Lens for dog agility / action

[DavidEccleston]

We're looking into options for a reasonably priced telephoto lens for capturing Dog Agility outdoors on a 7D.

I have it narrowed down to the 70-200mm F/4L IS USM and the 70-300mm F/4-5.6L IS USM.

The 200/300 primes are out, as they just aren't versatile enough. We love our primes, but we need a zoom here. The 70-200mm f/2.8 USM is out, as it doesn't meet my wife's demands for sharpness. Similarly the F/4 USM is not sharp enough. The F/2.8 IS versions are out of our price range and are too heavy. The 100-400 is also too heavy.

70-300mm F/4-5.6L IS USM is as fast, or nearly as fast as the 70-200 F/4 over the majority of the zoom range, only trailing significantly after 155mm, but that's offset by the extra 100mm of reach, so it sounds ideal, except for a few comments in Bryan's review. He mentions it focus-hunting more than other lenses of it's class. Is this commonly occurring thing I should be concerned about? He also noticed it front focusing in cases. While it's impressive for a lens to outpace the action, what we need is rock solid tracking.

Does anyone have demanding servo sample images, equivalent to what we might see in agility, that they could share crops from? Something small, fast, moving towards the lens. Perhaps some winter sledding or something?

If anyone can offer some insight into either of these lenses, or other lenses we should be considering, that would be great. If anyone has used both of these and can comment on their relative servo performance, we'd appreciate it.

[ddt0725]

I am completely tuned into this thread and very anxious to see what others have to say! I have been trying to capture alot of running toward me shots of my dogs and just having nailed them as consistently as I would like to! My best ones were taken with primes but of course, I missed the shot many times due to their lack of versatility ...my legs just aren't as quick as my dogs!

I just went through some of my action shots of the dogs and none of them were taken with the 70-200mm f/4 IS. I'm not saying I never took them with that lens, they just must have not been keepers.

If I could get shots like these out of a zoom, I would be happy!

Happy Boy! by Denise Trocio ( www.dtrociophotography.com), on Flickr

Go! Buddy! Go! by Denise Trocio ( www.dtrociophotography.com), on Flickr

Fast ball coming at you Bud! by Denise Trocio ( www.dtrociophotography.com), on Flickr

[andnowimbroke]

I have been trying to capture alot of running toward me shots of my dogs and just having nailed them as consistently as I would like to!

A 1-series body might help the most for that.

[Busted Knuckles]

Other than Bud having the same facial expression as a great white taking a seal......

I am not expert on the 7d focusing capabilities - I would think that is the driving issue???? Which of the lenses mentioned focuses fastest?

I have to say I am bit confused on the 70-200 2.8 not being sharp enough, yet you entertain the 70-300 - At 2.8 the DoF is razor then for these fast moving targets

[DavidEccleston]

Busted Knuckles, On the ISO charts, the 70-200 f/2.8 doesn't look sharpest, and it seems to be common knowledge that the older (not IS II) f/2.8 lenses were not as sharp as the f/4. The 70-300 we're considering is the L, which is supposed to be pretty sharp. On the ISO charts it looks very good, aside from 70mm, where it's just okay.

If you have real-world shots from the f/2.8 non IS that say different from the ISO charts, we'd love to see them.

[Richard Lane]

Hi David,

I would generally stay away from a variable aperture lens like this one for fast moving subjects.

To start off the 70-300 f/4-5.6L IS is going to be:
70-103mm = f/4.0
104-154mm = f/4.5
155-228mm = f/5.0
229-300mm = f/5.6

Here's a couple more points:

So, from 105 and up you will be getting a slower lens and from 155 to 228 you will be at f/5 and so on. At f/5.6 this lens will be 4 times slower than the f/2.8 lens, since for every 1 stop loss the lens will let in half as much light. So, from f/2.8 to f/4 the "lens speed" will be twice as slow and from f/4 to f/5.6 the "lens speed" will be twice as slow once again, that's 4 times slower shutter-speed than f/2.8.

For a fixed aperture lens like the f/2.8, the lens will always open up to f/2.8 to focus quickly even if you are at f/4, and then once the lens focuses it will close down to f/4 for the shot. So, you always get the benefit of faster focusing at f/2.8 even if you are at f/4 or narrower for DOF.

The other point is that f/5 to f/5.6 will further limit your shutter-speed if there is less than optimal light, so, you may be looking at higher ISO's or blurry shots. Also, if there is ever an event indoors, then your screwed.

The last point is that the f/2.8 lens provides a nicer blurring out of the background for better subject isolation, especially when their are people standing around on the sidelines or cars in the background, at these type of events. It will take some time to getting used to the narrower DOF, but once you do, you will greatly appreciate the f/2.8.

I hope this helps,

Rich


EDITED: Changed "focusing speed" to "lens speed".

[DavidEccleston]

Denise. I think what you're saying is the 7D and 85mm f/1.8 I have is fine, but I'll need second 7D with a 135mm f/2 and a third 7D with a 200 f/2.8, right?

[HDNitehawk]

Denise. I think what you're saying is the 7D and 85mm f/1.8 I have is fine, but I'll need second 7D with a 135mm f/2 and a third 7D with a 200 f/2.8, right?

And there is a problem with that

[DavidEccleston]

Richard, this is the first I've heard of the maximum aperture affecting the focus speed. I know there is the f/2.8 focus sensor for higher precision, but that an f/4 lens would focus half the speed of an f/2.8, or and f/5.6 being quarter speed, I've certainly never heard of that. The reviews for this lens don't mention this level of degraded performance either, and you'd think that would be a major concern to point out.

I'm aware of the other benefits of f/2.8, however the new IS II version of the lens is well out of our price range, and the previous versions don't have the level of sharpness we want.

We can't afford the best of the best, and we know we have to give up something for a reduced price. We've ruled out primes, which leaves slower aperture lenses, unless everyone agrees that it's not reasonable to expect one of these lenses to shoot agility.

[DavidEccleston]

And there is a problem with that

I think the price would exceed the 70-200mm f/2.8L IS II that I'm trying to avoid buying.