by Rodrigo

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EOS means "electro-optical system" and it describes BODIES with EF mount. EF means "electro focus" and it describes LENS MOUNT designed for this af. Therefore all "EOS lenses" are autofocus-by-wire* by definition. They usually have manual focus ring which you can use when AF fails. EF-M is an EF camera specifically designed for people who want to use EF ...


I don't know about the focus-by-wire bit, but this photo.net discussion thread includes side-by-side images of the mounts of a 5D and an EF-M, and shows that the EF-M did indeed have all the electrical contacts of the EOS mount. My guess would be that manually focusing with focus-by-wire will probably still work, since that's more about electronic ...


In addition to the LCD overlay in the viewfinder, covered well in this answer, some Canon lenses are focus-by-wire. Any of the STM series of lenses will not move focus elements when there is no power being supplied to the lens by the camera. From Bryan Carnathan at The-Digital-Picture: Additional typical Canon STM AF benefits include internal focusing, ...


Yes, it's normal behavior. The reason you're having problems is that the 5DMkIII has an LCD overlay in the viewfinder. This overlay is used to give you grid lines you can turn on and off and different AF point displays. Without power, the LCD becomes opaque. This behavior is identical in Nikon cameras with an LCD overlay in the viewfinder, and has long ...


Simple answer: yes. Inexpensive option: 'Bresson'. Here's a review. I have one for my 5100.


What you are showing isn't just a focusing screen. It is a focusing screen with two special focusing aids. First, it has a split prism, which works as a tiny rangefinder — when the two sides are aligned, the subject is in focus. Second, outside of that, the rough microprism ring gives a similar effect, with a different tradeoff between ease of focus and ...

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