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!

A Point about Focus

When you auto-focus, do you use one focus point?

You should. That way you, not the camera, determines where sharpest focus is achieved. Wherever that may be.

But you may not know this:

    1. You need light, distance, and a subject (with horizontal/vertical lines) in order for your camera to focus.
    2. Focus points are sensitive to horizontal or vertical lines.
    3. Some, like the point in the middle, is sensitive to both horizontal and vertical lines.
    4. Some cameras have multiple such both0way sensitive focus points.
    5. Some cameras enable more focus points to become both-way sensitive when faster lenses (like those with apertures of f/2.8 or better) are in use.

      Yes, knowing all that technical stuff will make you a better focuser.

      Click. Shhhh!

      A few tips for those of you who shoot ceremonies.

      Ceremonies are important to people. Whether this is a graduation, a wedding, a signing of some sort: there will often be a hushed silence.

      A silence you do not want to disturb. So today’s tips are about blending in and behaving appropriately at such venues.

      • First, dress in a non-conspicuous way. You do not want to be the centre of attention.
      • Ask the person in charge what you can do. Can you walk around? Use flash? Click away?
      • Ask if flash is allowed
      • If it is, bounce that flash rather than use direct light.
      • If it is not, you may still be allowed to use the focus assist on your camera’s flash. That’s the little red line pattern your flash can cast to help focus, and you can use this even when the actual flash function is disabled.
      • Turn off your camera’s focus beep.
      • If you have a Nikon SB-900 flash, turn off the “overheating” beep.
      • If you use off-camera flash, ditto: disable the beeps (notably on Nikon flashes)
      • Use a camera with a quiet shutter. I will grab my 7D if I want a quieter shutter sound. Some people even wrap their cameras. If you have a pro body such as a Canon 1D or 1ds, select the “Silent” shutter mode.
      • Use a longer lens and shoot from farther away.

      By using these common-sense precautions, you can give yourself and all other photographers a good name.

      Question of the day

      A reader recently asked this:

      I noticed in a forum that you much like the Pentax k-7. I am wondering whether you have used the Pentax K10D before and under what low setting should this or a any digital Camera take a photograph without the results being blurred. ie: 50mm 1.4 lens and at ISO 100. Are there any differences between film or digital sensitivity, should the results be the same and do you forgive digital cameras for its own idiosyncrasy. if it was film would digital cameras be better designed today. And finally, how is it possible for a camera to register a photograph out of focus when what you see is in focus?

      My reply:

      Yes, I have used both those cameras. They’re great, as are most all digital cameras today. The results should never be blurred if you do not want them to be. But with an f/1.4 lens set to f/1.4, you need to focus very carefully. Depth of field is minimal and even a very slight movement after focusing makes the picture blurry.

      Also, use one focus area that you choose and move that over the part of the image that should be sharpest.

      Sensitivity is the same: 100 ISO is equal to 100 ASA. Noise is not much different either. And you will find most experts agree that a modern sensor of, say, 10 Mpixels or more is at least as good as a negative. Beyond that, better. True, the dynamic range of film is greater, and it drops off gradually at the end, but sensors can be more sensitive. If you shoot in RAW, you minimise that difference.

      When what you see is in focus, the image should be sharp. But what you see is small, and perhaps you are moving the camera? Could it be motion blur? Or “slow flash” bluer due to slow shutter speed? Or are you perhaps moving the camera slightly after focusing?

      You may want to (re-)read this post here on why studio shots are sharper. And perhaps post an image you think is unsharp.

      Here’s one I took yesterday, of my niece’s cat:

      Click to see it in its full sharpness.

      Al's Not Home

      Canon cameras have several ways of deciding where to focus (these have to do with the focus spots), and two ways of deciding how to focus.

      You call the latter “focus modes”, and there are two: “One Shot” and “AI Servo”.

      • One Shot means that the focus locks (you hear a beep and as long as you keep your finger on the shutter, that distance remains locked.
      • “AI” is A I, as in “Artificial Intelligence”, not “Al” as in “Alan”; and a servo motor is a closely controllled motor with feedback loop. So that mode just means “continuous focus”.

      One Shot is for static subjects. AI Servo is for moving subjects,like these:

      I shot that yesterday, for the local newspaper. So since the young lady would not stand still, I had set my camera to AI Servo mode.

      Focus on focus

      I recently bought a Canon 7D camera.

      The reason I bought another camera when I have two pro bodies already? Amongst many other reasons: The 7D focuses better, while my Canon 1Ds MkIII and 1D MkIII cameras do not focus consistently well when shooting “wide open”. When I use a “fast” lens, one with a large aperture/small “F-number”, set to, say, f/1.4 or f/2, focus is inconsistent.

      And I shoot carefully. I use one focus point. The subject is contrasty and well lit. I am shooting at a shutter speed of ten times lens length (e.g. if using the 35mm lens, I am at least at 1/350th second). And yet – out of every five images shot like that, one or two are razor sharp, some are pretty good, and one will be blurry – focus blur, with the focus way out.

      This appears to be well documented online. “Fake Chuck” writes about it regularly, like here.  Another post here also mentions Canon’s sloppy soft focus versus Nikon’s razor sharp focus:

      All the Canon’s, all the way back to the Canon D30 deliver that famous soft focus look. Is it because Nikon (and now Sony) use a CCD sensor for focus and Canon uses a CMOS for focus?? If so, change it. if not, get rid of the trademark Canon soft focus once and for all. Nikon is so sharp it bites. Why?

      One other issue is that my cameras tend to pre-focus when the lens is wide open. But less when it is not wide open.

      Clearly, we need critically accurate focus if we are to shoot at f/1.4 (and that is why we spend thousands of dollars on f/1.4 lenses). And it can be done.


      I still shoot Canon, because I like the lens range and because I have over $25,000 invested in Canon equipment, such as my lenses:


      If, like me, you like to shoot wide open, I would recommend you do the following, apart from the obvious “shoot fast, use one focus point, look for non-equivocal focus areas”:

      • Use a tripod.
      • Use flash (or studio strobes).
      • Avoid being confused by the LCD display. On the 7D this shows sharp pictures. The low-level LCD on the 1D makes everything look blurry, especially when you zoom in all the way. Don’t be confused by this. It’s blurry when your PC or Mac shows  blur, not before.
      • Avoid wide open. At f/2.8 and above, it’s much better.
      • Take multiple photos of the same subject: one is bound to be sharp.
      • Live with some out-of-focus shots. As long as the rest are good.
      • Use the brightest possible light. Low light seems to make the camera focus less accurately, or a last differently.
      • Did I mention a tripod?

      So, does the 7D do better? So far I am happier. It is not perfect: a few out of focus pictures so far when I am shooting wide open. But so far my impression is: “significantly better”. The new focus modes help, of course (spot focus in particular).

      So.. stay tuned. And have fun, and do not worry too much about sharp focus.

      Another 7D post

      Canon 7D versus 1Ds Mark 3.

      I was in a hurry so this test is by no means complete, and it is not quite apples versus apples. That said, I just shot a light in my studio with the 1Ds MkIII and with the 7D. Same lens length, effectively:

      7D setup:

      • 35mm f/1.4L lens
      • 3200 ISO, f/5.6, 1/50th sec
      • AWB, standard camera NR settings

      1Ds MkIII setup:

      • 24-70 f/2.8L lens set to 46mm
      • 1600 ISO, f/4, 1/50th sec
      • AWB, standard camera NR settings

      In both cases I took the image into Canon DPP and did not adjustments at all. I saved as 1200 pixels long, and I saved it as an original size crop at 100% JPG quality.

      Large shots, 7D first:



      Now for the real size detail, 7D first – click on each to see them at original size:



      The first thing you see is that the white balance is off on the 1Ds MkIII, and is much better on the 7D.

      Also, the 7D looks sharper. More noise – it is 3200 ISO vs 1600 ISO on the 1Ds – but it is noticeably sharper.

      The other thing to note is that on the 1Ds, I needed several shots to get the camera to focus on the “Opus” name. Several were eway off. The 7D is behving more consistently.

      Note also that it is easy to be fooled: on the display, the 1D image looks soft at all times, while the 7D image looks crisp, sharp, wonderful. But that is partly due to the display.

      Next week I will do some proper controlled tests. But this already shows me they are at te very least comparable.