Hi Valentin, I am a wedding photographer in "low light" Michigan.
I professionally shot with Canon for years, then Nikon for a while, then 5 years ago settled in using Sony when they brought out the 24 meg FF A900 … which had the same sensor as the Nikon D3X I was using at the time. One main reason was to get at the Zeiss ZA AF optics I preferred. The other was a then considerable shedding of Pro body size and weight.
I now use a 24 meg FF Sony SLT A99 which is roughly the equivalent of your 5D-III except it is a SLT "Translucent Mirror" camera that acts like a mirror-less with a EVF rather than an optical one. It was this camera that helped me convert to electronic viewfinder use. I now also use a A7R which is truly mirror-less and really small.
A few observations and cautions.
1) Initially, EVF at a wedding is a bit difficult to get accustomed to. The bonus is that with the camera menu set to "Setting Effect On" you get exactly what you see in the viewfinder in every respect. The distracting part is you see overexposures or underexposures which can be startling at first.
If you shoot auto WB in low tungsten lit venues, the VF image will be grossly yellow/red unless you custom WB.
If you shoot a higher ISO in low light, the viewfinder shows gain and noise compared to an OVF. The view smears if you move the camera quickly in lower light ilke we often shoot in during reception events.
When you use strobes and are using a lower ISO in low light @ f/5.6 or f/8+, the viewfinder will go black.
2) With the camera menu set to "Setting Effect Off", mirror-less is similar to an OFV. This is the setting required for that type of strobe work.
3) Unlike my A99 and my second shooter's 5D-III, the A cameras are more complex to set up and to use. For one example, there isn't a dedicated button for ISO … you have to assign it to one of the buttons scattered around the camera then remember which one because it isn't marked as such. It just takes time to commit it to muscle memory.
4) The instant review of the last shot appears in the viewfinder as well as the LCD, and this is my biggest negative coming from an OVF. It was incredibly confusing when this first happened to me … shoot an decisive moment, and it "sticks" in the VF. The only way to avoid this is to completely turn instant review off … so you have to press a button to see the last shot on the LCD.
These are only meant as cautions regarding making a wholesale swap over to all Sony A kit for AF work at a wedding. It WILL slow you down at first, so I'd advise making a slower transition. This is NOT like changing OVF systems … it is a different learning curve.
Lenses:
I have the advantage that my A99 ZA optics work on the A7R camera using a LEA4 adapter that has an AF motor and Translucent Mirror in it … effectively making it a 36 meg version of the A99 that is a smaller. So, I only have the native FE 35/2.8 and 55/1.8. I had the FE 24-70/4, but it was to slow max aperture and it distorted to much IMO.
I only use the 55/1.8 at weddings. MY ZAs are generally larger on the A cameras just like your Canon Ls would be … but lenses like the AF ZA-24/2 are smaller, optically stellar, and focus very fast even in lower light thanks to the Sony AF assisted LEA4 adapter. That said, I find no difficulty with the FE-55/1.8 in lower light.
I have no intention to move to all A cameras for weddings/event work until the FE AF lens line up is more complete and better/faster than the 24-70/4 was. I tend to use the A7R for available light with the FE-55/1.8 (ISO 3200 is better than the 5D-III) … and also use it for off-camera strobe work at weddings.
Speed-Lights:
The native Sony pro speed-lights are simply too big and awkward on the little A cameras … I recently got the mentioned Nissin i40 and it is just the right size IMO … and a nifty little flash. I used it at a wedding this past week-end but in a limited manner until I come to trust it.
- Marc