RF 200-800 does not focus when starting at 800 mm

[Chandan_k]

I am Using RF 200-800 with my Canon R5 Mark 2 . I was having plenty of Issues with Using AF -  However Most are resolved reading through guides & community reading. However , One Thing is Still Bugging :   When I start shooting Shutter Priority , and Start focussing after Zooming the Lens at 800( without aiming the Subject, I syaert with 800 straight , it Does not Auto Focus with Back Button or any Other mechanism. However, When I gradually start Focussing 500/600 and Zoom out to 800 , the Focus worked Fine and I got Good Shots.  Is this a defect in my Lens or this is the way , this lens behaves ? Any responses on this will be appreciated. 

[Waddizzle]

Sometimes you have to give the AF system a nudge in the right direction.

What does the view through the EVF, look like when you zoom out 800mm?  Is there anything that is recognizable to see?

[Chandan_k]

nothing significant , just a mass of unfocussed background cluuter . 

[Waddizzle]

“…nothing significant.,,”

Exactly.  There’s also a setting that can disable the AF system when focus is impossible.  Disabling the AF under these circumstances minimizes hunting, which can lead to oscillation under the right conditions.

SOLUTION: The user must try to prefocus the lens so that the view doesn’t look like the underside of a storm cloud.

[Chandan_k]

Hi Waddizie , Thanks. Is that Setting: Lens Drive on AF Impossible with Options : Stop Focus Search, Or Continue Focus Search ? 

I also Own EF 70-200 , 100-400 - Surprisingly, never had seen this Issue Earlier. 

[SignifDigits]

Out of curiosity what AF mode are you using?  On the R6 M2 I can reproduce your issue with something ~1/3 FPV close and 2/3 far away with whole frame focus, but I think that may be a "feature" more than an issue.  Using any of the spot focus AF variations fixes that on my R6.  Many thanks to Waddizzle for pointing out then "impossible focus" option. The setting on the R6 M2 is found at AF menu 3 "Lens drive when AF impossible".  Online reference says that option is on menu 4 on the R5 M2.

[vantage]

@Chandan_k

I've got the same camera/lens and had have that problem. I've noticed since updating to firmware version 1.2.0 I haven't had it happen. That may just be related to the specific scene. 

What firmware version is in the camera? If not 1.2.0, it may be worth loading.

[SignifDigits]

Duh.  Sorry that I missed the camera detail!

[ebiggs1]

" Is this a defect in my Lens or this is the way , this lens behaves ?"

I am going to say that is the way it, and all simular super zooms lenses I have used behave also. I do not have or own the Canon RF 200-800mm f/6.3-9 IS USM lens but I do have or have owned almost every model of the 150-500mm and 150-600mm super zooms by Sigma and Tamron. Super zooms AF is a bit finicky sometimes.

[rgl47]

https://community.usa.canon.com/t5/EF-RF-Lenses/Focus-Issue-RF-100-300-f-2-8-USM/m-p/576859#M39000

Having a similar issue with the RF 100-300 USM. Your description of issue on your end is also part of the issue with my lens. No constructive solutions have been offered on my post. When I zoom out to full 300mm, or 420mm with the RF 1.4 TC on, it hunts and will not focus. Never did this until about 2 months ago. I have had the lens for about 14 months now and it worked absolutely perfect and phenomenal prior to. When I move the zoom a hair under 300mm or 420mm, it works as it should.