Put a large sensor on a wide aperture and you get a very shallow focus range.
Agree, I observed this from 6x9 photography and large scale darkroom work in the past. This is one part of the F=1.0 problems. But it is already worked into the specs. All these cameras list DOFs starting further away than their F=1.6 relatives. Some people ignore this until it hits them. That is a user problem.
I don't think it's factory focusing but Depth of Field you're observing.
My three 5442 f=1.0 lenses tell me a different strory.
The 3.6mm is supposed to have DOF starting at 2.6m. But it is still noticably blurred at 4m. It is even somewhat blurred at 9m. So this is not me looking at something outside the
stated DOF, this is the camera not being crisp
inside the stated DOF. Both 2.8mm lenses provide a clearer image at 4.0m, despite lesser magnification.
Why is it slightly blurred? It may not be focused, which is another way of saying the object isn't located in the
actual DOF. Or it may have a bad lens assembly. Or there may be some problem with the sensor. So let us take a look at the other lenses.
My two 2.8mm 5442 F=1.0 lenses tell a different part of the story. They are crisp in some distance zone. But it isn't the same distance zone for these two. Despite them being the same model, same settings. One lives up pretty much to specs, DOF starts at about 1.6m. At 1m, it is noticably blurry (which is quite OK, specs warned you). The other 2.8mm lens seems slightly blurry at the far end but renders well to about 1m. So in these two "identical cameras" the lens or focus has been adjusted differently. As these are just two samples, it gives you an estimate about the variability of factory focus adjustment.
If you take the angular turn difference between the 2.8mm lenses, take it to a 3.6mm lens and apply this angular turn it in the other direction, you would likely get a rather far off DOF. Maybe even beyond infinity. Which would bring us back to the 3,6mm lens. If you have ever used a manual focus camera lens, you will have observed that you have to turn the dial a lot for near distance changes. But it isn't such a big turn from 2.6m to infinity.
My first task will be to find out if my 3.6mm can render a crisp image with some help outside. Cause I would like to rule out the sensor as cause.
Edit:
I'd predict that the 5442 on a 1/1.2" and f1.0 will have a similar dof to a 4kx, simply because it's a similar sized sensor on the same aperture. However, I don't have one so until someone has tested it.....
I am not sure I understand your statement. To me it sounds as if you would like to take one of my 5442 f=1.0 lenses and just enlarge the sensor. Afaik, this would change nothing in the already existing region of the sensor. So the DOF would stay the same there. But perhaps this current lens would not illuminate the entire new sensor field or have severe distortion further out.
