Canon R7, Ef 100-400 ii and 1.4 Tc Bif Photos. Are these acceptable?

Ephemeris wrote:

Victor Engel wrote:

Ephemeris wrote:

Victor Engel wrote:

Ephemeris wrote:

Victor Engel wrote:

Ephemeris wrote:

davel33 wrote:

"So 1.4 tc doesn't improve iq"

There is NO extender 1.4x or 2.0x that will improve iq.

It only makes the image bigger.

There is a difference

I fell for that same trap.

It could help your AF get an in focus shot?

Or it could hinder, if the focus sensors require a wide aperture to work well.

Becuase of the amount of light? Not sure I quite follow.

It has nothing to do with the amount of light. Cameras using phase detection to focus (see https://en.wikipedia.org/wiki/Autofocus) rely on rays traveling through the lens at some distance from the center. The more accurate sensors require f/2.8, one of the reasons there are so many f/2.8 lenses. Adding a TC, you reduce, possibly, the number of focus sensors available for focusing. because those sensors can't see through the lens. This doesn't apply to contrast detection focusing.

Cameras like R5 and R7 that use dual pixel technology for focusing require a certain minimum aperture. With the recent introduction of several f/11 lenses, I'm guessing it must be slightly smaller than f/11. If I'm right, the dual pixel focusing would not work with one of those lenses plus a TC.

Im not sure that I follow.

Why would using a TC reduce the number of pixels available for focussing?

Think of it from the focus sensor's perspective. The view out the front of the camera from the focus sensor is through the aperture. There is a circle through which it can see. The focus sensor that uses phase detection uses one ray to the left and one ray to the right of this circle to determine whether the subject is in focus. When you add a TC, the size of that circle is reduced. If the ray the focus sensor uses is outside that circle, it can't focus.

But that is still suggesting that we can use a phase detecting camera above a focal length of 400mm, but we can? I personally don't go further than 560mm but I read in group of people out way past 800mm.

It's not focal length but aperture that matters. I can focus with my 600mm f/4 lens with 1.4x TC on my 5DS because the 5DS has an f/5.6 focus sensors (the middle ones). I don't think it has f/8 sensors, though, so I'll bet it doesn't focus well with a 2x TC. I'll give it a try next time I use the lens on my 5DS. I can still focus with live view, though, which uses the slower contrast detection.