Advanced Photography Tip 2: Back Button Focus
Recap of Tip 1: Shutter Speed
Here’s a quick recap on the previous lesson.
First things first, a little math lesson.
For images to be sharp, your shutter speed needs to be at least double the focal length. What does that mean? For my 50mm lens, I must, at a minimum, shoot with a shutter speed greater than 100. I choose to shoot in Aperture Priority mode (meaning I select the Aperture and the camera automatically chooses a shutter speed). So this means I still need to watch my settings because if my shutter drops below 100, I run the risk of losing sharpness. If it does drop I need to increase or decrease my aperture to adjust. I do this 100% of the time. Even if I have to set my aperture higher. Make sense? So for my 85mm lens, doubled would be 170 or greater. Got it? Good.
So why does this matter? It matters for several reasons; you can have the steadiest of hands, but if your shutter speed doesn’t support the setting, your image will not be sharp. I’ve tried it out. It’s 100% true 100% of the time. Just accept it as fact and move on.
Tip 2: Back Button Focus
Question: How do I get tack sharp images on every shot? Answer: Back Button Focus & Single Point Focus Selection
For years, I was using the traditional Focus and Recompose method, where I would press the shutter halfway down and then recompose. This method means you are physically moving your camera to take a picture – which creates movement from me recomposing and also from me pressing the shutter again. Why is this a good idea? Why did I ever think my images would be sharp that way?
So what is back button focus?
Back button focus using the AF-On button on your camera and instead of pressing the shutter button halfway down you use your thumb to press the AF-On button to focus the image, then press the shutter all the way down to take the picture.
What’s great about back button focus is the focus locks at that focal distance. That means that I only have to press it once and as long as I don’t move my feet I can take multiple images, and the same focal point remains in focus. This becomes more useful when you are doing a group setting and take multiple pictures in a row, but for single portraits, I don’t do this. I manually select my focal point every time, for every frame.
When shooting a portrait, the eyes have to be sharp or else the photo looks soft and blurry. So I compose my shot in my viewfinder then I manually move my focus point right between the eyes. It’s so sharp sometimes I can almost see detail from my reflection in the eyes. You can literally count the eyelashes when you focus this way. It’s amazing!
In Camera Settings
Follow these steps to turn it on:
1) Go into your custom settings menu (the pencil icon)
2) Select A (autofocus)
3) Select A5 (AF Activation)
4) Choose AF-ON only
5) Now instead of pressing the shutter halfway down, you will press the AF-On button
Here are some pictures for those who like visuals (taken with my iPhone).
Things to look out for:
Back to the whole depth of field concept, when shooting wide open only a small portion of the image is sharp, and when shooting at f 1.4 or f 1.8 it is even smaller. So if the person has their head tilted meaning their eyes are on a different level than each other, you run the risk of having one eye sharp and the other not, which can look slightly off. For portraits, both eyes need to be in focus.
Tips to Make Sure Both Eyes Are in Focus
- Increase your aperture to 2.8 or higher, and place your focal point on the bridge of the nose. Take the picture then zoom in as far as you can and make sure both eyes are in focus, and adjust if necessary.
- If you can’t get it sharp on both eyes, always focus on the eye closest to the camera, or just take the picture, or even better just move on and change the pose up. Why take a picture you know isn’t going to work or be used? Waste of time.
Unfortunately, once you notice how sharp your images can be, you won’t ever choose an image again if you miss the focus point. Sad but true. I always look at my pictures when editing and zoom in on the eyes. If for some reason I missed the focus on the eyes, I immediately delete the photo, even if it’s a fantastic photo. It makes such a huge difference to the quality and professionalism of your images.
Setting up Single Area Focus Mode
First you have to flip the icon to select the focal point. It looks like a bracket with a square inside.
Then you can manually see in your viewfinder the red square and use your joystick to move the focus points around.
Here's a picture of what it looks like inside the viewfinder.
Can I Check to See Where My Focal Point Is in Preview?
Yes. I’m glad you asked. You can tell your camera to show you where your focal point when previewing an image. It shows up as a red square. Here are the steps:
- Menu – Playback Menu
- Display Mode – check “Focus Point.”
- Select “done.”
Here are some pictures for those who like visuals.
** Note you have to have your focusing on S for Single Shot for this to work. It will not display on Continuous mode.
In the beginning, I would always zoom in to where the focal point was and see what was in focus and what wasn’t. But now that I know my lens, it isn’t necessary. I know that when I have the red square where I want it to be, everything is in focus.
There is also a Lightroom Plugin, called “Show Focus Points” that you can download for free that will show you in the Library view where your focal point is. This was very useful for me when I was learning how to use back button focus.
You can read more about it here.
Now that you understand the basics it’s time to practice. I spent ALL day one Saturday practicing this method. I’d take a few pictures, look at them in Lightroom, figure out what I did right/wrong, and try again until I had each image correct.
So here’s what I did.
I took a magazine and put it up against a wall. I adjusted my settings to my desired settings (f1.4 or 1.8 and double my focal length) and started practicing selecting my focal point between the eyes of the model on the cover and using my thumb to back button focus.
Then I’d try selecting different areas to see what happened.
After several hours of this, until it became something I could do without thinking, I practiced on a real person. I don’t recommend trying this out on a paying customer. So ask a friend or spouse to model for you. These pictures aren’t meant to be great, they are meant to be practice.
Tell your lovely model to move around and practice adjusting your focal point. This needs to be something you can do quickly and comfortably.
Remember the point of this is to create beautiful images straight out of the camera. So pay attention to your light, your ISO, and everything around you. Do not just take pictures and change the focal point. Make the picture as best you can.
After you are done, go back to your computer and see what worked and what didn’t.
Rinse and repeat until you are 100% confident in your mad new skills.
I’m not kidding when I said I spent all day.
Feel free to post your images in the comments or ask any questions. I’m always on my phone and would love to help out.
Advanced Photography Tip 3 - Spot Metering