How effective is R6's IBIS with EF Lenses?

DJaye wrote:

ArtHeals wrote:

I use a couple of Canon EF portrait lenses (135/2L & 85/1.8 USM) with EOS R and I don't have any major problems as i keep the shutter speed around 1/200 most of the time. But I was wondering how effective is the IBIS on R6 with these EF lenses. Is it still 5-axis with EF lenses or downgrades to 3-axis?

Some used R6's are popping up here and there and I am contemplating if its going to benefit my STILL images in any way - (No interest in video)?

Thanks in advance

I just made the switch to R6 from 5D4. I find IS working better than with my 5D including Sigma 150-600 and 70-300

R5/R6 IBIS only adds roll and X/Y translation correction to IS lenses.  If you seem to be getting better pitch/yaw stability, that may be due to the loss of the large slapping FF mirror, rather than the added IBIS.  "Roll" correction has nothing to do with magnification or focal length, and is for when you rotate the camera on the lens' axis during a long exposure time, not something that you're likely to benefit from with the relatively short exposures that many people would use at 600mm.  X/Y translation has nothing to do with focal length, but depends on how close you are to the subject, and the closer you are, and the longer the exposure (absolutely; not relative to the focal length), the more you are likely to benefit from it.  These 3 axes have questionable value for shooting telephoto at a distance.

You also now have larger pixels, so when you inspect at 100% pixel view, you are less likely to see the same amount of blur, because you're magnifying less.  For that reason, R6 users may be happier with the added IBIS than R5 users in general (and people with monitors with smaller pixels, as well), even if it turns out that as some of us suspect, that these roll and X/Y IBIS implementations actually add a little bit of blur if they are not actually needed.  In my experience with my R5, there seems to be waves of added blur that come in any sequence of images, about 1/2 pixel in size on average with the R5.  Out of about every 3 images, one will have less than 0.1 pixels of blur (good), one about 1/4 (OK), and one about 1/2 pixel (loss of fine detail), over a wide range of shutter speeds, which would be rock solid with my previous APS-C DSLRs (90D and 7D2), despite higher magnification at 100% pixel view with the 90D.  Unfortunately, such added blur can still make the system qualify for the claimed stops of stability by the CIPA standard, which is based on postcard-sized image viewing at 450mm, so Canon may never feel compelled to address the issue, even if it slightly ruins more possible otherwise-perfect keepers.  I have no confidence that my R5 will nail stability with a single shot with IBIS/IS enabled, unless the shutter speed is 1/1600 or faster, so even for non-action, I take a burst of at least 3 shots if the shutter speed is not fairly high, which creates a lot of extra culling work, and wears the shutter unnecessarily when using mechanical shutter or electronic first curtain.  With full-electronic shutter, the overhead is still there in culling time, even if I can get more near-perfect-stability keepers per second.