focus issues on 'sports' mode

[doctorfoz]

can anyone shed any light on the following?

over the weekend I was at a racetrack shooting motorbikes with my canon 300d (aka digital rebel) with a 28-200 zoom lens.

I set it to 'sports' mode but whenever I depressed the shutter, I was not hearing the distinctive 'beep' which told me that the autofocus was set.

In fact it seemed like the autofocus couldn't make its mind up what it wanted to do and was continually adjusting itself.

I'm at work, and can't 'RTFM'*, so I thought I'd ask you guys. Is it a feature of sports mode that the camera won't autofocus properly? Or was I just doing something wrong?

thanks in advance

foz

*read the pancaking manual

[Jam]

I am not sure if you can auto focus on a moving item. I know the rebel uses multiple points as part of it auto focus system, you may need to choose or change this to single point, otherwise it is down to you.

[doctorfoz]

thanks Jam

[Tyger]

doc, sounds like your lens was hunting a bit...those modes are not very helpful, it's best to use one of the creative modes like AV or TV and set your focus point to the center AF point. What kind of lighting was it that day? Indoor? Outdoor?

[doctorfoz]

Hi Tyger - it was outdoor. Cloudy but still quite bright. I was panning the camera most of the time as the bikes went past.

I'm still getting used to the idea of taking the camera off automatic (in terms of aperture, exposure etc) so wouldn't have the faintest idea what shutterspeed would be suitable for that particular occasion.

On a side note - would anyone out there recommend switching to single point autofocus permenantly? (or at least until something should call for multi point)
I've been a bit worried about the sharpness of some of my photos - perhaps this is the reason?

[Drazan]

when I shoot fast moving objects I'll prefocus on the ground or fence where I'm going to take the picture as soon as the bikes come around the bend. Then I also set up for multi-frame so that I get several bikes in relatively excellent focus and composition. Next time around I'll prefocus on a different position.

I don't have teh Cannon though.

Jade

[Tyger]

Hi Tyger - it was outdoor. Cloudy but still quite bright. I was panning the camera most of the time as the bikes went past.

I'm still getting used to the idea of taking the camera off automatic (in terms of aperture, exposure etc) so wouldn't have the faintest idea what shutterspeed would be suitable for that particular occasion.

On a side note - would anyone out there recommend switching to single point autofocus permenantly? (or at least until something should call for multi point)
I've been a bit worried about the sharpness of some of my photos - perhaps this is the reason?

absolutely! use the center point AF and switch your mode to AI servo. what kind of lens are you using? usually the rule of thumb for shutter speed is to set it equal to or greater than the length of the lens you are set at. For example if you are using a 70-200mm lens your shutter speed should be at 1/225 or even 320 if you are on a camera with a crop factor.

here's some links to some info that would help....
creative modes (http://www.photographycorner.com/articles/basics/modes-what-they-are-and-why-theyre-useful)

shutterspeed (http://www.photographycorner.com/blog/2007/05/articles-by-amy-shutter-speed-basics)

I would recommend to not use automatic anymore...best way to learn. The creative modes are easy to learn. I tend to use AV mostly but TV when shooting sports or birds. The link provided explains but in a nutshell AV let's you control the f-stop which gives you the desired Depth of field, shutter speed is is done automatically by the camera. TV lets you set the desired shutter speed and the f-stop will be done automatically. One of the downsides of doing this is the camera won't always determine the right settings causing your image to be over or under exposed....but it does a decent job most of the time. Shoot .Raw so that you can make adjustments afterwards if need be.

[Tyger]

I forgot to mention as well....depending on your lens, even on a cloudy day your lens will hunt meaning it doesn't lock it's focus point especially with action. Most people that shoot fast action recommend a lens that is f2.8 and under. I have a Canon 100-400mm f4.5-5.6 and I shot some qualifying runs at last years Toronto Grand Prix and although I got many keepers I missed many good shots because the lens isn't ideal for fast moving subjects. The AF on the lens and XT is too slow.

[doctorfoz]

well, the lens I was using is a Sigma 28-200 Aspherical IF F3.5-5.6

A quick google resulted in this review:

Summary:
This is not a bad lens. It's a mediocre, middle of the road, long zoom lens for people on a budget who decide they want one lens they can use for everything, as money is an issue. It's important to remember that most of the time, lenses with a zoom of more than 3x aren't going to be able to match the quality of their more modest range cousins - unless you're willing to spend a packet. 28-200 is about 7x. It's £150. Any quality fanatics aren't going to even entertain this lens, and it produces fairly soft images. Let us then focus on useability and performance, rather than pure quality. AF is precarious. In low light it's a... oh, no profanity. Ah. Also, focusing at 200mm is equally dastardly. If you want a lens where you don't have to resort to manual focus on occasion this is not the lens for you. It will not suffice for wedding, sport or wildlife photography, and quite frankly if I was paying you to photograph my wedding, I'd hope you would use better kit, you cheapskate. If you've tried this in the shop and found the zoom ring to be stiff, don't worry it will free up and become a fairy nice action. I'm using it on a digital camera and I've not found any noticable chromatic abberation, just remember that the 28-200 range is not that on a digital camera - on mine it becomes 42-300 which means it looses the convenience of being a lens that stays on your camera most of the time as the wide angle has vanished. It's a hunky-dory lens for the price, but you may end up wishing you paid more, and if you're on a budget and want a single lens to cover wide angle and telephoto just remember it looses that appeal on a digital camera. I'm reasonably happy with it, because I knew what I was paying and what you get at that price range. You get what you pay for in this business and if you're a beginner there's no point in shelling out for all the pro goodies because you have a job to do too. A good photographer will be able to coax quite a bit out of this lens, I should say.
Strengths:
It's all in one and it's cheap, no potentially image crippling quality issues.
Weaknesses:
I've seen better AF on a compact camera cheaper than this lens, softy softy approach to images won't appeal.

Now, I'm on a budget and using a digital - so I won't be doing that guy's wedding (lol).

thanks for your help tyger - and Jade. It's all very valuable info. I shall check out the links when I have more time.

doc