Camera with viewfinder tracerball focusing

Wouldnt it be nice to be able to move the focus point inside the viewfiner around using a thumb-operated tracer ball on the camera body. The cluster of fixed focus points common in todays dslrs are so limiting because they dont cover the entire frame. a single focus point moveable anywhere is what I need. Canon, are you taking notes?

Better..https://photography-on-the.net …&highlight=eye-control+af.

texshooter wrote in post #16982862
Wouldnt it be nice to be able to move the focus point inside the viewfiner around using a thumb-operated tracer ball on the camera body. The cluster of fixed focus points common in todays dslrs are so limiting because they dont cover the entire frame. a single focus point moveable anywhere is what I need. Canon, are you taking notes?

Just that this requires that the camera uses the image sensor for AF since a traditional phase-detect AF sensor can't do what you want.

And having the image sensor used for the AF points means the mirror can't block the sensor. So you either need a half-transparent mirror or a mirror-less camera with an electronic viewfinder.

When using Phase detect AF and an optical viewfinder you are working with an AF sensor that is mounted in the bottom of the camera. It get the light it works with by using a semi silvered section of the main reflex mirror and then a sub mirror to reflect the light to the bottom of the camera. The sub mirror only steals light from the viewfinder in the center of the frame, so is generally not noticed,the corners are generally a bit darker anyway so it evens out overall. For the OP's request to work you would have to be able to have an AF sub mirror that covered the whole of the viewfinder so would need to be the size of the main mirror. This would double the depth of the mirror box, and also double the lens registration (already just about the largest of any 35mm format SLR camera). Mind you it would need this extra depth to mount the control and and drive systems that would be needed to move the physical AF sensor to the spot that it needs to be located at. Even once you have done this you have the issue of showing the actual location of the AF sensor in the viewfinder. I guess you could now solve that by using a Transmissive LCD system as is used in the 5DIII/7D and I think 1Dx and 6D have them too, so now becoming mainstream at least.

The Eye Control Function referred to above is great if you can use it, I have never tried one, but it seems like Marmite it works for you and you love it, or it is the spawn of Satan. Even so it is only really of use for switching between fixed AF points. If if a truly moveable AF point were possible, I do not think that ECF is likely to be accurate enough to really control it effectively.

So now we are back to moving between fixed AF points. If Canoon won't reintroduce ECF, or ECF won't work for you you need an alternative. Canon had a really good system for controlling the active AF point. The little joystick, although it was actually very like using a track ball would be as it was a very short joystick. This was a standard part of the Prosumer level cameras for many years. It was available on all of the xxD models up to the 50D and is still on the 5/7D bodies. They even added an extra one to the pro 1 series cameras for use in vertical mode it was that useful (They've even added one to the battery grip for the latest 5/7D's).

Alan

Fortunately for what I shoot, I don't change AF points often. In most cases, too, I can just focus and recompose, hardly ever is my DOF so thin that I could move the plane off the subject material. I do like the different AF points and modes you get by camera orientation, I definitely use that.

For 45-61 AF points, I usually set the camera up to only use a subset, so moving around with a joystick isn't a big deal if I do have to move.

John from PA wrote in post #16982965
Better..https://photography-on-the.net …&highlight=eye-control+af.

it's a bit amazing that canon hasn't attempted to bring back ECF on a single digital body. I loved my EOS 3.

dbdors wrote in post #16985163
it's a bit amazing that canon hasn't attempted to bring back ECF on a single digital body. I loved my EOS 3.

Me too...But we keep waiting and waiting and waiting and...