Blurryeyed Loc: NC Mountains.

These guys are probably correct, your camera is not finding focus and the shutter will not release.

amfoto1 Loc: San Jose, Calif. USA

Probably the camera has a "feature" where it won't release the shutter until focus has been achieved. BIF are notoriously difficult to acquire and maintain focus upon. It will likely be even harder with a relatively slow focusing lens like your Tamron.

FYI: The ISO settings are related to exposure and have nothing at all to do with autofocus. Aperture Priority (Av) auto exposure mode also isn't directly rated to auto focus (except see below about using BBF and sometimes using fully manual exposure instead). Further, for fast moving subjects some people prefer to use a Shutter Priority (Tv) auto exposure mode, so that you can be sure the camera is using a shutter speed fast enough to freeze subject movement (probably 1/1000 minimum... maybe even 1/2000).

However, put aside the exposure mode and settings for now. They're mostly a separate subject from focus. Let's just talk about about auto focus instead.

To optimize your chances of getting some in-focus shots....

First check your user manual if there is option to turn off "focus lock" feature. I suspect there is no way to turn this off when the camera is set to One Shot autofocus mode. (This "focus lock" can be a useful feature for some subjects, such as macro where a "trap focus" technique can be used. Google it, if interested.) Someone else mentioned "Focus Priority", which is something that can be adjusted on some Canon cameras, but I don't think so on the SL1.

Switch your camera to "AI Servo" focus mode and that should disable the focus lock feature automatically. But more importantly, this is the continuous method of focusing that moving subjects like BIF require. You cannot use One Shot focus mode with moving subjects because once focus is achieved in One Shot the AF system stops and "locks", while the active subject moves out of focus. Fast moving subjects like BIF will instantly be out of focus, while you wait for the camera to "unlock" focus and restart the whole process... only to achieve, lock and then lose focus once again.

And definitely don't use AI Focus mode. (That really isn't a focus mode at all... set to AI Focus the camera is supposed to determine whether or not the subject is moving, then switch to use the correct mode: either One Shot for stationary subjects or AI Servo for moving subjects. In my experiments with AI Focus it causes a slight delay, doesn't always choose the correct mode and often failed to switch modes if the subjects stopped or started moving... all of which would be disastrous trying to shoot BIF. I stopped using it years ago and immediately started to get more in focus shots.)

For moving subjects, you must use AI Servo focus mode.

Further, the 9-point AF system in your camera is a fairly simple one. Switch it to use only a single AF point and then select the center point. That one point is higher sensitivity than the other eight. The center one is the only "dual axis" type of point in your camera, which helps it acquire focus faster and do a better job staying locked onto the subject. Using a single point will mean more work for you... because you'll need to keep the AF point right on the subject where you want the camera and lens to focus. But this the best way to use your particular camera for BIF.

You also might want to consider using "Back Button Focusing" (BBF). This is popular with sports and wildlife photographers, in particular. It basically removes the focus start function from the shutter release button half press and reassigns it to one of the buttons on the back of the camera. Doing this allows you to leave the camera in AI Servo mode all the time and use it for both moving and stationary subjects.

To set up BBF on your camera go into the menu and navigate to the Custom Functions. Scroll down to C.Fn-6 Shutter/AE Lock. Enter that and change it to option #3, AE/AF No AE lock. Once this is done the * button (AE Lock) under your right thumb on the back of the camera will act to start and stop autofocus. AF will no longer be linked to the half press of the shutter release button. Press * to start AF, keep pressing the button as long as you want AF to continue running and lift off the button when you want to stop AF from running.

BBF has several benefits. It puts you more in charge of when and where the AF works. It let's you start the AF and achieve focus first, while tracking a moving subject, then press the shutter release one or more times to take shots. Your not "restarting" AF every time you press the shutter release to take a shot. It let's you leave the camera in AI Servo mode and use that with both moving and stationary subjects. For example, without BBF you cannot "focus and recompose" a stationary subject with the camera set to AI Servo. You have to change to One Shot mode. But with BBF you can leave the camera in AI Servo and focus on the subject and once that's achieved lift off the * button to "lock" focus while recomposing. Leaving the camera in AI Servo mode also is helpful with many modern zoom lenses. A lot of them are "varifocal" designs, which means they don't maintain focus when zoomed. If you're using AI Servo the camera and lens will automatically correct any loss of focus that occurs when you change the zoom's focal length. Not having to stop to change focus modes is another bonus and makes for fewer missed shots.

One drawback of the above setup for BBF is that you no longer have the AE Lock function at the * button. Maybe you don't use it anyway. But if you do occasionally need it, you can go into the menu and change C.Fn-6 back to the default or option #1 (where half press of the shutter release causes AE Lock). However, I've always found it easier to simply switch to fully manual exposure mode and dial in the settings myself, rather than using AE Lock. That accomplishes exactly the same thing. If you instead change the custom function to option #1, don't forget to change it back. It can cause exposure errors to have AE Lock working all the time unless you're aware of it and work around it.

It can take a couple days to get accustomed to using BBF... but most people continue to use it once they see how much help it can be. Using various Canon cameras for over twenty years, I always have them set to BBF and leave them in AI Servo (I only change these settings on the rare occasions when I loan a camera to a friend who doesn't know how to use BBF and doesn't want to learn it.)

Finally, don't beat yourself up too much over problems getting BIF shots. It's one of the most difficult subjects to shoot. It's not uncommon for experienced shooters to take dozens or even hundreds of photos to get one or two they like. It's a little easier with premium gear that has extremely fast focus, such as the Canon 7D Mark II or 1DX Mark III DSLRs or the R5 or R6 mirrorless (those two mirrorless cameras' AF system is particularly advanced and helpful for this type of subject). Lenses with larger apertures (f/2.8) and ultrasonic focus motors are also faster to achieve focus and better maintaining focus while tracking fast moving subjects. But, of course, all these things cost money! In some cases.... a LOT of money!

I hope this helps!

pego101

The BIF works great here on my nikon

Blurryeyed Loc: NC Mountains.

LOL.... Works even better on my R5.

pego101

Wasn't BIF the guy in back to the future?

Nigel7 Loc: Worcestershire. UK.

When I want to travel light I take my EOS70D with the Tamron 18 - 270 which you mention. It is a good "one lens covers all normal focal lengths" lens but the focus is dreadfully slow compared with my Canon L lenses. IMHO not the lens for BIF.

bingonut Loc: Cape Cod

Thanks jeep_daddy for your help. Will try shutter priority.

reverand

The shutter should fire once the focus is locked in. However, if you're pointing the camera to the sky, there's nothing to focus on, so the shutter can't fire. If you need to take a picture of the sky, switch to manual, and turn the focus dial to infinity.