7D AF in AI SERVO (photos included)

Started Feb 4, 2013 | Discussions thread
Multi-SportsMom Contributing Member • Posts: 598
Re: 7D AF in AI SERVO (photos included)

Orange88 wrote:

Ondrej Zeman wrote:

A lot has been written about the AF of 7D. Some say it is brilliant, some find it faulty. Unfortunately I have to lean towards the second group. Perhaps it is due to camera/lens/user error or maybe simply my expectations are just too high? Look at the sequence of following images:

ht

(Shot in RAW and converted to JPG without any adjustments, used Canon 135/f2 L lens)
I set the camera to 1/1000, ISO 100, f2.0, AI SERVO, central AF point selected, sequence shooting. The car was travelling 50 km/h. Out of these 25 photos, I would consider 7 photos to be in focus, 18 out of focus.

It would seem like the camera/lens is slightly backfocusing, but why are some of the photos in focus? I tried experimenting with Spot AF and AF Expansion as well, but in both modes the results were even worse.

Could it be faulty lens? I get kinda the same results with Canon EF 200mm f/2.8 L II USM. Faulty camera? Maybe? User error? What am I doing wrong?

Some might say that the situation is extreme - well not really for me, as I shoot a lot of fast moving cars in lack of light and altough I don't shoot as low as f2 but very often at f2.8. If I knew I could trust the AF, I wouldn't mind shooting at f2.
Any tips welcomed.

How far away was the car? It looked to me like the windshield and driver were in focus but the grill of the car was slightly out of focus. Maybe you have a depth of field problem? At a distance of 25 meters the focus plane is only 1.2 meters in front of the focus point. As the car gets closer it should be even more difficult to get it entirely in focus at F2.0, right?

I agree with this. I have the same set up and shoot in AI Servo. I have had trouble with some shots looking focused and others don't. Shooting 2.0 and such a large object. I had to up my aperture when shooting basketball to get the athletes in focus. I would have used a higher ISO instead.

I have never shot a moving vehicle but would assume the contrast or lack of is hard to focus on.

I found that my photos that had such a large aperture would not be anywhere near looking focused if i shot subjects to far away. I dont know that you can shoot a large object at 2.0, so far away and have it looking sharp. If so Id like to know how.

can you see the car coming into focus when shooting? When I shoot moving objects it does take some time for the object to focus and refocus, when tracking. It sure isnt instant.

 Multi-SportsMom's gear list:Multi-SportsMom's gear list
Canon EOS 7D Canon EF 35mm F2.0 Canon EF 50mm f/1.8 II Canon EF 85mm f/1.8 USM Canon EF 135mm F2L USM +5 more
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