Taking Sharp Photos
Can You See the Details in Your Photo?
Sometimes when we take a picture in difficult lighting conditions, it doesn't live up to our expectations.
Often, the details are lost and you can barely recognize the faces of a group. Other times, pictures come out blurry because the camera wasn't still enough while taking the picture.
Worry not! Although there are many types of problems causing blurry and poorly defined pictures, there's a solution for all of them.
Would you like to know how it's done? Let's get right into it!
Sensor Resolution vs Real Resolution
How many times have you heard your friends say: "Hey, my phone has 41 megapixels, so it takes much better pictures than your 13 megapixel one".
Well, that's simply not (necessarily) true.
"Megapixel" is just a property of the the image sensor, an important part of every digital camera.
The sensor, which looks like a small, flat, "after eight"-sized rectangle, is divided into tiny little squares (pixels) which are further divided in 3 light sensitive semiconductors (Al, John and Jack...go check out my white balancing tutorial to find out who they are!) that gather light from the subject you are shooting at.
Every pixel contributes to create the final image, which is just a mosaic of the signal every pixel records. So, a 3000px x 2000px sensor on your camera, will generate 3000px x 2000px images on your screen.
So, the bottomline advantage of having more (mega)pixels is that you can divide the scene in smaller pieces, therefore you can zoom in your pictures and see even the most minute details of your scene.
So, if everything else is the same (lens, processor etc...) the more megapixels the better (to an extent), but always bear in mind that:
A higher sensor resolution does not always translate to a better real resolution
As a matter of fact, sensor resolution is nothing if the lens system is not up to par!
Think about it: do you really think all phones with a 12 megapixel camera perform identically? Check with your friends that have a phone with a different price point, but with the same amount of megapixels as yours and compare 2 pictures taken at exactly the same subject. You will be surprised.
Real resolution (a.k.a. resolving power), which is defined as the smallest distance at which 2 distinct points are visually distinguishable, strongly relies on the whole system, not just the sensor!
Keep that in mind when choosing your camera, especially if it does not have interchangeable lenses. Always ask to test the camera you want to buy.
Want to calculate your sensor resolution (in megapixels)? Shoot a picture, go into your image details, check for the "resolution" attribute, multiply the first number by the second, and then divide the result by 1 million (1000000)
1 - Get Your Subject in Focus
The first step to taking sharp pictures, is getting your subject in focus.
Most cameras feature an autofocus (AF) system, which tries to understand which subject you want to shoot and rearranges the lens system so that your subject will be in focus.
However, there are a few things you have to pay attention to, if you want to have the sharpest possible picture:
- Make sure the autofocus is focusing on the right thing. If it's not, fix it before shooting! In phones, for example, you can often tap on the area you want to be in focus, and the camera system will try to focus on it.
- In the dark, most AFs will not work very well, because they need light to focus. In those cases, try to focus manually, some phones and all DSLR/mirrorless systems allow you to do that. Just turn the focus ring (or move the focus slider) back and forth, until you find the position with the highest possible sharpness.
- If you are unsure whether the focus point you are using is perfectly accurate, use focus bracketing. This technique consists in shooting the same picture 10 or 15 times, changing the focus by a few millimeters back and forth at every picture. In this way, you can be sure that at least one of the pictures will be in focus!
Now, I talked about focus as if it was just a point in space, which it is, but the situation is a bit more complex!
In fact, while the "focus point" is indeed a point, the area that is in focus (a.k.a. depth-of-field, DOF) is actually a volume in space!
Look at the picture below. If focus was only a spot, how could the whole sunglasses be in focus? They are a 3D object right?
So another way of making sure your subject is in focus, is increasing your depth-of-field.
This is easy to accomplish in DSLRs and mirrorless systems, less so in phones and compact cameras:
- Move away from your subject: DOF increases proportionally to the distance from the subject...but be careful, you will be losing details when you move further away!
- Choose a lower zoom setting (or change a lens to one with a shorter focal lenght): the lower the focal lenght, the bigger the DOF. Like before, be careful not to lose details.
- Stop down your aperture: this is the gold standard, but it's normally possible only with DSLRs, mirrorlesses and advanced compact cameras. This is the only real way to increase depth-of-field, without having to increase your real or apparent distance with your subject. The f-stop number. a.k.a. aperture number, describes 2 things: how much light your lens can let in (lower number=more light) and how wide the DOF is (higher number=more DOF). It goes without saying that a gain in DOF results in a loss in light amount, so you have to compensate using a slower shutter speed (or a higher ISO), and that can cause loss of sharpness! Therefore play with your aperture cautiously, and run lots of tests! Also, don't use a too-high f-stop or your images will suffer from light diffraction, and become soft.
Relative amount of light let in by the aperture
Relative shutter speed or ISO to keep the same exposure
2 - Freeze the Action With Quick Enough Shutter Times
The single most prevalent cause of soft pictures is arguably motion blur.
This happens when, during the exposure of the scene to the sensor, the subject changes position. Even microscopic movements of a few millimeters can cause your image to lose sharpness!
So, how does this happen?
When you use a completely automatic camera setting, your machine will do its best to get the exposure right. In other words, the camera will try to make a sufficient amount of light reach the sensor, so that the picture will not be completely black.
While this is typically not a problem when shooting in the daylight, it can become an issue at night, and indoors with dim lights.
Cameras have 3 ways to increase the amount of light the sensor records:
- Reduce the f-stop number, which is not an option in phones and some cameras
- Increase the sensitivity of the sensor (ISO) which is possible, but it has limitations that we will discuss in the next paragraph
- Increase the amount of time the light flows towards the sensor (shutter time)
In difficult situations, phones and compact cameras will invariably increase shutter time.
What Kind of Camera Do You Use Most Often?
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Increasing the shutter time means the scene has more time to "move around", and this gives rise to our arch-enemy, motion blur!
Motion blur is a two-faced phenomenon. In fact in can be caused by:
- The subject actually moving in the scene
- The photographer's grip shaking, which causes camera shaking
Make no mistake — even if you have the firmest of grips, you hands will inexorably be shaking to an extent, and with long shutter times, this effect is exaggerated.
Down to business now, let's solve our motion blur problems!
- Use your flash. Although pictures taken with a camera flash can look pretty boring and dull, there's no doubt that it helps use quicker shutter times, and reduce or eliminate motion blur
- Use another source of light. A less boring alternative to in-camera flash, is to get some kind of alternative lighting device to brighten the scene. This can be anything between a car's front lights, and a carefully devised speedlite system, with flashes mounted on external tripods and what not. Get creative and learn to work with your environment!
- Use a tripod or a monopod. These devices provide you stability, helping to reduce or eliminate camera shake, so that you only need to worry about making your subject be still. If you don't want to spend too much money on equipment, a selfie stick (used as a monopod) and a GorillaPod will be enough, but my daily drivers are Manfrottos, and they are really hard to beat. This is my , it is really really stable and easy to operate despite the relatively low price point, and the same goes for my Manfrotto tripod. I always take it with me in my mountain trips and it never lets me down (as a matter of fact it also doubles as a mountain walking cane!). They are both also extremely well built and sturdy, I cannot tell you how many times I dropped them (I'm a bit of a clumsy monkey) and I never left as much as a nick in them. Manfrotto monopod
- Hug a tree. If you are stuck with no alternative, you need to get creative in reducing the shakes. One way of doing it is spreading your legs to increase your base area, which stabilises your center of mass and...hug a tree! Or a street lamp, or whatever else is really stable and sturdy. Then take a deep breath, hold it and shoot! You can also keep shooting while exhaling really slowly. It works better for some people.
- Hang or sit your camera. Your camera usually comes with a shoulder strap or something similar. you can use that strap to hang it to something stable (like a branchy tree or a coat hanger) to get sharper pictures. Another way to do it is sit it on something stable, like a rock, a shelf, a table, the ground etc...This method works best when coupled with the camera self timer: sit the camera, compose, get your focus, activate the self timer and stop touching the camera. Since you are not holding the camera, you cannot give it camera shake!
- Use stabilised cameras or lenses. Many high-end phones and cameras, and a lot of the lenses available for DSLRs and Mirrorlesses have an image stabilisation system. This essentially compensates for camera shaking, helping you shoot sharp pictures even with very slow exposure times. Be careful though, to have an image stabilisation system, lenses that look equivalent on paper may sacrifice some image sharpness. This is the case for my beloved , which has a far worse image sharpness in its stabilised version. By the way, that HAS to be the first lens you buy, it's just so much better than any kit lens, it's cheap and versatile...Most of the pictures you see on my articles are shot with that lens. Tamron 17-50 f/2.8 lens
- Use the reciprocals rule. This is a rule of thumb, and as such it will work for most people, but not for all people. It certainly works well for me. The rule states that the slowest speed at which you want to shoot is [1/(focal lenght) seconds]. For example, if you have a 50mm lens, you will most likely be able to take sharp pictures using shutter times of 1/50 seconds or faster. If you have a crop sensor (such as an APS-C or a micro 4/3 that most entry level cameras and mirrorlesses feature) you have to account for the crop factor. For example, Nikon APS-C sensors (like the one from my Nikon D90) have a crop factor of 1.5X. This means that a 50mm lens will effectively be a 50X1.5mm=75mm lens on my D90! Therefore, with my Tamron 17-50mm, shooting at 50mm I will be able to use times of 1/75 seconds and faster. Make sure you use this rule and you're almost guaranteed to take sharper pictures with no camera shake!
- Convince (or force) your subject to be still. This is normally easy when shooting people, you just tell them to stand still, and they (probably...) will. That's more of a difficult feat with animals, but I hope you will be able to convince your pet with a few biscuits! However, with inanimate objects and insects, you might need to "force" them to be still, for example you could tie a flower to a stable surface while you shoot it (untie it afterwards, respect nature!). Some insects photographers capture and kill insects with ethyl acetate before putting them back on their flower and taking the picture. As a research scientist I understand the need to sacrifice lab animals to advance human healthcare, but I really don't feel confortable in killing an insect just to take a picture of it. Anyway, it's not illegal, and nobody will judge you, it's your call!
Once you took care of camera shake and subject movement, you should be golden and motion-blur free! Anyway, always know the limitations of your camera system, and don't try to take a picture that just cannot happen, it will just leave you frustrated and dissatisfied.
3 - Optimise Your Camera and Lens settings
To be a good photographer, you need to be familiar with the technical aspects that come with it.
Part of your photography training must be knowing what changing ISO, shutter speed, f-stop number, zoom setting, will do to your picture.
Here's a short, non-comprehensive list of the main ways these settings will affect your picture sharpness:
- Shutter speed. You should know by now
- f-stop number. This is a tricky one. If you use the widest possible aperture, you will get a very narrow depth-of-field. This can, in some cases, lead to your subject being only partially in focus, reducing the overall feeling of sharpness. Also, using the widest aperture can cause some general loss of sharpness due to the very large amount of light accessing your lens and bouncing around in your system. On the other end of the spectrum, using a very narrow aperture, will cause light diffraction, which is essentially also caused by light bouncing around in your system, but in a different way. The outcome, however, is the same: a soft picture. So while it's true that using a very narrow aperture will improve the DOF and increase your chances of getting your subject in focus, it will eventually result in a loss of sharpness. What to do then? Every lens has a so-called "sweet spot" which is the f-stop setting at which the lens has the highest sharpness. This is usually a couple of stops below the maximum aperture, check on the net or find out yourself with a few experiments!
- ISO sensor sensitivity. This is a number a bunch of scientists came up with, that represent the amount of light needed for a sensor to record a signal and turn it into an image. The higher the number, the lower the amount of light needed. A standard DSLR ISO number (also called "ISO speed") is 200, but some cameras can go up to 3280000!!! Considering that at every doubling of the ISO number, the sensor needs half the light to generate the same signal, a camera with 3280000 ISO will need 16400 times less light to generate an equivalently exposed picture. That's more of less the difference between a candle and the sun. So where's the catch? Simple, using a higher ISO number will cause a proportional reduction in sharpness. This is because the sensor is trying to get a huge signal output from a very small signal input, and the signal amplification steps cause artifacts that look like wrongly colored speckles on your picture (digital noise). Digital noise will give our eyes a hard time distinguishing fine details (hence low sharpness), and therefore high ISO speeds should be avoided whenever possible.
So you can understand that something has got to give, if you want to take pictures in very dimly lit environments. You cannot expect miracles from your camera, but using ISO, shutter times and f-stop wisely, you will surely get sharper pictures in the worst of situations! Also, from these few tips you can extract an indication on how to take a razor-sharp picture in a well-lit environment:
- Set your f-stop on the lens' sweet spot
- Set your ISO speed at its lowest non-extrapolated setting (avoid the LO-1 LO-2 LO-3 settings, they are as bad as a very high ISO)
- Use the quickest possible shutter speed and stabilise the camera and the subject
4 - Mind Your Environment
Part of taking great, sharp pictures, has to do with the environment itself, and how and when you take the picture.
A few important rules:
- Shoot during the "golden hours", which go from the sunrise to 1 hour after sunrise, and from 1 hour before the sunset to the sunset. This type of lighting avoids weird light reflections on your subject, and are also ideal for portraits, because the light is "warmer" (check out my white balancing tutorial to see what that means)
- Don't shoot against the sun. Although shooting against the sun (which I call "Icarus", check out my 10 tips and techniques to take better pictures for an overview) can create some really remarkable pictures, it is not ideal for picture sharpness and exposure accuracy. Direct sunlight can be overwhelming for the camera, resulting in a loss of contrast, which is proportional to sharpness, and wrong exposure
- Shoot long distances early in the morning. If you want to take sharp pictures of a deep, long landscape, you have to be an earlybird. Get out in the mountains before sunrise, and wait for the golden hour. Start shooting and never stop until 1 hour after the golden hour. After that, you will start noticing a "foggy layer" appearing in the far distance, and that haze will become closer and closer as the day progresses. That's not great for picture sharpness. At all.
- Avoid shooting long distances in the city smog. Living in the city is great for some things, but not for air quality. Smog and microparticles deriving from all of those cars and buses rushing in the city cause an effect similar to the mountain foggy layer we just talked about. The advice is the same, if you want to shoot the "freedom tower" from the "top of the rock", you better get there early in the morning for maximum sharpness!
- Don't shoot in a misty weather. Mist diffracts light. We already talked about how that's bad for picture quality when it happens inside your lens, and this is not different, except it happens outside your lens. If you shoot in the mist, your pictures will not be as sharp as possible. Period.
Hope my tips to get sharper pictures help you in your quest to become a better photographer, and as I always like to say, when you know the rules, you can break them!
Photography is an inherently creative and visual art, so the important thing is to communicate an emotion with your shots, be them sharp or less sharp.
Have fun with following or breaking the rules and...
"memento audere semper".
Remember to dare, always.
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© 2017 Marco Arista