Need telephoto info

[The Ruptured Duck]

What focal lenths should I aim for?  I could be shooting anywhere from about 30ft to 100+ yds away.

How useful is IS when most of my shooting will be outside?

Thanks

[Rifleman]

What focal lenths should I aim for? ..........Thanks

How large a subject are you looking to capture in your final image ? You can always zoom out, if you have too much, but if you have too little, then the only way you can aquire what you want is to get closer to your subject........

How useful is IS when most of my shooting will be outside?

Thanks

It has nothing to do with indoors or out.......

Image Stabilization is fine for any time that you may run out of light which you may need for the shutter speed you want to shoot. This also affects aperture you may want to use to gain depth of field of focus.
Especially useful when using high magnification lenses.
Long focal length necessitates higher shutter speed. Higher shutter speed needs more light or wider aperture or higher ISO. Image Stabilization gives you to the ability to get the shot when the light level drops below minimum level for non-Stabilized systems........
It's a good thing !

[Omag 2.0]

First thing... what is your budget? You'll find that this might be the all important factor. You can find lenses up to 300 mm for reasonable prices ( the canon ef 70-300 mm I use has IS). Once you go over that, be prepaired to spend some cash.

Also try to read some users info on the specific type of photography you want to use the lens for. If you want to shoot small birds in the wild, you'll need a 500 - 600 mm lens for example. But when you want to do some racing-photography a 200 mm lens may suit you just fine.

Check out if there are any forums about digital photography in your country and read.

I find IS very usefull. Keep in mind that you'll need a shuttertime equal or faster to the focal length to get a blurfree shot with a non stabilized lens. ( ex. shooting at 300 mm means a shuttertime of 1/300 or faster). IS is really handy, as I've noticed. Because the IS is in my lens, I see the satbilized image in my viewfinder and it sure does eliminate a lot of movement at the tele-end.

[The Ruptured Duck]

Airplanes will be my main subject.  Mostly General aviation.

[Omag 2.0]

It still depends on your budget...

Tight budget