FS5: FS5 losing focus when switched off

M

mitchino

Member
Just want to ask if this is normal behaviour and why it happens?

I have a Canon 24-70mm Mk II attached to my FS5 using a Metabones Speed Booster. The lens is set to manual focus, the camera is set to manual focus, but if I focus on my subject, then switch the camera off, when I switch on again, the focus is way off.

It doesn't make sense to me as I am rotating the focus barrel on the Canon lens, it doesn't move after I've set it

I assume the metabones adapter is responsible? The camera makes some kind of focusing noise when I switch it on.
 
The focusing barrel of your lens is not linked to an absolute focus position, it does not need to move for the focus to change. In fact, when your camera autofocuses, the focus obviously changes but the ring does not move. The focus on Canon EOS lenses is not truly manual, it is controlled electronically, that's why you can rotate the focus ring continuously on most Canon EOS lenses. Same goes for the aperture. Body powers the lens and is involved in focusing process, it is likely that Metabones / FS7 combo "forgets" the focused distance (or affects the lens's memory of that if that's where this is stored). It's a hit or miss with the EOS lenses and Metabones, it is not 100% consistent how they behave. My Sigma 18-35mm keeps the same focus when turning on and off the camera.
 
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broughtonfilm said:
The focusing barrel of your lens is not linked to an absolute focus position, it does not need to move for the focus to change. In fact, when your camera autofocuses, the focus obviously changes but they ring does not move. The focus on Canon EOS lenses is not truly manual, it is controlled electronically, that's why you can rotate the focus ring continuously on most Canon EOS lenses. Same goes for the aperture. Body powers the lens and is involved in focusing process, it is likely that Metabones / FS7 combo "forgets" the focused distance (or affects the lens's memory of that if that's where this is stored). It's a hit or miss with the EOS lenses and Metabones, it is not 100% consistent how they behave. My Sigma 18-35mm keeps the same focus when turning on and off the camera.
Click to expand...

Well, depends on the lens. Some lenses, like the 85L are completely "fly-by-wire" and can not be operated without power. Other lenses, like the 70-200L or 24-105L are a hybrid of manual and electronic. You can manually adjust focus with or without power getting to the lens. There were "dumb adapter"(mechanical only) in the early days that allowed you to use Canon lenses, you obviously you had no aperture control, BUT you could still focus with lenses that were not completely "fly-by-wire" electronic focus control.
 
Yes, that's true and it creates even more confusion for people who want to use the lenses on non native camera. Still, in case of the lenses that are hybrid, the ring does not move when lens autofocuses (if I remember correctly), meaning that they are not permanently linked, there's no absolute focus distance relative to the ring position.
 
I have a non-speed booster Metabones for my F55 and I have never noticed it doing anything like that, but it's a different adapter. It may be performing some sort of "check" when it powers/boots up. Just guessing.
 
When you use the Metabones configuration app (like during a firmware upgrade), you have the option to "park focus to infinity upon shutdown to shorten its length for storage". Obviously this doesn't apply/work with all lenses, but if you have this option enabled it may indeed change the focus setting of your lens...

Piotr
 
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