When should I close my aperture?

TheGremmie said:

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Aside from making the picture darker, what qualities in my photos with change if I closed the aperture? My understanding so far is that it'll make my backgrounds blurrier.

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It will make the background sharper, not blurrier!

https://www.cambridgeincolour.com/tutorials/depth-of-field.htm

Tom Axford said:

It will make the background sharper, not blurrier!

https://www.cambridgeincolour.com/tutorials/depth-of-field.htm

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Yes.

This might be helpful as well:

OK, take the typical example. Apsc sensor camera with f3.5-5.6 kit lens. At f3.5 your people images will have a soft/blurry background.

At f5.6 the background is slightly less blurry, at f22 or whatever the maximum is for the camera, in theory everything should be in focus, no blurry spots, but you need to increase exposure time because less light os reaching the sensor.

People like to have portraits with extremely blurry backgrounds for some reason, but for landscapes this is less than ideal because nobody wants to see/ buy an image with a in-focus forest and a blurry mountain in the background. Another example, when you take an image of someone in front of a monument, like the Eifel Tower. You want both of them in focus, so you use a higher f value.

Took me 10 years to understand this.

Then again, i usually shoot in P mode and let the camera choose the f value. With compact cameras the in focus area increases as the camera has a smaller sensor.

So big sensor= shallow depth of field.

Tiny sensor= large depth of field when using the same f value.

I feel so wise right now. At the same time i understand i'm still a noob after all these years...

TheGremmie said:

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Click to expand...

It seems that you are using manual mode. There's nothing wrong with that but nor is there anything specially right with it. As you are learning it's a good idea to learn all the different ways in which you can operate your camera.

TheGremmie said:

Aside from making the picture darker,

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It only makes the picture darker if you keep the other parameters the same. The overall darkness (tonality) of the picture depends on the balance between the two components of exposure - aperture and shutter speed - and ISO. They are all graduated in stops ( a factor of 2 or 1/2 depending which way you go).

As a basic principle it's often (but not always) better to keep ISO as low as possible. After that you set aperture and shutter speed to give the tonality you want.

TheGremmie said:

what qualities in my photos with change if I closed the aperture?

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A lens can focus at only one distance; everything nearer or further away is out of focus to some degree. Fortunately, our eyes can see things as sharp even when they are slightly out if focus. This means that there is a zone of distances in front of and behind the focus distance where the photo looks sharp. This zone is called the Depth of Field (DOF). Other things being the same the DOF increases as aperture reduces.

So with your lens wide open its DOF will be as shallow as you can get; as you stop down to smaller aperture DOF increases.

TheGremmie said:

My understanding so far is that it'll make my backgrounds blurrier.

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So this is back to front - stopping down reduces background blur, often to a point where there is no blur in the background.

I said "other things being the same" but they rarely are. This link simulates the effects of the range of settings that affect DOF. https://dofsimulator.net/en/

For a lot of situations it is DOF that is the crucial factor in getting the type of shot you want; for example, landscape photographers usually want the whole scene sharp from front to back. For those situations aperture priority mode can be more convenient than using manual.

Often but (again) not always this will give a shutter speed that's fast enough to avoid blur without you needing to bother about exactly what the shutter speed is. But, of course, there are times when shutter speed is critical. In those situations shutter priority mode can be more convenient.

And then there are times when both DOF and shutter speed are critical: in that case you can use manual with auto ISO.

But whichever mode you use you need to understand the individual effects of aperture (deeper or shallower DOF) and shutter speed (more or less motion blur - with different considerations when the concern is camera-motion or subject-motioin blur).

To control depth of field, and to achieve maximum sharpness when that is important. Most lenses are not at their sharpest wide open, and give their best optical performance when stopped down a bit. Experiment to find the "sweet spot" for your particular lenses.

Rambow said:

OK, take the typical example. Apsc sensor camera with f3.5-5.6 kit lens. At f3.5 your people images will have a soft/blurry background.

At f5.6 the background is slightly less blurry, at f22 or whatever the maximum is for the camera, in theory everything should be in focus,

Click to expand...

A lens can focus at only one distance; everything closer or further away is out of focus to some degree. Unless the subject is a flat plane it's impossible for everything to be in focus.

It can look sharp but sharpness and focus are different things and it doesn't help to confuse them. Things that are slightly out of focus can still look sharp; how much they are out of focus depends on the aperture. The zone of distances in front of and behind the focus distance us called the depth of field and that is what you are describing.

Especially at wide apertures (with shallow DOF) the range of distances that look sharp depends on the focus distance. That's why it's important to distinguish sharpness and focus. If one says "focus at 5m and everything from 4m to 6m will look sharp" it's easy to understand. But one can't focus at 4-6m ...

Rambow said:

no blurry spots, but you need to increase exposure time because less light os reaching the sensor.

People like to have portraits with extremely blurry backgrounds for some reason, but for landscapes this is less than ideal because nobody wants to see/ buy an image with a in-focus forest and a blurry mountain in the background. Another example, when you take an image of someone in front of a monument, like the Eifel Tower. You want both of them in focus, so you use a higher f value.

Took me 10 years to understand this.

Then again, i usually shoot in P mode and let the camera choose the f value. With compact cameras the in focus area increases as the camera has a smaller sensor.

So big sensor= shallow depth of field.

Tiny sensor= large depth of field when using the same f value.

I feel so wise right now. At the same time i understand i'm still a noob after all these years...

Click to expand...

TheGremmie said:

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Aside from making the picture darker, what qualities in my photos with change if I closed the aperture? My understanding so far is that it'll make my backgrounds blurrier.

Click to expand...

That wouldn't be my first choice and it is limiting you a bit. (One thing) the aperture controls is how great an area in front of and behind the subject is in reasonable focus. It's trendy to have shallow focus, but it's not always the correct thing for the scene.

No, "picture darker" (or lighter) is the wrong way to look at this. That was correct in simpler box camera days when cameras used film and had one shutter speed. You have a fine camera with a lot of settings. Explore them.

It's a formula where the combination of ISO, aperture and shutter speed combine to give you a correct exposure. This can get very detailed and long. Do some research on the "exposure triangle".

"Background blurrier" is a bit more complicated. Yes, wide open the background could go "blurry", but lenses are not at their sharpest wide open either. It's also a bit distance dependent. Do some research on Depth of Field. There are great DOF apps and even a few websites that demonstrate the effect.

You're on the right track. It's a little hard to explain out of context/without an image to analyze.

Mark Scott Abeln said:

Mark S Abeln said:

Yes.

Click to expand...

This might be helpful as well:

https://dofsimulator.net/en/

Click to expand...

Mark,

That is very cool.

Steve Thomas

If you're using the slow zoom lens that comes with most bodies, you might not notice the difference unless you took back to back shots of something like a close-up.

The apertures are already narrow compared to a fast prime. At 50mm, you might be at f/5.6, where the prime might be f/1.4. The difference in dof would be obvious.

If you like to learn from books, here are a couple (among many) that give a brief and easy explanation -

The Beginner's Photography Guide: The Ultimate Step-by-Step Manual for Getting the Most from Your Digital Camera

Portrait Photography: From Snapshots to Great Shots by Erik Valind

And one with an exhaustive treatment, often recommended for aspiring pros -

Understanding Exposure, Fourth Edition by Bryan Peterson

Kelly Cook

Rambow said:

OK, take the typical example. Apsc sensor camera with f3.5-5.6 kit lens. At f3.5 your people images will have a soft/blurry background.

At f5.6 the background is slightly less blurry, at f22 or whatever the maximum is for the camera, in theory everything should be in focus,

Click to expand...

Gerry already explained that only things on the subject plane will be in focus, but other things will be acceptably sharp. However, for typical APS-C cameras and lenses, most things in a typical landscape scene will already by acceptably sharp at f/11. Occasionally you have to go to f/16. Often f/8 is enough. By stopping down more than you need to, you are making things that were already sufficiently sharp at the wider aperture less sharp, due to increased diffraction blur.

Stopping down a lens has the following effects:

1. Reduces the amount of light reaching the sensitive medium (= reduces exposure)
2. Reduces the amount of blur from lens aberrations
3. increases the amount of blur from diffraction
4. Increases the Depth of Field

Effect 3 is small at wide aperture, but increases as apertures are narrowed. Effect 2 is large at wide aperture but decreases as apertures are narrowed. As a result of the interaction of these two effects, most lenses tend to be sharpest when stopped down a few (1-4) stops from wide open.

Also, the f-number at which a lens tends to be sharpest seems to vary with sensor size. Many FF lenses are sharpest at around f/8. On APS-C it is often f/5.6. On MFT f/4 and on 1" f/2.8. The better the lens, the lower the sharpest f-number (because there are fewer aberrations to overcome). For instance, good FF lenses may be sharpest closer to f/5.6 while poor ones may only reach peak edge sharpness closer to f/11.

Most lenses are sharper in the centre of the frame than at the edge of the frame. On most of these, stopping down decreases the difference in sharpness between centre and edge - it sharpens up edges more then centres. A lens may reach peak centre sharpness at a lower f-number than peak edge sharpness.

On some lenses, stopping down may also reduce vignetting.

In A mode, (or Av mode if that's what your camera calls it) stopping down the lens will cause the camera to slow the shutter speed by the same number of stops. The net result of the two adjustments is no change in the amount of light reaching the sensitive medium (film or sensor) and no change in image lightness and noisiness, however the DOF will increase, lens sharpness will change, and motion blur will increase (due to the slower shutter). If Auto-ISO is enabled. the camera may instead increase the ISO setting, if the shutter speed is already at a predetermined minimum speed. This will have the same net effects as without Auto-ISO except that image noisiness will increase, and motion blur will not increase.

I would guess that the most common reasons why people choose to stop down are:

1. Increase DOF
2. Increase lens sharpness
3. Avoid overexposure
4. Force a slower shutter in A mode

TheGremmie said:

When should I close my aperture?

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Aside from making the picture darker, what qualities in my photos with change if I closed the aperture? My understanding so far is that it'll make my backgrounds blurrier.

Click to expand...

Stopping down has the following effects:

• Greater DOF
• Less light projected on the sensor for a given exposure time (thus a more noisy photo).
• In conjunction with a concomitantly longer exposure time, it can result in or increase motion blur.
• Greater sharpness for the portions of the scene within the DOF up to a point (lessening lens aberrations); less sharpness beyond that point (diffraction softening) -- this point will vary from lens to lens.
• Less vignetting (which will become insignificant past some point).
• Sun stars.

So, when should you stop down? The simple answer: any time the benefits listed above outweigh the disadvantages.

The simplest example is if there is so much light that wide open results in overexposure, even at your shortest exposure time (e.g. a photo at noon at f/1.2 1/8000 which would likely end up blowing out a lot of the scene).

Another common example is when shooting landscapes. Typically, you'll want everything sharp and within the DOF, so, as a first approximation, you'd choose the lens' sharpest aperture, and then stop down further if you need more DOF. If you have to stop down so far that diffraction becomes too much of an issue, you would consider focus stacking.

Stopping down is also commonly used to get desirable motion blur, such as blurred water in waterfalls, rivers, ocean waves, etc., or car light streaks in cityscapes, to show speed/motion for aircraft and cars, etc., etc., etc..

Astrophotography is another example. While the photographer can typically get everything they need/want within the DOF wide open, the lens may not be sharp enough or have excessive coma. Thus, one might stop down a bit to achieve the best compromise between noise, star trails, and lens aberrations.

There are a million of other specific situations, all with their own specific answers. However, the six bullet points above pretty much lay it all out -- it's just a matter of applying them to any given situation.

You would also need to close aperture if there is a lot of light. I was shooting outside in full sunlight. At wide open f/1.4 aperture, I couldn't get a shutter speed fast enough to stop overexposure. So I had to go to f/2.8 to get a shutter speed that wouldn't overexpose.

thinkinginimages said:

It's a formula where the combination of ISO, aperture and shutter speed combine to give you a correct exposure.

Click to expand...

ISO setting is applied after the exposure is finished. Because of that, it can't be a part of exposure.

thinkinginimages said:

Do some research on the "exposure triangle".

Click to expand...

"Exposure triangle" is something that shouldn't be researched because it's a misconception. You can do some research to find out why

thinkinginimages said:

It's a formula where the combination of ISO, aperture and shutter speed combine to give you a correct exposure.

Click to expand...

Exposure is given by teh combination of scene luminance, aperture (actually T-stop, but f-stop is a close approximation), and shutter speed. ISO is not a determinant of actual exposure. On some cameras in some modes the ISO setting will determine what exposure the camera will attempt to get.

thinkinginimages said:

This can get very detailed and long. Do some research on the "exposure triangle".

Click to expand...

Bad idea. The so-called "exposure triangle" doesn't actually model exposure. It is a flawed conceptual model.

TheGremmie said:

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Click to expand...

That's a crazy way to use the camera. It should take you no more than a few minutes to research the most appropriate aperture for a range of scenarios, and any rational mode of using the camera will result in a suitable shutter speed for a correct exposure.

Here's a clue. All my cameras have a default "User Preset" for landscape and general photography that starts at f/5.6. All my lenses work well at that Aperture setting, including those with zoom, and the DoF is usually OK for the average composition.

You only rarely need to include ISO in your juggling operation. Many use the auto-ISO feature as a "safety net" feature.

TheGremmie said:

Aside from making the picture darker, what qualities in my photos with change if I closed the aperture? My understanding so far is that it'll make my backgrounds blurrier.

Click to expand...

Wrong!

TheGremmie said:

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Aside from making the picture darker, what qualities in my photos with change if I closed the aperture? My understanding so far is that it'll make my backgrounds blurrier.

Click to expand...

There are four main factors in how dark or light your image looks:

1. Subject Illumination
2. Aperture
3. Shutter Speed
4. ISO

Subject Illumination (the light on your subject) is critical, but rarely gets talked about as it isn't a camera setting.

The "Aperture" is a variable size hole that you are shooting through. Aperture affects both the light reaching the sensor, and the Depth of Field (the range of distances where objects look to be in focus). Larger apertures let more light onto the sensor, but result in shallower Depth of Field. Smaller apertures yield more Depth of Field, but less light reaches the sensor. Keep in mind that most lenses tend to be at their sharpest when the are a couple of stops from wide open. Also, very small apertures can result in a loss of sharpness due to diffraction issues.

In a typical DSLR, a closed shutter blocks the light from reaching the sensor. When you take the picture, the shutter opens for a short period of time, allowing the light to momentarily hit the sensor. The Shutter Speed is simply how long the shutter is open. Movement while the shutter is open can result in a blurry image. Longer shutter speeds allow more light to reach the sensor, but also allow more movement blur. Shorter shutter speeds reduce movement blur but also reduce the light reaching the sensor.

The combination of Subject Illumination, Aperture, and Shutter Speed determine "Exposure". Think of Exposure as the count of photons hitting the sensor while the shutter is open. Higher Exposures (more photons) generally result in lower noise images. Low Exposures tend to result in images with more visible noise.

ISO sets the context for interpreting the count of photons. At low ISO settings we need to see a lot of photons to consider something white. At high ISO settings we don't need to see as many photons to consider something white. The same exposure may result in a very dark image at a low ISO setting and a very light image at a high ISO setting.

The ISO setting also guides the camera metering system. The camera's meter tries to target an exposure that will yield a good looking result at the selected ISO.

====

A big part of photography is finding the right balance between the various factors to find the best compromise.

If you are in a situation where light is somewhat limited a reasonable workflow is:

1. Choose the largest Aperture that gives you sufficient Depth of Field
2. Choose the slowest Shutter Speed that doesn't result in unwanted motion blur
3. Set the camera to Auto-ISO

This will get you the lowest noise image for your situation.

WryCuda said:

TheGremmie said:

A habit I've developed as I've been learning photography is just to leave my aperture open to it's widest setting, and doing most of my adjustments with the shutter speed and iso.

Click to expand...

That's a crazy way to use the camera. It should take you no more than a few minutes to research the most appropriate aperture for a range of scenarios, and any rational mode of using the camera will result in a suitable shutter speed for a correct exposure.

Here's a clue. All my cameras have a default "User Preset" for landscape and general photography that starts at f/5.6.

All my lenses work well at that Aperture setting, including those with zoom, and the DoF is usually OK for the average composition.

Click to expand...

That's a great approach for your APS-C cameras. Are the lenses for your a7 significantly sharper than those for the two others? If not, what happened to "f/8 and be there" for FF? You are getting less DOF with your a7 setting, and lenses of equal quality tend to need one stop narrower aperture on FF to get similar sharpness.

Mystery member said:

You only rarely need to include ISO in your juggling operation. Many use the auto-ISO feature as a "safety net" feature.

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Yes.

Mystery member said:

Mystery member said:

Aside from making the picture darker, what qualities in my photos with change if I closed the aperture? My understanding so far is that it'll make my backgrounds blurrier.

Click to expand...

Wrong!

Click to expand...

Indeed.