Help with Canon lens

[gmbfilter (Geoff)]

Have recently gone mad and purchased 40D. It came with a 17-85 IS lens and I would like to get EF 70-200mm telephoto Zoom. I don't care about Image Stabilisation. However I don't understand enough about the differences between the f2.8 and f4. How much difference does it make?
Any help would be great.

[Suzy_A]

Both the f4 and the f2.8 are very, very good lenses. The main difference is that the f4 is a LOT lighter but the exposure times to get the same result are obviously going to be longer for the f4. The f2.8 has a lot more glass and a lot more metal in it.

If you want use the lens for general - and in particular holiday - photos, the f4 is much better. Probably the IS f4 actually, then you can hand-hold without any problems in reasonable light.

But if you want to use it mainly for astro and you are not going to carry it up the top of mountains on your holiday, then the f2.8 is better.

I got the 2.8 non-IS. The images are just ever so slighter sharper and brighter than the IS version. Also the non-IS are quite a bit cheaper.

[gmbfilter (Geoff)]

Thanks for that. Going for f2.8.

[AlexN]

Good decision mate!

You Will Not Be Disappointed

[Ian Robinson]

So am I , I splashed out and told them I wanted the IS model , I don't just use my camera mounted on a telescope or a GEM and I want the added weather proofing too.

I am now officially BROKE for a while and will have start saving my pennies again.