Canon Autofocus in back light

when I shoot a person in back light I have big problem with the Af. The Canon 5d mark II can't find the focus.
I tried the ST-E2 but it don't send AF- help light when it's light in the room. Can I force the AF-light?

I shoot on free hand on short DOP, so live view or MF is not a good solution

How is it possible to help the AF to find focus on the persons face.

flashlight on the subject.

This has probably less to do with backlight then it has to do the subject is in very low light, relative to the camera. I shoot a lot of concerts where I'm shooting into the lights more often than not and seldom have a problem unless the subject has no light on them, relative to the camera.

windpig wrote in post #12092799
flashlight on the subject.

I need a very powerful flashlight and has to be around 5000k, that would mean some hmi-light. It's very expensive and heavy compared to a 580exii

bohdank wrote in post #12093070
This has probably less to do with backlight then it has to do the subject is in very low light, relative to the camera. I shoot a lot of concerts where I'm shooting into the lights more often than not and seldom have a problem unless the subject has no light on them, relative to the camera.

Yes, the subject is in less light. I use a flash. But the problem is the damn AF.

Use the flash to help your cameras AF to focus easier on the subject, as the flash projects a pattern of dots on whatever is infront of it then the camera can pick that up and use it to better focus on something.

/ Magnus

You're likely to need fill flash in that light anyway.

Maybe I was fussy, the back light is not a flash it's the sun, so there is strong light in the camera.
The AF-assist don't light up in strong sun light even if my main object is dark.

I tryed both ST-e2 and 580EX II but no one of the helps the AF i strong sun light.
I can't see any settings on custom to force the AF-assist.

There is no problem with the ST-e2 in a dark room the the AF-assit ights up and helps the AF.

What metering mode?

It sounds like your subject just doesn't have enough contrast/light where you're attempting to focus. You might try finding an object at the same distance, focusing on it and then composing around your subject...

Magnus3D wrote in post #12093723
Use the flash to help your cameras AF to focus easier on the subject, as the flash projects a pattern of dots on whatever is infront of it then the camera can pick that up and use it to better focus on something.

/ Magnus

He's using the 580 as an OCF flash with the ST-E2 as a trigger. They won't fire the AF assist beam when used OCF.

I must say that I see this issue frequently with my 7D too. If it's a backlit subject, the camera has problems finding anything to lock focus on.

I tryed use only the st-e2 just for AF Assist light, with no flash. I tryed st-e2 + 580ex flash in unbrella. And 580ex II directly on camera. And without anything.

I Shoot a person in front of a really large windowwall with bakclight from the sun.

If I go to a complte dark room there is no problem, in a backlighted room there is huge problem with AF.


Anyone know if Yongnuo st-e2 can force the AF-assit?

As far as I know, it's the camera that asks for AF assist. If the camera finds it's bright, but not enough contrast (since the AF sensor is blinded by the backlight), it will never ask for AF assist.

A few years ago I had read about a wedding photographer that was using a laser pointer that projected a pattern on a brides gown for the camera's AF to lock on to when shooting in low light. I may have seen it here in POTN, but couldn't find it. Not sure this would work or not in the case of having a backlit subject and of course you wouldn't want to blast anyones eyes with it. I never tried it, so I can't comment on if it works or not.

When you look at the person do you see anything other than a silhouette? If you can see detail in the person I would figure the lens should be able to as well. What focus mode are you using (auto or manual select)? Have you tried using a manual focus point and focus on their outline. That is going to be a high contrast area. Then recompose (if required) and take the picture.

I use AF-one shot and I selected the point manually. With my eyes I can see details in the face of the person, if I shoot with flash i can see details of course.

I shoot at short DOF and want to focus on there eyes.


Anyone know if nikon has better AF-system for this kind of situations?