Fire on Focus Confirm

I recently acquired a new toy: EF 100mm F2.8 L macro lens, and have had a few weeks to play with it. (I may share some picture if anything worthwhile pops out of the postprocessing.)

One thing I noticed was that it is very difficult to handhold macro shots at 1:1, even with a reasonable exposure time. One thing that would make life a little easier is if that camera could be set up to expose when the AF confirmation trips. I did not see any way of doing this on the 7D, but I was wondering if it is possible.

What I would like, is to put the lens in MF mode, maybe hold down the shutter button, but the camera will not take the picture until AF confirmation happens. It seems to operate this way in AF mode, I'm just wondering if it can bty done an MF mode as well.

Thanks for any advice here.

-joe

Joe,

On my camera (T2i) can use the exposure lock button to do just that. Depending on how you have your AF/AE options set in your custom menu (again, for me) the AE occurs when the AF hits. The same is true in MF when it beeps. Click hold the exposure lock button (on my camera it's the one that's the zoom-out button for live view and image review). There's an asterisk in the viewfinder to let you know it's locked. That'll hold the exposure for successive shots unless you take your finger all the way off the shutter. That seems to force it to a new exposure.

Not sure how to do it with an external trigger when it'll reset the exposure or not. I'm sure a little experimentation will show you how it works. In my office I point at a dark corner of my desk then the bright window and can clearly tell when the new or old exposure is being used.

Good luck

edit: ok, you said expose not exposure - my bad. let me investigate.

Joe,

Any reason you're not using AF then? If you're relying on the focus dot telling you it's got something in-focus I don't see much of a difference.

Joe

I am not sure the 7D would have a function to do what you are asking. I will be surprised if it does.

I think you are going backwards as far as getting macro shot in focus. If you want to use the confirmation light to determine when AF is achieved when using MF, it will be less accurate than if you use the AF engaged. You can get sharp pictures with the 100mm F2.8L IS at 1:1 and the lens is very capable of this (provided you are using the IS and your lens and camera’s AF system are playing well together). However the very best way to get sharp macro pictures is to use a tripod, in live view focus at 10x magnification, and also use a quick release.

Rick

Magic Lantern gives you the ability to capture a shot when focus confirmation occurs, but it isn't available on the 7D. I tried it out on my 50D, and while the feature worked, it was still a bit tricky to use (in my personal experience). From the Magic Lantern manual,

Quote:

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"Trap Focus: ON/OFF Takes a picture when the subject comes into focus. You need to set the to Manual focus (MF) and hold the shutter pressed halfway.

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http://magiclantern.wikia.com/wiki/U...ide#trap-focus

Congrats on the lens! It's not my most used, but by far my favorite! (portraits, mostly) When using hand held, try AI Servo if auto focusing. The 7D and 1D mkIV have the "Intelligent Macro Tracking" feature when the body detects a macro lens is attached.

Intelligent Macro Tracking (7D & 1D Mark IV only)

A very useful feature of the EOS 7D and 1D Mark IV cameras is its Intelligent Macro Tracking function. This helps reduce blur during macro shooting by recognizing when a Canon macro lens is attached and automatically adjusting the AI Servo sampling frequency when the lens is focused on a close-up subject. The AI Servo adjustment accounts for camera movement forward and back, a typical occurrence when moving in close for a macro shot as photographers rock back and forth, or a flower blows in the wind.

No special settings or Custom Functions need to be enabled on the EOS 7D and 1D Mark IV to take advantage of this; you only need to have the camera set to AI Servo AF mode, and be focused upon a small object at 1/3 life-size (0.3x magnification) or greater with a Canon Macro lens having an Ultrasonic focusing motor. With all other Canon lenses, or with a macro lens at magnifications less than 0.3x, AI Servo AF reverts to ordinary focus tracking operation.


-Chuck Westfall

http://www.ronmartblog.com/2011/08/understanding-canons-hybrid-is-and.html

Thanks a lot for the feedback, everyone. I guess I was looking for trap focus, but since I cannot run Magic Lantern, that is not an option. Oh well.

What I was trying to do was to use AF, but with my body serving as the focus motor, so that I could set the magnification to what I wanted, and move the camera until the scene was in focus, and then have the cameral automatically trigger at that right time.

I will try Servo mode. I generally keep the camera set to 1-shot, so this might help.

Joe, if you were to use a split-prism viewfinder window you could do as you suggest then when you think you're near focus only pull the trigger for AF at that point. It should be darned close to the mag you're looking for.

7D has ability to set priority in AI Servo mode for shutter release to AF, Tracking, release. C Fn III 2. The default setting of 0 is AF priority/Tracking priority.