Another issue with a 600mm F4 IS 2

Hi all, I am new to your forum.
I am a wildlife photographer and have had a recent issue with the 600mm F4-2. Early last week I did a shoot and no problems. Later last week did a bird shoot and high speed burst on my 7d Mk2 ran at about 5fps not 10fps. Put my other 7d Mk2 on the lens and it did the same thing. All other lens functions seem fine. If I put on any other lens I have on either camera they have max burst, no problems. It is just the 600 that does this.
I have shot thousands of photos thru this lens and both cameras without any problems. Both cameras are set up the same. AI servo, spot metering, single point focus, shoot raw files, etc. I have tried different lens settings, ex. mf then af, with the same result. Single shot, and silent mode shooting work on both cameras. The lens has never been dropped or even bumped hard. Saying that, it has been carried a lot in the bush on a tripod, with camera, battery grip, teleconverter, on a RRS tripod with a gimbal head. I am guessing but suspect possible deflection in the mounts, a contact, etc. etc. Just a guess.
Hopefully someone out there has had a similar problem like this and a possible solution. I can still use it as I primarily use this setup in single shot mode now. I use a 300 f.28 with 1.4 teleconverter for birds in flight. By the way both cameras have max burst with the 300 setup.
Thanks so much in advance for your suggestions
Colonel4446

Have you tried setting AI Servo to "Release Priority" ? If you get full burst speed with that setting, then it may be that the AF is working slower for some reason.

Colonel4446 wrote in post #18259789
Hi all, I am new to your forum.
I am a wildlife photographer and have had a recent issue with the 600mm F4-2. Early last week I did a shoot and no problems. Later last week did a bird shoot and high speed burst on my 7d Mk2 ran at about 5fps not 10fps. Put my other 7d Mk2 on the lens and it did the same thing. All other lens functions seem fine. If I put on any other lens I have on either camera they have max burst, no problems. It is just the 600 that does this.
I have shot thousands of photos thru this lens and both cameras without any problems. Both cameras are set up the same. AI servo, spot metering, single point focus, shoot raw files, etc. I have tried different lens settings, ex. mf then af, with the same result. Single shot, and silent mode shooting work on both cameras. The lens has never been dropped or even bumped hard. Saying that, it has been carried a lot in the bush on a tripod, with camera, battery grip, teleconverter, on a RRS tripod with a gimbal head. I am guessing but suspect possible deflection in the mounts, a contact, etc. etc. Just a guess.
Hopefully someone out there has had a similar problem like this and a possible solution. I can still use it as I primarily use this setup in single shot mode now. I use a 300 f.28 with 1.4 teleconverter for birds in flight. By the way both cameras have max burst with the 300 setup.

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What did Canon Customer Service or Canon Professional Services have to say about this?

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Stupid question, but what's your shutter speed? I know that maximum burst is slowed when your SS drops below a certain speed, so maybe that could be coming into play?

Hi,
Thanks much for your responses.
I contacted Canon tech. and they were baffled. Said to send in the lens and one camera to service. What I expected.
My cameras are set up AI servo first priority, equally balanced between release and focus. This setting has been this way from the beginning with both cameras. Approximately 20-30k photos have been shot through both cameras with no problem with burst speed until last week. Installing either camera on the 600 and you have reduced burst by about 50%. However. silent burst mode seems to be about the same. My shutter speed settings vary between 1/1600-1/3200 and higher if light permits.
Thanks again for your response.
Colonel4446