BEST ALL-PURPOSE LENS FOR 20D

I have the 20D with the 18-55mm kit lens. I am considering either the 17-40 L versus the 24-70L for general use and at a later time I will purchase a 100mm macro. Which of the 2 zoom lenses is best overall for alll-purpose use?

That depends on your definition of "all-purpose"
I like the Tamron 28-75 f/2.8 (would buy the Canon 24-70 instead, if I had the money), Canon 50mm f/1.8 and Tokina 17mm for wide-angle pictures.

Personally, I would keep the kit lens and buy something longer for starters - 100mm Macro or even some 70-200 f/4.

I agree with Oleg. Although not an L class lens, the 18-55 kit zoom is a decent piece of glass for general purpose shooting.
I then choosed the 100 macro because it's... a 100mm (160 equiv.) AND a macro lens (clever, isn't it?) and also the 50 f/2.8 for it's unbeatable perf/price ration for portraits in natural (low) light.

If you have to pick between those two I would go with 24-70L as it will add to your range and it is a better general prupose lens.

However, you already have a decent general purpose lens, so I would work on expanding the range first and then go back and improve the aperture and quality. And in the long term I would consider the 16-35 or 10-22 over the 17-40 as these would give you significantly more range over the 18-55. The 100 macro would be a better choice or maybe also consider the 70-200/4.

Just my opinion,

If you can afford the 24-70L then IMO that would be your best bet. At the time I couldn't afford the 24-70 & went for the 17-40L, it's rarely off my camera!

It all depends on your photography. What sub range on your 18-55mm do you use most? Is it 18-40 or 24-70mm? That should give you a very good indication.

The 17-40mm L equates to 27-64mm which is what I would call a standard zoom, similar to the 24-70mm L on a full frame camera. The 24-70mm L equates to 38-112mm which doesn't give you much scope on the wide angle.

38-xxmm lenses were run of the mill over a decade ago. They have now become obsolete as everyone tends to need a wider angle, 28mm at minimum, 24mm or wider preferable.

Remeber also it's easier to take a step forward to 'zoom' in than to take several step backwards to get a wider angle.

17-40 is a ultra wide-angle zoom and 24-70 is a wide-angle zoom. Dosen't the terminology suggest something? But of course there's about $400 price difference. If $400 won't break a heart, 24-70 will be a better "general purpose" lens, IMO.

I agree with your choice when it comes to a film or full frame sensor camera. For the 20D (see original question), I disagree. The 17-40mm is better due to the 1.6x conversion factor of the 20D, being effectively the same as the 24-70mm for full frame.

All purpose for me is a 100-400mm IS
Obviously imho "crop factror" has no bearing on it other than I get a longer 400mm

My point being,. that different people and different applications will profit from different lenses... there is no all purpose,..

And no one lens is best at being "All purpose" because the purposes are too diverse.

We can make our recomendations based on our needs and experience,. but NO ONE is more "right" on this than anyone else.

I don't agree. I have the 16-35 f/2.8L and the 24-70 f/2.8L and I use the 24-70 at least 2x as much as the 16-35 (which is still an awesome lens) for everyday shooting. If I only take one lens out of the house (on either the 1DMkII or 20D) it is the 24-70 The conversion factor only affects the field of view (FOV), not the reach of the lens.

That, and I have heard (and seen in my own shots) that the 24-70 is the sharpest zoom lens in the EOS line. I cannot give hard proof, just hearsay from different places both on the net and at the camera stores here in town.

It really all depends on what you are planning on doing in the long run. Not just three months from now. I bought my lenses so I can reach from 16mm to 560mm. Good luck.

I bought the camera to take medical pictures in the operating room. That being said, what I usually use it for is to take pictures of my son playing sports or of nice scenery when I visit places. Although ideally I would use a macro lens for the OR, a telephoto for sports and something else when sightseeing I would prefer to use 1 lens everything then add other lenses as I gain experience.

Well, the 24-70 offers Macro focusing range for up close imaging. I have used mine with a close-up lens and have gotten great photos.

The 24-70 is an awesomely versitle lens. I do not think it is something you could go wrong with.

Sorry for threadcrapping, but is the 20D kit lens the same as the Digital Rebel kit lens? Mine is also 18-55mm methinks....

I find the Tamron 28-75 excellent, but I often wish for a les that was just a bit longer. If the Canon 28-135IS were faster i'd get that instead.

I sometimes wish that my Tamron would be a little bit wider Well, I guess that I can't have it all ...