KYC #3: Why doesn’t my Camera Auto Focus & Focus Preset/Memory

Todays blog post covers two topics. One for people just starting  off with photography and the second for the more experienced ones. So let’s  start with the basics first and then look at advanced ways of utilizing your lens memory (ya the lens has some memory functions as well).

Basics : Why Does My Camera Not Focus:

Lets start with some scenarios when your camera refuses to focus/click. Do any of them sound familiar?

  1. The lens just keeps making a whizzing sound and does not click?
  2. You tried to click the sky and the camera refused to click?
  3. A scene where you had a small twig on which a bird is predicted to perch and your camera refused to focus on it?
  4. You were taking a close up of a vibrant flower and the camera acted weird and did not allow you to click?

The first 3 items in the above list fall under the basics of how the camera autofocuses. It autofocuses based on the contrast in the scene and without contrast it struggles. What you can do in such situations is to help the camera by trying to find a more contrasty subject in the same plane of vision or help by manually assisting the camera by rotating the focus ring.

For e.g. Imagine if you are planning to catch a bird on a thin twig (birds repeat their perches). Chances are that your camera will struggle to auto-focus. Now, try focussing first on the base of the twig where it is connected to the thicker stem/branch or the ground. Doing so, helps the camera find the area better/quicker.

The 4th point essentially means that you have a problem of being too close to the subject. If you check, each lens contains of an MFD value which stands for Minimum Focussing Distance of that lens. If the subject is closer than that, the camera will not be able to acquire focus.

Keep in mind that if you know why the camera isn’t focussing, the solution is very easy. So always try to get the ‘why’ cleared.

While I am at this topic, lets take a look at a very interesting feature of memory recall that some lenses come with

Advanced : The Focus Preset/Memory:

Both Canon and Nikon offer this feature in the high-end lenses. Lets take a look

Canon : Ever noticed that serrated ring in front of the focusing ring in your big telephoto lens? Take a look at the image below to know what I’m talking about

Now this is a pretty nifty tool to have for cases where you want to pre-focus at a particular distance. Take for e.g. a Perch that a bird repeats every few minutes. Assuming that is more than 1 such perch, what you could do is

  • Focus the camera on the perch first.
  • Make sure the focus preset switch on the side of your lens is set to ‘On’ or ‘On with Sound’
  • Then, press that SET button.

With this, the camera now has memorized the distance. You can go about clicking other birds (while standing/sitting at the same spot of-course) and when a bird comes back to this perch, all that you need to do is turn that Focus Preset Ring a bit and the camera will snap back to the preset focus distance.

Low Light, Low Contrast, Prefocus

Nikon : Take a look at the following images. Do you see the Memory Set button and the Memory Recall Switch?

These two controls need to be used together to help the lens memorize a focus point. So lets take the same case as earlier.

  • Focus the camera on the perch first.
  • Make sure the Memory-Recall switch on the side of your lens is set on it.
  • Then, press that Memory SET button.

With this, the camera now has memorized the distance. You can go about clicking other birds (while standing/sitting at the same spot of-course) and when a bird comes back to this perch, all that you need to do is press any of the Focus buttons on the front-collar of the lens

Believe me, its very helpful in places where that perch is tiny and difficult to focus on due to lack of contrast.

Low Light, Low Contrast, Prefocus

Low Light, Low Contrast, Prefocus

So all you telephoto guys who’ve never used that focus preset ring, go and give it a whirl.

More about those focus buttons on the lens and focussing in future blogs as they can function differently under some scenarios

Hope todays KYC helped you. As always, please keep sharing and commenting.If you like what you read, please do consider Subscribing to my weekly blogs here : Subscribe

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This entry was posted in Advanced Photography Tips, KYC, Tutorials and tagged , , , , , , , , , .

4 Comments

  1. Saju Devassy June 13, 2017 at 3:52 am #

    Thanks for covering my topics one by one, guruji !

  2. Surya June 23, 2017 at 7:27 am #

    Very nice informative blog..

  3. Vijay Mandave June 26, 2017 at 7:53 am #

    Very informative Rahul. Never know that lens also has such a wonderful features.

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