PetaPixel

Double Focusing Doesn’t Lead to Sharper Photographs

Have you ever learned that you should autofocus on the same point twice in a row to achieve optimal focusing? Apparently it’s a tip that’s often taught to beginners. Roger Cicala over at LensRentals decided to run some tests to see if this theory has any merit:

[If communication between a camera and a lens is one-way], AF may be more accurate if you ‘double focus’, meaning you push the shutter button halfway down until the AF beeps, then release and push it halfway down again. The idea is that you’re providing the camera a ‘recheck’ of the AF point and a chance to fine tune focus. I was taught to do this when I started photography but I have no idea if it really helps. So I thought we’d look at that [...]

If the two click AF method works better than one click AF, that might give us some indication that the system is open and without feedback. Maybe. If it isn’t I’m not sure it means there is a feedback loop. Maybe AF is as accurate as it gets no matter how many times you pre-focus.

After a battery of tests, Cicala came to the conclusion that “pre-focusing” a camera does absolutely nothing for the accurate focusing of photos.

Autofocus Reality Part 2: 1 versus 2, old versus new (via Gizmodo)


Image credit: Lens by 14zawa


 
  • http://tambnguyen.com/ Tam Nguyen Photography

    Interesting. I’ve never heard of such tip to double focus. Maybe I’m not on the beginner level yet.

  • 9inchnail

    I have NEVER heard of this and I have read a lot of blogs and books when I started out with photography. So this whole article is based on one person giving stupid advice to another person. This is not a commom misconception and not really worth writing an article about.

  • jdm8

    I’ve never heard of it, but I have only had an SLR for five years now, before then, I didn’t give much thought or learning to techniques.

    This may have been valid some time ago, and it might just be an artifact of older focus technologies.

  • http://profile.yahoo.com/TTJPJIMOTWXFW7C24RPHBDTPOQ Swinginjonny

    I’ve never heard it either but I do it all the time. (I have never given it as a tip in a workshop.) It has nothing to do with the camera’s AF accuracy but with my own error as well as the movement of the subject and verifying that I focused on the right spot to start. It has improved the percentage of my shots that are correctly focused by a significant margin.

  • http://twitter.com/jonlurie Jonathan Lurie

    Sounds like an “urban legend”. The time to focus a second time is if the camera or subject moves.

  • http://www.facebook.com/people/Ted-Marlow/100001906709174 Ted Marlow

    what is this af function??? all my cameras except for the phone are MF

  • Roy

    Nor does leaving the lens hood in the reversed position, but judging by the photo over this article, people still do that too.

  • http://www.facebook.com/people/Kathleen-Grace/1504717315 Kathleen Grace

    I have heard this before, actually once from a wedding and portrait photographer that I worked with, and once actually heard it in a photography workshop. It’s not an urban legend in my experience. I have sometimes double-checked my focus not for that reason but to make sure I’ve gotten a small area in focus.

  • Mark Perry

    Uhm.. it’s called refocusing due to potential positional change of subject or camera–I’ve never heard anyone claim this “technique” is some sort of mystical secret function of camera AF systems.

    It’s a bit like claiming that looking both ways twice before crossing the street doesn’t have any noticeable difference on my survival because I wasn’t struck with a car whilst doing it.

  • http://twitter.com/zak Zak Henry

    Or if you zoom. Even though some lenses are supposed to have a fixed focus on zooming, when going from wide to tele the accuracy of the initial focus drops.

  • Mansgame

    I have never heard of this and neither have any other photographers I know. It sounds like something that was made up by Roger Cicala over at LensRentals to try to get visitors to his site. Kind of shameless if you ask me.

  • Bry

    That would be a quick way to get your hood out of the way (say for using a flash) without stowing it. Why?perhaps your bag lacks space for a large piece of plastic? Or perhaps you might need said hood in the next few minutes, which would make stowing and retrieving a hassle?

  • Roy

    Possibly, but I don’t see a flash being used in that photo, nor have I ever seen it in the field where someone had their hood reverse-mounted. Often times there was plenty of stray light though, that would have been blocked if the hood had been used properly.

  • http://twitter.com/darntonviolins Michael Darnton

    I have always done this in the assumption that since I hear the second focus action in the motor (something that’s hard to miss), it must be doing something. One might note that in the article he only covers Canon, so he’s proven his point for Canon, only.

  • http://www.facebook.com/MILLER74MD Mark Miller

    For me, back button focusing has been much better for focusing than any other technique. There are plenty of articles out there instead of me explaining it here.

  • NikonUser

    here is what give you sharper images: f/11

  • NewJerseyGuy

    Keep looking – if you ever spot me outside you’ll find that I a)always keep my hood on on reverse (no matter what lens I’m using) so that it’s not somewhere else when I really need it and b)I can access it right away but ONLY if I need to use it since c)I don’t subscribe to the size matters camp or d)the one that believes that it’s fine to use a hood with a flash.

    Final reason e) if you’re out in a pair of jeans with your camera, a wallet and your car keys – where else could you park the hood?