03-20-2026 09:30 AM
My 70-200 f2.8 L IS is not performing at it's best at f2.8. Needs a service... I shoot in Manual most of the time while doing low-light events. I just assumed I could set the Aperture Range on my R5 to Minimum and Max values for this event. e.g. I'd say Max aperture was f3.2 and Minimum say f8 (unlikely to work higher than f5.6 anyway). When I toggle the C.FN 2 settings that max aperture jumps from f2.8 to f4. Offering nothing imbetween. In the other modes I can, of course, set aperture to whatever I want f3.2 f3.5 yada yada.
What am I doing wrong, or is this just a peculiar limitation of the system?
03-20-2026 09:43 AM - edited 03-20-2026 09:44 AM
For us to answer your question it would be helpful to know what 70-200 f/2.8 L lens you are using. There are three generations of the EF lens and two versions of the RF that I'm aware of. If you're using EF, then please also share the make/model of the converter. I am guessing that it is possibly a function of the lens you're using and its' communication with the camera rather than something in the camera.
03-20-2026 09:55 AM
It is an
03-20-2026 09:56 AM
5d MK IV tested regardless of lens attached.
03-20-2026 09:56 AM
@richclark Welcome to the forums. Which exact EF version are you using. Canon has made 7 different versions in the EF Mount. Between F/2.8 & F/4 version. They’ve also made 3 versions in the RF Mount too. So a Full and Complete name is needed. So we can assist you. Note older lenses have hardware limitations making some features of your camera unavailable.
03-20-2026 10:01 AM
See Above.
03-20-2026 10:08 AM
@richclark Do you have your camera set to whole stops, 1/2 stops or 1/3 stops. I believe older lenses have aperture limitations. Like the widest aperture setting is NOT possible when the aperture range is limited. Newer EF lenses are more optimized for video. They’re usually designed with a stepless aperture. They smoothly change between apertures for video work. While older ones just jump from setting to setting. New RF lenses offer 1/8th stop or even 1/32nd stop aperture options for video mode.
03-20-2026 10:17 AM
Both bodies are set to 1/3 stops for Exposure Level Increments but that does not impact the Aperture Range in CFN2. I guess it is just default settings.
03-20-2026 10:21 AM
What lenses are you using that’s causing this? Older lenses have limitations such as not supporting step-less aperture motors. They’ll just jump from setting to setting.
03-20-2026 10:56 AM
After more testing it is less about the lenses and more about the functionality within the bodies. With or without a lens makes no difference. I can access all apertures in varying modes when working. It was just about not being able to set a custom range from 3.2 on a specific lens that is poorer at 2.8.
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