Focus Modes

photo of head bust print artwork

I’ve written this article for the March 2022 edition of the photo club Viewfinders Newsletter (pages 6-7).

Cameras are equipped with advanced autofocus systems that are often hard to understand. Knowing how to use the autofocus system effectively is essential to get sharp images. A badly-focused, blurry image can ruin a photograph and you cannot fix it in post-processing.

You must keep in mind the fact that autofocus functionality depends on what camera type and model you are using. So you need to learn how your camera’s autofocus is working and practice to master it.  

This article is based on “Autofocus Modes Explained” by Nasim Mansurov (photographylife Oct 2020)

Manual Focus

You can of course disengage the autofocus system and make the focus using your hand and your eye, sometimes helped by peaking systems. In some situations that will be the only way to get a sharp image, for instance sometimes when there’s a window between you and your subject.

How is Autofocus Working ?

For autofocus systems to function properly, they need an area of high contrast. If you use your camera to focus on a white wall with no texture, or a blue sky without any clouds, your autofocus system will try to focus a few times and eventually give up. 

That also means that AF needs light to properly work. If not enough light is reaching the sensor the AF will rapidly struggle to get the focus right, therefore the added value of lenses with a high opening (low F).

Phase Detection AF vs Contrast Detection AF

Phase Detection AF uses a dedicated hardware (an array of microlenses). As light passes through these microlenses, it splits up into a pair of images. The distance between these images is then measured to see how far front or back-focused the subject is.

Contrast Detection AF relies on software algorithms that “probe” through areas of an image for edge detail.

Some sensors (e.g. Canon DUAL AF) are integrating the microlenses removing the need to have a specific sensor for AF.

DSLR vs Mirrorless Autofocus Systems

In a DSLR (mirro down), a part of the light reaches the AF sensor through the semi-translucent mirror.

In live view (mirror up)  the DSLR and the Hybrid cameras are working exactly the same way : The AF is done thanks to the light reaching the main sensor.

Focus Points and AF-Area Modes

Cameras allows photographers to choose which focus points, the little squares in the viewfinder, will be used by the autofocus system. That can be a single one, e.g. for focusing on an eye in a portrait, a block of them or even all of them.

Autofocus Modes

Single AF (AF-S) / Single Area AF / One-Shot AF Mode

The “Single AF” mode (AF-S)  will snap into focus once, and if your subject moves, it won’t reacquire focus even if you continue half-pressing the button. Hence, the focus remains “locked”.

Continuous AF (AF-C) / AI Servo Mode

The AF-C mode will automatically re-adjust focus if you or your subject move. All you need to do is continue half-pressing the shutter button and the autofocus system will automatically track movement and adjust focus.

AF Auto (AF-A) / AI Focus AF Mode

Some cameras also have a mode called “AF Auto” (AF-A) which is basically a hybrid mode that automatically switches between AF-S and AF-C modes. If the camera thinks that the subject is stationary, it switches to AF-S, and if the subject moves, it will automatically switch to AF-C mode. 

Face / Eye / Subject Detection

As our cameras are becoming more and more powerful from a computing point of view, new autofocus modes are appearing. For instance, some cameras are now able to detect a face or even eye in a scene and focus on this element. These capabilities are relying on so-called Artificial Intelligence (AI) / Deep Learning (DP).

Back-Button Focus VS Shutter Focus: Which One is Right For You?!

Often referred as “back-button AF,” this feature lets the user customize the camera so that focusing is performed by pressing a rear button. The shutter button still wakes up the camera with a half-press, and fires the shutter with a full press downward.

By separating AF activation from shutter release, it’s possible in some cases to be more effective with AF, and not have the focus thrown off if something momentarily enters the picture area while you’re shooting.

Advantages of using back-button focus are : Easier to lock focus, Easier timing of shots, Less risk of focus error with moving subjects, Easier over-riding of AF with full-time Manual focus and Easier macro and close-up focusing.

I’m always using it for years. In fact, that’s the first default setting I’m changing when using a new camera.

My suggestion : Give it a try for a few photo sessions and then decide what’s best for you.


Back-Button Autofocus Explained :

Autofocus Modes Explained :

What is Deep Learning AF: how does Canon’s AI-powered autofocus work? :

Exploring Canon’s intelligent autofocus system :

Continue Reading

Adobe Lightroom and Photoshop: New functions that eases post-processing

I’ve written this article for the April 2022 edition of the photo club Viewfinders Newsletter (pages 6-7).

This article is showing you some new functions available in the April 2022 versions of ADOBE Lightroom Classic (LRC) and ADOBE Photoshop (PS), but most of the major photo editing softwares are providing similar or sometimes event better capabilities.

If you’re not using ADOBE, just launch a search on the web for the functions presented here with the name of your software.

Continue Reading

Meet Me

As you maybe know I’m a member of Viewfinders photography club of Brussels.

Each month a member of the club presents itself and his motivations for being a photographer in the club’s newsletter. In January 2021 that was my turn. So just click to discover a little bit who I am and why I taking pictures.

Meet Philippe Clabots – Viewfinders Newsletter Jan 2021 – Page 8

I am Philippe Clabots, from Brussels. I am married and
have two kids and, since mid-2018, one grand-daughter.
I’m a club member since Sept 2012 and an associate
committee member since 2018. I think I’m one of the few
club members who’s native from Brussels.
I used to travel for my job, spending nearly two days a week
in Paris for 10 years, but now I’m, as most of us, a
I’ve always been attracted by photography but my passion
started in 2007-2008. In 2009 I’ve bought my first digital
SLR, a Canon 50D. Since then I’ve moved to full-frame with
a Canon 6D and then a Canon 6D Mark II. I’m buying good
Canon EF lenses for more than 10 years now, from 14mm to
400mm, and I’m not keen to through them away. So my
next move will be one of the Canon full-frame mirrorless
Self-taught, I was formed thanks to readings, Facebook
groups, perseverance, the will to improve myself and
thousands of photos.
I am nevertheless convinced that the essential element of
this progression, or rather initiatory journey, is the
encounters I made during these years. Meetings with photographers, who will recognise themselves, but also,
since 2014, with the public during the exhibitions in which I
have the unceasing pleasure of participating.
Initially centred on opportunistic photography, depending
on my daily life or my travels, I am moving more and more
towards coherent sequences of images with the aim of
telling a story, transmitting an emotion or bearing witness
to a moment in life.
In 2018, we are four photographers to have set up the
« Bruxelles Pixels » collective, joined late 2019 by Hélène, a
famous VF member. We’re currently starting the
preparation of our 4th exhibition that will take place late

Newsletter Viewfinders – Jan 2021 – Page 8

Continue Reading

My Current Workflow : Viewfinders Dec 2020 TTT

J’ai présenté lors de la réunion mensuelle de mon club photo la manière dont je gère mon flux photographique (workflow). Vous pouvez trouver la présentation utilisée ci-dessous en PDF ou la parcourir en ligne (MS Powerpoint Slideshow).

J’avais déjà abordé le sujet sur ce site en 2010 et 2018.

Continue Reading

Méthode Brenizer

La méthode Brenizer permet de dépasser les limites de votre objectif et de votre capteur pour créer une image ayant une profondeur de champ extrêmement courte rappelant les images effectuées avec un appareil moyen/grand format.

J’ai déjà publié deux articles consacrés à la méthode Brenizer en 2016.

En décembre 2018 j’ai eu le plaisir de présenter cette méthode lors d’une réunion de mon club photo Viewfinders.

Il vous suffit de cliquer l’image ci-dessous pour parcourir la présentation faite ce jour là. En espérant que la méthode vous inspire et que vous fassiez quelques essais de celle-ci. N’hésitez à publier ceux-ci en réaction à cet article sur ma page Facebook.

This is a very interesting method to overcome the physical limitations of your lens and create images (especially portraits), with an incredible shallow depth of field.
This technique, made popular by Ryan Brenizer, is based on a panoramic image stitching (in Photoshop and other image processing software) where several images of the subject and around the subject are digitally merged together to create a large file with a wideangle of view.

Viewfinders Newsletter Jan 2019
Continue Reading