As you would expect, there are differences between photos taken with a large aperture versus photos taken with a small aperture. Aperture size has a direct impact on the brightness of a photograph, with larger apertures letting in more light into the camera compared to smaller ones. However, that isn’t the only thing that aperture affects.

Usually, the sharpest f-stop on a lens will occur somewhere in the middle of this range — f/4, f/5.6, or f/8. However, sharpness isn’t as important as things like depth of field, so don’t be afraid to set other values when you need them. There’s a reason why your lens has so many possible aperture settings.

Aperture f numberphotography

You can think of an aperture of f/8 as the fraction 1/8 (one-eighth). An aperture of f/2 is equivalent to 1/2 (one-half). An aperture of f/16 is 1/16 (one-sixteenth). And so on.

Vitreous is the substance that fills the middle of the eye. Posterior vitreous detachment (PVD) occurs when the vitreous pulls away from the retina.

Aperture f numbercanon

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F-stop vsaperture

These blades form a small hole, almost circular in shape — your aperture. They also can open and close, changing the size of the aperture.

A lot of photographers really care about the maximum aperture that their lenses offer. Sometimes, they’ll pay hundreds of extra dollars just to buy a lens with a maximum aperture of f/2.8 rather than f/4, or f/1.4 rather than f/1.8.

You might have seen this in your camera before. On your camera’s LCD screen or viewfinder, the f-stop looks like this: f/2.8, f/4, f/5.6, f/8, f/11, and so on. Sometimes, it will be shown without a slash in between like f2.8, or with a capital “F” letter in the front like F2.8, which means the exact same thing as f/2.8. These are just examples of different f-stops, and you might come across much smaller numbers like f/1.2 or much larger ones like f/64.

Read on to learn more about how OCT works. This article also explains the conditions that OCT can help with and what happens during the procedure.

Hopefully, you know how fractions work. 1/2 cup of sugar is much more than 1/16 cup of sugar. A 1/4 pound burger is larger than a 1/10 pound slider.

Why is large maximum aperture in a lens so important? Because a lens with a larger maximum aperture lets more light into the camera. For example, a lens with a maximum aperture of f/2.8 lets in twice as much light when compared to a lens with a maximum aperture of f/4.0. This difference could be a big deal when shooting in low-light conditions.

F-number calculator

Since people care so much about maximum aperture, camera manufacturers decided to include that number in the name of the lens. For example, one of my favorite lenses is the Nikon 20mm f/1.8G. The largest aperture it offers is f/1.8.

An ophthalmologist may use OCT to help confirm a diagnosis if a person is displaying symptoms of certain eye conditions. Below are the symptoms that may lead an ophthalmologist to use OCT.

Why is your aperture written like that? What does something like “f/8” even mean? Actually, this is one of the most important parts about aperture: it’s written as a fraction.

Without treatment, diabetic retinopathy can lead to blindness. OCT can help a medical professional diagnose diabetic retinopathy.

In its early stages, diabetic retinopathy usually does not cause symptoms. Some people may notice changes in their vision, such as problems seeing things that are far away.

You already know the answer to this question, because aperture is a fraction. Clearly, 1/8 is larger than 1/22. So, f/8 is the larger aperture.

Typically, the “maximum” aperture of a lens, which is also often referred to as “wide-open” aperture, will be something like f/1.4, f/1.8, f/2, f/2.8, f/3.5, f/4, or f/5.6.

Measuring the thickness of the different layers of a person’s retina can help an ophthalmologist diagnose a number of medical conditions, such as age-related macular degeneration (AMD) and glaucoma.

If a person has received dilating eye drops during OCT, their eye may be sensitive to light for several hours after the procedure.

f-number formula

The second page of our aperture article dives into every single effect of aperture in your photos. It includes things like diffraction, sunstars, lens aberrations, and so on. However, as important as all that is, it’s not what you really need to know – especially at first.

Thanks for the explanation. As a newbie I could not figure out why the aperture number increased in value even though the opening decreased. Knowing now that the value is actually a fraction has eliminated the confusion.

A person may not experience any symptoms if they have early stage glaucoma. Over time, a person may slowly experience vision loss.

Unfortunately, you can’t just set any f-stop value that you want. At some point, the aperture blades in your lens won’t be able to close any smaller, or they won’t be able to open any wider.

By allowing an ophthalmologist to do all the above, OCT can help them diagnose certain eye disorders and guide specific treatments.

One of my friends once had the mirror of his DSLR break in extremely cold weather – not a problem with mirrorless cameras, of course.

A medical professional can use OCT to help diagnose AMD. It can be suitable for helping diagnose both early and advanced-stage AMD.

I'm Spencer Cox, a landscape photographer based in Colorado. I started writing for Photography Life a decade ago, and now I run the website in collaboration with Nasim. I've used nearly every digital camera system under the sun, but for my personal work, I love the slow-paced nature of large format film. You can see more at my personal website and my not-exactly-active Instagram page.

Optical coherence tomography (OCT) is a form of noninvasive imaging test that creates high-resolution, cross-sectional images of the inside of a person’s eye.

Adjusting your aperture is one of the best tools you have to capture the right images. You can adjust it by entering your camera’s aperture-priority mode or manual mode, both of which give you free rein to pick whatever aperture you like. That is why I only ever shoot in aperture-priority or manual modes!

Glaucoma is a group of eye diseases that damage the optic nerve. Glaucoma can lead to a person experiencing vision loss and blindness.

If someone tells you to use a large aperture, they’re recommending an f-stop like f/1.4, f/2, or f/2.8. If someone tells you to use a small aperture, they’re recommending an f-stop like f/8, f/11, or f/16.

By that same logic, an aperture of f/2 is much larger than an aperture of f/16. If you ever read an article online that ignores this simple fact, you’ll be very confused.

Researchers say the drug aflibercept performed better in a clinical trial than bevacizumab in helping wean people off treatments for wet age-related…

OCT can help an ophthalmologist see the different layers of the retina. This helps them map and measure the thickness of these layers.

A lot of photographers ask me an interesting question: What does the “f” stand for in f-stop, or in the name of aperture (like f/8)?

Diabetic retinopathy is a complication of diabetes that causes damage to the blood vessels in the retina. Learn about its causes, symptoms, and…

Photographers generally don’t care as much about the smallest or “minimum” aperture that the lens allows, which is why manufacturers don’t put that information in the name of the lens. However, if it matters to you, you will always be able to find this specification on the manufacturer’s website. A lens’s smallest aperture is typically something like f/16, f/22, or f/32.

They must then remain still and follow the instructions of the person carrying out the procedure. These instructions will direct the person to look in certain directions throughout the scan.

On the flip side, you should be able to see why landscape photographers prefer using f-stops like f/8, f/11, or f/16. If you want your entire photo sharp out to the horizon, this is what you should use.

That is an important concept! Often, you’ll hear other photographers talking about large versus small apertures. They will tell you to “stop down” (close) or “open up” (widen) the aperture blades for a particular photo.

During the scan, a person may focus on a target within the scanner. They may also see a red line appear during the scan.

OCT can help an ophthalmologist diagnose a number of medical conditions including problems with the macula, AMD, glaucoma, and different types of retinopathy.

Prolonged high blood sugar levels can damage the retina. This occurs when diabetes damages the blood vessels that supply the retina with blood.

OCT can also help medical professionals diagnose optic nerve disorders. This is because an ophthalmologist can use OCT to spot changes to the fibers of the optic nerve.

That’s a great question. I constantly use my cameras in colder weather than 32F, no matter what they’re rated for. Even sub-zero temperatures (still talking Fahrenheit) don’t concern me, although I don’t think the camera warranty would still apply if something did go wrong in those temperatures.

The other more important impact is depth of field – the amount of your photo that appears to be sharp from front to back. For example, the two illustrations below have different depths of field, depending on the size of aperture:

Working f-number

Quite simply, the “f” stands for “focal length”. When you substitute focal length into the fraction, you’re solving for the diameter of the aperture blades in your lens. (Or, more accurately, the diameter that the blades appear to be when you look through the front of the lens).

The macula is a small area in the center of the retina. It plays a role in helping people clearly see the details of objects.

This is why portrait photographers love f-stops like f/1.4, f/2, or f/2.8. They give you a pleasant “shallow focus” effect, where only a thin slice of your subject is sharp (such as your subject’s eyes). You can see how that looks here:

VERY helpful article for this novice. As you are in Colorado, perhaps you can help on this topic: I’m going on a northern lights tour in a few weeks, and am considering getting a camera better than my iPhone. I’ve read many articles recommending various cameras (Sony a6000 keeps coming up), but then when looking at specs, most [affordable in my budget] cameras state an operating temperature only down to 32f. I’ll be in Norway with tens in the teens and 20’s. Are the manufacturer specs to be taken seriously for real-world use? Would I ruin a camera using it in temps 20 degrees cooler than its rating?

Take a look inside your camera lens. If you shine a light at the proper angle, you’ll see something that looks like this:

OCT is not the same as a computed tomography (CT) scan. OCT uses light rays to create images, and CT scans use X-ray beams.

PVD can cause a person to develop vitreous traction. This is a condition that occurs when part of the vitreous remains stuck to the macula during PVD. This part of the vitreous then pulls on the macula, causing symptoms of vitreous traction.

Optical coherence tomography (OCT) is a type of noninvasive imaging test. Ophthalmologists use OCT to create high-resolution, cross-sectional images of the inside of a person’s eye.

F-number lens

This is very interesting! As you can see, in the f/4 photo, only a thin slice of the lizard’s head appears sharp. The background of the photo is very blurry. This is known as depth of field.

This is a cool concept. It also makes it easy to visualize why an aperture of f/4 would be larger than an aperture of f/16. Physically, at f/4, your aperture blades are open much wider, as shown below:

Thank you so much for explaining this topic in a way I finally understand ! I have just started photography using a Nikon d3200 with 70-300mm lens primarily for wildlife .. I wish I had read this article before I started !

The f-stop, which is also known as the f-number, is the ratio of the lens focal length to the diameter of the entrance pupil. If you did not understand that, don’t worry, because there is a much easier explanation of it for beginners. In very simple language, f-stop is the number that your camera shows you when you change the size of the lens aperture.

f-stop photography

If you have a 50mm f/1.4 lens, the largest aperture you can use is f/1.4. Professional constant aperture zoom lenses like a 24-70mm f/2.8 will have f/2.8 as their maximum aperture at every focal length. Whereas cheaper consumer-grade lenses such as 18-55mm f/3.5-5.6 will have their maximum aperture change depending on focal length. At 18mm, the maximum is at f/3.5, while at 55mm, it changes to f/5.6. In between is a gradual shift from one to the other.

For example, say that you have an 80-200mm f/2.8 lens fully zoomed out to 80mm. If your f-stop is set to f/4, the diameter of the aperture blades in your lens will look exactly 20 millimeters across (80mm / 4), whereas at f/16, the diameter will be reduced to mere 5 millimeters (80mm / 16).

As we have previously defined, aperture is basically a hole in your camera’s lens that lets light pass through. It’s not a particularly complicated topic, but it helps to have a good mental concept of aperture blades in the first place.

Below are some examples of photographs captured at different f-stops from f/2.8 to f/16, to give you an idea of how they are used in the field:

As a beginner photographer, you might have heard of such terms as f-stop or f-number and wondered what they actually mean. In this article, we will dive into these in detail and talk about how to use them for your photography.

Central serous retinopathy is a condition that occurs when fluid builds up under the retina. Medical professionals may also refer to this condition as central serous chorioretinopathy.

Instead, just know that the two biggest reasons to adjust your aperture are to change brightness (exposure) and depth of field. Learn those first. They have the most obvious impact on your images, and you can always read about the more minor effects later.

I always find that it’s easiest to understand depth of field by looking at photos, such as the comparison below. In this case, I used a relatively large aperture of f/4 for the photo on the left, and an incredibly small aperture of f/32 for the photo on the right. The differences should be obvious:

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Of course, putting everything into practice is another matter. Even if this entire article makes sense for now, you’ll still need to take hundreds of photos in the field, if not thousands, before these concepts become completely intuitive.

You can think of depth of field as a glass window pane that intersects with your subject. Any part of your photo that intersects with the window glass will be sharp. The thickness of the glass changes depending upon your aperture. At something like f/4, the glass is relatively thin. At something like f/32, the glass is very thick. Also, depth of field falls off gradually rather than dropping sharply, so the window glass analogy is definitely a simplification.

During a CT scan, a medical professional aims the X-rays at a part of the person’s body and quickly rotates them around the body. The CT scanner processes the signals that these X-rays produce. The CT scanner then creates cross-sectional images.

During OCT, an ophthalmologist uses a beam of light to scan an area of a person’s eye. The OCT device then measures the light that the structures within the eye have reflected back.

There is no research to prove that exercises can help with drooping eyelids. Learn more about this here and find out about other treatment options.

Luckily, you have the building blocks. Aperture and f-stop aren’t complicated topics, but they can seem a bit counterintuitive for photographers who are just starting out. Hopefully, this article clarified some of the confusion, and you now have a better understanding of the fundamentals of aperture.

The OCT device then uses these measurements to create images of a person’s retina that are cross-sectional and three-dimensional.

In some cases, an ophthalmologist may administer dilating eye drops before the procedure. This is to help widen the pupil to make imaging easier.

These are the main aperture “stops,” but most cameras and lenses today let you set some values in between, such as f/1.8 or f/3.5.