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05-11-2016, 10:22 AM   #91
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This "problem" has been going on for years concerning Pentax digital bodies.
Some lenses I own, have come pretty close to touching the upper part, just above the lens mount, on the front of the camera.
To be honest, with every new Pentax body, I look for this space, and it's very close on a number of lenses.

I hate to say it, but this is a Pentax oversight for not anticipating more clearance just off the lens mount.
Some lenses get immediately "fat" just off the lens mount, and Pentax should have given just a bit more clearance.

Sigma seems to have other problems, but this lens-scratch thing, is definitely a Pentax oversight.
I have a Bigma, and I am happy to know I need to be careful or not mount it if I can't live with a little scratch.

Additionally, the pressure to make that scratch, is probably enough to lift the lens mount so the contacts short out, or the camera freezes.
Thus, we now have the mechanical reason for Sigma lenses to be freaking out when they are attached to a K1.

Once you get the scratch/groove, I'll bet Sigma lenses work just fine.

****See my comments below as I learn more about how Sigma lenses have a wider lens mount****


Last edited by LaurenOE; 05-11-2016 at 10:40 AM.
05-11-2016, 10:24 AM   #92
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QuoteOriginally posted by awaldram Quote
Strange everyone of my Pentax lens have almost identical mount diameters that is 12 lens ranging in age over 30 years.
Not the case on this side of the globe My collection ranges a little more time-wise (K, M, A, FA, and recent DA), but I don't know that makes much difference.

I don't have calipers to measure, but eyeballing my Pentax-brand lenses mounted to the K-3 indicates a fair amount of mismatch (never more than 1mm or so +/- at the edge)* from the body flange. Switching to my Super Program and the A 50/1.7 that would have been kit and lens body rear diameter (mount is flush) is a full 2mm greater than that of the camera mount flange. The small diameter of the Super Program mount is readily apparent by noting the position of the A contacts relative to the flange edge, BTW. The K-3 has about 1mm space at that point and sure enough the A 50/1.7 mates to the K-3 almost exactly.

FWIW, I was surprised to see that much variability in body and lens flange diameter. I would have assumed a standard size through most of the range since day zero.


Steve

* The DA 50/1.8 flange is a full 2mm smaller diameter than the K-3 flange, but is a close match on the Super Program...go figure.
05-11-2016, 10:28 AM - 6 Likes   #93
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Nope.
The published Pentax K mount specs from day one have specified a maximum diameter of 65mm. This goes back to the fully open original K mount, reproduced 1:1 here in this Soviet spec sheet.

This maximum has never changed, I repeat never changed on all of the published k mount specs, even the later closed ones. Sigma's non-conformant "K" lenses have slightly wider mounts. They have been able to get away with it in the past due to the fact that Pentax has always previously left a bit more extra room than they do with the K-1. But the fact is, had they actually paid to license the mount and conformed to the spec (or even simply copied the diameter on existing Pentax lenses), they would never have run into the problem.

This is 100% on Sigma.

QuoteOriginally posted by richmondthefish Quote
Its a shame people blame third party vendors for this as if they are fortune tellers. It reminds me of the out lash Adobe got when the retina iMac was released and Lightroom was very slow. Everyone started yelling at Adobe but its not like Apple worked with them so they would have an update so that their software would be efficient with a 5k display. The hip thing is to develop these technologies in secret, release them and let the third party manufactures scramble.
05-11-2016, 10:31 AM - 1 Like   #94
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Pentax made some pretty fat new lenses for the K-1 Yet they fit without scratching. The wide mount plates sigma uses are just lazy design. Should Ricoh have given us an even higher body or a smaller pentaprism magnification to accommodate Sigma lenses? Should they have compromised the design of the K-1 to accommodate sigma lazyness? I don't think so.

05-11-2016, 10:31 AM   #95
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QuoteOriginally posted by dcshooter Quote
Nope.
The published Pentax K mount specs from day one have specified a maximum diameter of 65mm. This goes back to the fully open original K mount, reproduced 1:1 here in this Soviet spec sheet.

This maximum has never changed, I repeat never changed on all of the published k mount specs, even the later closed ones. Sigma's non-conformant "K" lenses have slightly wider mounts. They have been able to get away with it in the past due to the fact that Pentax has always previously left a bit more extra room than they do with the K-1. But the fact is, had they actually paid to license the mount and conformed to the spec (or even simply copied the diameter on existing Pentax lenses), they would never have run into the problem.

This is 100% on Sigma.
Hmmm...If you put it that way, I guess it can be all on Sigma for being just a bit off.
Too bad Pentax came too close with the front of the body.

I'm now 50/50 about this.
05-11-2016, 10:31 AM   #96
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QuoteOriginally posted by gryhnd Quote
I couldn't even notice this last night, but in broad daylight I do see a fine scratch but it's really no big deal at all. All of my main lenses are Sigmas and most are on that list. But this isn't a fatal problem as I see it.
WOW!!

If that's all the problem with the Sigma lenses, i would DEFINETELLY WON'T worry at all !!

Besides, If some really are concerned about the possibility of a eletrical disconnection, I would prefer to chin a little on the sigma mount ratter than let it scratch the body, but to be honest, as a photojournalist, mine actual camera are scratched bit worst than that all over it anyway

Last edited by sungibr; 05-11-2016 at 10:41 AM.
05-11-2016, 10:32 AM   #97
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QuoteOriginally posted by FantasticMrFox Quote
Except Sigma lenses work on all the other manufacturers' cameras, and on all Pentax bodies except for the K-1. I find it hard to see Sigma at fault here, rather Pentax should have tested whether existing third-party lenses fit on the K-1 when they were developing it. They don't have a crystal ball at the Sigma head office.
I don't believe Pentax has any responsibility to make their cameras backward-compatible with third party lenses, especially those that are known to be reverse engineered and thus do not comply with a published design spec. (Interesting there seem to be several Sigma problems, but no Tamron yet).

Pentax never promised anyone K-1 would mount all previous third-party lenses.

I know it is disappointing to people who own Sigma lenses - but that's the risk, I guess

Last edited by monochrome; 05-11-2016 at 10:41 AM.
05-11-2016, 10:34 AM   #98
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Wrong. All but the original manual K mount have been licensable by other companies. Tamron and Tokina, for instance, have both licensed the various KAF mount specs through royalties, codevelopment agreements, and in-kind business arrangements.

QuoteOriginally posted by FantasticMrFox Quote

None of the third party manufacturers pay any of the camera manufacturers licensing fees for their mounts. This is a mutually beneficial relationship - camera makers benefit from there being a large selection of lenses available for their mounts because it draws customers to their system.

.


05-11-2016, 10:34 AM   #99
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QuoteOriginally posted by D1N0 Quote
Pentax made some pretty fat new lenses for the K-1 Yet they fit without scratching. The wide mount plates sigma uses are just lazy design. Should Ricoh have given us an even higher body or a smaller pentaprism magnification to accommodate Sigma lenses? Should they have compromised the design of the K-1 to accommodate sigma lazyness? I don't think so.
If Sigma has played fast and loose with the spec...then they reap the loss.
Sounds like Sigma might need to make a spec'd lens mount as a warranty replacement.
That might be the easiest fix.

Good to hear all the feedback/data.
05-11-2016, 10:35 AM   #100
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QuoteOriginally posted by D1N0 Quote
So how would a lens scratch the body? Is the plastic housing running into the pentaprism housing above the mount?
I've just checked this, since I found it hard to believe. It's not the plastic housing, but the metal ring bearing the bayonet and the contacts. That ring's diameter ist far larger than on a Pentax original lens, and that ring touches the camera body.

On the Pentax 18-55/3.5-5.6 WR lens, that ring has a diameter of a wee bit less than 59 mm.
On the Pentax 24-90/3.5-4.5 it's even smaller with about 58.5 mm.

But on the infamous Sigma 70-200/2.8 II Macro HSM this ring has a diameter of about 65.6 mm.

And this part touches the camera body and --yes, indeed-- leaves a scratch mark.

So there are now two reasons for Sigma to repair that lens.

Other Sigma lenses are slighty smaller, the 70-300/4-5.6 OS DG for instance is about 62.5 mm in diameter, as is the 8-16/4.5-5.6. The 10-20/4-5.6 is even smaller than that.

These measurements are not extremely precise due to the shape of that ring, it's outside is not cylindrical, but with a tapered shape; the smallest diameter is towards the camera, and I've just held a caliper onto it.

But definitively the 70-200/2.8 needs some work with that ring.
05-11-2016, 10:39 AM   #101
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QuoteOriginally posted by funktionsfrei Quote
I've just checked this, since I found it hard to believe. It's not the plastic housing, but the metal ring bearing the bayonet and the contacts. That ring's diameter ist far larger than on a Pentax original lens, and that ring touches the camera body.

On the Pentax 18-55/3.5-5.6 WR lens, that ring has a diameter of a wee bit less than 59 mm.
On the Pentax 24-90/3.5-4.5 it's even smaller with about 58.5 mm.

But on the infamous Sigma 70-200/2.8 II Macro HSM this ring has a diameter of about 65.6 mm.

And this part touches the camera body and --yes, indeed-- leaves a scratch mark.

So there are now two reasons for Sigma to repair that lens.

Other Sigma lenses are slighty smaller, the 70-300/4-5.6 OS DG for instance is about 62.5 mm in diameter, as is the 8-16/4.5-5.6. The 10-20/4-5.6 is even smaller than that.

These measurements are not extremely precise due to the shape of that ring, it's outside is not cylindrical, but with a tapered shape; the smallest diameter is towards the camera, and I've just held a caliper onto it.

But definitively the 70-200/2.8 needs some work with that ring.
well luckily sigma said this:
QuoteOriginally posted by Sigma:
We are planning to provide a repair service for this issue. We will make a further announcement on our website when specific details, such as the service period, are finalized.
In addition, please also refer to the usage notice related to this announcement below.
Whether they will do it under warranty remains to be seen.
05-11-2016, 10:40 AM - 1 Like   #102
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I joined the Pentax Community because of the durability and ruggedness of their cameras and lenses... (oh, and this awesome forum... But that's a given!)
I've held "prosumer" bodies from Canon and Nikon and Sigma and they all felt cheap to me.
Pentax cameras have a heft to them that I like, a feeling of ruggedness and durability...

If you compare it to cars, the same goes for Jeep...
People used to buy Jeep Wranglers for their ruggedness and simplicity. It's a vehicle that's supposed to get dinged up and scratched up and dirty (IMO).
I used to hear this all the time, "If it's not dented and scratched up and muddy, you're not driving it the right way..."

I think the same applies to our Pentax, right?
05-11-2016, 10:40 AM   #103
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QuoteOriginally posted by D1N0 Quote
They widened it for WR.
...and narrowed it for the A-series bodies (M too?) as compared to K-series...

I have known for years that the mount flange on my Ricoh film SLRs was different than my Pentax bodies of the same age, but would not have guessed that Pentax fiddled with the mount from model to model. What I take from this is that it is not wise for me to assume things about the lens mounts.

BTW...are you sure about widening for the WR? If so, I would expect a different flange diameter for the *st-series bodies vs. the 2006-2007 era K-series dSLRs (designed to work with the original DA* zooms, Pentax's first sealed lenses).


Steve
05-11-2016, 10:42 AM   #104
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QuoteOriginally posted by LaurenOE Quote
Additionally, the pressure to make that scratch, is probably enough to lift the lens mount so the contacts short out, or the camera freezes.
Thus, we now have the mechanical reason for Sigma lenses to be freaking out when they are attached to a K1.
You are quite possibly correct. If the lens does not mount cleanly, all bets are off in regard to control and power transmission.


Steve
05-11-2016, 10:56 AM - 2 Likes   #105
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QuoteOriginally posted by FantasticMrFox Quote
rather Pentax should have tested whether existing third-party lenses fit on the K-1 when they were developing it.
Pentax should design their camera around their competitors' lenses?
You're joking, right?
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