IBIS Question (technical)

Started Aug 23, 2012 | Discussions thread
Anders W
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Re: IBIS Question (technical)
In reply to Dr_Jon, Aug 23, 2012

Dr_Jon wrote:

I don't know if this has been brought up before, if so then apologies, but searching for IBIS gets an astounding number of hits on this forum and I couldn't find this mentioned in my attempts at looking.

I should also point out I shoot Panasonic m43 and FF Canon (well, plus a RX100), so only use OIS, hence can't experiment.

What I want to know is the effect IBIS has on the corners of the image. I'm assuming as the lenses get longer the movement gets larger. I don't know what the maximum movement an E-M5 (for example) allows. However the tests of some m43 lenses show a fair amount of corner fall-off at wide apertures. If you are then moving sidewards in the image circle does that give lop-sided issues? Also is there the "room" in the image circles of both the Oly and Pana lenses for this? (This is presumably a plus for OIS systems, which can handle a long lens and a fair bit of movement and still centre the image circle on the sensor. Provided the lens has OIS of course.)

No trying to start a flame war between IBIS and OIS, just really curious, especially as my GF1 is due an upgrade (GH3 perhaps, lets see what the answers here are).

John

Edit - I've seen Sony talk of sensor travel of 5mm in any direction for their IBIS - that's a lot for a small-ish m43 image circle if Oly are comparable.

You are right that a sensor-shift system must use more extreme parts of the image circle and that this will imply more vignetting and less resolution in some corners than others, with the positively and negatively affected corners varying randomly from one image to the next.

However, since the image circle doesn't have a very sharp border line and since the movements we are talking about are limited (I don't know the exact number but I'd guess a mm, possibly two, in each of the four directions), I think the impact is almost imperceptible.

Further, I am pretty sure that OIS lenses have similar issues. These lenses move just a few lens elements (the OIS group) to shift the image around and I am pretty sure this implies a loss of performance whenever the image has to be shifted away from the center.

Where did you see Sony talk about 5 mm in any direction? 2.5 mm each direction and thus 5 mm between extreme left and extreme right doesn't sound entirely unreasonable to me but 5 mm in each direction sounds a bit extreme.

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Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
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