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05-12-2016, 10:21 PM - 1 Like   #271
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QuoteOriginally posted by distudio Quote
I promise to post pictures.
Pls do.

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05-13-2016, 12:07 AM   #272
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QuoteOriginally posted by noelpolar Quote
My 70-200/2.8 OS HSM is pretty close...... but usable

I can see a small gap between the mount rings at the top, but that is obviously not giving you any functionality problems since you say "usable".

---------- Post added 13-05-16 at 09:28 ----------

QuoteOriginally posted by Mock Quote
I also want to add that Adaptall-2 mounts, and their matching mirror lenses (eg. 55B) are no problem.

That is good to hear
05-13-2016, 01:27 AM - 1 Like   #273
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QuoteOriginally posted by Bengan Quote
I can see a small gap between the mount rings at the top, but that is obviously not giving you any functionality problems since you say "usable".
Glad to see it's usable, but the gap may well allow dust grit or water to get in a bit easier than before, and there must be some pressure where there should be none. Who knows what that could lead to in the future, so it's not *only* a cosmetic 'scratch' issue as Sigma imply. Glad they seem to be willing to provide a fix, and though the announcement doesn't explicitly say it will be a 'no charge' fix, I would expect that to happen.
05-13-2016, 01:30 AM   #274
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Has anyone tries these Sigmas on K100D ? Maybe Sigma have not tested these lenses even with all the previous DSLR models.



05-13-2016, 01:46 AM   #275
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QuoteOriginally posted by Dave L Quote
Glad to see it's usable, but the gap may well allow dust grit or water to get in a bit easier than before, and there must be some pressure where there should be none. Who knows what that could lead to in the future, so it's not *only* a cosmetic 'scratch' issue as Sigma imply. Glad they seem to be willing to provide a fix, and though the announcement doesn't explicitly say it will be a 'no charge' fix, I would expect that to happen.
That minute gap will also create focus consistency errors across the frame, particularly in the case of wide angle lenses. That's my concern, not so much the sealing issue.
05-13-2016, 02:13 AM - 1 Like   #276
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QuoteOriginally posted by distudio Quote
That minute gap will also create focus consistency errors across the frame, particularly in the case of wide angle lenses. That's my concern, not so much the sealing issue.
True, that's the kind of thing I was hinting at by 'pressure' and 'who knows what?', slight body or lens mount distortion is possible too, slight loosening of the mounted lens on other cameras or in the future, tiny bits of scraped plastic getting inside the lens or body, who knows what. But I'm sure some people are willing to take the risk as none of this is certain or for them is insignificant.
05-13-2016, 02:31 AM - 3 Likes   #277
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Wow. This thread took a turn over the last 24 hrs; arm waving, screaming and at one point I think I even saw a semi-naked woman rolling down my screen!

QuoteOriginally posted by distudio Quote
LOL, plainly you're not an engineer


A scratch is interference. Interference is contact pressure. Contact pressure imparts bending moment. Bending moment creates unforeseen stress. Stress is always accompanied by deflection.

Send it to Sigma, file the lens mount or dremel the DLSR. Personal choice, but the fundamental problem needs to be dealt with - discount and ignore at your own risk.

(In defence of distudio, I personally wouldn't dremel the body but that's just me. The cutaway image suggests the skin is cast, not pressed and the existing little groove is cold machined. His suggestion is not invalid, just dependant on operator competency and accepting some risk.)


Last edited by jawsy; 05-13-2016 at 02:43 AM.
05-13-2016, 03:56 AM - 1 Like   #278
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QuoteOriginally posted by jawsy Quote
A scratch is interference. Interference is contact pressure. Contact pressure imparts bending moment. Bending moment creates unforeseen stress. Stress is always accompanied by deflection.
QuoteOriginally posted by distudio Quote
That minute gap will also create focus consistency errors across the frame, particularly in the case of wide angle lenses. That's my concern, not so much the sealing issue.
QuoteOriginally posted by Dave L Quote
Glad to see it's usable, but the gap may well allow dust grit or water to get in a bit easier than before, and there must be some pressure where there should be none. Who knows what that could lead to in the future, so it's not *only* a cosmetic 'scratch' issue as Sigma imply.
All good points. In 2016, Japanese engineering shouldn't allow these problems to develop.

BTW, as Barry Pearson has found on the other forum, it's not just some Sigma lenses being crowded off the K-1 mount. His K-mount Samyang tilt-shift was also experiencing some issues tilting across it's full range on the K-1 too.
05-13-2016, 03:59 AM - 1 Like   #279
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To summarize all discussion...

The problem is simple - Sigma even can't produce mount ring for K-lenses under specification - not wider than 65 mm (max. diameter),
never checked the real diameter of real Pentax cameras - 58.5-59 mm, doesn't pay any licence fee to Pentax.
05-13-2016, 04:09 AM - 1 Like   #280
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QuoteOriginally posted by ogl Quote
The problem is simple - Sigma even can't produce mount ring for K-lenses under specification - not wider than 65 mm
It's not that simple. Not all lenses - even Pentax-made lenses - are 65mm diameter tubes pointing straight out from the mount. Most grow wider than that as they leave the mount.

And over the years, Pentax has progressively reduced the flat, unobstructed space available over the top of the mount ring, from about 1cm in the case of the 'old' K-1, down to about 1mm in the case of today's K-1. Thereby causing problems for lenses that are fatter than 65mm as they leave the mount.

The ever-increasing Pentax pentaprism overhang above the mount further complicates the situation for some K-mount lenses that need 'room to move' when mounted on the camera.
05-13-2016, 04:21 AM - 1 Like   #281
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QuoteOriginally posted by rawr Quote
The ever-increasing Pentax pentaprism overhang above the mount further complicates the situation for some K-mount lenses that need 'room to move' when mounted on the camera.
I'm sure a few Tamrons will be affected too. I have the 28-75 f/2.8, and on my K-3 / K-3II it's tricky to get at the aperture ring release button if, for some reason, you want to switch out of auto-aperture mode and select it manually. I can only guess it'll be trickier still on the K-1...
05-13-2016, 04:22 AM   #282
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QuoteOriginally posted by VoiceOfReason Quote
You need a DFA 150-450 Rupert, and I need the subject of your last picture.
I am the subject of Rupert's last pic!
05-13-2016, 04:26 AM   #283
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QuoteOriginally posted by rawr Quote
It's not that simple.
But Sigma makes 65.7 mm... Anyway, it's not Ricoh's problems and it's Sigma's risks.
05-13-2016, 04:39 AM - 2 Likes   #284
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QuoteOriginally posted by BigMackCam Quote
it's tricky to get at the aperture ring release button if, for some reason, you want to switch out of auto-aperture mode and select it manually.
I think you may have hit upon why Pentax have been shrinking down the space above the lens mount over recent years - they stopped making lenses with manual apertures long ago.

Since all they produced were DA lenses with no manual aperture control, they felt confident that they could save a bit of space in that area of the lens-body interface without impacting usability or lens operation.

They didn't, however, study the market carefully enough, particularly the lenses customers were using, nor the K-mount lenses 3rd parties were producing - many of which were designed on the historical assumption of a certain amount of free space around the mount.
05-13-2016, 04:47 AM - 2 Likes   #285
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QuoteOriginally posted by braver Quote
So the fun part of this, before D-FAs, I was eyeing the Sigma Art lenses as the next LBA target. Now I can safely wait until they produce the new batches that are K-1 safe. There will be a whole new market, and every Sigma transaction will be accompanied with a clarification: this lens is made after K-1 Sigmacalypse, it's safe on K-1!

A+
This is such an overblown issue. At first I couldn't even see the mark. Then the light hit it just right an I can see the shinny line the width of a human hair and about 3mm long where the lens is touching the body. I will send my Sigma 50mm lens into Sigma for new mount because I want it calibrated and the firmware updated in the process. My 85mm has always been my fastest and most accurate lens and I don't really want them to touch it. Since most of the people who bought the K-1 and own Sigma had already tested the Sigma lenses on our bodies, we already have the cosmetic mark, so sending my lenses to Sigma really wont matter at this point.
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