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telefocus and movie servo

Started Mar 1, 2022 | Discussions thread
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stevet1 Senior Member • Posts: 1,300
telefocus and movie servo
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Since this involves a Canon camera, I’m going to go ahead and cross-post it.

I have a Canon T8i and a 55-250mm lens.

My camera is set at Movie Servo and continuous autofocus.

I have a problem with autofocus at long telephoto distances. If I aim the camera at something long distance, it focuses easily, but if I shift the camera to something closeup, my lens will slowly focus on the subject, but if I then lift the camera and aim at something far away again, the lens refuses to focus. I have to start zooming back out before it will begin to focus on that far away subject.

Just for the heck of it, I slapped a 50mm prime on my camera, and the movie servo worked flawlessly.

I did a little reading in the manual this morning, and read that movie servo on my camera doesn't work when zooming or if the image is magnified.

Even though I wasn't technically "zooming", I think my camera has a problem when "zoomed". The servo mode kicks in when I start zooming back out.

I also read that some cameras have a movie servo sensitivity scale. Mine isn't that sophisticated. It's either enabled, or disabled, period.

Also, just for the heck of it, I slapped on the 18-55mm kit lens that came with the camera, and didn't have any problems.

It's just with those long telefocus lengths, at least with the 55-250mm lens that I have.

Steve Thomas

 stevet1's gear list:stevet1's gear list
Canon EOS Rebel T8i (EOS 850D) Canon EF-S 55-250mm f/4-5.6 IS STM Canon EF 50mm F1.8 STM Canon EF-S 18-135mm F3.5-5.6 IS USM
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