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PLEASE HELP: Brand new EOS R6 slow writing to buffer


Just bought a brand new EOS R6 after viewing hours upon hours of Youtude video reviews on the R6 & R5..


PROBLEM: For JPEGS in FULL sensor mode I have 99 shots allowed in my buffer. I use the fastest SONY G series cards that I have, but tried other favorite cards. It takes 2mins 30 secs to write the full 99 shot buffer to my card !!! .....If I switch to 1.6 crop mode for smaller files, it takes 1min 45secs !!!!


THIS CANT BE GOOD !!! ......WAY too slow.


Can someone please time their own write speed when their buffer is down to zero ?? I take sports action photography in one burst after another. I therfore can eat up 99 shots real quick.


Either I have a defective camera, or I have a setting turned ON that should be off.....Not ONE review has mentioned a slow buffer writing issue for the R6. I even tried switching card slots, and writing to one card only. No change.







Welcome to the forum.


I do not have your camera, so I cannot be of direct help, but one thing that slows down wite speed is any in-camera processing.


Do you have any lens correction options selected?

John Hoffman
Conway, NH

1D X Mark III, Many lenses, Pixma PRO-100, MX472, LR Classic





I have used that with all my Canon cameras and never had an issue. I turned it OFF on my R6 and my lord, it writes instantly...It is unreal.


THANKS so much !!! I never would have guessed that.



To clarify: I had DIGITAL LENS OPTIMIZER set to HIGH !!


If you disable it, or set it to STANDARD you are ok. Only in HIGH did the camera SLOW down writing to the card.




I'm not familiar with Sony G cards, but what is the sustained write speed on those?


Note that many cards print theoretical reads directly on the card, but one has to dig in order to find the sustained write speeds.


e.g. a so called 170 MB/s SanDisk card is actually only 30 MBs for sustained writes.


EOS 5D IV, EF 50mm f/1.2L, EF 135mm f/2L, 600EX-RT (x6), ST-E3-RT
EOS C70, RF 24-70 f/2.8L IS, EF-EOS R 0.71x

Sony G cards are 299 writing.   I compared it to many others. For sure, the fatest.



FYI, I believe that 299 write speed is only theoretical.  Those cards appear to be "V90" cards which means sustained writes are actually 90 MB/s.


EOS 5D IV, EF 50mm f/1.2L, EF 135mm f/2L, 600EX-RT (x6), ST-E3-RT
EOS C70, RF 24-70 f/2.8L IS, EF-EOS R 0.71x

Good catch by John.


I always shoot in RAW and leave all of the in-camera image processing/correction turned off.  I believe that sort of correction is far better done in my workstation in post rather than tying up camera time and battery power during an event. 


I use an HP workstation with a pair of fast Xeon 6 core CPUs and digital lens optimizer will load both CPUs to 20 to 30% for a few seconds while running DLO and the workstation has a lot more computing power than what is in my 1DX series camera bodies.


Unless you have a need for immediate jpg output, do yourself a favor and shoot in RAW to really take advantage of your new camera's capabilities.  The R6 has plenty of buffer depth for sustained RAW files shooting for any but the most unusual requirements.



EOS 1DX M3, 1DX M2, 1DX, 5DS R, 1D M2, EOS 650 (film), many lenses, XF400 video