aperture Archives - Infrared Conversions, IR Modifications & Photography Tutorials

What Is Aperture Priority And How To Use It?

As you learn and develop your photography skills you’ll discover why aperture priority is such a useful setting in helping you take photos. This mode on your camera is incredibly important, but unless you know when and how to use it it is just another function on your camera. Read on and learn all about aperture priority and the best ways to use it for your next photo shoot.

What is aperture priority?

This semi-automatic camera mode allows you to set the aperture manually and let the camera selects the shutter speed automatically. While this may sound simple, this is an incredibly valuable setting to have when taking pictures. The reason this is valuable is that it gives you complete control over the aperture which determines your depth of field. This is really important because your depth of field determines how much of your focal plane is going to be in focus. For example, say you had selected shutter priority and you are taking a cityscape shot. The camera might set your aperture is to f/2.8 to allow you to achieve your shutter speed. So you will end up a vast part of your photo blurred. By selecting aperture priority you can ensure that your depth of field is going to be correct for what you are photographing.

This option is also a much faster way to take pictures when you compare it to the manual mode. In manual mode, you need to select all of the settings yourself to achieve perfect shots. If you are shooting any sort of fast-moving scenarios like a street scene, there simply won’t be enough time to do that. If you master aperture priority, you can quickly adjust the settings as you need to, so that you can get the perfect shot every time.

Advantages of aperture priority

There are a few advantages of using aperture priority. The first advantage as mentioned above is that you can better control the depth of field of images. The aperture on your camera (also known as the f/stop) is what determines your depth of field. If you want a blurry background for your images, you will use a smaller f/stop number (wider aperture). Using a higher number will make your background and the foreground be in focus given you a greater depth of field.

Aperture mode can also give you more creative control over your shots, allowing you to separate background and foreground, depending on what you want the focus to be in your images.

Lastly, you can respond quicker by using aperture priority. You don’t have to stress about your shutter speed (as long as it isn’t too slow) when snapping pictures, which gives you less to worry about.

How to select and use aperture priority?

First, select aperture priority mode on your camera by moving the dial to A on most cameras and Av on Canon cameras.

Next, select the aperture manually by determining the f/stop number that you need to use for your shots. What’s excellent about aperture priority mode is that the camera doesn’t change this setting while you take your pictures. But this means that it’s crucial that you change your aperture for different scenarios. So if you have just taken a portrait of someone and then you are taking a landscape shot, remember to adjust your aperture.

There are of course occasions when by selecting your aperture to get the exposure correct, the camera has to select a slow shutter speed. If your shutter speed is too slow it will mean that your photos will suffer from camera shake and look blurred. You have a couple of options on how to solve this issue.

You can either increase your ISO to allow you to have a faster shutter speed. But the higher your ISO is, the more noise will appear in your photos. So for example, if you are able to increase your ISO a bit and achieve the right shutter speed, then that will be fine. But if it means increasing it too high (i.e. above 1000 ISO, you may want to try the solution below).

The alternative to increasing your ISO is to compensate on the exposure by a combination of shutter speed and aperture. For example, you may find that by selecting a slightly wider aperture, even though your photo is slightly underexposed, you can fix it in post-processing. Most of the time the solution is a mix of both. So increasing the ISO a little and selecting a slightly wider aperture.

When to use aperture priority?

There are a few situations where you should use aperture priority. Generally, anytime that your depth of field is important, you should select aperture priority. But if shutter speed becomes more important than you should select shutter priority. For example, if you are photographing moving subjects that you want to freeze, then shutter priority is what you need.

Aperture priority is also a good mode to select for everyday outdoor photography in travel or street photography. Because most of the time there will be sufficient light, you won’t find your shutter speed becoming an issue. But in lower light conditions it will, so at that point, you need to look to the solutions that I mentioned above.

What’s excellent about aperture priority is that you can take great photos without having to worry or stress about adjusting all the settings. Your camera will be doing most of the work for you so you can concentrate on seeing the photo opportunities. But its important to know that this mode isn’t the ideal approach for all purposes. If you are working with flash or panorama photography, manual mode is a far better setting to get the best images. But, aperture priority mode can be a valuable setting for you to use in your photography.

What Is The Exposure Triangle?

One of the most important concepts of photography is something known as the exposure triangle. But don’t worry it is not a mathematical equation and once you learn what it is, it’s actually pretty simple to understand. There are three components in the exposure triangle. These are shutter speed, aperture and ISO. It is called the exposure triangle because of the relationship these three variables have with each other that determine how a photo is taken and what it looks like. In any photograph, these three elements work together. Which means changing one affects the others. To help you understand this and be able to use these components correctly, here is a simple guide on the exposure triangle.

Shutter speed

This is an important aspect for anyone in photography. The shutter speed refers to how fast the aperture in your lens opens and closes. The faster this is the less light enters the camera. Which is why for example when you are photographing in low light conditions, you need a slower shutter speed. Because this opening and closing of the aperture will be slower it will allow more light to enter the camera.

The shutter speed is also important in helping you be able to freeze motion in your photos. So the faster the movement of your subject the faster your shutter speed needs to be.

Why is shutter speed important?

The shutter speed will determine how the image will be captured. For example, as mentioned above when using a slow shutter speed the sensor of the camera is exposed for a significant time. So besides being able to capture darker scenes with the right level of exposure, it also has an effect on moving objects by creating motion blur. This is a creative technique that all photographers use to help show motion in images. Whether it’s waves crashing onto the beach, a dancer or even a light trails from cars, they are all possible through the shutter speed.

Aperture

To understand aperture better, think of it as the pupils in your eyes. If you walk into a dark room, your pupils get bigger to allow more light to enter your eyes. If you then walk out into bright sunshine your pupils become smaller to limit the amount of light entering your eyes. The aperture on your camera works in exactly the same way. The only difference is that you will have to control the aperture on a camera.

Putting this concept into use for photography, it means that if you photographing in low light conditions, you need more light to enter the camera. So a wider aperture is needed in places like covered markets. But if you are photographing outdoors in bright conditions you will need a smaller aperture otherwise your photos will be too bright.

Why is aperture it important?

The aperture not only controls the amount of light that enters your camera but also your depth of field. In other words how much of your image is sharp from the foreground to the background. The wider or bigger your aperture is, the shallower your depth of field (smaller part will be in focus). The smaller the aperture the greater your depth of field will be. For example, in a landscape scene, you will generally want all of the image as sharp as possible. So a small aperture should be used. But for example, when you are taking a portrait of someone, you can use a wider aperture, as they are the only part of the image you need in focus.

ISO

Back in the days of film, ISO would refer to the sensitivity of film to light. In digital photography, all that has happened is that film has been replaced by a digital sensor. ISO controls how sensitive your sensor will be to light. The higher the ISO the more sensitive your sensor will be which means you can take photos in darker conditions. But this comes at a price. The higher your ISO is the more noise you will see in your photo. This will have a negative effect on the overall quality of your photo by making it less sharp.

Why is ISO important?

The reason that ISO is so important is that there are times where you have no other option but raising your ISO. Because otherwise you simply will not be able to capture a photo because of the lack of light. The is especially important in situations where you have to shoot handheld and need to have a fast enough shutter speed to avoid a blurred photo.

They are all linked together

These three elements are all linked together and changing one will affect the others. But it also allows you far more flexibility in being able to choose the settings that you want. For example, as I mentioned earlier, in landscape photography, you will need a greater depth of field which means a smaller aperture. A small aperture will not allow as much light to enter the camera as a wider aperture. So to compensate for this, your shutter speed will need to be slower. A slower shutter speed will mean that even though your aperture is smaller, it will be open for longer allowing more light to enter the camera.

On in another example, let’s say you are photographing someone dancing indoors where there isn’t a lot of light. To be able to capture a sharp photo you will need a fast shutter speed. You can either achieve this by raising your ISO or by selecting a wider aperture. Because if your aperture is bigger, it won’t need to stay open as long as a small aperture. Allowing you to be able to use faster shutter speeds.

The relationships between these three elements in photography form the basis of any photo. If you want to take better photos, you should spend time learning and practising how to use the exposure triangle. Over time it will become second nature to you and you will quickly be able to select and change settings knowing the impact it will have on other elements in the exposure triangle.

Aperture Priority Or Shutter Priority – Which To Use And When?

Anyone with a DSLR or Mirrorless camera would have probably seen the initials Av or Tv on their mode dial (or somewhere on their camera). But most newbie photographers avoid these elements and just go straight to the auto setting. Whilst auto settings on cameras have advanced a lot in the last few years, they are still no match for actively taking control of the photo taking process manually. After all, that is the whole point of an expensive DSLR camera. Not only do high-end cameras take better quality photos but they also give you more control. Aperture and shutter priority modes are commonly used by photographers and are very easy to understand and utilize. So, if you are unsure what aperture priority or shutter priority modes are and when to use them, then read on…

The basics

Before understanding and being able to use these modes, you need to have a basic understanding of the photo taking process. There are three main elements that determine how a photo is captured and looks. These three elements are shutter speed, aperture, and ISO. Together they are referred to as the exposure triangle. As the name suggests these three elements of photography are linked together and so a change in one has an impact on another one. On manual mode on a camera, the photographer is responsible for adjusting all three of these elements. Whilst that gives a lot of control sometimes it isn’t feasible and can mean missing the key moment because you are changing settings. This is where shutter priority and aperture priority can help immensely.

Aperture priority

Every time you click to take a photo, the shutter that is situated in your lens opens and closes to allow light to hit the sensor in your camera. The amount that the shutter leaves open is indicated as an f/number. The higher the f/number the smaller the opening for light to get into the camera. This is important because how much this opening is, determines your depth of field. In other words how much of your image is sharp from the foreground to the background.

The higher your f/number the more your image will be sharp from front to back. The lower your f/number is the shallower your depth of field will become. So for example, if you are taking a portrait of someone, you will ideally want their face to be in focus and the background blurred so that they stand out. In this scenario, you would use a low f/number to achieve this. But in landscape photography where you need more of the image to be sharp, you will want to use a higher f/number.

Aperture priority mode allows you to set this f/number so that any photo taken will be at the desired aperture. The camera then automatically sets the other components of the exposure triangle (i.e. ISO and shutter speed) to ensure the photo can be taken at this aperture.

When would you use aperture priority mode?

This mode is ideal when you want to have control over your depth of field. So for example, if you are photographing a person in daylight you can set your aperture knowing that the camera can then do the rest. Or for example in landscape photography, if you are using a tripod, then you can set your aperture as this is a key setting to ensure you have the depth of field required. Another example would be if say you are photographing something close-up like a flower or food where you need a fairly shallow depth of field.

Where you need to be careful when using aperture priority mode is when there is a chance that your shutter speed will end being too slow or your ISO will be too high. For example, if you are photographing in low light condition and have set your aperture to f/18, then the camera will either have to raise your ISO really high to capture the image. Or if you have set a maximum on your ISO setting on your camera it will select a slow shutter speed. Anything less than 1/60 sec and your image will likely be blurred due to camera shake (unless you are using a tripod).

So if you are going to use aperture priority mode, make sure:

Your shutter speed isn’t going to be too high
Your ISO isn’t going to be too high (as this will mean noise in your image)

Shutter priority

The other element of the shutter opening and closing that is vital to photographs is how long the shutter remains open. Naturally, the smaller the opening is to allow light into the camera the longer it needs to stay open. For example at f/22, your shutter will need to stay open longer to allow enough light in to be able to capture the image. How long this time needs to be will be determined by the available conditions. If you are photographing in bright sunshine it would be less time. But in low light conditions, your shutter may have to remain open for seconds or even minutes!

The other factor is what you are actually photographing. For example, a statue will not move so you can use slower shutter speeds to capture sharp images. Whereas if you are photographing a racing car you have to use faster shutter speeds to be able to freeze the action. So as you can see, there may be times where you will be more concerned about the shutter speed rather than the depth of field.

Shutter priority mode allows you to set your minimum shutter speed so that the camera will not select anything slower when you take a photo. But of course, this means that the camera will then select the aperture and ISO automatically (unless you have set a minimum ISO).

When would you use shutter priority mode?

This mode should be selected when your shutter speed is key to capturing a photo. This is generally when you are photographing moving subjects where you need to ensure that you have a shutter speed fast enough to freeze the action. Sport, wildlife and even people moving or dancing are all examples of when you will likely need to use shutter priority mode.

But as per aperture priority mode, shutter priority also comes with factors that you need to consider. For example, if you have set your camera at a fast shutter speed but there isn’t enough light, your camera will raise your ISO. But if it is too high, it will mean too much noise in your photos which will then make them look soft. Or the camera might choose a wider aperture (i.e. shallower depth of field) which might mean that your subject won’t be sharp.

So if you are going to be using shutter priority mode, make sure:

Your ISO is not going to be too high
Your depth of field (i.e. aperture) will allow you to capture the subject or scene in focus

Most cameras will allow you to set various factors such as maximum ISO even when using these modes. So, you can fine-tune your settings to ensure you can capture the image you want. Of course, it will take practice and you have to accept that you will end up with some blurred images. But if you can master these modes it will go a long way to ensuring you can capture great photos.

A Simple Explanation of Aperture

If there’s one thing about photography that confuses newcomers(and often the rest of us) it’s the idea of aperture. What is it? Why is it so complicated? How does it affect your photos? Well, aperture isn’t complicated or impossible to understand, it’s just unfamiliar. And like most unfamiliar things the more you learn to about it the less intimidating aperture will be.

In this article I’m going to show you just how not complicated aperture can be. You’re going to learn the basics of aperture and how it relates to the focus and shutter speed of your photographs.

Aperture and the Dreaded F-Number

Let’s start off by explaining what aperture is and how it is measured. The idea of aperture in reality is astoundingly simple and there’s honestly only a few things you truly need to know to conquer the subject.

What is Aperture?

OK, let’s just get this out of the way right off the bat…aperture by its very definition is simply a hole. As it pertains to photography, aperture is the hole in the lens where light passes into our cameras. That’s it.

See, not so scary! However, the way aperture is measured is the cause for anxiety in some because, there again, it’s measured in a fashion that most of us don’t readily understand. But don’t worry, much like everything it becomes easy once you understand one fundamental thing….

F-Numbers

Trust me. You are neither the first nor the last person to be completely perplexed when it comes to understanding the way aperture is measured. The notion of ‘F-Numbers”(sometimes called f-stops) has been the source of a lot of confusion because they simply don’t make much sense in terms of how we normally think about our physical world. In short, the F-Number is nothing more than a ratio between the focal length of the lens and the diameter of the aperture being used. So an aperture of F4 means that the focal length is four times larger than the selected aperture. An aperture of F8 means that the focal length is eight times larger and so on and so forth. Now this is where things get a little weird….The larger the F-Number, the smaller the actual opening. The smaller the F-Number the smaller the actually opening. Look at this quick example:

It’s going to be OK…take a deep breath and realize that it actually makes sense mathematically but you’re not going to have to understand anything more in depth than that for most practical purposes. Just know that it the larger the physical opening of the aperture the smaller the F-Number will be.

Aperture and Depth of Field

There are a surprisingly large amount of factors that determine the final depth of field or your image and aperture size is one of them. Generally speaking, the wider the aperture(smaller F-Number) the more shallow depth of field will become. This means that smaller apertures(larger F-Numbers) will bring more of the scene into the range of focus than will larger apertures. Take a look at these Chess pieces and see what I mean.

Not only does aperture play a key role in focusing but it also spills over into your shutter speed. Speaking of shutter speed….

Aperture and Shutter Speed

The relationship between aperture and shutter speed is extremely simple and yet extremely important. Simply put, larger apertures allow more light to enter through the lens. More light means faster shutter speeds can be used. This is where the phrase “fast lenses” comes from because lenses with larger aperture allow for faster shutter speeds.

So, faster lenses with wider maximum apertures are capable of shooting more effectively in low light conditions because they allow more light to pass through them. A lens with a maximum aperture of F2.8 is considered to be “faster” than a lens with a maximum aperture of F4.

Final Thoughts on Aperture

In a way all this might sound like an oversimplification but it’s essentially all you really need to know about aperture. The manner in which aperture selection relates to depth of field and shutter speed will take you a long way in photography. Aperture isn’t scary! Having this simple knowledge will help you better understand exposure, make smarter lens choices and generally control your images much more effectively.

Diffraction and IR Photography

A few years after I began my photography adventure I took a photography class that came free with my first SLR camera. I thought I knew a lot about photography. After taking the class I thought I knew all there was to know about photography. Funny thing is that all these years later I’m still learning, almost on a daily basis. One photography class take away for me were all the details about depth of field and aperture. When I went to any action event, I’d shoot at high f/numbers so everything was in focus (before the days of auto focus). Some years later while working on my undergraduate degree, I became interested in optics. I was hired to work in an optics research lab (see my holography post). It was then I started learning about the wave nature of light and how diffraction occurs. I mostly worked with lasers. So most of my diffraction experience was with monochromatic light (one color). Below is a shot of textbook linear laser diffraction through a small opening. This is the effect on light as it passes through small openings. This also occurs in photography with all the colors diffracting different amounts, but occurring simultaneously.

My interest in photography began to mesh with what I had learned about optics. I had always wondered about white light diffraction, especially in camera optics. It turns out that diffraction can be a fairly significant issue with camera lenses. You can shoot everything at f/22 and have great depth of field and focus. But there’s a trade-off. As the aperture size decreases, diffraction increases and becomes more visible. There is diffraction at all f/numbers though its more pronounced at smaller apertures.

I like to understand where all my lenses are sharpest and where they are soft. So when I added another medium format lens to my fleet, I decided to do a little more testing. Interestingly, my 165mm f/4 LS medium format lens has a minimum aperture of f/32. At this aperture diffraction makes the image quite soft. It is so evident that it’s even evident in the live-view display.

I shoot IR almost exclusively with medium format lenses. Check out my blog topic on medium format lenses. They are huge, but I really like using them. Here’s a comparison to a 50mm f/1.4 Minolta manual focus lens that I bought with my 35mm SLR. These are the lenses I included in my testing for this blog (except for the Minolta lens).

Left to right in the rear: Pentax 67 55mm f/4, Pentax 67 75mm f/4.5, Pentax 67 165mm f/4. Front row: Minolta MD 50mm f/1.4

I found some level of diffraction in all three of the lenses I tested. On this particular test subject (my neighbor’s palm tree), diffraction is much less evident in the 55mm and 75mm lens, but very clear in the 165mm lens. This is partially due to the minimum aperture size of f/32. The animations below are all 740nm IR photos, shot with a custom white balance. No other processing was done.

Pentax 67 55mm at f/4, f/11 and f/22

Pentax 67 75mm at f/4.5, f/11 and f/22

Pentax 67 165mm at f/4, f/11 and f/32

Diffraction is inversely proportional to aperture diameter. So diffraction is less visible as the aperture diameter increases. Unfortunately, diffraction is proportional to the wavelength of the light being shot. This means more diffraction at longer IR wavelengths. For those of us shooting IR, we will likely have to use a slightly larger aperture vs. when shooting the same equipment in color. If you shoot IR around 740nm, diffraction will be about 30% worse than at the center of the visible spectrum (about 550nm). That seems significant but doesn’t seem to affect my images much. However, you should keep this in mind if you’re planning to shoot IR at small aperture diameters (large f/numbers).

You may have noticed something else that is evident when shooting at small apertures. Any dust or streaks that happen to be on the lens, filter or sensor become much more evident at smaller apertures. Take a look at the speck to the upper right of the bird in the 165mm image above. The dust spec is invisible in the f/4 image, but very clear in the f/32 shot. Yet another reason to open up those apertures.

First test shot from my new 75mm Pentax 67 medium format lens (shot at f/11)

I find that most of my lenses are sharp around f/11 when shooting at 740nm. So that’s where I mostly shoot. It matters little to me if the exposures are longer. I always shoot IR with a tripod so I can take full advantage of the lens sharpness. If you’re interested in some light diffraction theory, there’s an interesting article I found discussing diffraction and photography. One last detail to consider. The onset of diffraction occurs earlier in crop sensor cameras vs. full size sensors. So if you’re shooting with a smaller sensor, you may need to open your aperture more than would be necessary on a larger sensor. Lots to keep in mind.

So what does this all mean? Well, if you typically shoot at large f/numbers, with a crop sensor camera and/or shoot IR photos, you can probably increase your image sharpness by opening the aperture slightly. Do your own tests on the lenses that you use most frequently. It’s important to know where your lenses perform best whether you shoot color or IR. Most importantly get out and shoot. It’s the only way to learn.