Back Button Focus

It was in the autumn in the high alpine regions of the Colorado Rockies when Mount Evans Road finally opened last year and I was able to make the drive to the summit. I had high hopes of seeing abundant wildlife, based on the reports of my competitors who had made the trip in previous years.

I had gotten an early start and made the first toll gate around sunrise, but I was a bit surprised at how long it took me to get up to Summit Lake. I had seen quite a few cars go past while I was paying my fee and I feared that the summit parking lot was going to be full. So I pulled into Summit Lake parking lot and spotted a ranger. I asked him how long it would take me to hike from there to the summit, and whether or not I would see any wildlife. He advised me to just drive the last few miles, that the hike would take hours and rain was coming in. He also told me the bighorns and the mountain goats would be on the summit.

So I jumped back in my truck and headed for the summit, where I parked and gathered up my gear. I looked for the trailhead and was glad to see only 1/4 of a mile to the summit. I looked diligently as I neared the summit for the animals only to be disappointed, nothing in sight. As I rounded a turn in the trail the summit facilities came into view below and much to my surprise, it was surrounded by animals just walking around the parking lot area, right along with the people. Well, there was no way I was going to have come that far without touching the summit plaque, so I just walked a bit further and made sure that m feet were planted on the summit of a 14er. Of course it didn’t count as a climb from only a 1/4 mile away, but I got the feel of 14k feet plus just the same.

Went back down to the facilities where I took about one million pictures of the goats and marmots standing around … the only problem there was making sure there were no people in the background to give away the ridiculous proximity of people and animals. Clouds rolled in and I really wasn’t too keen about driving down the highway in heavy rain, so I packed up and headed back down.

On my way back down I noticed a gathering of vehicles on the side of the road so I looked and saw a huge herd of both bighorns and mountain goats on both sides of the road. They were a bit far off for my 200mm lens, but I thought I’d get a few shots anyway… when again, much to my surprise, a baby bighorn started running towards me. I pushed down the shutter button and held it, getting probably 20 images before the little guy turned aside.

This is where the point of the story comes in… Of course the camera focused the first time I pushed the button and every image after that was out of focus 🙁 I wasn’t expecting such action, so I had my Canon 70D on one shot mode. It was after experiencing the disappointment of so many failed images that I got to thinking maybe I should learn back button focus. I had heard that it was the best way to photograph unpredictable sports and wildlife subjects.

So naturally I have managed to procrastinate and delay implementing it for another six months… but for some reason, last night was the night to take the plunge. So I got on the internet and looked up how to do that with m 70D. I found a number of tutorials describing how to accomplish the camera settings and buttons, but nothing about what to actually do when shooting and when to use it!

The first thing I learned is that you have to go into the most obscure custom functions and set the shutter button for exposure only. Having the shutter button focus turned on conflicts with the operation of the back focus button, so you will need to consult your camera manual to determine how to do that.

Once that is done, look for the back focus button. On the newer Canon DSLR’s, it is called AF-On. To operate in back button mode, it is advantageous to put the focus mode in continuous mode, or AI Servo on Canon cameras. With a still subject you then depress the back button to focus and let go of the button. The camera will stay focused at that distance until you click the back button again. You can recompose as many times as you like before  focusing again.

Now here’s the really good part. If the subject goes into motion, you can just click the back button and hold it down while continuing to track the subject with the camera. As long as you hold the button down the camera will operate in continuous mode, refocusing constantly while you concentrate on composition and getting the pictures! So with one simple and easy to use button, you can quickly operate the camera in all the focusing modes that you might need. Separating focus and exposure also allows you to get more accurate exposure metering than having both done at the same time with the shutter button. Using the shutter button half push to lock focus and exposure only works if you don’t drastically recompose. With the back button focus, the shutter button activates the exposure on the new composition.

So, as you can see if I had been using the back button for the baby sheep I could have pressed and held while the animal was approaching and I would have had many sharply focused images instead of just one.

Steve Krull is a prolific sports and nature photographer selling prints and stock images online as S.W. Krull Imaging at various sites and agencies. Click this link to view all the products and services offered by Steve Krull and S. W. Krull Imaging. Additional services include, wedding photography, portraiture and model portfolios, and event photography. Additional products include fine art stock imagery, prints and gift items