KNOW that this will not work on dSLRs or is it also surmise based on the pictures?

[RioRico]

The following is untainted by actual new information, merely old knowledge and raw assumptions.

My old knowledge is that 1) the Pentax register (flange focal distance) is 45.46mm, and 2) there's about 12mm between the camera mount and the edge of a swinging mirror. Let's say we leave a couple mm safety margin. This means PK lenses could theoretically be as short as 35mm with no retrofocus elements needed.

My major assumption: Pentax-Ricoh won't make K-mount lenses that will stick so far into the mirror-box area that a SLR mirror will be fouled or damaged. To do so would totally screw-up Pentax's famed backwards compatibility. Another assumption: Pentax lens design engineers take a conservative approach to fittings. That means, adequate safety margin, and no radical designs.

Based on all the above, I don't expect any XS lenses that would be unusable on a K1000 let alone a K5. And I *do* expect some XS lenses that extend a little deeper into the body, but no more than 10mm. How soon for these? Other than a cheap 50mm, no others are on the lens roadmap. Therefore wild-ass speculation will proliferate for years. Y'all have fun now!

[thibs]

Well any DA lens is for all intend and purposes is useless on a K1000 anyway...

[konraDarnok]

Pentax-Ricoh won't make K-mount lenses that will stick so far into the mirror-box area that a SLR mirror will be fouled or damaged. To do so would totally screw-up Pentax's famed backwards compatibility.

New Pentax bodies typically offer good backwards compatibility, but that's not really true of the lenses -- whether they don't cover the image plane or lack aperture control. I'd say the XS series is the beginning of the end for SLRs in the K mount.

I know people keep hoping for "full frame," but do they really expect Pentax to maintain 3 separate incompatible K mounts? XS, DA, and D-FA? In addition to their 645D and the Q lines?

The XS however, will take all lenses -- and a 'pro' version, unlike the K-01, would have nice big bright eye-level EVF.

[monochrome]

New Pentax bodies typically offer good backwards compatibility, but that's not really true of the lenses -- whether they don't cover the image plane or lack aperture control. I'd say the XS series is the beginning of the end for SLRs in the K mount.

I know people keep hoping for "full frame," but do they really expect Pentax to maintain 3 separate incompatible K mounts? XS, DA, and D-FA? In addition to their 645D and the Q lines?

The XS however, will take all lenses -- and a 'pro' version, unlike the K-01, would have nice big bright eye-level EVF.

I keep thinking if XS lenses would realy be struck by a mirror swing, wouldn't Pentax modify the lens mount so it could only mount to a clear body (it would be KAF3)? What would keep me from accidentally mounting some DA**XS to a K10D?

Say, put a pin on the lens mount or change a bayonet so XS lenses can only mate to KAF3. No indication of that so far.

[Blue]

Herein lies the problem and source of the confusion. PentaxImaging states this about the 40XS.

PENTAX KAF mount is compatible with current and past K-mount compatible cameras.

PENTAX - smc PENTAX-DA 40mm F2.8 XS Lens

There is similar info on the BH and Adorama sites about it. Is this info correct or wrong? PentaxImaging is an official Pentax entity and they better be correct bofore someone screws up a mirror etc.

Plus, here is the pic of it form PentaxImaging

[Kunzite]

There is another possibility. Pentax could re-design the mirror mechanism so an APS-C camera won't require the same mirror clearance as a FF or a current APS-C model. In other words, they could do exactly what Canon did.
That lens doesn't seem to protrude that much into the mount. Without precise measurements it's impossible to say, but IMO it's definitely plausible.

[konraDarnok]

I keep thinking if XS lenses would realy be struck by a mirror swing, wouldn't Pentax modify the lens mount so it could only mount to a clear body (it would be KAF3)? What would keep me from accidentally mounting some DA**XS to a K10D?

Say, put a pin on the lens mount or change a bayonet so XS lenses can only mate to KAF3. No indication of that so far.

Dunno, but the picture of the TBA XS in this thread sure looks like would interfere with the mirror. My informal measurement produced 7mm from the inside of the flange before the mirror gets in the way. If Pentax is just pushing the mount to the limit like the Canon EF-S why didn't they release XS lenses before the K-01? It seems to me, they are not going to be backwards compatible with SLRs.

[DreTAX]

When i first saw that lens i did a quick measure of the mirror box and came up with 10mm for lens designers to work with to safely, so i have to agree with Rio Rico.This one looks like a redone 15 f4. The idea of the XS lens for the K-01 seems to be just to shrink size and create - XS - extra sales of reworked lenses for those of us who can't resist the smaller version. After all a K mount lens is a K mount lens!

[Smolk]

Based on the distance scale visible in the image of this lens I would say it is about a 30mm. Which is what I would expect.

[Docrwm]

Herein lies the problem and source of the confusion. PentaxImaging states this about the 40XS.

PENTAX - smc PENTAX-DA 40mm F2.8 XS Lens

There is similar info on the BH and Adorama sites about it. Is this info correct or wrong? PentaxImaging is an official Pentax entity and they better be correct bofore someone screws up a mirror etc.

Plus, here is the pic of it form PentaxImaging

We're not talking about the 40XS - it's been pretty well established that it will work on the K-5 by the Singapore Pentax Group. We're talking about the ADDITIONAL K-01 lens pictured at the start of this thread, for which there is some reason to believe it may not fit. We just don't know and won't until it is unveiled at CP+ or loaned to a Pentax group like happened with the 40XS in Singapore.

[monochrome]

Dunno, but the picture of the TBA XS in this thread sure looks like would interfere with the mirror. My informal measurement produced 7mm from the inside of the flange before the mirror gets in the way. If Pentax is just pushing the mount to the limit like the Canon EF-S why didn't they release XS lenses before the K-01? It seems to me, they are not going to be backwards compatible with SLRs.

IMHO they would be pretty damned irresposinble to not make an XS lens unmountable on a legacy K-mount camera. Think if your K-5 mirror struck the rear element of an XS lens - it isn't a legacy body just yet.

Pentax could easily add a pin or flange to the XS lens mount to make them unmountable in legacy K-mount bodies, and modify the K-01 body mount (and any subsequent body) to allow XS. I don't see a special slot or hole in the K-01 images.
Would that then be a KAF3 mount?

There's no indication of anything like that yet.

So "designed especial;ly for K-01" might just mean very shallow. Remember, body size only really matters when a lens is attched - and our entrant will likely be smaller - even with a stocky body - the the other guys' entrants are with their elnses attached.

[Blue]

We're not talking about the 40XS - it's been pretty well established that it will work on the K-5 by the Singapore Pentax Group. We're talking about the ADDITIONAL K-01 lens pictured at the start of this thread, for which there is some reason to believe it may not fit. We just don't know and won't until it is unveiled at CP+ or loaned to a Pentax group like happened with the 40XS in Singapore.

Duh, or I would have linked it. However, it would be odd for them to put out several XS lenses with some of the compatible with mirrors and some of them not. I would expect similarities in the mounts among the XS series. That was the point. The registration distance is the same.

Edit: Why don't you Singapore folk post some test images with 40XS and a dSLR for us backwoods hicks.

[sveinmb]

IMHO they would be pretty damned irresposinble to not make an XS lens unmountable on a legacy K-mount camera. Think if your K-5 mirror struck the rear element of an XS lens - it isn't a legacy body just yet.

I guess it was just pretty damned irresponsible by Voigtländer to create the 12mm f5.6 and the 15mm f4.5 for Nikon f-mount then. Not to mention Nikon with their own 6mm, 7.5mm, 8mm and 10mm fisheye lenses..