EF 600mm F/4 L USM Mysterious Switches

[Jeffb]

I recently acquired this old lens and it's in great shape.  However, there are two switches on the side of it I can't find out what they do.  (See Photo) 

[rs-eos]

I couldn't find a manual for this yet, but this Canon Support Article will hopefully shed some light.

[Jeffb]

Thank you. 

I haven't been able to find a manual either.  That top button appears to turn on and off the Beeper tone when using the Focus Preset.  If I were to guess, it looks like the bottom "M. Focus Speed" would be for Manual focus speed???  

[MikeSowsun · Accepted solution]

This is from a lens review:

“Manual focus is a focus-by-wire design - a motor drives the lens focusing as the well-damped focus ring is turned. This design requires the camera to be powered on to drive the motor. Although FTM (Full Time Manual) focusing is available, you first need to press the shutter release half-way (or AF-On button) and achieve AF lock. Then FTM focusing will work as long as you keep the shutter release pressed half way. An especially nice feature is the adjustable manual focus speed. A switch allows selection of three focus speeds: 1 = 1/2 standard (for precision), 2 = standard and 3 = 2x standard (for fast-moving subjects).”

“Like most of the super telephoto lenses, this lens has a preset feature. To use this, achieve the desired focus distance and slide the Focus Preset slider switch toward the camera. A "beep" indicator will be heard if the signal selector is turned on (another small switch). The preset focus can be later recalled by turning the knurled reading ring in either direction (before the shutter release is pressed half way - which locks focus) and holding it while the picture is taken. There are some situations for using a preset focus distance, but in reality, it is probably not used it very often.”

[Jeffb]

Thanks!   

[deebatman316]

Many of Canon's early USM lenses required Electronic Manual Focusing. The following lenses listed below have electronic MF. EF 300mm F2.8L USM, EF 50mm F1.0L USM, EF 28-80mm F2.8-4L USM, EF 1200mm F5.6L USM, EF 200mm F1.8L USM, EF 600mm F4L USM, EF 85mm F1.2L USM, EF 85mm F1.2L II USM, EF 400mm F2.8L USM, EF500mm F4.5L USM, EF 400mm F2.8LII USM. All of these telephoto and super telephoto lenses listed above have been replaced by a newer IS equipped version. That doesn't use an electronic focus ring. Except the EF 85mm F/1.2L II USM lens which still has the electronic focus ring. Makes sure "USM Lens Electronic Manual Focus (older cameras)/ Lens Electronic Manual Focus or Manual Focus After One Shot (newer cameras)" is Enabled or the focus ring WILL NOT WORK. Newer USM EF lenses incorporate a clutch system to prevent damage to the AF motor. ALL RF lenses utilize an Electronic Focus Ring regardless of USM or STM.

-Demetrius

Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM