Letters to the Editor: Problems with a Camera’s Autofocus

Chris Gampat The Phoblographer Canon 35mm f1.4 L II review product images (2 of 7)ISO 2001-125 sec at f - 2.8

Letters to the Editor is a recurring series where Chris answers specific emails/letters that could benefit more than one photographer, interesting questions or questions that come in often. Have a question? Send it to chrisgampat[at]thephoblographer[dot]com with subject: Letter to the Editor: (Your name here).

Hey folks!

We’re back with another edition of Letters to the Editor. This week’s question comes from Juli who has a problem with the autofocus performance with her camera. Now as many of the more advanced shooters know, this can be affected by a whole number of issues but nailing down the one in particular can be tough.

Here’s Juli’s letter.

Hi Chris:

I see so many more images that are so much sharper than my own, I mean razor-tack sharp. Most of mine are disappointingly soft. I’ve attached a couple.

I wondered if some of the sharpness I see in others’ images come from HDR, but I doubt they all do. I’ve tried to shoot at high shutter speeds, try to use as low an ISO as possible to reduce noise, narrowed the aperture to increase depth of field, use “L” series Canon lenses, and all mostly to no avail.

I am reading up on information from Canon about focusing (I have a 7D) to see if I can use other focus modes to get better results.


– Juli



Hi Juli,

Chris Gampat The Phoblographer Canon 7D MK II review product images (8 of 10)ISO 4001-25 sec at f - 4.0

What you’re experiencing is a very typical case of a problem with beginners. Before I go on, I’m going to come flat out and tell you that you don’t need Canon L glass to get sharp images.

In the one image you sent me, you’re experiencing misfocusing: the camera focused on the guy in the front of the audience instead of the children. There are a number of reasons that could have caused this and from the situation you’re in, I’m going to do my best to explain:

  • You probably didn’t manually select a specific focusing point. If you’re telling the camera to use all the autofocusing points then the camera will focus on what it thinks you want in focus and that may not be what you actually want to have in focus at all. This needs to be a two way communication process between you and the camera. So you’ll probably want to press the back * button and then the M fn. button on the front then scroll through using the back camera dial or the front shutter dial. Keep scrolling until you choose the setting with the focusing point and a dot in the middle.After this, you should configure the back joystick on the camera to be able to move the focusing points around when you shift it. This way when you’re shooting, you can tell the camera where you specifically want it to focus.
  • You shot this image with a 24-106mm f4 L IS at 1/80th and ISO 3200. Yes, the lens has image stabilization, but that’s not going to help here because of the reciprocal rule of shutter speeds.Now, follow along:Chris Gampat The Phoblographer Canon 7D MK II review images extras (1 of 31)ISO 16001-60 sec at f - 1.4The reciprocal rule of shutter speeds means that you shouldn’t shoot at a shutter speed less than the reciprocal of your focal length in order to get a perfectly stable, camera-shake free photo. Since you’re using the Canon 7D, every focal length you shoot with means that you need to multiply the number by 1.6x. That means you need to be shooting at around 1/168th. In other words, go for 1/200th of a second. Then you’ll need to raise the ISO levels up enough and open the aperture.Image stabilization is designed to help with this, but you generally shouldn’t use it as a crutch.
  • One other problem that can be occurring: there could be a problem with the calibration of the focusing. The 24-105mm f4 L IS is notorious for having this problem, it used to be my bread and butter lens until that drove me to frustration. It’s best to send the camera and lens to Canon telling them about this problem and they’ll fix it for you hopefully.

Other tips on getting sharper images:

  • I will always tell everyone to use a flash, but I understand that not everyone knows how to do it properly, so don’t keep that in mind until you want to become more advanced.
  • When you’re shooting, don’t use the LCD screen. Use the viewfinder and calibrate the diopter for your eyes. It’s based on your eyesight. Just look through until the text in the viewfinder looks and appears clear to you. Using the LCD screen makes you less stable.Chris Gampat The Phoblographer Canon 7D MK II review images extras (7 of 31)ISO 2001-2000 sec at f - 1.4Look at it like this: take a 50lb weight and hold it with your arm outstretched. Chances are, your arm is going to be super shaky. Then pull the weight in closer to your body and what you’ll see is that you’ve got more stability. The same idea applies to using a camera. Tuck your elbows into your chest as best as you can.
  • I generally hold my breath when I shoot and release the shutter at the top of it because that’s just what works for me. Others exhale, let all the air out and then shoot. To each their own, whatever works. Try both methods.
  • Manually select a focusing point. Want the camera to focus on a person’s eye, then move the point onto the eye.

As a matter of ISOs and HDR, HDR images only look sharper because of the toning. When you shoot RAW and edit, you’ll begin to understand this. ISO 6400 on the 7D has an output that can easily be fixed with software like Adobe Lightroom using the noise reduction too. But in general, it’s very tough to get super sharp images at higher ISO settings.

I hope this helps. I often tell people of all walks to not worry about gear unless they genuinely have a need for it. If you don’t need a flash then don’t get one. If you don’t need a 600mm lens then don’t spent the stupid amounts of money on it. Instead, just develop your skillset. In the end, that’s what will help you get the images.

  • Steve Solomon
    Unknown Unknown Unknown Unknown

    Excellent article! If you use a good tripod or at the very least, a monopod, along with AF calibration and proper selection of focus point, your number of sharp images should rise dramatically! The PD AF “calibration issue” with some DSLR/lenses is precisely what made me find mirrorless (FujiFilm in particular), as with any mirrorless system, AF is acquired directly off the sensor, thus negating the need for calibration. Either the system is in optimum focus or it’s not. No need for manual calibration! (If the latter is true, then you know there’s a physical problem, rather than a front/back focus issue.)
    Good luck!

  • Unknown Unknown Unknown Unknown

    I used to own the Canon 7D and loved that camera! I combined it with the Canon EF-S 17-55mm f2.8 and I shot a lot of newspaper gigs including local theater with that lens. Manual focus is key in low light (and in all situations) just as described here in this article. Back in college(in the 90’s) they didn’t have IS lenses, so we learned how to hold ourselves steady and the camera bodies steady. You kinda hold/grip it towards you and out at the same time, with your feet out, using yourself like a tripod.

    I then invested in the Canon 70-200mm f2.8 L non IS lens. I never shoot at less than 1/200 sec with this lens and it was well worth getting. Not as heavy as the IS version, and not quite as pricey). Keep shooting and practicing. Good luck!

  • eastbayjay
    Unknown Unknown Unknown Unknown

    This is great! I can definitely use sharper images too.

  • 9MW
    Unknown Unknown Unknown Unknown

    One possible reason was neglected — uncalibrated phase detection AF. This possibility is inherent in all DSLRs (and 35mm film SLRs as well). The PD sensor is located somewhere in the camera body other than the sensor (or film) plane. Also it sends data back to the the AF motor in the lens semi-open loop. This is my crude understanding of the process but it is the reason higher end Nikon and Canon DSLRs have a feature called “AF fine tune” or something similar.

    It is simple to test for this problem by comparing AF results with and without Live View.since in Live View the contrast detection AF sensor is built right in to the sensor and functions closed loop. Use a tripod, a subject with good contrast, widest aperture possible (narrow DoF). Just compare two shots. If the the through the viewfinder focus is softer than using LV then that’s your problem. If they are the same the problem lies elsewhere.

    When ever you have a deep DoF situation such as wide angle lens and landscape it will be a mostly a non-issue. However, the situation above (low ISO & fast shutter) suggests a wide aperture and narrow DoF which where the problem is most likely to be observed.

    PS: Expensive lenses are not immune — of my own lenses, the worst case was a 50mm f/1.4 – generally considered a very top-notch lens.

    • ChrisGampat
      Unknown Unknown Unknown Unknown

      It’s said in simpler terms

      • 9MW
        Unknown Unknown Unknown Unknown

        No doubt. I make no claim to being a great communicator. Nonetheless, it is a very common situation when DoF is narrow and can lead to great frustration as even perfect technique and great equipment won’t cure the problem if present. The only cure other than “fine tune” is to use Live View.

        It takes only a few minutes to do the LiveView vs non-LiveView test. That will either confirm the problem or eliminate one variable in the equation.