Lance Lee wrote:
When I used 40D class cameras, almost never. Not only did the outside points seem less reliable, but I found them hard to pick. Using the joystick in the diagonal direction was close to impossible.
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You don't have to use the joystick. You can use the rear wheel to cycle through the AF points. With just 9 AF points it takes less than a second to cycle through all AF points. I have not used a 1D body much but of all the other bodies that I have used (30D/40D, 5D I/II, Various Nikon, Sony and Pentax DSLRs), I find the 40D AF selection to be the fastest and most convenient.
And yes on a 40D I changed AF points all the time. Not so much on some of the other cameras which have weak outer points.
When shooting events/people (which it what it sounds like you plan to do) I change AF points a lot to adjust for changes in composition.
When I owned a 40D I did not hesitate to use any/all AF points with slower lenses or when stopping down (i.e. DOF was not really thin). With F/2.8 and faster lenses where I was shooting wide open I tried to stick to the center point more to get the benefit of the enhanced precision sensor.
Pixel Perfect wrote:
I will choose whatever AF point is best for the composition. I don't like to focus and recompose especially with very fast glass where DoF is an issue when recomposing.
Agreed!
With a lens like the 85 1.2 close to wide open, a "focus and recompose" strategy can move that 2-4 inch focus zone to an ear, etc. when you want it on one eye.
My success rate with focus and recompose in those situations was less than 50%. With AI Servo and the correct AF point, it is much, much higher.
Every camera offers a learning experience that takes some practice to learn. We have great tools today though with the 5D3 & 1DX! Even the T4i is finally pretty good (like the 60D & 7D.)
Very rarely. When I first got the 7D I used it often just because I could, but I find it easier to just use the centre point off the back button and recompose. I generally shoot at moderate apertures, if I were wide open I think I'd be swapping them around to ensure a more accurate focus.
Light scattering. You didn't learn the Rayleigh's law formula back in school? If you don't remember the equation, at least keep in mind that the scattering is inversely proportional to the fourth power of the wavelength.
With my 7D I ride the joystick like a madman as it will lock in almost any light. The points on my 60D are also excellent albeit not as dense but I tend to lock-AF-recompose as the tap pads for selecting AF points is bothersome and I often miss. I select points n my 5D2 in decent light but resort to center-only when it gets dim.
I found even on 5D II, unless light was quite low, outer points locked on fine in one shot, but where useless in servo under the same conditions. 5D II servo was centre point only, but with 5D III, 7D, 1D II/II/IV outer points work fine for servo, although my paranoia means as light drops I'll usually move back to centre point(s) for servo.
I change center points quite often, it's relatively unusual with the landscape and architectural photography I mostly do to have the center point fall on the place where I want to focus. But I have a 1DsIII and I've found the outer focus points on that camera to be as reliable as the center point. With my 5DII, on which the outer points weren't consistently reliable, I resorted to focus-and-recompose more than switching to an outer focus point.
Wow seems like this is a function whose use varies greatly between users. Had the chance to shoot a 7d this past weekend and must say the joystick and second click wheel is a life saver compared to the aperture and focus point adjustments on the T2i! Thank you for all the feedback!
I currently own 1D4/1D3 and used to own a 40D. Please anyone correct me if I'm wrong, 40D can accurately focus using an off-center AF point only with an f/2.8 or faster lens. That is, when using a 40D with a 24-105L F/4 lens, while it can focus using an off-center AF point, it's not always accurate unless you have good lighting and the subject isn't moving (more light portraiture setting). Now, 5D3/1DX/1D4 bodies have off-center cross-type focus points sensitive to F4 and faster lenses. I know I'm over-simplifying it a bit here, but read up on the various camera specs on the AF point sensitivity.
