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hanalwala Jun 14, 2011 7:46 AM

Flamingo's in flight...
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In Dubai we have a place called Ras Al Khor where we have mangroves and where we can see flamingo's year round. I went there this evening to take some pictures of the flamingo's. Now I have two problems to discuss:

a). My camera is Canon 60D and I used my Canon 500mm f4.0L USM (non IS)lens and also fixed TC1.4x on it to get close ups. As soon as I fixed the TC 1.4x the auto focus function stopped. (the click sound and the light stopped). I removed the TC and the auto focus started.

I then took my Canon 70-200mm f2.8L ISM (with IS) and with this lens used the TC1.4x and there was no problem at all and the auto focus also worked.

Could you please tell me why the auto focus did not work when I put the TC on the Canon 500mm ?? Your advice will be very helpful.

b). Removing the TC from the Camera/Lens I took some pictures with the flamingo's flying. The setting were ISO320, f/8 and f/10 shutter speed between 1/500 to 1/1200sec, spot metering. All Servo focus. I was not able to get any sharp focus images. Could you please advice??

I am planing a trip to Tanzania this August to see the migration and before that I get to get my hands set to sue my new toy..... Thanks in advance everyone for your kind help...

Bob Nichol Jun 14, 2011 4:18 PM

The TC introduces a 1 stop loss so the f/4 lens becomes an f/5.6. It was evening and the light was getting dim so my guess is the AF gave up because you exceeded the AF working range: -0.5 - 18 EV. The 70-200mm f/2.8 still worked because it only became an f/4.

As for the focus problem, what AF point selection mode were you in, Auto 9 point or Manual? If manual it would have been difficult to keep the active AF point on a subject bird.

You have to consider atmospheric effects as well. Smoggy, humid, or dusty environments will limit the usable range you can shoot.

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