[Gimbal]

To be fair Pentax hasn't released any FF bodys with IBIS yet, so saying that it is proven isn't really right.

But saying that Fuji don't have IBIS because of image quality reasons is absolutely backwards.
That means they prefer an image with blur all over the entire frame, which is totally useless, instead of an image which (in worst case) has one or two corners slightly darker then normal. For quality reasons...

[LensBeginner]

I would have to question someone posting such claims without any real knowledge of the Pentax system. Since Pentax has successfully used IBIS for years I think that should weigh a bit heavier than claims from an internet pundit.
And he conveniently forgets k-mount was designed for FF. Or did not bother to check.
IBIS works on Pentax, enough said.

do you say that because it work on APS-C or on FF as well?
K mount is a FF mount, but FF actually means that it was born as "film FF without SR", not as a "digital FF with SR taken into account since its inception"
Don't know much about the subject so I'm curious.

[aurele]

To be fair Pentax hasn't released any FF bodys with IBIS yet, so saying that it is proven isn't really right.

the distribution of the Pentax K1 will soon make this statement false

[clackers]

Have Sony A7II and A7RII owners found their pictures now worse than the earlier, non-IBIS versions? :bemused:

[pathdoc]

To be fair Pentax hasn't released any FF bodys with IBIS yet, so saying that it is proven isn't really right.

But saying that Fuji don't have IBIS because of image quality reasons is absolutely backwards.
That means they prefer an image with blur all over the entire frame, which is totally useless, instead of an image which (in worst case) has one or two corners slightly darker then normal. For quality reasons...

I can't see them allowing the K-1 to make it into production without ensuring that this issue was taken care of. The Ricoh website indicates that they put a LOT of work into the updated SR system - although "update" is the wrong word; more like
"redesigned".

You would think that this would have shown up in beta testing if it were a valid problem.

[HopelessTogger]

Pentax are claiming 5 stops of benefit from SRII.

That's a lot if true.

[Na Horuk]

What its saying , is that image quality suffers from having smaller mount and applying SR.

Let's just be clear on what exactly he said.
a) He said that mounts that have narrow diameter, will end up having more difficulty in producing an image circle large enough to cover FF sensor and the extra dimension needed for the SR to be effective.
This might be true to some extent, but let's not forget that there were mounts like m42 and even m39 and m37, which covered the whole FF film plane (and these mounts had same register distance as K-mount, they were just narrower). This shows that it comes down to lens design. Some lens designs require a large back element; and of course the mount size will limit this. But the Pentax K seems to be decently wide enough. And even if it does limit some types of designs, we don't really notice this "hole." We have plenty of lenses available for Pentax, from fast UWA 14mm f2.8, fisheye, superzoom, telephoto (like DA 560mm), and so on. So the mount narrowness limitation has not yet, as far as we can tell, been a serious problem for Pentax K

b) He also said that making a lens that covers the FF sensor + the SR extra, it means you need to make a bigger lens.
Again, this heavily depends on the lens design. Just the SR might not require so much extra image circle diameter. Yes, you need a bigger lens to produce a bigger image circle in some cases (compare Q lenses to 645 lenses), but you can get away with quite compact designs. We can see that with lenses like DFA 100mm WR - it is telephoto, FF, allows SR, and it is super compact (pretty sure it is as small or smaller than other brand's 100mm macro lenses; and it still has stunning image quality). Another example could be the FA 50mm f1.4, and I'm sure we can find other cases of compact lenses with fast aperture and good image quality that allow FF and SR (as in, they don't make compromises just to accommodate SR). Again, I don't think this limit has been reached in Pentax K. Sony E might be different, but that is because it has a dramatically short register distance. This is why so many Sony lenses are much bigger than Pentax equivalents. If you put a Pentax DA limited lens on a K-01 or K-S1, you can get a smaller overall package than some Sony E camera+lens combinations; despite Pentax cameras being much thicker.
Also, the estimates on how much extra image circle is required for SR have been kind of odd. I've read that it takes only 1mm or that it takes a lot of extra space. I guess it depends on the lens' focal length/magnification. So macro or super telephoto lenses would require the most extra space (incidentally, those are the kinds that the 645 mount has in-lens SR, right?)


c) He then said that you can make a regular size lens on a narrow mount, and then just apply digital corrections to combat the optical problems; but that this will affect the image quality negatively.
Now, applying digital corrections does technically reduce image quality. But the only corrections necessary for the problems he mentioned would be vignetting correction (already available, lots of people use it; not a big deal), digital SR (lots of brands use it; I don't like it, but in some cases its unavoidable. Pentax only uses digital SR in video mode of cameras introduced after the K-01; does not use SR for photos)
Also, with modern sensors that capture 12, 14 bits; and modern fast CPU and lens profiles, digital corrections will not really become noticeable for a while. You really have to push things for the optical corrections to ruin these files

Conclusion: While the things he said could technically become problems, they are not problems yet. Maybe for lenses like 24mm f1.2 or some other truly exotic designs; but not many manufacturers are making those, they are just hypotheticals. The SR requirements are being blown a little out of proportion to emphasize why Fuji did what it did.
But! He might have been talking about the Pentax Q. The Q is different from K mount in many ways, so those things he mentioned might be more problematic in the Q series. I can't really comment on that, though. Definitely a smaller mount, with smaller register distance; but Pentax hasn't really explored the Q lineup fully. We haven't seen really fast primes yet or really UWA glass with fast aperture.

So no, Pentax mechanical SR does not negatively affect the image quality (if you use it right!), and it does not limit lens designs very much.

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Last edited by Na Horuk; 04-03-2016 at 04:55 AM.

[Gimbal]

I can't see them allowing the K-1 to make it into production without ensuring that this issue was taken care of. The Ricoh website indicates that they put a LOT of work into the updated SR system - although "update" is the wrong word; more like
"redesigned".

You would think that this would have shown up in beta testing if it were a valid problem.

Oh I'm sure that it will not be a problem, the sensor isn't moving that much.
And if it has to move to it's extreme limits you are already shaking way to much for a successful result anyway.

[Zygonyx]

The obvious fact we can recall from this interview if any, is Fuji's official confirmation that their X-mount is limited to APS-C ; which i stated since the beginning, from deduction via camerasize.com comparison site

[Mikesul]

Have Sony A7II and A7RII owners found their pictures now worse than the earlier, non-IBIS versions? :bemused:

Of course not. They are ecstatic about their photos. These theoretical analyses are always highly suspect if they do not use actual photos. Clackers question is right on. Look at the pictures from the A7RII they are lovely. The K-1 will certainly have no problems.

[traderdrew]

I think enough has been said but just one more pro and con. I've read and heard about lens stabilization breaking down at some point after a lot of use. I've never heard of SR breaking down after a lot of use.

[jatrax]

do you say that because it work on APS-C or on FF as well? K mount is a FF mount, but FF actually means that it was born as "film FF without SR", not as a "digital FF with SR taken into account since its inception" Don't know much about the subject so I'm curious.

What I am saying is:
1) Pentax has used IBIS for many years on APS-C, they understand how to make it work
2) k-mount was originally designed as a FF mount
3) The Pentax K-1 was designed from the ground up with IBIS in mind
4) When the K-1 specs were announced Pentax did not reduce the number of stops for SR, but actually increased it. That seems to indicate they are very confident with FF IBIS
5) The K-1 is a pivotal camera for Pentax, not a huge reach to say make or break for the brand. Does anyone really think they did not make sure IBIS (one of the key technology advantages of Pentax) is working?
6) Pentax already explained on the new website the challenges of making IBIS work on the K-1: Challengers | PENTAX K-1 Special site | RICOH IMAGING
7) These claims of IBIS not working sound more like a company that does not have the technology trying to trivialize it because they cannot compete in that area.

[monochrome]

7) These claims of IBIS not working sound more like a company that does not have the technology trying to trivialize it because they cannot compete in that area.

Corporate strategists have the industry knowledge and foresight to look many years into the future. Component suppliers share design paths in a general way with customers; customers share design goals with component suppliers. Competitor plans sometimes leak, or can be guessed. Sensor manufacturers capital investments are very visible years in advance - what is Sony doing with their fresh capital? What size sensor fabs are they building? (I surely don't know, but does Fuji?)

Perhaps Fuji sees that Sony and Pentax have solved large-sensor IBIS and have an idea where that will go.

[jatrax]

Perhaps Fuji sees that Sony and Pentax have solved large-sensor IBIS and have an idea where that will go.

No where good for Fuji's mount I'm guessing.........................

[LensBeginner]

What I am saying is:
1) Pentax has used IBIS for many years on APS-C, they understand how to make it work
2) k-mount was originally designed as a FF mount
3) The Pentax K-1 was designed from the ground up with IBIS in mind
4) When the K-1 specs were announced Pentax did not reduce the number of stops for SR, but actually increased it. That seems to indicate they are very confident with FF IBIS
5) The K-1 is a pivotal camera for Pentax, not a huge reach to say make or break for the brand. Does anyone really think they did not make sure IBIS (one of the key technology advantages of Pentax) is working?
6) Pentax already explained on the new website the challenges of making IBIS work on the K-1: Challengers | PENTAX K-1 Special site | RICOH IMAGING
7) These claims of IBIS not working sound more like a company that does not have the technology trying to trivialize it because they cannot compete in that area.

Well, thinking about it the shorter registration distance could make the difference, all other things being equal, since with the same last-element-to-sensor distance, the last element would be nearer to the mount, thus minimizing vignetting.
I don't know much about lens design, but the different registration distance could work to Pentax's advantage, as Na Horul says.

Regarding the argument that "IBIS must be working correctly because Pentax is selling the camera", well, that's a fallacy, and I don't trust a company, any company, that much.
I sincerely hope it's working as advertised, but - just to be the devil's advocate for once - they could have solved the hypothetical issue with a lens profile and be done with it.