View Single Post
Old Dec 15, 2007, 9:14 AM   #28
Senior Member
NHL's Avatar
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,567

JohnG wrote:
Ah, but that's the beauty of technology. At 10 fps, even ifI wasgetting a poor keeper rate of 60% that' s 6 in focus frames a second.
... and that's the way any camera should work in the burst mode!
IMO there's nothing wrong with this MRkIII and all this AF issue is just a red herring - Even the camera manual says so: When "Drive speed priority" is selected, the focusing might be slightly off, but the shooting speed will be fixed.

-> Some one just decided to arbitrarily compare it to a MrkII in a narrow set of circumstances. What about others? I'm not knocking the MrkIII in anyway - Check all my posts - In fact I'm actually defending it:

How many times a second can you press the shutter in one-shot:-) :-)
All I need is one shot even if it takes me 365 days to do it :lol::-):G
-> This where we differ...
Photography is, at least, for me to relax and to take time to enjoy nature. If I miss a shot I'll gladly go back to the same spot on my next vacation to relive the things I've missed. One of my car for example can do 0-60 in less than 5s, but how many time do I time myself? I enjoy the build, the handling, and the ergonomis instead, and rather take the long road and relax after a long work (not in photography) week!
This is not to say that I don't use the high-frame rates nor the 45 AF points on my 1D when needed. In fact my field is technical and I do appreciate all the innovations Canon's have put in their design, but frame rates sit very low on my list of priority (or high-ISO for that matter)...

And even in one shot there's no guarantee of perfect focus - forums are full of soft images from people using one shot.
Haven't we been here before? :?

o One-shot AF does not guarantee perfect focus, but it is always stop spot on an AF point (or points) which was lit up when that one shot was released - Correct?

o AI-servo on the other hand does not stop focusing and no AF point is lit up - Correct?
-> If you notice the lens dither back and forth in AI-servo to anticipate the movements so if you take a single shot in this mode with a very narrow DOF lens like a fast tele prime, that single image will fall into three categories: In focus, front or back focus:
" When I have my Mark II on a tripod, with a 400mm f2.8 lens focused on a brick wall, with a single focus spot, AI Servo, the lens twitches. The lens is constantlly making small adjustments. Basically from a soft image to a sharp image. As I described the platform is stable and the subject is stable, so it is not a camera or subject movement problem."
"It is normal for the camera to hunt when AI servo mode is used to acquire focus on a stationary object. One-shot mode should be used to focus in this situation. In AI Servo AF, the camera continuously samples the AF detection data at varying rates of frequency depending on the light level"
NHL is offline   Reply With Quote