A question regarding pixel size and the number of pixel

[DavidMillier]

I think I must be doing something wrong. I'd quite like to know what. Until then, I will stick with AF-S because it is reliable and trustworthy.

There is no reason whatsoever to use AFC for static subjects. None.

Agree. No reason to use AFC for static subjects. AF-S could maybe even be more accurate (smaller focussing box also), but so far I didn’t encounter any problems (accuracy and speed). when using AF-C. So, you could also say, that there’s no reason (at least for me) to use AF-S instead of AF-C.

In fact, manual focus (with magnification and/or peaking) might be even better...

Sorry to budget in here: I have started using AF-C with my A7RV 2 years ago. Doesn't make a dime of a difference either way, static or moving. Everything, we'll, not everything-everything but mostly 100% is in focus. All the time.

Deed

But are we talking about the same thing?

In AF-C mode with my A7Riv, if I point the centre focus point at say a book on my bookshelf and half press the shutter release, then move the framing to something a bit closer, it refocuses. If I then move it to a different object on the shelf it refocuses again, even if I move it just a fraction.

This is the expected behaviour with AF-C and I imagine exactly what you experience. The camera constantly refocuses in real time on whatever is under the centre point as long as I hold the half press.

It makes sense it does this for moving subjects. But for static subjects, once I have focused the camera, I want to be free to move the framing around until I have the composition I want without the camera refocusing: I have already chosen my focus point, I don't want the camera changing this. AF-C is really disconcerting for static subjects because it keeps focuses on whatever is under the focus point, and not what I want it to focus on.

I suspect the camera can be switched to some other mode where it will continue to hold the focus on and track the book I first focused on as I adjust framing, but I don't understand the AF system and what the settings need to be set to make it do this.

EDIT: I may have made some progress. This site https://enthusiastphotoblog.com/setting-up-sony-a7riv/ recommends setting AF-C and flexible spot tracking. I've tried this and it appears that when I focus on something and half press, it locks the focusing point and if I move the camera the point stays on the original focused object and the focusing box moves around the screen to compensate. Not only this, if there is a person in the frame, AF automatically finds the eye and locks on this even if you wave the camera around. This is pretty cool! Welcome to the 21st century, Dave!

Good that you've found more information about this! And it's exactly what I mean. And then it doesn't have to find an eye, if you don't want that (there doesn't have to be an eye anywhere to keep your focus locked). Locking onto a specific part (inside the small square, which I always start out centred), and keeping this part in focus even when you recompose/ move around…that's the attractive part. Very handy and effective also. I only wished the focussing square could be set as small as in AF-S. In Fuji GFX cameras. Not possible, or so it seems.

I switched from A7RIV to GFX. What MF do you use (I presume , you use a MF as well..not sure, while typing this)?

GFX50s

 

[JimKasson]

In short: I thought that selecting 3000x2000 crop would be a good way to compare sensors, e.g. if I like it or not.

Then you are stacking the deck in favor of 2000x3000 sensors and against any higher resolution sensor.

That would be correct if the sensor was 2000x3000 pixel, but my sample pics are crops.

What difference does that make? It's still stacking the deck.

How would you compare sensors with different pixel sizes?

As I've said repeatedly here, at same print size. If you have the right resampling software, at same image size on the screen.

Look, I noticed within my photo containers that I often liked certain images better regarding the look. Turns out, that this happened when the pixels were larger. Somebody here suggested that I was wrong and my bias came from influencers, whatever.

Sorry. I didn't say that, and there are assumptions there that are IMO unjustified.

I found it offensive to just say that without evidence. The same poster also said that neither eye af, nor AF-C was working for him on Sony cameras. Possible. But, looking at my experience with Sony and bit off. So we possibly have different ideas as to how photography works in 2025.

You never addressed pixel size. Did I overlook this or was this deliberate. Or, neglible, nothing to see and my shots inconclusive?

You asked about DR and pixel size. For the same size sensor with the same technology, same image size DR is not related to pixel size in any meaningful way.

Deed

--
https://blog.kasson.com

 

[mujana]

I think I must be doing something wrong. I'd quite like to know what. Until then, I will stick with AF-S because it is reliable and trustworthy.

There is no reason whatsoever to use AFC for static subjects. None.

Agree. No reason to use AFC for static subjects. AF-S could maybe even be more accurate (smaller focussing box also), but so far I didn’t encounter any problems (accuracy and speed). when using AF-C. So, you could also say, that there’s no reason (at least for me) to use AF-S instead of AF-C.

In fact, manual focus (with magnification and/or peaking) might be even better...

Sorry to budget in here: I have started using AF-C with my A7RV 2 years ago. Doesn't make a dime of a difference either way, static or moving. Everything, we'll, not everything-everything but mostly 100% is in focus. All the time.

Deed

But are we talking about the same thing?

In AF-C mode with my A7Riv, if I point the centre focus point at say a book on my bookshelf and half press the shutter release, then move the framing to something a bit closer, it refocuses. If I then move it to a different object on the shelf it refocuses again, even if I move it just a fraction.

This is the expected behaviour with AF-C and I imagine exactly what you experience. The camera constantly refocuses in real time on whatever is under the centre point as long as I hold the half press.

It makes sense it does this for moving subjects. But for static subjects, once I have focused the camera, I want to be free to move the framing around until I have the composition I want without the camera refocusing: I have already chosen my focus point, I don't want the camera changing this. AF-C is really disconcerting for static subjects because it keeps focuses on whatever is under the focus point, and not what I want it to focus on.

I suspect the camera can be switched to some other mode where it will continue to hold the focus on and track the book I first focused on as I adjust framing, but I don't understand the AF system and what the settings need to be set to make it do this.

EDIT: I may have made some progress. This site https://enthusiastphotoblog.com/setting-up-sony-a7riv/ recommends setting AF-C and flexible spot tracking. I've tried this and it appears that when I focus on something and half press, it locks the focusing point and if I move the camera the point stays on the original focused object and the focusing box moves around the screen to compensate. Not only this, if there is a person in the frame, AF automatically finds the eye and locks on this even if you wave the camera around. This is pretty cool! Welcome to the 21st century, Dave!

Good that you've found more information about this! And it's exactly what I mean. And then it doesn't have to find an eye, if you don't want that (there doesn't have to be an eye anywhere to keep your focus locked). Locking onto a specific part (inside the small square, which I always start out centred), and keeping this part in focus even when you recompose/ move around…that's the attractive part. Very handy and effective also. I only wished the focussing square could be set as small as in AF-S. In Fuji GFX cameras. Not possible, or so it seems.

I switched from A7RIV to GFX. What MF do you use (I presume , you use a MF as well..not sure, while typing this)?

GFX50s

Ok. Unfortunately I don’t know anything about focussing capacities of the 50S.

--
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