Help me decide: EF-S 17-55 f/2.8 IS USM or EF 24-70 f/2.8L USM

[TheKingInYellow]

I've been making some big upgrades lately, including the shiny new EOS 7D that is sitting on my desk right now. My last major purchase for the foreseeable future is my standard zoom. This one is driving me nuts, far worse than trying to decide between the 5D2 and the 7D.

EF-S 17-55 f/2.8 IS USM
PROS:
IS, basically the equivalent of f/1 light gathering
Slightly cheaper
Better wide end for a crop body

CONS:
Known to collect dust internally
No hood
No carry pouch

EF 24-70 f/2.8L USM
PROS:
Basically perfect glass
Weather sealed
Better construction
L resale value

CONS:
No IS
A little long on the wide end for a crop body

The only real weakness of the L is the lack of IS. If I want hand-held indoor ambient light shots the 17-55 has a *huge* advantage here. However, this will be primarily a walk-around and portrait lens, neither of which would derive a huge benefit from IS. I don't need a ton of reach either, I have the 70-200 f/2.8 for that.

Given that the costs are almost identical, I just can't decide... I need your opinions please!

[OsmosisStudios]

Originally Posted by TheKingInYellow

EF-S 17-55 f/2.8 IS USM
PROS:
IS, basically the equivalent of f/1 light gathering

This is so wrong. So so so wrong. It's f/2.8 light gathering with a 2 stop IS. IS is NOT light gathering.

Originally Posted by TheKingInYellow

EF 24-70 f/2.8L IS
(...)

CONS:
No IS

The only real weakness of the L is the lack of IS.

You're contradicting yourself. You've listed it as having IS but it doesn't.

In either case, it depends on what other lenses you have or are planning. If you intend to have an ultra-wide, then the 24-70 makes more sense. If not, then the 17-55 makes more sense.

[private]

24-70 - that way it'll work if you ever decide to go FF

[TheKingInYellow]

Originally Posted by OsmosisStudios

This is so wrong. So so so wrong. It's f/2.8 light gathering with a 2 stop IS. IS is NOT light gathering.



You're contradicting yourself. You've listed it as having IS but it doesn't.

In either case, it depends on what other lenses you have or are planning. If you intend to have an ultra-wide, then the 24-70 makes more sense. If not, then the 17-55 makes more sense.

To your first point, I know that IS does not affect aperture, but it does affect your ability to gather light by giving you stable, crisp images at longer shutter speeds. Light gathering is both aperture and shutter speed (and ISO) so it does affect your ability to gather light.

And the 24-70 does not have IS, I meant to type USM, not IS.

[TheKingInYellow]

Originally Posted by private

24-70 - that way it'll work if you ever decide to go FF

This is a good point, I would need to replace my macro as well though, so I'm reluctant to do so.

It's a fairly big part of my decision to get the 7D over the 5D2 (along with the vastly improved AF).

[Dirt_Bike_Ryda]

i'd go the 24-70 on the gounds that it is an L series lens, if you want a wider lens. get the 16-35 lens

[OsmosisStudios]

Originally Posted by TheKingInYellow

To your first point, I know that IS does not affect aperture, but it does affect your ability to gather light by giving you stable, crisp images at longer shutter speeds. Light gathering is both aperture and shutter speed (and ISO) so it does affect your ability to gather light.
.

IS allows you to use a slower shutter speed, but does NOT gather any more light. IS is a bonus. It alters your ability to use slower shutter speeds in certain situations, but wont help with any kind of movement other than your own.

People rely far too much on VR/IS/OS/whatever.

[TheKingInYellow]

Originally Posted by OsmosisStudios

IS allows you to use a slower shutter speed, but does NOT gather any more light. IS is a bonus. It alters your ability to use slower shutter speeds in certain situations, but wont help with any kind of movement other than your own.

People rely far too much on VR/IS/OS/whatever.

So are you saying shutter speed has nothing to do with gathering light? Exposure is a function of ISO, aperture and shutter speed, right?

I'm not trying to be argumentative, but I fail to see how enabling longer shutter speeds doesn't improve your ability to get proper exposures in low light...

[GadgetRick]

I would get the 24-70. I have the older version (28-70) on my 50D (crop body) and it hardly ever leaves the body.

Also, you'll notice most pros also have a version of this lens and use it quite a bit as well.

I've never found the lack of IS to be terribly limiting with this lens. It's a nice to have, not a need to have in this range (imo).

It is also one of the better lenses out there.

[inkista]

Originally Posted by TheKingInYellow

I'm not trying to be argumentative, but I fail to see how enabling longer shutter speeds doesn't improve your ability to get proper exposures in low light...

Try it on moving subjects. Then you'll get it. Using stabilization isn't the same as having a larger aperture is all that OS was saying. IS in no way is the same as actually having f/1.0 as a max. aperture on the lens. You won't get the DoF, or the faster shutter speeds you could with a wider aperture. Also, I agree that the three-stop estimate is overly generous. I've consistently gotten only two stops out of IS on my 24-105, not three, despite Canon's marketing claims, and iirc, the 17-55 has the same 3rd-generation IS as the 24-105.

Not to mention, that your own handholding technique will give you a lower bound at some point on shutter speed. IS is not like a larger aperture, neither does it mean you can throw away your tripod.

What is more like having a wider aperture is having a digital body that gets good clean high iso, because that way you get the shutter speeds and the light. Still don't get the paper-thin DoF, though.

To me, the decision comes down to what you want the lens for. The 17-55 is going to be a better landscape/environmental portrait lens, the 24-70 L a bettter available-light portrait lens. Both have great resale value. Both have great optical quality. To me, it mostly boils down to: how much do you need the 17-24 range?

Me, personally? If I'm chasing low-light, I go for a fast prime. Give me f/1.2 over f/2.8+IS any day. I can always use a monopod. I can't always get a higher shutter speed.