Focusing beyond f/5.6 with the 7D

[Romy Ocon]

One nice feature of the 7D is the ability to auto-focus in Live View (contrast detect AF or CDAF) using lens combos with apertures of f/8 - f/11.


Note - CDAF at f/8 to f/11 might not work with some third party lenses when using wired TCs. In this case, one needs to use an unwired TC or just tape the usual pins of reporting TCs.


CDAF is slower than conventional autofocus (phase-detect AF), but it's much faster and more accurate than manual focus. MF is tough to execute even with Live View zoom because the slightest touch on the focusing ring of a long birding lens will make the image in the LCD jump around.

This feature of the camera has added a new shooting technique to my capture workflow, and this is specially effective for non-active birds when using lens combos with apertures of f/8-f/11.

1. Set the AF to Live Mode (contrast-detect method in Live View).

2. If the subject is a good distance away (which is often the case, otherwise a TC won't be needed in the first place), set the focus limiter of the lens, if so equipped, to the farther setting. This will lessen the hunting during CDAF operation.

3. Point the combo to the subject and frame the the bird using the viewfinder (VF), manually adjust focus so the bird is more or less recognizable or nearly sharp in the VF.

4. Press the "START-STOP" button (to the right of the VF) to activate still image Live View. Place the focus rectangle over the subject and either half-press the shutter button or press the AF-on button to focus using CDAF. When the focus locks, one can either take the photo using a remote switch, or disengage from Live View and shoot the conventional way, using the VF and the shutter button.

This technique sounds somewhat complicated, but it's actually very easy to execute with little practice. Here's a sample from this morning's practice session, not presented for aesthetics of course, but to illustrate the technique.



Zebra Dove (Geopelia striata, resident)
Shooting info - Paranaque City, March 08, 2010, 7D + 500 f4 IS + Canon 2x TC, 475B/3421 support, 1000 mm, f/11, ISO 200, 1/320 sec, manual exposure in available light, contrast detect AF in Live View, 20.7 m distance, cropped/processed/resized to 1500x1000.






Uncropped, resized full frame





Processed 100% crop

[Toto Gamboa]

Hi Mastah, I got a question on this feature in 7D. After making a shot, does the cam resets back to full frame view (1x) in your LCD from let's say 5X or 10X view? In the 50D, I find this feature very handy when using my 2X TC but everytime I use it, it resets back to 1X from 5X or 10X view which makes it cumbersome if you quickly attempt to make another shot.

[Romy Ocon]

Yes, Toto.... the view resets to 1x after the shot, and this is true (IIRC) for all EOS DSLRs with LV that I've used.

[Edu Lorenzo Jr]

Nice feature mastah, I too have a question: (actually two)

AF on live view is also available on the Nikon D300s and it also uses contrast detection versus phase detection during non-live view shooting.
Question is, have you tried it while shooting video? I tried it on the D300s and the result was that the camera recorded the lens motor's whirrrrrrrrrrrrrrrrr... I guess it is time to buy an external mic?

Second question:
Does live view shooting with Canon keep the mirror up during the whole time you are in live view? My concern is shooting a backlit subject or straight up to white clouds.. would this "burn" the sensor faster?

[Romy Ocon]

Edu, the sound of CDAF will be picked up even by an external mic. Worse, Canon's implementation of CDAF often entails varying the brightness of the scene to enhance contrast, and that will ruin the footage. So I use CDAF before recording and not during. Not sure if the varying scene brightness happens in the D300s too.

AFAIK, all video-capable DSLRs raise the mirror during LV or video recording. I wouldn't shoot a video of the sun because that might fry the sensor. As regards bright skies (but no direct look at the sun), I'd guess it's safe. Of course, intensive use of video will result into the earlier onset of hot or dead pixels compared to shooting stills alone. Canon/Nikon service are supposed to be able to map out dead pixels though, so this should not be a major concern.

[Clemn A. Macasiano Jr.]

Hi Romy, does this apply to 5DmkII ? Thanks

[Romy Ocon]

Mar 9, 2010 6:24:25 GMT Clemn A. Macasiano Jr. said:

Hi Romy, does this apply to 5DmkII ? Thanks

IIRC, the 5D2's CDAF works only with f/5.6 or brighter lenses. You can use a non-reporting or wired TC to get CDAF at f/8-f/11 with the 5D2.

[Edu Lorenzo Jr]

thanks for the response mastah,

The varying brightness is really a pain. I was so happy when I saw the LV-AF and wanted to immediately take it to its limits. I tried pulling back to 80(from 400) with my hand slowly while holding the focus button and all I recorded was the motor whining and the image transforming from blurred to absolutely unidentifiable.

As for the hot pixels, one blog I read said that those are sometimes caused by shooting in the heat (and directly at glaring objects like welding) but disappear by their own once the camera is shot at colder temperature. I am not sure on how true this is, but I guess it means that it should not really be that much of a concern.

[Toto Gamboa]

Thanks for the reply Mastah! One thing more, how I wish I can do the focusing using a remote shutter during CDAF. Is there a remote control that allows this?

I wish this is possible as everytime i CDAF, i have to press the AF-ON button during the focusing. With the shake my hand is generating, sometimes you cnat discern whether the subject is focused sharply. Only when the shake is gone that you know if focused is well achieved or not, then the focusing cycle goes again.

Doing this via remote might solve the problem.

[Romy Ocon]

Yes, CDAF is possible with a remote switch on the 7D, but not on the 40D and 5D2.

Mar 10, 2010 5:27:33 GMT Toto Gamboa said:

Thanks for the reply Mastah! One thing more, how I wish I can do the focusing using a remote shutter during CDAF. Is there a remote control that allows this?

I wish this is possible as everytime i CDAF, i have to press the AF-ON button during the focusing. With the shake my hand is generating, sometimes you cnat discern whether the subject is focused sharply. Only when the shake is gone that you know if focused is well achieved or not, then the focusing cycle goes again.

Doing this via remote might solve the problem.

[Toto Gamboa]

Mar 10, 2010 5:48:07 GMT Romy Ocon said:

Yes, CDAF is possible with a remote switch on the 7D, but not on the 40D and 5D2.

Mar 10, 2010 5:27:33 GMT Toto Gamboa said:

Thanks for the reply Mastah! One thing more, how I wish I can do the focusing using a remote shutter during CDAF. Is there a remote control that allows this?

I wish this is possible as everytime i CDAF, i have to press the AF-ON button during the focusing. With the shake my hand is generating, sometimes you cnat discern whether the subject is focused sharply. Only when the shake is gone that you know if focused is well achieved or not, then the focusing cycle goes again.

Doing this via remote might solve the problem.

hmmm another pogi points for the 7D What remote shutter do you use mastah?

[Romy Ocon]

Mar 10, 2010 7:44:11 GMT Toto Gamboa said:

hmmm another pogi points for the 7D What remote shutter do you use mastah?

It's the wired one - RS 80N3, Toto.

[Toto Gamboa]

Mar 10, 2010 7:52:07 GMT Romy Ocon said:

Mar 10, 2010 7:44:11 GMT Toto Gamboa said:

hmmm another pogi points for the 7D What remote shutter do you use mastah?

It's the wired one - RS 80N3, Toto.

Thanks Mastah.

[Clemn A. Macasiano Jr.]

Thanks Romy .... Btw, I tried it with my 300 mm 2.8L IS with and with out TC on 5DmkII and it worked. I even tried stacking TC2x and TC1.4x together without any tape and it's still worked.

At first I encountered a problem ... When I change the Live-View-Mode from Quick mode to Live View .. then it was resolve.

I tried both RS-80N3 and TC-80N3 shutter cable ... no difference. Both cable worked.

How I wish it will focus when you half press the shutter cable. Pressing the AF button on the body exaggerate the vibration. But I'm sure I.S. will alleviate the issue.

Thanks for the technical insight.

Mar 9, 2010 10:45:24 GMT Romy Ocon said:

Mar 9, 2010 6:24:25 GMT Clemn A. Macasiano Jr. said:

Hi Romy, does this apply to 5DmkII ? Thanks

IIRC, the 5D2's CDAF works only with f/5.6 or brighter lenses. You can use a non-reporting or wired TC to get CDAF at f/8-f/11 with the 5D2.

[Conrad Arellano]

Thanks Romy for this truly excellent tip. I just got my 7D and tested the setup with the canon 1.4x TC and the 400mm f5.6 and the combo truly works.

I even tried it with my phottix cleon II wireless/cord remote and it focuses when you half press the shutter button in both wireless and cord function. The 7D will not auto-focus if you disable the 7D shutter button and map it on the AF-On button.

No more taping the pins and auto focus is still quick for me. Thanks again