I recently purchased an EOS RP with an RF24-105 f4-7.1 IS STM lens for my daughter to use while out on photography shoots with me. After working with the combination for a short while, I noticed that the lens differs from the L-series lenses that I use in that there is a Focus/Control switch instead of an AF/MF focus mode switch (note that this Focus/Control switch only exists on five of the RF series lenses). The Focus selection on this lens is only functional if manual mode is selected from within the menu system or if the AF ON button is pressed. If the menu option is set to AF, this switch only serves the purpose of disabling the control function of the ring (as far as I can tell). This situation was also tested using the RF24-240mm F4-6.3 IS USM, having the same switch design, giving the same result. I also tested the process using my RF24-70mm f2.8 L IS USM lens and the AF/MF switch functioned correctly (not a camera limitation).
The outcome was that in AF mode (menu selection), the control ring has two functions associated with this switch... control and control lock. In MF mode (menu selection), the control ring has two functions... control and focus. Are there settings that would allow the switch to more closely function as the higher end lenses? I am looking to have a means whereby the focus mode position allows the ring to allow manual function at all times. Is this a possible firmware update change or is it "hardwired" into the lens itself?
All STM lenses are “focus-by-wire”. The focus ring is electronic. There is not mechanical connection to gears or motors. This means the camera must provide power to the lens in order for the focus ring to function. This means the metering system must be activated by half pressing the Shutter Button. Of course, there are other ways to wake up the metering system.
That is a camera kit lens, a super zoom, so I think that similar design considerations could apply. That particular USM lens could also be focus-by-wire. The focus ring does not necessarily have to be directly connected to any mechanisms or gears.
This is only speculation, on my part. What do the User Manuals say about the lenses and their control rings?
Actually ALL RF Mount lenses have electronic focus rings/ focus by wire. This even includes USM lenses. These USM lenses use Nano USM AF Motors. Which uses similar technology to STM lenses.
EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 28-135mm F/3.5-5.6 IS USM, EF 50 F/1.8 STM & EF 70-200mm F/2.8L IS III USM
EOS 40D & 5D Mark IV
430EX III-RT & 600EX II-RT
Most RF lenses include a dedicated "Focus Ring" plus a programmable "Multi-function Ring". The lenses you mention, instead have a single ring which shares both purposes. That eliminates the "AF/M" switch and provides the "Focus/Control" switch instead. As you have determined, in most RF body modes manual focus is immediately available by keeping the switch in "Focus" and half-pressing the shutter release. In the "Control" position the Ring becomes strictly a control ring so it's function is selected from the long list of provided options.
I haven't checked the RP, but have checked on both an EOS-R and R5 and "Focus" is not one of the "Multi function" menu options. It would seem that providing "Focus" as a menu option would be redundant to simply leaving the switch in the "Focus" setting and engaging manual focus override by touching the ring.
On the R5, manual override is immediately available by default in all but the custom modes.
RF24~240, this is an interesting subject. I grabbed a 100~400 which is the only non L lens I own. It operates like my other lenses. "Lock", "AF/MF" and "IS" with fulltime manual focus if I wish.
RF24~240 and similar. "Focus or Control" - According to the manual, the lens only allows one or the other. The focus ring is electronic and can be used to manually focus in AF situations, but once you set to "Control" there is no more MF.
Thanks for bringing this to light guys!
Bay Area - CA
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