Short answer: Switch to aperture priority mode, set your aperture to f/11 or smaller, and take a picture of a light coloured wall or clear sky.
If you see dirt or dust in the final image then this could be from the lens or the image sensor. If you have another lens to swap out then you’ll be able to narrow it down to the sensor or lens, or both.
Why Does This Work?
This trick works particularly well because the dirt or dust will look like dark specks against the light consistent background of a wall or the clear sky.
The reason it helps to use a small aperture, large f-stop, is because of how this impacts the angle of the light rays coming into the lens. When the aperture is narrow the light rays coming in are at a narrower angle and so the dust gets directly in the way and casts a shadow on the sensor.
When using a large aperture, e.g. f/1.4, the light rays are coming in from a much wider angle and getting behind the dust to an extent. This means it will not cast as harsh a shadow. At an aperture like f/1.4 you are unlikely to see any dust.
When is Dust A Problem?
Dust is particularly a problem when you are using narrower apertures so is more likely to be an issue for landscape photography. In general, any situation where you are using a smaller aperture because you want a large depth of field, or because the light is bright, then you are much more likely to have dust show up in your pictures.
Also, the same point applies about a light consistent background as we mentioned above. In landscapes, the dust is particularly noticeable in the sky or flat overcast clouds.
Fortunately this is easy to fix because it mostly shows up in plain areas without detail. I’ve used the Spot fix feature in the standard Windows photo app to remove most of these spots:
Here’s another example, I was taking a picture of the sunset. Even at f/11 this seems fine without noticeable dust:
Then I upped the f-stop to the max on my A6000 setup at f/36 to try and get sunbeams, a sunstar effect, and suddenly there’s loads of dust:
So How Do You Clean Your Sensor?
First try removing the dust with an air blower, then use a single use swab to really get it clean. Check out this great video from hikyletaggart for a visual guide:
You are not meant to use compressed air, as this has moisture in it, and you are not meant to use a microfibre cloth in case you drag dirt across the sensor and scratch it. But at least with scratching it, you don’t need to be too worried as your sensor should be scratch resistant and tough. Check out this video from Arthur R where he has to try hard to scratch a sensor:
Short answer: The hyperfocal distance is the shortest camera to subject distance where the depth of field is infinity.
Short Video Introduction
Check out this video from Matt Granger for a great quick introduction to hyperfocal distance:
Maximising Depth of Field
Hyperfocal distance is about maximising your depth of field. It’s about maximising the area that is acceptably sharp in the image we are capturing. When you set focus to the hyperfocal distance the depth of field starts half way from the camera to the hyperfocal distance and continues to infinity.
PhotoPills have a great online tool for finding the hyperfocal distance for a wide range of cameras.
Below is a section from a hyperfocal distance table for the Sony A6000:
Focal Length (mm)
From this we can see that if the aperture is set to f/8 and the focal length is 28mm then our hyperfocal distance is 4.93m. This means as long as our subject is at least half way towards this distance, e.g. 2.47 metres away or further, then they will be within the depth of field and ‘acceptably sharp’.
Why is This Useful?
Having a very large depth of field, from near in front of the camera to infinity, is particularly useful for landscape photography. In the below image the dry stone wall in the foreground is in focus and so are the distant hills.
When setting focus manually, for instance on an older camera, then setting focus at the hyperfocal distance means you can shoot freely. As long as your subject is beyond half way to the hyperfocal distance then it should be acceptably sharp, as well as everything in the background.
Hyperfocal distance is also useful because when we know this distance we know that if our subject is further away than the hyperfocal distance and we focus on them, then everything behind them will be acceptably sharp because the depth of field will be infinity.
Short answer: Depth of field is the distance between the nearest ‘in focus’ object to the furthest within your frame.
Shallow Depth of Field
For example, check out the below image. This image has a very shallow, small or narrow depth of field. Only part of the button is in acceptable focus so this depth of field is just a few millimetres.
Also notice that it’s a very small part of the button that is super sharp. Just the “O” in the centre and then above and below this is a small area of acceptable sharpness which counts as our depth of field and then focus drops off gradually. This is why we talk about acceptable sharpness, depth of field isn’t an exact portion of perfect focus it’s a section of acceptably ‘in focus’.
What Counts As In Focus?
In order to talk about what counts as in focus first we need to understand what a circle of confusion is. A circle of confusion is caused by light rays not perfectly converging on the camera sensor or film.
If you took a picture of a point of light and it was in perfect focus then the light rays would converge to form a point on the camera sensor. Anything outside of perfect focus would form a spot on the camera sensor and this spot is a circle of confusion.
What counts as in focus is an acceptable size for the circle of confusion. Essentially this is the size at which the circle of confusion still looks like a point to us; practically looks like a point and so is an acceptable size and acceptably sharp.
So how do you know what the distances are that are acceptably sharp? That’s where you can use a depth of field table if you are interested. PhotoPills have a cool calculator where you can put your camera details in.
Here’s a snippet of one for the Sony A6000 with a focal length of 16mm:
Subject distance (m)
So how do you read this? If I set my camera to f/8 and the distance to my subject is 1m then the depth of field is 1.94m. The subject is the sharpest part of the image and the 1.94m DOF is spread in front of and behind the subject.
What about a depth of field of infinity? In this case everything behind your subject will appear in focus and part of the distance to the subject is included in the depth of field.
Aperture and distance to subject are included in the table because they have such a large impact on the depth of field. Which we’ll explore below.
Aperture and Depth of Field
The size of the aperture has obvious impact on depth of field. In the table above you can see that the larger depth of field, f/4, has smaller depths of fields than the smaller apertures.
This is something to keep in mind when you are shooting especially if you want to take photos with background blur and bokeh. It’s also easy to play around with, switch your camera to aperture priority and set the f-stop to the lowest value you can and see what the effect is.
Why does aperture have such a large impact on depth of field? Aperture impacts depth of field because it impacts how shallow or wide the angle of light rays coming into the lens are. Rays coming in at a narrower angle stay within the acceptable circle of confusion from a greater distance in our scene.
That’s a little tricky to get your head around and visualise so I recommend watching this video from Dylan Bennett on YouTube. He shows how the angle of the light rays coming in impacts the DoF.
The key point to bare in mind is, a lower aperture creates a shallower depth of field and so background blur is more likely, or more intense. If you want to take a portrait with background blur then you should switch to aperture priority and use your lenses’ largest aperture, lowest f-number.
If you are taking a photo and want more of the field in focus, for instance when taking a landscape, then set the f-stop higher, e.g. 11.
Distance to Subject
The distance to your subject also effects depth of field in a significant way. The closer you are to your subject the shallower the depth of, and the farther you are from the subject you wish to focus on the greater the depth of field.
You can see this in the depth of field table above. Even at 2.5m from your subject, with a 16mm lens, the depth of field is infinity for all apertures of f/5.6 or smaller.
Why is this? This is for the small reason as aperture impacting DOF. When you are closer to your subject, it fills more of your frame and the light entering the lens is coming from a greater area. As a result the light is coming in at a wider angle so the depth of field is shallower.
This is also demonstrated well in the above video from Dylan Bennett.
Focal Length and DOF
Focal length also has a significant impact on DOF. The longer the focal the length the shallower the depth of field, and the shorter the focal length, the greater the depth of field.
This is consistent with the points we spoke about for aperture and distance to subject. When the focal length is longer, then you are more zoomed in to your subject. The subject will take up more of the frame and so the light is coming in from a wider angle.
When the focal length is smaller, e.g. a wide angle lens like 16mm, then the subject takes up less of the frame and the light is coming in at a narrower angle causing the depth of field to be longer.
Here’s that depth of table again for Sony A6000 and a 16mm focal length:
Subject distance (m)
Here it is again but with a 35mm focal length:
Subject distance (m)
The depth of fields are greatly reduced with none of the apertures getting to infinity for the small section I’ve presented here.
Short Video Introduction
Check out this video from Kellan Reck for a quick introduction to depth of field and how you can effect it:
When you focus your camera, whether manually or with auto-focus, what you are doing is moving the glass elements in the lens and getting the light coming into the lens to converge on the sensor or film.
If the light coming into the lens converges, comes to a point, behind or in front of the camera’s sensor then the image will appear out of focus.
A similar example is if you use a magnifying glass to burn a hole in a leaf. In order for the light to be focused enough for the hole to be burnt, the light generally has to come to a point. In order to position the point of light on the leaf you either adjust the position of the magnifying glass, or you adjust the position of the leaf.
This is similar to what is happening inside your camera lens, the glass elements within the lens are being moved so that the light is brought together on the camera sensor. If you manually turn the focus ring, or use auto-focus, it’s the elements inside the lens that are moving in order to create an in-focus image.
Short answer: Lens hoods shade the front of your lens reducing unwanted lens flare.
Lens flare is caused by bright light hitting your lens. This creates artefacts in the image, such as the ring of speckled light in the above image, and glare across an image. Glare creates a washed out look with low-contrast.
In the above image the lens flare in the centre of the image mirrors the shape of the aperture.
What Does a Lens Hood Do?
The main purpose of a lens hood is to shade the front of your lens to reduce the chance of unwanted lens flare. For example, on a sunny day if you take a photo towards the direct of the sun but not at the sun, then the bright light still hit the front of your lens and cause lens flare. If you are using a lens hood, however, then lens flare should be prevented in this situation.
The same is true if you were taking a photo at night in the direct of a spotlight but not directly at the spotlight. A lens hood would also help you out there.
Protecting The Lens
Lens hoods also physically protect your camera lens by creating a barrier between the front the lens and the rest of the world. If you bump your camera against a wall or put it down heavily, the lens hood is going to stop the front element of the lens making direct contact with a hard surface. For this reason, most photographers will leave their lens hoods on all of the time.
Why Do Lens Hoods Come in Different Shapes and Sizes?
The lens hood is designed for the particular lens you use it with. When you bought your lens it may have come with the hood, or when you look to purchase one you will noticed that the hood is made for a particular lens or range of lenses.
The petal shape lens hood is used on wide angle lenses and zoom lenses. Essentially, sections have been taken out of a straight tube so that the lens hood does not get in a wide angle shoot. This won’t be as effective as a closed tubular lens hood, but the priority is to shade the lens without getting the hood in the shot.
A long prime lens and telephoto lenses are more likely to have a tube shape lens because this is more effective at providing shade. As long as the focal length is long enough then the hood won’t get into the shot so the petal shape is not required.
Short answer: F-stop is a setting on your camera lens that directly relates to aperture and the amount of light coming through the lens. A low f-stop, e.g. f/1.4, lets in more light than a higher f-stop, e.g. f/16.
What is Aperture?
First lets quickly cover aperture, the aperture of your camera lens is the diameter of the opening letting light in to your camera. For example, 40mm.
When you adjust the f-stop on your lens you are adjusting the size of the aperture and adjusting the amount of light reaching the sensor. The lower the f-stop the wider the aperture. This is why a low f-stop is more effective in low light and a higher f-stop will prevent your photos from being overexposed on sunny days.
Focal Length Matters Too
F-stops also take the focal length of the lens into account as well.
Broadly speaking, the f-stop is focal length divided by aperture.
F-Stop = Focal Length / Aperture
So a 100mm lens with an aperture of 50mm is on the f/2 setting. And a 50mm with an aperture of 25mm is also on the f/2 setting. In this way both lenses are letting light onto the image sensor at the same luminesce.
This is why a zoom lens, one with a variable focal length, can also have a variable lowest f-stop. For instance, the kit lens for the Sony A6000 has a focal length of 16-50mm and an f-stop range of f3.5-5.6. This is because the aperture cannot open wide enough to provide an f-stop of f3.5 at a focal length of 50mm, this would require an aperture of around 14mm. However at a focal length of 16mm only a 4-5mm aperture is required for the 3.5 f-stop.
So What Are F-Stops?
F-stops are a measure of the amount of light being let on to the image sensor or film. It takes into account both aperture and focal length so that the f-stop is constant across different lenses. A lower number means more light is being let in through a larger aperture and a higher f-stop means less light is being let in through a smaller aperture.
The f-number on your camera can be set at discrete intervals from the following scale:
The difference between each f-stop is one stop. A stop is a unit used to measure light exposure. One stop difference is either half or double the amount of light coming in, depending on whether you are stopping down or stopping up.
F-stops are also available between the numbers in the range above and these are fractions of a stop.
Going from f/2.8 to f/4 is stopping down, you are halving the amount of light coming in to the camera. Going from f/11 to f/8 is stopping up, you are doubling the amount of light being let in.
Effect on Depth Of Field
The most important points about using f-stops on your camera are to keep in mind that the lower the number the more light being let in. And that a lower number produces a shallower depth of field. This is how you create background blur and the bokeh effect.
A shallow depth of field is a great way to create a photo with a professional feel, by blurring the background in a portrait you remove distraction and the same is true of photographing an object.
Then, of course, if you wish to keep as much as possible in focus, then use a higher f-stop.
What’s Right for My Photo?
This is all about experimenting and getting a feel for the results you can produce. Switch your camera to aperture priority mode, you will be able to control the f-stop and see the impact of depth of field and all other settings will be set automatically.
The minimum f-stop available on a lens is a key feature to look out for when considering a purchase or understanding the lenses you already have. If you want to create background blur or want to take photos in low light you want to get a low f-stop number. More affordable lenses with low f-stops are typically prime lenses where the focal length is not adjustable. So this is going to be a trade off in flexibility of focal length against other priorities.
Check out the kind of photos that are possible in low light with lots of background blur with an f/1.4 from North Borders:
In Depth Video on F-Stops
Here’s a great video from Dylan Bennett on YouTube. He goes into detail and covers why the numbers in the f-stop scale are so specific:
Short answer: Dynamic range in photography is the difference between the lightest parts of an image and the darkest parts. In photography, this is usually measured in f-stops.
The Subjects Dynamic Range, Your Cameras, and Your Eye’s
In photography there are three ways in which dynamic range is usually covered. The main one is your camera’s dynamic range. A good camera should be capable of capturing 12-15 f-stops of data within a single image. Resource: How-To Geek
The human eye has a static dynamic range of about 6.5 f-stops which adjusts to match the scene within a luminance range of about 46.5 f-stops. Resource: Wikipedia. However, this is hotly debated online with many different numbers being used and is enough for it’s own post. See some of the debate on Digital Photography Review.
Then there’s the dynamic range in the scene you are capturing. If the dynamic range in the scene is greater than the dynamic range of your camera, light and dark shades will become crushed into one which is called clipping.
Clipping happens when there are subtle differences in light and dark shades that are being lost because they are outside of the dynamic range the camera is capable of capturing all at once. In the above photo the sky is a uniform white when there were subtle details in the clouds on the day. Everything that is near to white is being counted as white and the detail is not present in the image. This is clipping and in the above example this creates a blown out sky which is a common effect of clipping.
How your camera will typically set it’s range is by picking out the middle grey of the scene and then allowing the dynamic range to extend equally from that point. So if your scene has more range than your camera is capable of you will get dark greys coming out as blacks and near-whites as whites as well.
You can get a good sense of this by looking at your camera’s histogram.
Your camera’s histogram shows you the distribution of light in a captured image and live in your scene. If the values in the graph are all on the right then this means the scene is bright and is an indication that you might be missing information in the highlights. If your camera gives you a live histogram of your scene then you can adjust your exposure, for example by using a faster shutter speed, and see if there are details you were missing.
Likewise, if all your values are to the left then this shows this is a dark scene you are capturing. Here’s a good video from Matt Granger on YouTube who discusses some of the finer points of using histograms:
Shooting in RAW
To increase the dynamic range available in your images then you should shoot in RAW. A RAW image is an unprocessed image and so contains more information. You will have access to greater shadow and highlight details when editing a RAW image than an image format like a JPEG.
What is HDR?
HDR stands for High Dynamic Range. This is a technique where multiple images are taken of a scene at different exposures and then combined to create an overall image which displays a greater dynamic range than your camera is capable of taking in one shot.
In the above image you can see that there are details in the clouds which are subtle shades of grey and the grass is bright, almost luminescent, as well. If you were to take this as one image you might find that having details in the clouds means sacrificing brightness in the grass and poppies. Or if you focus on having the grass bright then the sky will be blown out.
Short answer: Yes absolutely. Solution: use a file sharing service like Dropbox or Google Drive instead if quality matters for what you’re aiming to do.
Facebook Messenger absolutely does compress the images that you upload. This is simply to save bandwidth when you come back to view the image on the platform and to save on storage space. As you can see above, by compressing the original image over 4MB has been saved in terms of the image size.
The resulting image at 3641x2048px is plenty big enough for most uses, especially if you are viewing the image on a mobile. However, if the image quality matters then you should use a file sharing service instead of Facebook Messenger to share images. For example, if you are sharing images to go on a website then it’s best to share the files through something like Dropbox or Google Drive instead of sharing using a messaging platform.
Short answer: Bokeh is the aesthetic quality of the unfocused part of an image. Another term for this is lens blur.
What does bokeh mean?
Bokeh is used to reference the out of focus part of an image and the aesthetic quality of that part of the image. With this in mind, you might not like the bokeh in a photo and called it bad bokeh. Or, as will more often be the case, you’ll mention bokeh because you like the quality produced.
Bokeh is most commonly mentioned when circles of light are present in the image. These are commonly called bokeh circles or bokeh balls. Bokeh circles will most often be present in night time shots, as in the photo above, but can also be present in day time shots:
What are bokeh circles?
When a point of light is out of focus this is rendered as a larger ball of light by your camera lens. This is what we mostly think about when we think of bokeh. If you type bokeh into Google, this is present in most of the images you see.
How does aperture affect bokeh?
A large aperture, f/2 for example, will create more background blur, a more obvious bokeh and larger bokeh circles. As you narrow your aperture, by increasing your f-stop, the out of focus portion of your image starts to become clearer, the bokeh will be less noticeable and with smaller bokeh circles.
There is no right way of course, it’s all about your preference and the look you wish to achieve. Typically though when a photographer wants background blur, for instance in a portrait, and very noticeable bokeh they will use a fast lens, for example on that can shoot at f/1.4, and will have the aperture wide open.
Where does the term bokeh come from?
Bokeh is derived from a few Japanese words that are used to describe related concepts like blur, mental haze and playing dumb, in nuanced ways. Find out more in Wikipedia’s Origin section.
The English spelling “bokeh” was popularised in a 1997 issue of Photo Techniques. In an article called What Is ‘Bokeh’? by John Kennerdell.
The most common pronunciations I’ve heard are bo (like bow) and ka, bo–ka. Or bo–kay, like bouquet. Or bo–keh, with the Ke sound from a word like Kenneth.
To add to the confusion to the issue here’s a video from Photogearnews to show how many pronunciations people will use:
If it helps, I say bo–ka but that’s just easier for me to say.
How to take a bokeh effect photo
Taking a photo with bokeh is as simple as taking a photo that’s completely out of focus, or has an out of focus part.
To create noticeable bokeh use a low f-stop on your lens so that the depth-of-field is shallow. Then ensure there is distance between your subject and the background, experiment with this to get the effect you want.
How to create different bokeh ball shapes
The shape of the bokeh circle is defined by the shape of the opening on the lens. This is why bokeh circles can have edges, the edges come from the aperture blades. The smaller your aperture, the greater the effect of the blades on the shape of the bokeh circle. This is because the blades are more closed in. There are lenses specifically designed to create rounder bokeh with more circular aperture blades.
In the below image you can see the bokeh circles have edges caused by the aperture blades:
You can dramatically change the shape of the bokeh circle by placing a piece of card with a shape cut out in front of your lens. This is how you can create bokeh circles in heart shapes, stars, or anything you like. Check out this tutorial from Christopher Frost on YouTube for a demonstration of this:
What creates textures in bokeh balls?
This can be dust and particles on your lens, so if you want a smooth effect then make sure your lens and sensor are as clean as possible. But this can also be a quality of the lens itself, which you won’t be able to get rid of. This is another reason why some lenses are designed specifically for bokeh effect, e.g. the smooth effect and round bokeh circles that most people would consider desirable.
How do you get swirly bokeh?
This is created by the lens, typically a vintage or lomography lens. For example, the below image was taken with a vintage lens, Helios 44M-2 58mm, to get the swirly effect. This lens in particular is popular for this effect.
Short answer: Golden hour in photography is the time briefly after sunrise or before sunset when the sun is low in the sky and the light is orange/red.
What Causes Golden Hour
When the sun is low in the sky it has to travel through more of the earth’s atmosphere in order to reach you, rather than beaming straight down as it does during the day. As the white light travels through the atmosphere the colours with shorter wavelengths, like blue and green are scattered leaving behind the red and orange end of the spectrum. This is why the light we see is orange/red.
No, the term is used purely to indicate a short amount of time close to sunrise or sunset. People just use the golden hour as a way to refer to a time when the light is more orange than typical daylight and a good time for taking photos.
Take Advantage of It
The golden hour is absolutely something you should keep in mind if you like the aesthetic. In general, shadows are not as harsh and highlights will not be as bright. In general your images should have less dynamic range than a clear day and will have a warm feel.
Golden Hour Sample Galley
Check out some photos I’ve taken during golden hour. As always, these photos are free to use with an image credit.
Short Video Introduction
Here’s a short 2 minute introduction to the topic from Dean Rojas on YouTube:
Longer Video on Golden Hour
Check out this video from Channel 8 on YouTube for a more in depth dive into the topic, including what causes the golden hour and shooting tips: