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10-10-2017, 07:29 AM   #1
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Does IBIS affect precise focusing and exposure metering?

I have checked what Nikon had to say in favor for their in-lens image stabilization system. Here is a link:

Why VR is built into the lens | Empower Your Hand-held Shooting | Nikon

The article says that their system enhances the ability for precise focusing and exposure metering caused by hand shaking, because the image arrives at a stationary sensor. I am not convinced. If this was the case then my K5 should focus and meter with more precision with steady shot disabled. I can not feel any difference. What do you think, is this Nikon statement at least partly true?

10-10-2017, 07:40 AM - 1 Like   #2
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I think they just want to sell vr lenses.
10-10-2017, 07:58 AM   #3
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Sales hype is a beautiful thing.
10-10-2017, 08:14 AM - 1 Like   #4
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In theory, for stationary objects, optical stabilization would help accelerate and improve focusing. But optical stabilization is unlikely to improve exposure estimation except in cases of very low light levels with point-light sources and exposure logic that exposes for those tiny highlights (e.g., night skyline or astrophotography). If the scene is normally lit or if the scene contains no small highlights or if the exposure logic uses average light levels, them VR will do nothing for exposure precision.

For non-stationary objects, optical stabilization is likely to cause unpredictable effects on focusing because the stabilizer would be fighting the panning and tracking actions of the photographer.

For IBIS and Pentax cameras, any effects on focusing or exposure setting would only be seen in live view but there would still be the issue that stabilization might help focusing on stationary object but might hurt focusing on moving objects.

10-10-2017, 08:17 AM - 1 Like   #5
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I think it might be true. Since the Pentax sensor is not hard mounted, it may jiggle a bit during exposure. I think it is also why the K1 suffers some issues at certain speeds with certain lenses. It may be related to the harmonics of the camera/lens assembly. I really don't think it is shutter shake, but sensor shake that is the problem. I also wonder if allowing time for the sensor to settle is one of the factors in auto focus performance on moving targets. It would not bother me if Pentax dropped IBIS on a few models if auto focus performance could be improved. I like it and use it, but I have always felt it comes at a price.

Does anyone know how much force it takes to move the sensor if shake reduction is off? Can it still be wiggled a bit? Shake reduction my not be the thing for larger sensors. Moving more mass means more inertia to overcome to start and stop any correction process during exposure.
10-10-2017, 08:36 AM   #6
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I think that if their statement was mainly true they would admit that their system is not practical for someone who grows year by year in photography because there is no way to stabilize images using legacy non VR lenses. They should have incorporate IBIS in at least some of their advanced bodies to stabilize non VR lenses. This IBIS could be automatically switch off when a VR lens is mounted. Then the user could benefit from the alleged advanced focusing and metering system of in-lens stabilization. They do have top notch fast and accurate focusing system though. I wonder if there is a grain of truth in what they claim.
10-10-2017, 08:49 AM - 1 Like   #7
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Having invested so heavily into VR lenses (the pro zooms at least), I don't see them switching to IBIS. Neither would Canon. I hear Fuji is going to (from a friend that is into Fuji system), Sony is, Panasonic is, Olympus, Pentax. I don't think if ibis was such an issue, all those companies would go into it and would instead make VR lenses.

---------- Post added 10-10-17 at 08:50 AM ----------

BTW if Fuji X-T3 would have IBIS it would be so tempting to get one

10-10-2017, 09:27 AM   #8
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It seems extremely unlikely that IBIS hurts Pentax AF unless it's at the level of R&D spending -- Pentax spends money on developing better IBIS that could have been spent on developing better AF. Removing IBIS would not help Pentax AF at all because the IBIS and AF subsystems are completely independent from each other. If anything, it's Nikon and Canon that could be hurt by their stabilizer systems to the extent that their AF systems might be affected by the time it takes the lens VR system to stabilize.

I agree with awcreo that Nikon and Canon are extremely unlikely to add IBIS to their existing DSLR systems because it would kill sales of "Pro" VR lenses.

(BTW, optical stabilization is inferior to IBIS because it cannot correct for rotation. And Pentax IBIS offers several advantages over Nikon VR such as user-controlled anti-aliasing, horizon leveling, composition adjustment, pixel shift, and astrotracer.)
10-10-2017, 10:16 AM - 3 Likes   #9
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I just read that article and have just consigned my K1 and 40 years of Pentax lens collecting to the dustbin. How could I have been so stupid to think that Pentax would know better than Nikon.

It saddens me to think that over all these years of posting pictures you all have been lying to me saying "nice shot" while thinking all the time .."what a wobbly old photo"

I wont make the same mistake again
10-10-2017, 10:19 AM - 2 Likes   #10
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It's not the first time I hear about this. The problem is that these claims are never backed up with hard data, even anectodal ones. Although it looks to make sense in theory, this doesn't mean this has any significant advantages in the real world. Have you ever seen a test showing that AF works better with IS on vs off on a Nikon or Canon camera ? Never for me, even if it's actually quite easy check this. Have you ever heard a Nikon or Canon user complaining that its camera AF doesn't work well unless using an IS lens ? I never heard them complaining of this. And for all I know, their cameras seems to AF just fine even with non IS lenses.

IS is around for something like 20 years. Since then, I guess we would have heard a lot about this if IS was making any significant difference in AF performance.

And even then, the theory only make sense if you take it from a human perspective. Yes, for us the image is shaking because we're relatively slow compared to an AF system. Don't forget that an AF module isn't like our eyes and brain. A modern AF module does thousands of iterations each second to calculate the focus. The image has to shake a lot to make any meaninful difference between each of these iterations...

Last edited by CarlJF; 10-10-2017 at 11:24 AM.
10-10-2017, 11:17 AM   #11
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Do people spread stories about IBIS because they have invested in a brand that doesn't have it?
10-10-2017, 11:49 AM   #12
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Ibis really works, especially if you mix it with ois. That combo is amazing. No issues with either olympus or pentax when it comes to focusing


10-10-2017, 12:12 PM - 1 Like   #13
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QuoteOriginally posted by Hidrieus Quote
The article says that their system enhances the ability for precise focusing and exposure metering caused by hand shaking, because the image arrives at a stationary sensor.
I'f you're using a long focal-length lens, and the image is jiggling around significantly in the viewfinder (and even going in and out of view), it could definitely affect focusing and exposure. This would be a more extreme case, however, but it also might be the type of situation where the OIS stabilization is most useful.
10-10-2017, 12:35 PM - 1 Like   #14
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QuoteOriginally posted by leekil Quote
'f you're using a long focal-length lens, and the image is jiggling around significantly in the viewfinder (and even going in and out of view), it could definitely affect focusing and exposure. This would be a more extreme case, however, but it also might be the type of situation where the OIS stabilization is most useful.
I'd agree with that as I've had some AF lock issues with DA300 and DFA150450 aimed at stationary subject. So, I've done an experiement: perform 100 AF operation from the same defocus position, toward a stationary target, hand held and on a tripod, I could confirm that the AF lock success on tripod was something like 99% locked and in focus, while handheld it was barrely around 80% AF lock rate and in focus shots. So, I could not say that OIS improves exposure metering that much as the average illumination has more to do to environment, but for AF, OIS is definitely easing the job of the AF servo. no a big deal for wide to short tele lenses, but much more relevant with long lenses.

Last edited by biz-engineer; 10-10-2017 at 06:22 PM.
10-10-2017, 01:38 PM - 1 Like   #15
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At issue is not whether IBIS makes precise focus difficult, but whether optical (in-lens) stabilization improves the image available to the PDAF sensor. In theory, stabilized optics should provide a less ambiguous signal to the PDAF system.


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