Why the aperture remains wide open when using manual mode?

[Yaazkal]

I'm intrigued about why if I set everything manually: speed, ISO, aperture, and focus, the aperture remains wide open all the time and is not closed at the desired f-number (only until the shoot time).

The only way I got it closed all the time is if I use autofocus and lock the focus with the AF-L button. It happens on X100VI and X-T3 for me, I have no idea about other models or brands.

Maybe I'm wrong, but does it make sense? Maybe the lens remains wide open in manual focus because it helps the user for easier focusing? how if anyway the exposure preview is set?

NOW, Why do I want the aperture to remains closed all the time? For faster response when I press the shutter, that way I can have an immediate response on photography like street, fast-moving subjects or in studio shoots with flashes for photographing things in middle air and crashing objects. If the aperture remains closed, I prevent the little lag between the press of the button and the actual taking of the image.

Yes, I know I can better anticipate the shoot, but I'm interested to know why technically the cameras have that behavior. And yes, the natural view is not enabled, I keep the manual mode preview enabled.

PS: I've asked in Reddit without luck. I hope to have it here.

 

[pifilos]

I might be wrong but I think it is to help focus precisely to the point you need.

 

[Erik Baumgartner]

The aperture is automatically wide open for precise focusing. Half-press the shutter button to lock AE for a shooting aperture view, or set up a custom button for Depth of Field Preview if you want to focus stopped down

You can also focus manually in AF-S mode using AF+MF which also get you a stopped down shooting aperture view.

 

[MJ_Photo38]

it's to help achieve critical focus : wide open aperture means narrower depth of field, and it's easier to see what's in focus and what is not.

If you switch back to AF-S or AF-C, the aperture closes down.

Note that any kind of automatic aperture or automatic shutter speed mode will result in the aperture going wide open in exactly the same way as when you use manual focus (this time to maximize light gathering for the live view)

 

[io_bg]

I'm intrigued about why if I set everything manually: speed, ISO, aperture, and focus, the aperture remains wide open all the time and is not closed at the desired f-number (only until the shoot time).

The only way I got it closed all the time is if I use autofocus and lock the focus with the AF-L button. It happens on X100VI and X-T3 for me, I have no idea about other models or brands.

Maybe I'm wrong, but does it make sense? Maybe the lens remains wide open in manual focus because it helps the user for easier focusing? how if anyway the exposure preview is set?

NOW, Why do I want the aperture to remains closed all the time? For faster response when I press the shutter, that way I can have an immediate response on photography like street, fast-moving subjects or in studio shoots with flashes for photographing things in middle air and crashing objects. If the aperture remains closed, I prevent the little lag between the press of the button and the actual taking of the image.

Yes, I know I can better anticipate the shoot, but I'm interested to know why technically the cameras have that behavior. And yes, the natural view is not enabled, I keep the manual mode preview enabled.

PS: I've asked in Reddit without luck. I hope to have it here.

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

 

[MJ_Photo38]

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

If that was the reason, then it would be wide open at all times, in any focus mode.

Yet it's not in AF-S nor AF-C while in manual mode.

 

[Erik Baumgartner]

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

If that was the reason, then it would be wide open at all times, in any focus mode.

Yet it's not in AF-S nor AF-C while in manual mode.

AF-C operates at shooting aperture because it needs to focus and be exposure-ready continuously, but it is wide open in AF-S to focus (with some exceptions in very bright light), then closes down and exposes at shooting aperture - you will see a wide aperture view until you lock exposure with a half-press. This is why AF-S is (can be) much snappier in very low light relative to AF-C with a stopped down aperture.

 

[MJ_Photo38]

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

If that was the reason, then it would be wide open at all times, in any focus mode.

Yet it's not in AF-S nor AF-C while in manual mode.

AF-C operates at shooting aperture because it needs to focus and be exposure-ready continuously, but it is wide open in AF-S to focus (with some exceptions in very bright light), then closes down and exposes at shooting aperture - you will see a wide aperture view until you lock exposure with a half-press. This is why AF-S is (can be) much snappier in very low light relative to AF-C with a stopped down aperture.

I don't remember this behavior... and I've been shooting mostly AF-S on both my X-T1 and 2.

The only moment I remember seeing the X-T2 open up a closed down lens in AF-S was in dim condition, but in normal light I don't remember it doing it.

I'll verify this tonight.

 

[Erik Baumgartner]

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

If that was the reason, then it would be wide open at all times, in any focus mode.

Yet it's not in AF-S nor AF-C while in manual mode.

AF-C operates at shooting aperture because it needs to focus and be exposure-ready continuously, but it is wide open in AF-S to focus (with some exceptions in very bright light), then closes down and exposes at shooting aperture - you will see a wide aperture view until you lock exposure with a half-press. This is why AF-S is (can be) much snappier in very low light relative to AF-C with a stopped down aperture.

I don't remember this behavior... and I've been shooting mostly AF-S on both my X-T1 and 2.

The only moment I remember seeing the X-T2 open up a closed down lens in AF-S was in dim condition, but in normal light I don't remember it doing it.

I'll verify this tonight.

--
(G.A.S. and collectionnite will get my skin one day)

It does stop down in good light as there is plenty of light for a clean EVF view and a better DOF preview, but it will still open wide for a split second for initial focus acquisition when you first press the shutter button.

 

[Bruce in Virginia]

Fun fact (or maybe just old codger comment)

I think the oldest SLR I still own was manufactured in about 1975.

In that timeframe they also left the lens at max aperture while framing and focusing, because you had to focus the lens your self. When you pushed the shutter button down halfway (to the depth of field preview mode), it then stopped the lens down to the actual aperture.

 

[MJ_Photo38]

Fun fact (or maybe just old codger comment)

I think the oldest SLR I still own was manufactured in about 1975.

In that timeframe they also left the lens at max aperture while framing and focusing, because you had to focus the lens your self. When you pushed the shutter button down halfway (to the depth of field preview mode), it then stopped the lens down to the actual aperture.

That's how Nikon F mount cameras work. Lens is wide open all the time and only closes down for the exposure.

same thing from 1959 to 2020 ! The D780 still works like that.

 

[MJ_Photo38]

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

If that was the reason, then it would be wide open at all times, in any focus mode.

Yet it's not in AF-S nor AF-C while in manual mode.

AF-C operates at shooting aperture because it needs to focus and be exposure-ready continuously, but it is wide open in AF-S to focus (with some exceptions in very bright light), then closes down and exposes at shooting aperture - you will see a wide aperture view until you lock exposure with a half-press. This is why AF-S is (can be) much snappier in very low light relative to AF-C with a stopped down aperture.

Okay, so I just tested that really quick :

In AF-S, when you change your aperture value, it closes down, opens up only for focusing, then goes back to the aperture setting you selected.

So it's not wide open all the time in AF-S, but you were right, it opens up only for focusing (unless of couse you shoot wide open already)

 

[Erik Baumgartner]

The the more light reaches the sensor, the better the focus system works. That's why the lens will stay wide open until you half press the shutter.

If that was the reason, then it would be wide open at all times, in any focus mode.

Yet it's not in AF-S nor AF-C while in manual mode.

AF-C operates at shooting aperture because it needs to focus and be exposure-ready continuously, but it is wide open in AF-S to focus (with some exceptions in very bright light), then closes down and exposes at shooting aperture - you will see a wide aperture view until you lock exposure with a half-press. This is why AF-S is (can be) much snappier in very low light relative to AF-C with a stopped down aperture.

Okay, so I just tested that really quick :

In AF-S, when you change your aperture value, it closes down, opens up only for focusing, then goes back to the aperture setting you selected.

Yes, focusing is quicker and more accurate with more light to work with, and a shallower DOF is better for focusing precision.

So it's not wide open all the time in AF-S, but you were right, it opens up only for focusing (unless of course you shoot wide open already)

The aperture opens up in lower light as well (scaling up a dark, stopped down image to normal viewing brightness makes for a noisy EVF experience).

--
(G.A.S. and collectionnite will get my skin one day)