5D4 Low light ability in live view better than the viewfinder?

[wockawocka]

Hi all,

Just wanted to ask a quick one about low light af ability. If memory serves me correctly the cross points focus at F2.8 but anything faster, like a 1.2L lens won't assist focus even though more light reaches the sensor?

If so, does this also translate to the dual pixel AF when in live view too, or is it much better?

 

[Sdiver2489]

Hi all,

Just wanted to ask a quick one about low light af ability. If memory serves me correctly the cross points focus at F2.8 but anything faster, like a 1.2L lens won't assist focus even though more light reaches the sensor?

If so, does this also translate to the dual pixel AF when in live view too, or is it much better?

Dual pixel AF doesn't use the same focusing interface. Live view focusing is more sensitive to light then the phase detection assembly. Typically the more light any sensor gets though the easier time it will have focusing. For example the A6000 sometimes struggles to focus when the aperture decreases to F8-9.

 

[Sharlin]

If memory serves me correctly the cross points focus at F2.8 but anything faster, like a 1.2L lens won't assist focus even though more light reaches the sensor?

The smallest aperture at which the wide-baseline diagonal cross-type sensors function is f/2.8, but I don't see why they wouldn't work better with an even larger aperture. The size of the secondary mirror might be a bottleneck, maybe?

 

[ahsanford]

Also, re: lower light, the 5D4 has -3 EV focusing through the viewfinder but -4 EV focusing through LiveView. That is a first for Canon, I believe.

It's also perhaps the only weakness of the 5D3 AF I've experienced (besides black servo markers) in 4 years of 5D3 ownership. At concerts and indoor events where I can't use a flash, a number of lenses just can't lock in really low light. Going from -2 EV to -4 EV would be a gamechanger for that application (though admittedly it's a niche/rare need on my part).

- A

 

[raptor3x]

If memory serves me correctly the cross points focus at F2.8 but anything faster, like a 1.2L lens won't assist focus even though more light reaches the sensor?

The smallest aperture at which the wide-baseline diagonal cross-type sensors function is f/2.8, but I don't see why they wouldn't work better with an even larger aperture. The size of the secondary mirror might be a bottleneck, maybe?

You got it, the submirror assembly acts as a virtual aperture.

 

[Sharlin]

Also, re: lower light, the 5D4 has -3 EV focusing through the viewfinder but -4 EV focusing through LiveView. That is a first for Canon, I believe.

It's the first time Canon has published a spec for LV low-light focusing. However, the 80D DPAF also keeps focusing down to ~1EV lower light than the discrete AF sensor (the latter is spec'd as -3EV but that figure is a bit optimistic according to tests.)

Another thing to keep in mind is that non-center discrete AF points only go down to -1EV but in Live View you get that -4EV focusing over most of the frame!

 

[ahsanford]

Also, re: lower light, the 5D4 has -3 EV focusing through the viewfinder but -4 EV focusing through LiveView. That is a first for Canon, I believe.

It's the first time Canon has published a spec for LV low-light focusing. However, the 80D DPAF also keeps focusing down to ~1EV lower light than the discrete AF sensor (the latter is spec'd as -3EV but that figure is a bit optimistic according to tests.)

Another thing to keep in mind is that non-center discrete AF points only go down to -1EV but in Live View you get that -4EV focusing over most of the frame!

People pick on mirrorless for more reasons than you can count, but the potential of reading AF straight off the sensor is staggering. It's in its infancy now, of course, but not giving (as much) of a damn about max aperture of the lens, massive span of AF coverage, the thumb-swipe AF select feature the EOS M5 is kicking around, etc. give folks who don't give a damn about size a functionality boost to look forward to.

- A

 

[pokerz]

Canon proves that Liveview AF is superior to OVF in low light condition.