AFD68 Loc: Saugerties, NY

Look at the 70D. I shoot with it and although still a crop sensor, it has a 19 point focus and 7 fps. I shoot with the canon 70-200 2.8 IS. A great combo for action. You also need a card that can handle that kind of data transfer.

dan r wilson Loc: Marquette,MI da UP eh, Gods country

Camera Canon 7D lens Canon 100 to 400 L you can get this from adorama used for $1800 give or take with a one-year warranty on both. This is what I shoot and am very happy with it for the price range without spending 10 grand on something

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Check this guy's photostream out - I know he uses a 100-400L, not sure which body - he gets great results with slower, larger birds. Most of his small birds are either perched or hovering. He did some of his hummingbird shots with the help of a speedlight, which still was not fast enough to freeze the hummer's wings.

https://www.flickr.com/photos/57424667@N04

anotherview Loc: California

As well, the term "fast lens" misleads. This term reflects that the lens achieves a larger aperture opening, and thus allows shooting in situations with less light while producing a good exposure.

In addition, referring to the Exposure Triangle, a larger aperture opening enables a faster shutter speed for a given exposure. The "fast" part comes from this fact.

Your telephoto lens likely has its largest aperture opening in the neighborhood of f/3.5 or f/4.

A fast lens typically has an aperture of f/1.4. Compared to an aperture of, say, f/4, an aperture of f/1.4 represents a two f-stop difference.

These two f-stops translate, for example, to a difference of shutter speed between 1/30th sec and 1/125th sec -- given ISO remaining constant.

Newer cameras control noise better, thus allowing a higher ISO setting with less noise. This improvement, in view of the Exposure Triangle, enables using a faster shutter speed.

You can see your question naturally leads to a discussion of the Exposure Triangle in relation to lens aperture and camera capability.

I hope this comment helps.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

I generally agree with everything you said, but if a camera sensor is given more light and contrast, as is possible with faster lenses of F2.8 to F4, it will acquire focus faster, with less hunting and more accuracy. Your camera will have tracking options so that you can set the interval at which it will lose focus when something comes between the subject and the camera. Low contrast and low light levels will challenge any lens that has F5.6 or smaller as a maximum aperture.

Also, cameras have two types of focus sensors, cross type, which detects movement in the vertical and horizontal directions and others that only do vertical detection and are correspondingly less accurate. Cross type sensors are more sensitive, faster and more accurate with faster lenses, and do not perform as well with smaller aperture lenses.

I believe Canon is now using cross sensors arranged diagonally.

So, lens aperture most definitely affects autofocus performance.

This is a good reference article that covers this topic:

http://www.cambridgeincolour.com/tutorials/camera-autofocus.htm

PNagy Loc: Missouri City, Texas

Although I shoot with a full frame camera, I will give you some traditional advice; compromise on the camera before the lenses. The birds and other animals you shoot are often at a distance, so you need reach. The three lenses I mention below are very good for this:

1. Canon 28-300mm F3.5-5.6 IS. The greatest advantage if this lens is that it can frame the animals whether they are close to you, or relatively far away. It is bright enough, sharp enough, and responsive enough to shoot anything it can frame outdoors, and it can frame nearly anything. It cannot accommodate the 1.4 or 2.0x expanders.

2. Canon 70-200mm F2.8 IS. This is a super sharp lens, whose only limitation is framing. It overreaches for some birds that are too close, and does snot reach far enough for others. I use a 2x expander on it to reach farther, but have to carry another body with a different lens if I do not want to miss some animals that are closer.

3. Canon 400mm F2.8 IS. This is a great lens for very sharp images of animals at some distance. It reaches even farther with an expander, but has framing issues, especially with subjects that are too close.

gwbarr Loc: Pocahontas, AR

Thanks for all the information, it is greatly appreciated.

wingclui44 Loc: CT USA

It's the new 80-400mm AF-S, not the older 80-400mm D, correct?
I am consider replace my broken Sigma 50-500mm with either this Nikon AF-S zoom or the new Tamron 120-600mm. I have read some review about this Tamron, they said the AF on the long end is a bit slow and some time hunts and misses and the image is a little soft.
The price are a great different too, suggestion?

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Yes, I was commenting on the new 80-400 VR. This is an ok lens, definitely overpriced, and not as good as the 100-400 L from Canon. I find it better than the old AF-D, but that is not saying much. I have not personally had much experience with the 150-600 Tamron, but my first impressions were that it offers pretty sharp images. I would need to see how it works in low light with low contrast subjects, which is often where third party lenses fall short.

picsman Loc: Scotland

Yes it is the new 80-400. I suggest two things 1) rent the lens to try it out, and 2) look at the DXOmark measurements for super zooms, you might find that there are other lens that will meet your needs. Eg nikon 70-300.

amfoto1 Loc: San Jose, Calif. USA

Actually it's a combination of lens, camera and user skill that makes for fast, effective, accurate autofocus. All three have to be considered.

First, the camera...

Canon T2i/550D and T3i/600D have a rather simple, 9-point AF with only one of the more sensitive/faster "cross-type" points... the center one. This AF system is essentially the same as was found on the 20D and 30D. If you restrict the camera to use only that center point, it will give the best performance. But it will be on you to keep that AF point right on target, exactly where you want it to focus, even with fast moving targets. (This is not a bad technique to use most of the time, even with more sophisticated AF systems discussed below.)

Other Canon cameras have more advanced autofocus. Beginning with 40D and in the 50D, 60D, a 9-point AF is used, with all nine cross-type (the center point is still further enhanced as a diagonal cross-type). The T4i/650D and T5i/700D have both inherited this AF system.

7D and now 70D use a 19-point AF system, all of which are cross-type (center point enhanced). The increase in AF points allows for multi-point "Zone" patterns that work well with fast moving subjects, where up to 9 AF points act in unison, sort of like one really big AF point. The 7D also has an "Expansion" points mode that starts with a single, pre-selected point but allows the immediately surrounding points to take over from it.

But there's more to it than that. Processor speed... and other demands on the processor... also play an important role. The T4i and T5i both have a faster, more powerful Digic 5 processor. A further enhanced Digic 5+ is used in the 70D. Your T2i and the T3i use a Digic 4.

Actually, so does 7D. However, 7D has dual Digic 4 processors to support fast 8fps image throughput. Perhaps more importantly to this discussion, it also has a separate chip dedicated to driving AF (similar to 1D series cameras).

All the Rebel/xxxD series and the 70D, 60D and earlier xxD series use a single processor, that shares responsibility for both AF and image handling. Now 70D has the more powerful Digic 5+, which allows it to have a frame rate (7fps) close to that of 7D, supports the more sophisticated AF system giving nearly the same level of AF performance as 7D.

Camera viewfinders vary, too. In general, you'll do better with a larger, brighter viewfinder, even though you are not using it to focus manually. It's just easier to see your subject and keep the AF point(s) on it. The Canon Rebel/xxxD cameras use a penta-mirror to keep cost and weight down, but isn't as bright as a true pentaprism such as is used in the Canon xxD and xD cameras.

Also look at the coverage of the viewfinder, 100% or close to it is more ideal. Canon 7D has 100%. 70D is close at 98%. Most of the Rebel/xxxD models are closer to 95%. And there is viewfinder magnification... a 1.0X viewfinder is the biggest and grandest view, offered by the 7D. 70D is close with 0.95X. Rebel/xxD series are typically about 0.85X. It's a trade-off, though. Higher coverage and magnification numbers also make for bigger, heavier and more expensive cameras (7D is actually a little bit heavier than full frame 5D Mark II).

Finally, some Canon cameras feature Micro Focus Adjustment (MFA). This allows fine tuning of focus accuracy for each of the user's lenses. No Rebel/xxxD series camera has this (they and their lenses can be calibrated, but only by a camera technician). 5D Mark II, 50D, 7D have the first version of MFA, which allows a single adjustment on up to 20 different lens models. 70D, 6D, 5D Mark III and 1DX all have a second version of MFA, allowing adjustment on up to 40 serial-number specific lenses, with two adjustments possible on zooms (one at each end of the focal length range). MFA is sort of the "icing on the cake" for serious pixel peepers looking for that last little bit of precision! There are manual procedures to do MFA, as well as third party softwares that can help automate it. Note: Sigma's latest "ART" lenses also allow the user to calibrate them for greater accuracy, though a separately sold USB dock is needed to do this adjustment.

Regarding The lens...

Ultrasonic Motor focus drive or "USM" lenses are typically the fastest and most precise focusing. Canon now also has a Stepper Motor or "STM" focus that's quiet, smooth and fast... Though generally not quite as fast as USM (STM focus is ideal for videography). The least expensive lenses commonly use "micro motor" focus drive, which is the noisiest, least accurate and slowest.

Sigma has had similar "HSM" ultrasonic motor focus drive on many of their lenses for some years now. Recently, Tamron has begun adding their version, called "USD", to their lens offerings. Not all have USD yet, but more are added each year, generally beginning with their more premium "SP" lenses. I don't believe Tokina offers anything similar, but they seem to have optimized micro motor focus drive for better performance than most, particularly in their more "pro-oriented" AT-X series lenses.

Larger aperture lenses also can help AF performance, up to a point. An f2.8 lens allows more light to reach the AF sensors in the camera, than does and f4 or f5.6 lens.

However, it needs to be noted that some super large aperture lenses (f1.2) actually are designed to focus more slowly (even with USM or similar), using what's called "long throw focus" to emphasize accuracy over speed. Due to these lenses' very shallow depth of field potential, high precision has to take precedence. The same is true of macro lenses, which generally aren't as fast focusing as non-macro lenses in similar focal lengths.

The center AF point of most Canon cameras also is optimized for peak performance with f2.8 and larger aperture lenses.

Now in good light, you might not notice much difference between larger aperture lenses. For example, I use 70-200 and 300mm lenses a lot. Enough so that I have two of each... both f2.8 and f4 versions (which also give me choice of a lighter/smaller lens for some situations). In good light, I don't notice much difference in their AF performance. But in low light the f4 lenses are a little slower and slightly more prone to hunting. Not bad, by any means, but I can tell the difference. When light is challenging, even on one of my 7Ds with their excellent AF system, every once in a while an f4 lens will struggle a little to keep focus. In even worse light, f2.8 lenses will too, of course. But they are a bit more tolerant... as well as bigger, heavier and a whole lot more expensive.

"Pro" grade lenses are also often optimized for focus performance. Canon has paid a lot of attention to their high end L-series focusing characteristics (their 70-200s, 135/2, 200/2.8, 200/2, 300mm and up, are all optimized for top AF performance).

But some of Canon's non-L are also quite fast focusing and good at tracking movement The EF 50/1.4 USM is far better than the micro motor drive EF 50/1.8... Their 28/1.8 USM, 85/1.8 USM and 100/2 USM lenses all are very fast and accurate too. Haven't tried the new 24/2.8, 28/2.8 and 35/2 IS USM lenses yet, but I imagine they are good. EF-S 10-22 USM, 17-55 IS USM, 15-85 IS USM lenses are tops, too.

Some lenses have Focus Limiter feature, that restricts AF to working within a certain range, to help speed up AF performance.

Focal length is another factor... Shorter focal lengths don't need to move their focusing elements very much to achieve focus... Plus they naturally render deeper depth of field effects, which tend to hide any slight focus error pretty well. Longer telephoto lenses, with shallower depth of field, are less forgiving.

I also feel Image Stabilization (IS) helps focus performance. I've seen some try to argue that it slows AF... but I just don't think so. I've been shooting with IS lenses for around 12 or 13 years now, and another benefit of lens-based stabilization (Canon and Nikon) is that it stabilizes the image in the viewfinder, too, which can help the photographer keep on target. (Sensor-base stabilization doesn't show in optical viewfinders, but might be effective in some of the new electronic VFs.)

And, the user...

The photographer is another key factor in AF performance. First thing, they need to set up the camera and lens correctly. For moving subjects you must be in AI Servo focus mode. Many sports/action shooters also like to use Back Button Focus technique, separating AF from the shutter release button. You also have to work to keep the AF point on the subject, right where you want the camera and lens to focus.

Some cameras have more advanced controls, allowing some tweaking of AF to suit specific situations. For example, there's a setting on 7D, 5DIII, 70D and 1D series cameras that tell the camera in certain situations to ignore objects that might come between you and the subject. These have to be used carefully and properly, though. That setting also will slow the camera adjusting to a moving subject's sudden change in direction. So while the more sophisticated settings can help when used right, they also can cause problems if used wrong.

Even with a variety of AF patterns and automation available to me, I use a single, manually selected AF point most of the time. With my 7Ds, I'm more free to use any of the 19 points it offers, because they are all the better cross-type (... especially compared to my 5D Mark II, which only has one cross-type at the center in one mode, or three at the center in another mode. 5D2 is just not a great action/sports camera, but is very nice for some other things. 5D Mark III has a much more sophisticated and capable AF system, that added about $1000 to the price of the camera.)

Using a single point, especially in AI Servo mode that doesn't have any form of Focus Confirmation (because focus never locks... it updates and runs continuously), you have to learn to trust the camera and yourself. You have to get a feel for the micro seconds it takes AF to lock onto a subject, and to recognize situations where it might lose tracking. You can't always see if focus is achieved in the viewfinder, but with experience will get a feel for what the camera and lens are capable of achieving.

For best possible AF performance, I'd take any filter off the lens and use a properly fitted lens hood. Filters slightly reduce resolution (at best) and can reduce contrast and/or add various flare effects, which may cause some AF issues. Some lenses really don't work well with filters (Canon 100-400). A lens hood, on the other hand, keeps extraneous, oblique light off the lens, which also might confuse AF in some situations.

Keep the lens elements front and rear clean, too. Any significant amount of dust on them can scatter the light that the AF system needs to do its job. And occasionally dampen a clean rag with a few drops of isopropyl alcohol and wipe the electronic contacts on the rear of the lens.

Stop the lens down a bit... f5.6 instead of f4 will give a little greater depth of field, which can cover some minor focus error. AI Servo isn't quite as accurate as One Shot focus, but AI Servo is necessary for moving subjects. (Live View focus is the most accurate... but also quite a bit slower and not usable with moving subjects in most cases... 70D has new Dual Pixel Live View focus though, which might be a bit of a game changer). With a long telephoto, f5.6 and even f8 still can render more distant backgrounds strongly blurred, to help the subject "pop".

Finally, don't be too tough on yourself. Practice with your particular camera and lenses, plus more familiarity with your subject will improve your percentage of in-focus shots... but we all have some misses. We just don't share them. You can improve your odds in a variety of ways, as mentioned above. Also it can help to shoot more... use continuous shooting mode on your camera to take a series of shots and it's more likely one or more of them will "nail" focus. Higher frame rate cameras might be better at this... but also lead to a lot more time spent at the computer checking each shot later! I often use short bursts of two or three shots, knowing that one or two might miss focus.

But, you asked about what lenses might be better...

Some lenses to consider... Reasonably affordable (note: their ain't many quality, long lenses under $1000 new... prices below are approx. from memory):

- Sigma 120-400 OS HSM (about $900)
- Sigma 150-500 OS HSM ($1050)
- Tamron 150-600 VC USD ($1100)
- Canon 400/5.6L USM ($1350, note: doesn't have IS, need to keep shutter speed up and/or use a monopod)
- Sigma 50-500 VC USD ("Bigma", $1400)
- Canon 300/4L IS USM + 1.4X teleconverter ($1350 + $250-450)
- Canon 100-400L IS USM ($1600 its push/pull zoom design is popular for BIF, airshows)
- Sigma 120-300/2.8 OS HSM + 2X teleconverter ($3400 + $300-450).

In general, I have used and have the most faith in the performance of the Canon lenses. But a lot of people use one or another of the third party lenses and give them high marks, too. So be sure to look into them, too.

I'll not go into the really expensive lenses... such as Canon 300/2.8L IS USM, 400/2.8L IS USM and 200-400/4L 1.4X IS USM. They're great and have top AF performance, but most folks wouldn't include them on a list of "affordable" lenses.

Have fun shopping!

wingclui44 Loc: CT USA

Thank you for the suggestion!

wingclui44 Loc: CT USA

Thank you for your input, I will look deeper and wait.

wingclui44 Loc: CT USA

Thank you for the information, I will use whatever I decide to get on my Nikon Df, but I won't get any other Sigma for sure, I only have the "Bigma" for five years with moderate using on my old d200, it's auto focus stopped working right before my trip to Alaska last month. I was very disappointed.

anotherview Loc: California

Thanks for adding to my comment.

The OP will want to take account of your description, too, of how camera focus mechanisms influence focus acquisition.

It appears he may have to upgrade his gear to do the kind of photography he has in mind.