New Lens

[mapache]

Have been thinking about this for 2 years now and finally went out and bought Canon 2.8 70-200 IS lens. Took the following picks just to learn a bit. Late in the day with low light, cloudy, etc. but curious if anyone has suggestions on how to sharpen up a bit. ISO 400, f2.8, 1/400. Also noted that in Rebel xti camera was not able to do rapid "sports" mode shutter speed and keep dog in focus at f2.8 because auto focus kept grabbing the grass behind. Anybody know if it's possible to pick 1 focus point AND get camera to rapidly take photos?

[finnbay]

When shooting sports, I ALWAYS only use the center focus point.

[panthrcat]

When shooting sports, I ALWAYS only use the center focus point.

yeap, me too! geeez how I wish I could buy one of them lenses,, you lucky duck!! once you get the hang of it, I bet you won't be dissappointed!!

my rebel xt I was able to pick a focus point,, you'll have it in there somewhere how to fix the focus point

[Steve Foss]

Mapache, as you know, shooting moving subjects in that light is the biggest test of your camera/lens' autofocus capabilities.

Here are some perspectives that should help. Not all necessarily aimed at your situation, mapache, since some of it deals with things you haven't asked about, but it should also help answer your questions.

Your camera model delivers increased auotofocus speed and performance when shooting an f2.8 lens and using the center focus point. Use a slower lens or choose other focus points and the performance drops just a bit. Also, allowing the camera to control which focus point is selected slows things slightly more and yields more out of focus images in action situations. Selecting the center focus point, using Ai servo focus mode, and practicing keeping that focus point on a moving subject will get you where you need to be.

Also, if you take it out of the "sports" automated mode and use Av (aperture priority) or Tv (shutter speed priority), you'll be the one in control of aperture and shutter speed. I use Av all the time unless I'm in manual exposure mode, and in sports/action situations I spin the top dial to ensure the aperture is wide open, which delivers max shutter speed. And if that's not enough shutter speed to freeze action, I increase iso until I get the shutter speed I need.

Using one of the preset automated modes makes the camera "think" a little harder to come up with the right settings than if you take control, and the more the camera has to think, the slower it is to take a picture. That's not much difference in speed, actually, but even small slowdowns can cost you in action situations. Auto iso mode is another slowdown for the camera.

In most outdoor action situations, unless the light is very low, I set the camera to Av with the sutter wide open and select iso400. With an f2.8 lens, that'll usually get the job done outside in daylight.

Enjoy!

Mighty handsome dog there, by the way. Irish terrier?

[mapache]

Thanks for the info. I wasn't aware of the AF servo mode and after reading up on same, seems very helpful. Curious on the iso setting. Thinking way back to the film days, was always under impression to shoot lowest possible iso as the higher numbers led to grainy pictures and less depth of color. Not saying this was right, just my impression, how dow iso affect image/color quality in the digital world?

Yes dog is Irish Terrier. Good buddy but full of mischief.

[Dbl]

The shot the lowest ISO possible still applies...except! Todays digital cameras produce relatively low noise at high ISO's compared to film. If you need a faster shutter speed I would not hesitate to up the ISO. The higher you go in ISO image quality will suffer to a small degree. So much is dependent on proper exposure, if you get it right it will not affect your image quality nearly as much as underexposure will.

Really the best thing you could do is go ahead and try out all those cool ISO ranges and compare some images side by side and see what you think. I will guess you will pleasantly surprised at how well today's cameras handle high ISO shooting.

[supercool6]

Going back to your original question, the best solution is more light. You would have greater depth of field and would have brought more of the photo in focus. Lack of bright light means something got to give, everything is related.

-low f-stop = good for low light, but your going to have a shallow depth of field or less in focus

-low shutter speed = good for low light, but your going to get blur

-low ISO = good for least amount of noise or pixels, but you got lower your f-stop or shutter speed and now your in the in the viscous cycle...all caused by low light. One of three has to give, you just need to know what end result you want. I guess my answer to your question (for this level of light) would be to open up the f-stop by two, and raise your ISO. A lot can be fixed in photoshop...

Sidebar topic, to replicate your photos on a bright day would be interesting to try. I really like the way the 2.8 narrowed the depth, and I would bet you had the lens close or out to 200mm. You could drop the ISO and up the shutter speed and see how your camera handles that situation.

[MN Shutterbug]

You could drop the ISO and up the shutter speed and see how your camera handles that situation.

If he drops the ISO, the shutter speed is also going to drop. There ois certanily nothing wrong with shooting at ISO 400.

[supercool6]

Originally Posted By: supercool6

You could drop the ISO and up the shutter speed and see how your camera handles that situation.

If he drops the ISO, the shutter speed is also going to drop. There ois certanily nothing wrong with shooting at ISO 400.

Not if the light increases. I was trying stay that if you trying shooting this same shot in bright daylight at F2.8, you would increase your shutter speed and lower your ISO.