What is chromatic aberration?

Chromatic aberration is an optical phenomenon in which the camera lens is unable to focus the different wavelengths of light on the same plane (in this case the image sensor) in order to produce a correct image, resulting in a halo or fringe around objects.

This is especially noticeable in high contrast situations and when shooting at wide apertures. Such a situation is presented below, where the hands of a statue were shot against a bright sky, resulting in a bad case of purple fringing.

Image taken by Mike Baird

It should be noted that color fringes may also be caused by other factors such as lens flare or the camera's sensitivity to the different wavelengths of light but since chromatic aberration is the most common cause it will be the main subject of this article.

The (somewhat) simple physics

As you might imagine, DSLR lenses are a complex piece of equipment but for the sake of simplicity, let's consider them as a single piece of glass.
When light hits the lens it is refracted, ie, it changes direction. As most people probably know just by looking at the rainbow, visible light is comprised of different wavelengths which are perceived as different colors. What happens in this situation is that the different wavelengths are bent differently by the lens, causing them to diverge (a phenomenon known as dispersion) and hit different planes, as shown in the following diagram:

This will cause the sensor to pick up "misplaced" colors at certain spots, resulting in the familiar chromatic aberrations.

Camera lenses and chromatic aberrations

In order to correct this problem, lens makers came up with ways to minimize the divergence of light waves. The cheapest solution is usually used in consumer level optics like the common 18-55mm kit lenses and is known as an achromatic lens design. It uses a second lens that has a different dispersion than the main lens and tries to converge the light rays in order to try to correct both spherical and chromatic aberrations that light suffers when passing through the first lens. However, this isn't a perfect process and small imperfections are still present.

A simplified diagram demonstrating how achromatic lenses work

What is used in higher end lenses is an apochromatic lens design, in which a third element is added, correcting even further the aberrations.

A simplified diagram demonstrating how apochromatic lenses work

In addition to this design, lenses like the Canon EF 70-200mm F2.8L IS (and all other L lenses, for that matter) contain super-low dispersion glass, which as the name implies, doesn't disperse the different wavelengths as much, minimizing this problem. Because low dispersion materials like fluorite are usually used, the final lens cost is driven up quite a bit, which partly explains why they cost so much in the first place.

How to avoid it on the field

Avoid high contrast situations

This might seem like a no-brainer but it really helps to downplay the optic design imperfections, especially if using consumer level lenses like most of us do. Common suspects include fences, tree branches and shooting a subject against a bright sunny sky.

Stop down your aperture

While it is very tempting to use a wide aperture to get nice bokeh, if you get some fringing try to stop down the aperture at least one stop. This will greatly help minimize the visible aberrations.

Avoid the extremes of your zoom lens

Not only in life but also in photographic lenses it is said that virtue is in the middle. Zoom lenses usually perform better when using its middle focal lengths. For example, when using a 70-200mm zoom, shooting at 135mm will usually wield better results than at 200mm.

Avoid super zoom lenses

Unless you don't want to carry extra weight, like when going on vacations, avoid super zooms at all costs. They have terrible chromatic aberrations on the wide end. Alternatively, get some prime lenses, as they are generally optimized to reduce these optical artifacts and are relatively cheaper and lighter.

How to correct it in Photoshop

After opening your image in Photoshop, go to Filter -> Distort -> Lens Correction…

On the right side panel you should find a set of controls named Chromatic Aberration.

Depending on your image, you should try to correct the fringing in the best way you can by adjusting the sliders. To do this in an optimal way make sure you are viewing the image at a magnification of 100% or more.

You might have to move only one or both sliders: it all depends on the image you’re dealing with. In this case, I had to move both.

Moving the Fix Red/Cyan Fringe slider to the left will correct red fringes, while sliding to the right will conversely correct the cyan fringes. The Fix Blue/Yellow Fringe slider works in a similar fashion.

The Before and After Using Photoshop

Original Shot

This is how raw image looks like. It was shot with Canon 400D, using kit lens 18mm-55mm at 55mm, f16 and exposure 1/125. ISO I used was 100 to keep noise level as low as possible, and my white balance was set to Flash light as we were shooting with strobe lights.

I have to say that when I chose this shot from whole bunch taken, I was pretty happy with it already. But my domain says that everything can be better, even if it seems to be perfect already.

It is very important to know what you want to do, before you start, to avoid complications in the process.

What I didn’t like straight away, was the shape of the bottom part of models face. Also, some colors seem to be a little bit off.

Photoshops Camera Raw

I like to use Photoshops Camera Raw, as it is integrated with Adobe Bridge and Photoshop, making my life a bit easier.

I use Adobe Camera raw to fix colors to my own liking. I tweaked Temperature and Tint a little bit.

Next was fixing Vibrance and Saturation to even out some imperfections of the skin tones.

Last adjustment was changing of overall colour tones of the image. To do this I used the Split Toning tool in Camera Raw

Once you have the colors you are after, hit Open Image button to open it in Photoshop.
This is how my shot looks like:

Rollover the image to see the difference that our adjustments made.

Skin Imperfections

After opening the photograph in Photoshop, the first thing you want to do is get rid of all the dust you have on your sensor, spots, blemishes etc. on the models face. I do this all with the Patch tool.

You have to be very careful, as this technique if over done tends to change, or even blur skin texture.
It takes time to master this technique, but trust me, it is worth that time practicing it.

Defining Face Shape

Having dealt with imperfections in our photo, it is time to sculpt our models face a little bit with the Liquify tool. I mentioned earlier that in this shot, chin area is my main focus.

I like when the face is more defined by sharper lines in general, but that is personal preference.

Airbrushing

There are billions of airbrushing tutorials, everyone has their own way of doing it.

I like when it is done as natural as possible, but that can be achieved only if you did good work removing spots to begin with!

I always airbrush with the Stamp tool with opacity set to very low, around 20%, and by hand. This allows us to sculpt a models face even more.

As you can see difference between our before and after are very few. This is because it is very easy to go one step to far and change our model into an overdone plastic doll.

Dodging & Burning

As we come closer to the finishing the image, Dodge & Burn becomes a useful tool.

Again, be wary of overdoing it, as it might create an unnatural effect, and ruin all our hard work.

Finishing Touches

Now when most of our work is done, it’s time for finishing touches.

I darkened the background a bit and added a warming photo filter, to get that “punch” with a warm touch.

Rollover the image to be stunned by the end result!

You’re welcome to download the source files from this project to take a closer look if you wish. I hope you enjoyed the process and results.

Download the Source File

Materials Needed:

• 2 Strobes
• Shoot Thru Umbrella
• Big Octagonal Softbox
• Tall Black Gobo (deflector)
• Round Silver Reflector
• Big Octagonal Softbox

A Case Study in Lighting

This article in a close look at a project I recently worked on. Together with Stylist Natalie Svikle, we teamed up to create an fashion story that will be based on the way french woman dress. We called it L’Affaire Parissienne.

Step 1: Finding Perfect Model

It took a long time, before we found right model.
We needed someone very soft and friendly on the face, with cheeky smile that will bring an under layer to the shoot.
After about a week going through model books, we found Cathy from Compton Model Agency, here in Dublin.

She was sweet, nice and most important for our project, she had that French quality, even though she is not French at all.
She was the one we wanted…

Step 2: Setting Key Light

I wanted to create a natural feel to the photographs. I decided to use an Octagonal Softbox as main light source, on tcamera right. Setting it up close to model will give very nice soft light wrapping around her face. This is similar to light you might get from the sun shining through light clouds.

Following idea of keeping light natural, the main source will have to be placed just above our models head, and pointed a little bit down. Keep an eye on the shadow under her nose and chin, they can’t be too long.

Step 3: Background Light

After setting my main light, I thought that the background (even though it is white) came out in my test shot too dark. Also, the model was casting a shadow which I didn’t want.

I needed additional light in the back. A Shoot Thru umbrella was the perfect solution: it gives nice, soft light, with quite an obvious hot spot. I placed it on the left of the camera.

As a White Shoot Thru umbrella is a type of light modifier that has very broad range of emitted light, it will also brighten up a whole scene a little bit. We will take care of this extra light in the next step.

Step 4: Deflector, Reflector and Flag.

First of all we have to get rid of light spilling on our model from Background Light. To do this, I used Black Gobo (a kind of flag used to block light) as a Flag and at the same time it helped me to deepen the shadow on the models left side. Creating nice contrast between the well lit background and the model’s left side, I gain more focus on the clothes she is wearing.

Everything seemed to be ready for shooting. But shadows created by my key light, under the chin and nose, were a bit too dark.

A Silver Reflector was the perfect solution. Placed just under the camera, flat on the floor, the reflector bounced light coming from the key light and filled unwanted shadows with soft light.

Step 5: Camera Settings

Everything was shot with simple (yet powerful) Canon 400D and kit lens 18-55mm @ 55mm. As you can see, even with low budget camera it is possible to get very attractive shot.

My white balance was set to flash, I find it easier than adjusting in Adobe Camera Raw. I used ISO 100 to get away from any possible noise, and thanks to f16 I could be sure that everything will be sharp in the shot (this is very important in fashion photography). Exposure time was 1/125.

photography: Maciej Pestka
Styling: Natalie Svikle
Makeup: Ciara Hanlon
Model: Cathy @ Compton

This post describes some basic tips to improve the quality of wildlife photography. Anyone interested in capturing more compelling images of animals will find it useful in furthering the development of their skills.

Why photograph wildlife?

Nature has been one of the primary subjects of photography for over 115 years.  The natural beauty that surrounds us in the form of landscapes, plants, and wildlife is a compelling subject to capture in still images. 

But more than that, the experience of taking photography of wildlife is one of the most thrilling forms of the craft.  There is something deeply compelling—almost primeval—about sharing a wooded glen with wild animals, gaining their trust, and documenting their beauty and behavior. 

Wildlife is not the easiest subject to capture.  It often requires larger, telephoto lenses, or if your interests lie in the tiny, macro lenses that allow for magnification and close focusing.  Wildlife is most active at dawn and dusk—time when light is not always cooperative.  Fast telephoto lenses are an option if you have a nice line of credit available, but they’re not always necessary.  Today’s manufacturers have some more affordable, slower telephotos that can be used to capture great wildlife images. 

In this article, I will share with you some of the tips I have collected over the past several years in capturing beautiful wildlife with my camera.

Time to Invest in a New Camera?

If you are truly interested in wildlife photography, you will need a digital SLR camera.  Most of the point-and-shoot models simply don’t have the reach you will need to safely photograph wild animals, and ultimately lack quality when it comes to taking a half decent photograph.

Popular Digital SLR Cameras

Nikon D60 10.2MP ($484.43)

A great starter camera that comes with a 18-55mm f/3.5-5.6 Lens. If you’re just looking to get started with Digital Photography, this is a nice starting point and won’t require a huge investment up front.

Canon Digital Rebel XTi 10.1MP ($599.95)

Essentially the same package you get with the Nikon D60, only from Canon. If you’re a Canon person, you may prefer this setup.

Canon Digital Rebel XSi 12.2MP ($679.99)

Another fine choice for starting photographers (includes the stock 18-55mm f/3.5-5.6 Lens).The additional $100 buys you several notable improvements from the XTi, plus an extra 2MP for slightly higher image resolution.

Nikon D90 12.3MP ($920.00)

The D90 made quite an entrance into the marketplace of Digital SLRs after it was announced that it included a High Definition (720p), smooth (24fps) video capture feature. It’s a Digital Camera, and Video Camera that performs incredibly well for its price tag. No lens included.

Canon EOS 5D Mark II 21.1MP ($2,892.03)

This isn’t the camera you buy unless you’re really taking Photography seriously (and you’ve probably been doing it professionally for a while if you’re even considering purchasing). Oh, and it has HD video up to 1080p, though there are some setbacks. More research is suggested if you’re looking into getting this. Lens sold separately.

Getting Close & Keeping Steady

Animals are inherently more sensitive to the shape and form of an upright human being than they are to vehicles.  You can attribute this to the thousands of years we’ve spent hunting them for food.  The fear that animals have for humans is well deserved.  Many wildlife photographers use expensive and complicated blinds to hide their presence from animals.  In the right circumstances though, you already have a working blind—your vehicle.

Some more cautious animals will flee at the sight of a vehicle.  Kestrels, for instance, flee at the sight of a car as much as they do a human being.  But many species feel much more comfortable around them than they do people, especially in national parks where vehicles are a common sight, such as Rocky Mountain National Park or Yellowstone.   I can’t tell you how many times I’ve been able to get remarkably close to elk in Rocky Mountain National Park. 

Unfortunately too often, a tourist with a point-and-shoot camera comes along and steps out of their vehicle and approaches the animals.  The elk shy away or bolt into the trees, and my shoot is over.

Stabilizing your camera inside a car isn’t often easy.  You can set up some tripods so that you can shoot from the driver or passenger seat, but some wildlife photographers find the tripod too constrictive, especially when photographing animals on the move.

In those situations, your window is your friend.  Roll up your window to the level at which you want to set your lens.  Buy some cheap pipe insulation with a slit down one side at any hardware store. Slip this over the edge of the glass of your window and you can comfortably rest your lens on the edge.   I have seen photographers use bean bags for the same purpose. 

Remember the rule of thumb to eliminate camera shake: you should be shooting at a shutter speed at or above the effective focal length of your lens.  That means if you shoot like I do with a 70-300mm lens on an Olympus body with a 2x sensor crop factor, you need a shutter speed of at least 1/600th of a second to help ensure that your image will be as sharp as it can be. 

Tripods and the window edge trick can help lower this shutter speed, as well as cameras or lenses with image stabilization.  The kind of blur we’re talking about isn’t always obvious when you check an image with your LCD.  With this rule of thumb, you help reduce the chances of being disappointed with what you thought were great shots in the field, but turned out to be blurry or soft when loaded onto your computer. Don’t be afraid to increase your ISO to get the shutter speeds you need. When shooting fast-moving animals such as birds in flight, you may want a shutter speed as high as 1/1000th of a second to freeze your subject. And of course, proper technique in stabilizing your camera can go a long way.

Most photographer recommend that you use at least a 300mm (35mm equivalent) telephoto for wildlife photography (if you need to learn more about different kinds of lenses, this article can help) . Any less and you will have difficulty filling the frame with your subject. But no matter how much reach your longest lens gives you, you’ll always be left wanting more. Teleconverters can be used, at the cost of sharpness and f-stops, but for bird photography involving small subjects, they may be your best option.

Practice Your Skills

Before spending a fortune on a photography expedition to Africa, hone your skills in your own backyard. My area of Colorado is rife with red-winged blackbirds in the spring.  They can be found around nearly any body of water, and the males are claiming and protecting territory from nearly every tree branch or cattail.  Their focus on competitors and attracting a mate means that their guard is down more than it would be at other times, and the cattails they often frequent are conveniently located at eye level. 

I have found that red-winged blackbirds are an excellent “practice subject” to work on my skills of approach, framing, and general technical work (exposure, focus, and the general fiddling of knobs and buttons).  They are common enough that if you blow an approach by moving too quickly or loudly, another will most likely present itself shortly.  But they are not so easy to catch.  Dark subjects against light backgrounds can be a technical challenge, and learning to expose the blacks of their feathers along with that red patch can really hone your skills.

Blackbirds may not be common in your area, but most likely, some form of wildlife frequents the parks and fields in your area.  Find a good “practice subject” and work on your basics, so that when you go after bigger, more impressive animals, you will have a solid foundation in the basic techniques and you will stand a better chance of capturing a great image.

Know Your Subject

Get to know your subject’s behavior.  Read books and talk with hunters or experts on the species.  Your local university may have researchers who special in the animal you’re trying to capture.  Politely ask them for tips via email—often they will be more than happy to share their expertise, provided you’re respectful of the animals. 

Some knowledge you will only gain through experience.  I’ve spent most of the winter travelling to Rocky Mountain National Park on a weekly basis.  Of particular interest in this park are the herds of wild elk.  A large bachelor herd is my favorite subject, but finding them in time for the good light was not easy at first. Over time, and through trial and error, I began to understand how weather affected which altitudes the animals could be found at.  Colder weather or snow would push them down into lower elevations where it they were easier to find and photograph.  Also, I learned which park entrances they were most likely to be near at the time of  day I was photographing them.  Other photographers in your area may be able to share this information, but I think if you can spare the time, it’s more fulfilling to learn their behavior on your own.

Speaking of parks, the local rangers and park staff are an excellent resource for learning the activities and whereabouts of great subjects.  I often swing into the pay station later in the morning to chat with the rangers about how things have been inside the park.  As amateur photographers, we’re not able to spend all of our time out there, but the rangers do, and they excellent resources at your disposal.

Capture Action!

Starting out, I was content to capture any animal in focus, properly exposed, and decently composed.  I didn’t care so much what they were doing in the image, so long as I got them in the shot and they weren’t just a speck in the distance.  As you develop your other skills, however, you will find that the most compelling and successful images are one that capture an animal in action.  It’s common sense, but often, we forget in the excitement of just being near the animal that that closeness is not easily conveyed through still photography. 

Capturing action requires more patience than just getting the animals in the frame.  It’s nearly impossible to approach an animal without impacting its behavior somewhat.  They will often be rattled or cautious in your presence.  It takes time for the animal to settle back into its routine, to forget that you’re watching. 

Increase your chances of capturing hunting or feeding behavior by photographing at dawn and dusk.  The golden hour is great not just for light but for locating wildlife as well.  Many animals are nocturnal or at the least crepuscular, so they are on the move at these times.  Being out half an hour before sunrise or an hour before sunset will help ensure that you find your subjects when they’re doing something more interesting than chewing their cud.

One last tip for capturing action with birds of prey was recently shared with me by wildlife photographer Vic Schendel.   In his years of wildlife photography, he’s discovered that raptors often defecate shortly before taking flight.  When you have the bird in your frame, and you see this happen, starting firing off shots, because you are likely to catch a much more impressive image of the bird taking flight than if you had taken a shot while it rested on a tree branch or telephone wire.

Photographers keep facing more and more questions and charges for breaking the law, making it important now so more than ever to understand your rights and responsibilities as a photographer. In this article, we’ll go over such rights, as well as Model Releases.

Where and What can I photograph?

The general rule is that you can photograph mostly anything you like as long as it’s in a public place. You do not need to have permission to photograph in public, this include photographing building and parks as well as people that are in public areas.

If you’re on public property you can even photograph private property, for example standing on the street and photographing someone’s garden. If you are on private property you can photograph until someone ask you to stop (a sign prohibiting photography counts as well) and you must obey such a request.

There are exceptions to this rule, for example military installations or other subjects that can be classed as national security. However infrastructures such as bridges are not included in such a list. Another exception is, even in a public space, places like dressing rooms, restrooms or people entering their code at the ATM machine — photographing at these places counts as invading a person’s privacy.

So to summarize, here are some examples of things you can photograph, if you’re in a public space you can photograph adults, children, law enforcement officers, accidents, criminal activities, celebrities, airports and train stations.

What to do when people question you

There is a good chance that somewhere along the way in your photography experience, someone is going to confront you. Everything from regular citizens to security personal and law enforcement officers might question your activity and ask you to stop photographing. They might say it’s for security reason and refer to acts like terrorism, this is not a valid reason for them to ask you to stop what you are doing. As long as you’re in a public space you have the right to photograph.

First of all, act politely and stay as calm as possible. You do not need to explain why you are there or what you are photographing. In most cases you do not need to disclose your identity (depending on your country/state you might need to do so if it’s a law enforcement officer that is requesting).

You do not need to give them your camera/memory card nor do you need to delete the images. Unless they have a court order or are arresting you (again, depending on your location) they have no right to take your equipment.

If you are asked to delete photographs or asked to hand over your equipment ask for their identity and who they work for. Also ask what legal reason they cite for doing this to you. If this happens to you, you might want to consider taking legal action or contact your local newspaper.

How and Where can I use/publish my photographs?

Okay, so you have the right to photograph mostly anything, but are you allowed to do whatever you want with the photographs you took? The short answer is: No, there are rules and laws surrounding how you publish and distribute your photographs.

Once again, I cannot stress this enough, the laws are not the same all around the world so make sure you know what the laws says in your area before you do something you will later regret. A wrong decision can end up costing you a lot of money, not to mention your reputation as a respectable photographer.

In most areas the main difference in your rights is depending on if the photograph is used commercially or not. If your photograph is not commercial, i.e. considered art, you have much more rights to publish and use your photograph. For example, in most countries you are allowed to publish and sell photographs that are considered art without a legal release from the model/person in the photo. This means that you can go around the city photographing people in everyday situations and sell the prints or have a show at a gallery without notifying the people you photograph.

However if you intend to use the photograph in any commercial situation you will need a model release from the model. An important note is that if you sell the photograph to a commercial agency they are responsible for getting the model release from both the model and you as the photographer. If they publish your photograph without a model release you are not to blame — however all serious agencies requires a model release for every photograph they buy.

There is one gray spot though, photographers portfolios. They are used to display your work, just like commercials, but in most countries they are considered art and you do not need a model release to publish a photo on your portfolio.

News photographs, even though they can be used to sell newspapers, do not require a model release to be published and sold.

As you can see this is a rather complex issue, and I haven’t even talked about how different it is from country to country, so it’s important that you check this yourself before doing a job.

Model release

I’ve talked quite a lot about model release, which is a form of a legal document that basically states that you as a photographer holds the rights to the photograph and can do what you want with it. These legal releases can be made very simple or they can be quite detailed; in most cases a simple one will do just fine. Before doing a large-scale job, contacting a lawyer will be well worth the money to avoid any legal problems later on.

I have designed two different samples of model releases, which could be used as a guide to what you might need/want. These samples are not intended for actual use, they are supplied as guides and should be used as such.

The first one is a standard model release to be used when photographing a model for commercial use. It gives the photographer complete rights to the photographs.

The second one is a specific model release for a type of modeling that is becoming more and more common, Time-For-Print. Time-For-Print is the idea that the model gives you his/her time and for that they receive an agreed upon amount of prints for compensation. This is common for models starting out and wanting to build up a portfolio and for photographers doing the same thing. This model release is more flexible and gives options on what compensation the model is expected to receive.

If you’re doing a planned photography session with people; models, weddings, children etc. always have them sign a model release. It’s for your own safety! Do not just throw the paper on the counter and force them to sign it, it’s important that they understand what they are signing and explain what it is. They are signing away their rights to the photograph of themselves or their children; it’s understandably that they might have some questions or concerns so you should be thorough.

Running into problems when taking photographs over, and over again? Here’s a handy guide that will help you troubleshoot your problems, and improve your shots all at once!

Rather than stretch this out over several articles, it seemed like a good idea to provide solutions to common problems in Photography all in one informative list. Please be sure to ask any questions if you’re having problems not mentioned here!

Blurry Images Caused by Poor Focus

Photos that aren’t sharp are almost always caused by focus problems — either you, or the auto focus didn’t do their job correctly. If you are using auto focus and still get blurred photos it might be because the camera used another focusing point rather than the one thought you intended to use. Another reason might be the setting of the focus and then moving the camera without refocusing.

Blurry Photos Caused by Camera Shake

Camera shake is a result of unsteady hands or a too long of a exposure. To counter this you can change the shutter speed, or make the exposure time shorter. If you don’t want to change the aperture you can always change the ISO setting. Higher ISO will create noise, but noise is better than a blurry image caused by too long of a exposure time. Another option is to use a tripod or monopod.

For more information about this topic, you may like to read our tutorial on Proven Ways to Reduce Camera Shake.

Stop Motion Blur in Photographs

This is the result of photographing a moving object with a too long exposure… no matter how steady you are. A faster shutter speed is the only solution in this problem — some action sports require speeds as quick as 1/1000+.

Too Much Contrast

The sensor is not able to pick up the whole spectrum of light and expose it correctly in some situations. Unless you want to manipulate your photographs in post-production (such as HDR) you have two options: either select the part of the scene that is most important to expose correctly, or use a graduated ND filter to get the entire scene exposed correctly (primarily used in landscape photography).

Add More Contrast

Low contrast can be a result from photographing in bad lighting conditions, or in unique instances, environments can play a role in this problem (such as a snowy landscape). This is most often easily fixed in Photoshop by using the adjustment layer Levels to change the black and white point. The example photograph is lacking contrast due to stray light reaching the sensor, which can be countered by using a lens hood.

Here’s a good article that shows how to Correct Lighting and Contrast Problems in Photoshop.

Prevent Lens Flares

A lens flare is created when the lens picks up stray light. The best way to block out this unwanted light is to use a lens hood. Different lenses create different lens flares — cheaper lenses usually create uglier flares than high-end lenses, but even with a high-end lens one should always use a hood to minimize the risk.

Prevent Double Lights

This is an optical effect that can occur in low light situations in combination with some (often cheaper) lenses. A UV filter can increase this effect, so if you notice these types of odd lights on your night photographs you might want to consider removing the UV filter for the duration of the shoot.

Underexposure

Not enough light reached the sensor, you need to change the exposure settings to get a correctly exposed photograph. Either a slower shutter speed, a larger aperture or higher ISO — or all of them combined.

Read more about Exposure in Photography.

Overexposure

Too much light reached the sensor — you need to change the exposure settings to get a correctly exposed photograph. Either a faster shutter speed, a smaller aperture or lower ISO — or all of them combined.

Read more about Exposure in Photography.

Dark Corners — Vignette

Vignette are dark corners in a photograph, which occur when the light is not evenly distributed on the sensor or when the flash just lights up the center of a shot.

Many lenses, even high-end, create this effect when opened wide (largest aperture). To fix this problem simply stop down the aperture a few stops and this should even out the distribution.

Lens distortion

Mostly a problem when photographing architecture with a wide-angle lens. A lens below 50mm usually creates some distortion but in most cases this is not visible. However when you are photographing straight lines (such as buildings), standing close to the object and pointing the camera upwards you will more easily see these distortions. Take a few steps backward or change to a more suitable lens.

For more information, read our article about different Camera Lenses.

Skewed horizon

You were either holding the camera skewed or the tripod was set up uneven. Some DSLR cameras have the ability to change the focusing screen and install one that has guidelines. This is rather easily fixed in post-production by rotating the image, but you will loose some of the edges.

Red eyes

This effect occurs when the flash is located close to the lens and is a common problem with our modern point-and-shoot-cameras due to their placement of the flash. To prevent red eyes, do not use the cameras internal flash if your camera has one. Use an external flash that you can bounce on a wall or on the ceiling.

Reduce Noise in Photographs

Most likely due to a high ISO setting, but can also be caused by long exposures. To prevent noise, use a low ISO setting. If you have photographs with much noise you can always use a software to remove it, such as Photoshop or Noise Ninja, though some detail will be lost of course.

You can learn more about ISO, Aperture, and other essential subjects in our Photography Basics article.

Photo is yellow/orange tinted

The camera is most likely to have miscalculated and thought the photograph was outdoors and added orange tones to compensate. The white balance is the fault here, and if you’re photographing in RAW there’s no problem since you can easily just change the white balance to a desired level. If you’re not using RAW-files then you might want to check your settings in the camera — most cameras have W/B setting for indoors and outdoors, as well as custom settings and auto. The fault could also be that you used a flash that bounced off an orange surface as well, so try to always bounce the flash at a neutral surface, such as gray.

Photo is blue tinted

These photographs look very cold and are most likely due to a miscalculation by the camera and just like the previous problem discussed, you can fix it the same way. Another reason why a photograph can get a blue tint is because of large amounts of UV-light, to reduce this problem use a UV-filter that prevents the UV-light to reach the sensor without affecting the overall quality of the photograph. (Not a problem for most digital SLR cameras.)

Photo is half black

The flash doesn’t sync correctly with the camera (shutter). This problem was more predominant before the digital era, but old flashes can still cause problems with newer technology. Either buy a new flash or learn which shutter speeds work best — 1/125 and 1/60 are usually good.

Chromatic aberration

Chromatic Aberration (sometimes also called “purple fringing”) is an optical effect and it’s seen as purple edges around an object, sometimes green edges on the opposite side are also visible. This effect is most common in situations with strong contrast, such as sunlight against dark objects or black text on white background. The problem is more prominent on zoom lenses, the longer the range the worse the problem usually is. To prevent it you could use a smaller aperture — shooting with the lens wide open will enhance the problem.

Sensor Dust

These gray spots are usually caused by sensor dust. The best way to get rid of this problem is to keep your gear clean and dust free. The sensor is very sensitive and cleaning it will mean that you expose it to further risks. Some photographers send their cameras to be cleaned while others clean the sensor themselves. Choose which option you like best.

Want to Learn More About Photography?

If you’d like to learn more about Photography, Lenses, and Equipment, be sure to see the rest of our Photography Tutorials! If you’re a beginner, you may want to check out our Photography Basics Tutorial. Also feel free to leave a comment here, and someone will try to answer your questions as quickly as possible!

The Crop Factor is a term that can be heard quite often in the world of digital photography. What does it mean that a camera has a crop factor of 1.6x and how does it affect your focal length? We try to untangle this issue and describe it as clearly as possible.

The subject of crop factors and focal length multiplier can be a bit confusing and hard to understand at first — I will try to explain it as simple as possible but yet informative enough for you to get the entire picture.

The size of the sensor is what controls the crop factor, and it’s always compared to a 35mm film size. So when people talk about Full Frame they are talking about cameras that have a sensor the same size as a 35mm film (24x36mm).

As you can see in the illustration above, a body with a crop factor captures only the center part of the image. The image itself is round because that’s what the lens produces, and the sensor only picks up the light that reaches it. A full frame sensor will capture edge to edge of what the lens capture.

It’s important to know that the crop factor changes the field of view, it doesn’t actually change the focal length, since that is something that is decided by the design of the lens. The same results could be produced by taking a photograph with a full frame camera and crop it to only show the center — however it would require a camera with a good enough sensor that such a small crop would still produce a good quality image. These high-end sensors are currently only found in the top of the line cameras from Nikon and Canon.

What it also means is that the perspective doesn’t change with the crop factor, if you stand on the same spot and take a photograph with a full frame camera with a 50mm lens and then take another photograph with a 1.6x crop factor camera you will get the exact same perspective (the 1.6x camera will however not have the same view of field).

When people say that a 50mm lens is the natural focal length they talk about perspective in relations with the human eye, and as stated above, this is the same even on cropped bodies, a 50mm lens still produces a natural looking photograph. To test this, use a 50mm lens and look through the viewfinder with one eye and have your other eye open, you will notice that the perspective looks the same for both eyes, no matter if you’re using a cropped body or not.

Lenses designed for Crop Factor cameras

To counter this issue, most lens manufacturers have designed some lenses that are only meant to be used on cameras with a crop factor (i.e. not on full frame bodies). These lenses often produces a smaller image circle so if they were used on full frame bodies they would create a black edge, much like circular fish eye lenses do. Since the problem with crop factor is mainly negative with wide-angle lenses it’s almost entirely that focal range that has designated digital lenses.

Here is a list of the name camera manufacturers call their digital only lenses.

• Canon — EF-S
• Nikon — DX
• Sony — DT
• Pentax — DA
• Sigma — DC
• Tamron — Di-II

One thing to remember is that the crop factor is still in use even on these cameras and you must multiply the given focal length to get the “correct” focal length. For example, Canon has an ultra wide EF-S lens that has a focal length of 10-22mm, on a body with a 1.6x crop factor the focal length corresponds to a 16-35mm. So don’t believe that you do not need to multiply the focal length just because you have a lens designed from cropped bodies.

How it affects your photographs

There are both positive and negative affects with the crop factor, let’s talk about the positive aspects first.
To get the “correct” focal length you need to multiply the focal length with the crop factor. When I say correct I mean the focal length that the lens acts like, not what it truly is. My camera has a crop factor of 1.6x and that means that a 50mm lens is a 80mm lens (50×1.6=80). It also means that a 100-400mm lens is actually a 160-640mm lens. That’s a very good thing in most situations. You loose 60mm on the short end but gain 240mm on the long end — rather significant. With telephoto lenses the crop factor is often desirable, since it extends your “reach” quite a bit.

Another positive affect is that almost all lenses are much sharper in the middle and softer on the edges. How can this be a good thing? Well with a camera that has a crop factor you only get the center of what the lens sees (unless it’s a lens designed for crop factors as described above). So with a crop factor you only get the center and therefore the best performance from your lens.

Now over to the not so good aspects of the crop factor. Wide-angle lenses, this is a big minus on the bodies with smaller sensors. As the example above, the 10-22mm ultra wide turns into a 16-35mm lens, and for example a 17-40mm lens turns into a 27-64mm lens. You simply do not get the same wide angles with a crop factor, the edges are cut off and field of view is more limited.

Another negative affect is that the extra focal length you gain also means that you increase the risk for blur due to camera shake. The rule that you should have a shutter speed of 1/focal length is no longer true. For this rule to be true you first need to multiply your focal length with the crop factor of the body.

Full frame camera often have a larger viewfinder as well. When I’m comparing my old 35mm film camera with my 1.6x crop DSLR it actually makes me a little bit sad inside. The viewfinder on the 35mm camera is so large and bright where as the DSLR’s viewfinder is although bright still very very small.

There is one more thing a smaller sensor affects, but it would be hard to classify it as either good or bad. Different sizes of sensors change the depth of field. A smaller sensor will give you greater depth of field (more in focus) and a full frame sensor will give you a narrower depth of field (less in focus). If this is good or bad is dependent on what you desire, either you want as much as possible in focus or you want to isolate your subject as effective as possible.

I hope I didn’t confuse you too much. This is an important part of digital photography to understand, at least the very basics of it.