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IBIS & Lens corrections

pegelli

Well-known member
Depending on where exactly the sensor is during exposure I would think that generally 2 corners could be better, while the other two could be worse. However my guess is that the effect of the small sensor movement might not be all that significant, but we'll see in practice what it gives.
 
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Vivek

Guest
Only a few microns (or less) need to be shifted at the focal plane to achieve stabilization with a telephoto lens. With WA, it will be negligible. So, nothing will be additionally added to make things worse. If a Summicron M 35mm shows mush and dark corners elsewhere, for example, it will be the same and not worse.

PS: To give a sense of scale- 6 micron is the average thickness of a household aluminum foil. Can you see the edge?
 

pegelli

Well-known member
If you measure it it's about a half mm on an extremely bouncy camera. So even in the extreme it's 2%, which is in my mind quite insignificant for corner performance of a lens.
 
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Vivek

Guest
Now imagine this technology put to use for shift/tilt functions at will (Pentax have allowed the shake sensor to be used for shift)! :)
 

Annna T

Active member
Why (bigger than the A7II)?
If you want to shift as much as with a TSE lens, you need about 12mm room in each direction (up, down, left, right) plus room for the shifting mechanism.

So (24mm + (2x12mm)) x (36mm + (2x12mm)) : the space needed reaches medium format territory : 48mm x 60mm.

I can't imagine a body of the A7 series size able to handle that : the A7II has a bigger grip and is slightly higher and deeper, but not up to that either.
 
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Vivek

Guest
If you want to shift as much as with a TSE lens, you need about 12mm room in each direction (up, down, left, right) plus room for the shifting mechanism.

So (24mm + (2x12mm)) x (36mm + (2x12mm)) : the space needed reaches medium format territory : 48mm x 60mm.

I can't imagine a body of the A7 series size able to handle that : the A7II has a bigger grip and is slightly higher and deeper, but not up to that either.
I am glad you posted this as this the most common of all misconceptions. :)

The shifting (and tilt!) mechanism is already built in and all we need is the right software (check how Pentax do it. There is a link here: http://www.getdpi.com/forum/pentax/45385-how-turn-any-lens-into-shift-lens.html).

1 pixel shift does not need any mm extra. It is in micron territory. What is also important to note is that you do not need a lens with a larger image coverage!

The numbers you have put out are for a lens and not for the sensor.
 

Annna T

Active member
I am glad you posted this as this the most common of all misconceptions. :)

The shifting (and tilt!) mechanism is already built in and all we need is the right software (check how Pentax do it. There is a link here: http://www.getdpi.com/forum/pentax/45385-how-turn-any-lens-into-shift-lens.html).

1 pixel shift does not need any mm extra. It is in micron territory. What is also important to note is that you do not need a lens with a larger image coverage!

The numbers you have put out are for a lens and not for the sensor.
The question is about how much shift you need ! It is much more than what you need for IBIS. It is not a question of microns.
 
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Vivek

Guest
The question is about how much shift you need ! It is much more than what you need for IBIS.
Nope. Some day it will become clear. There is a long way to go before Sony issues such a firmware (fat chance!) and also obliterate medium format digital backs, lenses and all those expensive grips, iphone holders and such in that process. :)
 

pegelli

Well-known member
I watched the Pentax video, impressive but in the end a quite small effect and not yet comparable to what can be achieved with a full shift lens. In the end if you want to achieve the same result optically of shifting the lens up 12 mm the only alternative is to shift the sensor down 12 mm. In the end it's all relative movement of one vs. the other.
 

Annna T

Active member
I am glad you posted this as this the most common of all misconceptions. :)

The shifting (and tilt!) mechanism is already built in and all we need is the right software (check how Pentax do it. There is a link here: http://www.getdpi.com/forum/pentax/45385-how-turn-any-lens-into-shift-lens.html).

1 pixel shift does not need any mm extra. It is in micron territory. What is also important to note is that you do not need a lens with a larger image coverage!

The numbers you have put out are for a lens and not for the sensor.
I looked at the video, but it isn't showing any powerful shift : look at the brown building at the foot of the tower : there is still a strong convergence of the verticals, because there is not enough shift. If he had chosen a usual square building for his demonstration, you would see it more clearly. You get some correction, but not enough for architecture shooting.
 

Godfrey

Well-known member
How would lens corrections work with the sensor moving around to support IBIS? Just thinking about WA lenses and corner corrections for light loss, casts, sharpness etc..
A7 II SteadyShot in action - YouTube
Olympus mFT cameras have had IBIS and embedded lens corrections working together since 2009. They work well; the stabilization system has not presented any issues. I can't imagine that the A7II would be any different.

Why do you think the IBIS presents any more difficulties than an OIS system?

G
 

jagsiva

Active member
Olympus mFT cameras have had IBIS and embedded lens corrections working together since 2009. They work well; the stabilization system has not presented any issues. I can't imagine that the A7II would be any different.

Why do you think the IBIS presents any more difficulties than an OIS system?

G
Because it is FF, so edges are already an issue and for RAW converter corrections, the correcting algorithm would need to know the position of the lens relative to the sensor. Olympus at mFT, is using a much smaller sensor and corners are not as much of an issue.

Combine with the shortest flange distance of most cameras out there, the Sony projects some pretty shallow angles from the the corner of a WA lens onto the sensor. This again has colour cast issues. Things like LCC's in post-processing can be used to overcome this, but you still need a reference point between sensor and lens.
 

Godfrey

Well-known member
Because it is FF, so edges are already an issue and for RAW converter corrections, the correcting algorithm would need to know the position of the lens relative to the sensor. Olympus at mFT, is using a much smaller sensor and corners are not as much of an issue.

Combine with the shortest flange distance of most cameras out there, the Sony projects some pretty shallow angles from the the corner of a WA lens onto the sensor. This again has colour cast issues. Things like LCC's in post-processing can be used to overcome this, but you still need a reference point between sensor and lens.
I disagree. FT lenses are designed to just cover their sensors, particularly at the wide end, so the technical issues are really very little different. Only Sony lenses will have lens corrections; they're designed for the sensor and the mount too, so Sony can take the sensor movement and the coverage into account.

Sensor movements for stabilization, particularly at the wide focal lengths, are very very small. Larger movements are needed for longer lenses. And the same issues you cite for IBIS are there for OIS as well.

G
 

Uaiomex

Member
Even most dedicated lenses have a few extra mils of leeway. Wides have the least but then again they would need much less shift to compensate for camera shake.
Eduardo


I disagree. FT lenses are designed to just cover their sensors, particularly at the wide end, so the technical issues are really very little different. Only Sony lenses will have lens corrections; they're designed for the sensor and the mount too, so Sony can take the sensor movement and the coverage into account.

Sensor movements for stabilization, particularly at the wide focal lengths, are very very small. Larger movements are needed for longer lenses. And the same issues you cite for IBIS are there for OIS as well.

G
 
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