Why is it blurry?

A question I get a lot from students is “why is this picture I made so blurry?”

We all want super-sharp pictures, and are disappointed when our pictures come out less than perfectly crisp. And then we wonder why.

The bad news: this question can be confusing because first, you need to distinguish between four distinct causes of blurriness. Yes, four: motion blur, focus blur, computer-generated unsharpness and camera-unsharpness. And their sub types: 11 reasons in all.

And then, once you know what caused it, you need to figure out how it came about.

Microphone shot against blurry background, by photographer Michael Willems

Microphone shot against blurry background

The good news: I can almost always tell very easily. And with a bit of training, so can you. And then you can find solutions.

So let’s look at why a picture can be blurry, shall we?

First there is motion blur:

  1. The shutter speed was too slow. This is by far the most common cause I see. Using a 100mm lens at 1/10th of a second is not going to work unless you are very lucky. (A general, very rough, rule of thumb: stay faster than “one divided by your lens length”. So on a 50mm lens, stay faster than 1/50th second. And so on). Solution: turn on more lights, go to a higher ISO (though this has problems too), open your aperture, or use a better lens with a larger aperture. Or use a tripod.
  2. The subject is moving. This is common too. If your subject moves, a tripod will not help! Solution: select a faster shutter speed or try panning with your subject.

Then there are various causes of focus blur:

  1. Simply out of focus, due to focus error. I see this a lot too. Solution: use one focus point, aim that at your subject (the eyes!), focus/lock focus, and shoot without repositioning yourself. Do not let the camera select where to focus.
  2. Out of focus due to very narrow depth of field. This is common with fast lenses. An f/1.8 lens (you need one!) has very selective depth of field, so move even a few millimeters and that eye will be blurry.
  3. Missed focus – due to the subject moving away after you focus. Solution: in these cases use AI Servo/AF-C rather than One Shot/AF-S.

Then there is what I like to call “signal unsharpness” (low signal to noise ratio, for engineers):

  1. The subject is dark. Dark pixels contain the noise and the muddy, unsharp image parts. Solution: light well!
  2. You are using high ISO. This leads to noise. Solution: use as low ISO as you can, use a faster lens, and turn on more lights.
  3. You are using noise reduction, which leads to blurriness. Solution: as above.
  4. You have increased the RAW image’s exposure, which generates extra noise. Solution: try to expose well in the camera and “expose to the right” (see previous posts here: search for them on the blog using the search field above right).

Finally there is camera unsharpness:

  1. Anti-moiré blur. Your camera adds blur to avoid Moiré patterns. Solution: use sharpening.
  2. Your lens is badly adjusted. This happens. Solution: have it fixed, or on professional cameras, do a lens micro adjustment.

I hope the above does two things. First, explain why this is complex, which explains a lot of the confusion (and I hope I removed some of that confusion). Second, help you with strategies to fix the issue.

Tip: Take lessons to learn about this stuff from the pros. Go to your local Henrys, or if you are an emerging pro to www.cameratraining.ca, and explore the possibilities. We make things simple!

Reader question: Focus

RG, a regular reader, asks:

I just still struggle getting my subject in sharp focus.

I shoot in Auto Focus mode on my Canon Rebel XSi (usually in Program Mode). I manually select my “red” indicator and try my best to focus on what I want sharp. But what do I focus on when my subject doesn’t fall neatly on one of the AF points? I tried to pick the nearest one to my subject — sometimes it comes in focus, sometimes not.

If I am taking a portrait of two people’s faces and they are cheek-to-cheek — sometimes one face is sharp while the other is not! Annoying! In that case, where do I place the red mark on?

Great questions. And the answer comes in three parts: motion blur, focus blur, and depth of field.

Let me start by saying “it’s not just you”. Everyone struggles with focus. I do, too.

  1. One important reason is that we are more critical today than in the past – we zoom in. Take your blurry picture and print it at 4×6 and it will probably look just great!
  2. We take many more pictures in low light, where we would not have tried in the past.
  3. We have two distinct kinds of blur: focus blur and motion blur. They are easy to confuse.

So then let’s start with motion blur. Your first picture’s unsharpness was mainly due to motion blur: it’s a shaky picture. It was taken at 1/30th at f/1.8 on a 50mm lens. The 50mm lens works like an 80mm lens on your Canon Digital Rebel. To get sharp pictures, a rough rule of thumb is: “stay at one divided by the ‘real’ lens length – preferably twice that”. So you should be at 1/80th second, maybe even 1/160th second, when handheld. 1/30th is  pushing it. No problem trying, but steady the camera, lock it onto your face, don’t breathe, and take the picture ten times, then pick the sharpest one. Or… use a tripod. Or go up to a higher ISO value to increase the shutter speed.

Now to focus blur. The second picture is blurred mainly due to focus: the closer part of the girl’s clothing is sharp while her face is not. That could also be motion (her motion this time – not yours; she is turning her head) but it is to a large extent it is focus.

You are focusing with one focus point: this is always the way to do it! But what if there is no focus point where your subject is?

How, in other words, do you take a picture like this?

Selective focus


Actually that is quite simple and I want you to reproduce that picture now. Use a technique called “focus – recompose – shoot”:

  1. Select a focus point near the subject;
  2. Aim that focus point at the subject;
  3. Focus by pressing half way down. Wait for the beep that indicates “in focus”. A green dot appears too, at the same time.
  4. Hold your finger there – do NOT let go! But also do not push all the way down.
  5. Now recompose the picture (while still holding your finger down).
  6. Now finally push down to take the picture

Hah – your hand is now still sharp, since pushing half way and holding your finger there locked the focus distance, until you either let go or push down.

Finally to depth of field. What if you want more than one thing to be sharp?

  1. Use Aperture mode (Av), and select a not-too-small Av Number. f/1.8 will give you very very shallow, selective, depth of field. f/5.6 gives you much more sharpness (but slower speed); f/16 and much of your picture is sharp (but now even longer shutter speed so you must use a tripod and tell people to not move).
  2. Aim at a point in the middle, So if you have to shoot three rows of hockey kids, focus on a kid in the middle.

So now you know how to avoid blur, how to focus accurately, and how to get enough in focus.

All you need to do know – and you know what I am going to say: practice!

Learning technique

Today, a tip and a request.

First, the tip.

How do you learn to “pan” your camera along with a moving object (like a bicycle travelling traversely through your picture)? So that the object appears to not move much, while the background is a streak? How do you learn this in the absence of cyclists riding through your living room? You pan and follow your hand. That’s how.

  1. Set your camera to S/Tv mode
  2. Select a shutter speed of 1/15th second (a good starting point).
  3. Hold your hand out as far as it can go.
  4. Focus on it. Wait for the beep and then hold your finger on the shutter to lock that focus distance.
  5. Now rapidly move your entire body around, so your hand describes a circle around you.
  6. Half way through that circle: click. (Do not stop moving to click!)

Try this technique, and repeat until you are happy. Your images may look somewhat like this:

You thus get to practice the technique that gets you images like this:

Did you find that a useful tip? Then I have a request for you.

I teach these and many photographic techniques –  a tip a day! – because I want to give back and help disseminate information and knowledge as widely as possible. I want the world to learn photography, and I think I can be a small part of that.

But you can help me too.

First: send me questions. About anything photographic.  I’ll do my best to answer them in a timely manner right here. That way, your question benefits others too.

Second: help me with the blog. Apart from small contributions, which are always welcome (see the link on the right), even more importantly, you can link to me. Mention my blog to friends and to others who many be interested. Link from your blog or from your facebook page. Tweet. Mention me on your web site. If you are helped by this, you can do me a big favour by spreading my name, and that of this blog, as widely as possible. This is an ongoing request!

That way I get better known, and I get to help more people. In this way, we all help each other. I firmly believe that this is the way the new economy works. Social media, sharing, the Internet: we now grow value by collaborating, not by “hoarding and hiding knowledge”. People who do not yet understand this will eventually find out that the old “make money by keeping knowledge secret” paradigms are dead.

And the world will be a better place for it.