Andrew J wrote:
Does anyone now question the glowing reviews that first came out?
Not really, many of the early ones I read looked at IQ and with static subjects so did not test AI-Servo. They also didn't seem to be testing it on older bodies, which seem to be the major source of problems here.
mfpm wrote:
Thank you
Well I'm not.I can assure you that. I don't even have this lens because I'm waiting for Canon's response
But I don't have fun bashing a lens because it seems fun to do it or because I bought a Honda and expected it to behave like a Ferrari
Again, what's the big deal on having to bump the AF button? It doesn't require much exercise...
Have you even read the complaints? It's the complete lack of focusing on some bodies, not just the need for bumping. Besides that, it works fine on other bodies. People like the lens they just want it to work on more Canon bodies as a compatible lens should. The main problem is even Tamron themselves are saying it works fine on bodies like the 7D and every end user is reporting otherwise. People are just wanting Tamron to fix the issue so they can buy and use the lens. It's a great deal for a nice lens but ..................
And what's the big deal with having to bump the AF button?? With my 300mm f/4L IS+tc1.4 and canon 5d mark III I still have to bump the AF button more often than not
You all must be very rich and be able to afford a Canon 600mm or maybe are expecting a $1000 lens to compete with a $12000
Too bad you don't know what you are talking about. Maybe if you knew how AI Servo is supposed to work, you would know that you should not have to bump the AF button when tracking a moving subject. And maybe if you had read the threads on the problem, you would see that it does not occur with the camera used in that link.
And nobody said they expect it to compete with a $12,000 lens. They expect it to compete with a similarly priced Sigma lens that has no problem focusing with any Canon body.
So try getting your facts right before putting in your 2 cents worth.
mfpm wrote:
^^^ when said I was waiting for Canon's response, obviously it isn't to the response to Tamron's problem... but their response to these new lens eating canon's 100-400mm and 400mm f/5.6 market. Meaning: I'm waiting (and hoping) for a replacement of one of those canon lenses
Also I know how AI Servo is suppose to work.I know it is exactly how you say, but and AGAIN, what's the big deal on having to bump the AF focus button if on my old camera AI servo doesn't work how it is suppose to with this lens? I don't think it is such a big inconvenience. Would I be happier if it worked how it is suppose to? of course I would. Would it keep me from buying a lens knowing that I need to do the extra effort of bumping a button but saving thousands of dollars? of course not...Show more →
Well you go and bump all you want. There are plenty of others that expect this lens to work properly, regardless of the price.
And FYI: This thread is just to gather information about how many returned this lens due to the AI Servo AF problems with certain Canon bodies.
The people that have returned this lens are not interested in your bump-around solution.
Well, I'm no expert on AI Servo. However I do get a kick out of all the bashing on this post. It becomes humorous after awhile. I have the lens on my 5M3 and it focuses as well or better than my Canon 100-400 with a 1.4 extender. Easier to use and It's sharper too. I love this lens. I'm sorry you are all having problems. So you returned yours for FULL REFUND - best to just get on with your lives and get over it. Hope you have a great day.
If you're a Canon photographer and you shoot moving subjects then you're probably aware of AI Servo. This article is a brief introduction to it with a few tips that might help you use it more effectively.
What is AI Servo? AI Servo is Canon's predictive autofocus system. The name is derived from the use of Artificial Intelligence used to predict the speed and distance of the moving subject. It greatly increases your chance of getting a sharp image when your target is moving. How does AI Servo work?
There are two key concepts at work. •Predictive autofocusing
As you might imagine, predictive autofocusing happens whenever AI Servo is on and there's a readable subject with predictable movement.
•Shutter release control
Shutter release timing is controlled by the photographer for single shots and the first shot in a burst. Shutter release timing is controlled by the camera for subsequent shots in the burst.
You can see AI Servo in action. With the shutter button pressed halfway track the motion of a moving subject with the active focusing point. You should be able to see the lens continuously autofocusing.
In AI Servo, you can tell whether the AF system is tracking the subject by observing the in-focus indicator in the viewfinder below the picture area.
Figure 1 from Canon’s "EOS-aD Mark II manual"
Figure 1 from Canon's "EOS-1D Mark II manual"
If you *can't* see the focus confirmation light, the system is tracking. If it is blinking rapidly, the system is telling you that it is not tracking. This is slightly different from the camera's behavior in One Shot AF. In One Shot, the in-focus indicator blinks when the subject can't be focused, but it lights up when focus has locked, as opposed to no in-focus indicator appearing when the subject is being successfully tracked in AI Servo AF.
Techie gorp
The EOS-1D Mark II is the first Canon to have two CPUs taking care of the functions of focusing and driving the lens.
Dividing tasks means decisions can be made simultaneously rather than in sequence. For example, in One-Shot AF mode, AF processing, SI display (i.e., illumination of the active focusing point in the viewfinder) and aperture stop-down are executed in parallel with lens driving and mirror flip-up. In AI Servo AF/Predictive AF, statistical prediction using the focusing data from previous focusing operations is incorporated. The number of focusing operations per unit time is twice as many as the 1D's. With shorter time intervals and more repetitive focusing operations, the predictive AF control works effectively from the first shot even with subjects moving erratically. Should the subject's movement change just before shutter release, the shorter focusing operation interval means the predictive AF control has a higher probability of catching it.
The AF CPU is a 33 MHz, 32-bit RISC (reduced instruction set) microcomputer that handles area AF detection and auto AF point selection. The camera CPU is a 32 MHz, 32-bit RISC microcomputer that controls lens communications, lens driving control and predictive AF statistical calculations. As a result, all the processing is faster than with the EOS 1D's AF control. One-Shot AF speed is faster and AI SERVO AF focusing precision is higher. - Chuck Westfall
Figure 2 from "Getting the Most from your EOS-1 Class Digital SLR"
Figure 2 from "Getting the Most from your EOS-1 Class Digital SLR"
Developing AI Servo shooting techniques
The first rule of thumb is that if you want that first shot in AI Servo to be sharp then you should be tracking the subject for at least 1-2 seconds prior to shutter release.
Focus Points • Single point AF is generally better for team sports and situations where you're trying to select a subject from a group.
• AFPS (Automatic Focus Point Selection) is generally better for individual sports and wildlife such as birds and running animals where your subjects are by themselves.
Custom Functions 1. C.Fn. 4-3 This setting is preferred by many sports shooters. It provides several advantages. ◦ Focus is now engaged with the * button on the back of the camera with your thumb instead of depressing the shutter half-way.
◦ This isolates exposure from focus. Exposure is now calculated when the shutter is depressed.
◦ This reduces the number of accidental shutter firings.
◦ The camera is more responsive in focusing.
2. C.Fn. 17 This setting expands the AF activation area. ◦ 0 - default - only the selected AF point or points are active
◦ 1 - expands the active focus area by a radius of 1 around the manually selected AF point. Up to 7 AF sensors around the manually selected AF point can be activated. This can be useful in low contrast situations.
◦ 2 - expands the active focus points up to 13 AF sensors around the manually selected AF point. This is camera and lens dependent.
The default (0) is the fastest performing but 1 and 2 can increase the chances of finding a small subject or one in low contrast conditions.
Conclusion
Well, that's the basics of AI Servo. It's a very powerful tool for photographers. Hopefully this will help you get started in getting more keepers on those moving subjects. For a deeper understanding check out the information sources at the bottom of this page.
***As one can see if you read and understand the above, AI Servo focus tracking is a very intricate and precise set of commands that need continuous input to work correctly.
Norm, you are getting a kick out of it? I am dying over here. As I stated long ago, it was severely overhyped by the Internet Camera Community (ICC), but it performed really well for a lens that was $1070 and that it was excellent for beginning to somewhat serious hobbyist.
I am also waiting to buy all of those dirt cheap 100-400s.
Received on January 20th from B&H, shot extensively with it with both of my 1D IV bodies, and returned it January 24th for a full refund. Static shots were excellent but trying to shoot BIF, which was my primary desire for having this lens, was abysmal.
mitesh wrote:
I kinda like the proverb: "it is better to remain silent and let others think you are a fool, than it is to open your mouth and remove all doubt."
, this looks like a paid Tamron employee post to me.
