Lens Dilemna (24-70 17-55IS thread)

So I have a 40D and am primarily doing indoor candid shots (new baby). I currently have a 24-70 2.8, and a 50mm 1.4.

My conundrum is often times with the 24-70 wide open, I just don't wind up with enough usuable light to get a decent shutter speed for my hand it seems. The 50mm at 1.4 does better obviously, but the sneaker-zoom, and shallow DOF when shooting it wide open result in lots of messed up shots.

My question is about the 17-55 IS. How much slower on the shutter speed can you reasonably expect to get for lets say 40mm shots?

Also, for shots in the 24-55mm range, is there really a noticable quality difference between the 24-70 and 17-55? Or is any improvement the 24-70 have washed out by the IS on the other lens?

Anyhow I'm just trying to figure out if I should add the IS to my lineup, and if so should I get rid of the 24-70. The only bigger dilemna is figuring out where to ship the thing if I do buy it so the wife won't see the package.

Thanks in advance for any help

djscrib wrote in post #4759089
My question is about the 17-55 IS. How much slower on the shutter speed can you reasonably expect to get for lets say 40mm shots?

You should be able to handhold at pretty slow shutter speeds (probably down to 1/15 @ 55mm), but babies, and people for that matter, tend to move--so if even though you can handhold and get a sharp picture, anything under 1/60 is a little slow for people pictures IMO.

Certainly a 17-55 is a sweet lens, as is the 24-70, but personally I'd consider getting a flash and keeping your shutter speeds up.

I have a 580ex2 for a flash, but am trying to "blend in" slightly better at social gatherings. I can sort of get away with it with the camera, but add on the flash and it's not so inconspicuous.

I had looked at the primes, but figured they would have similar problems to the 50mm 1.4 for thin DOF issues. I guess i was hoping the IS would provide me the ability to shoot at 1/30 or so at 2.8 and get sharp images.

I gotcha, I'm the same way--a lot of times I prefer to be inconspicuous so I just use a prime and deal with the shallow DOF. Personally I found that the f/2.8 just wasn't quite fast enough for indoor low light stuff--not because I had trouble with shake, but more because my SS was around 1/30 or lower and if people moved at all, they were a blur.

As both are f/2.8, you're only going to get so far without flash. That's part of the reason I stick with my 24-105mm f/4 which is sharp as hell, and supplement with a 580EX II. That being said, you may want to look at a 35L or 24L. Both are f/1.4 so they're as fast as your 50mm, but wider for those indoor shots.

35L is my next lens!

Well here's a related question. How do you determine if you have a steady or shaky hand?

Sounds like a simple question but its kind of like something like 80% of drivers say they are above average.

So if I had a shaky hand, then IS would help a lot, less shaky, it would probably help less.

I wasn't sure if there was the equivalent of focus charts for setting up gridlines or something at a fixed distance and taking a photo to gauge "shake blur".

djscrib wrote in post #4760002
Well here's a related question. How do you determine if you have a steady or shaky hand?

Sounds like a simple question but its kind of like something like 80% of drivers say they are above average.

So if I had a shaky hand, then IS would help a lot, less shaky, it would probably help less.

I wasn't sure if there was the equivalent of focus charts for setting up gridlines or something at a fixed distance and taking a photo to gauge "shake blur".

Assume the 1/focal length (or 1/1.6x focal lenght for 1.6X cameras) applies to you unless you have a good reason to think you are better.

Personally with non-IS lens I try to get 1/3 or 2/3 stops faster than the 1/focal length rule with my 5D. By 2/3 stops I can pretty much count on not losing any shots to me shaking.

So for me with an 85mm lens for instance:
1/125 - All keepers
1/100 - Nearly all keepers, sometimes I think I see the faintest hint of softening.
1/80 - Most keepers, a few to chuck and I think more get that hint of soft.
1/60 - Lots in the chuck bin
1/40 - Most in the chuck bin

If you are a nationally competitive pistol shot or a neurosurgeon perhaps you will be a lot better than this. Don't count on it though.

The other IS consideration is that people who are awake and talking can't really be shot below 1/60, and 1/80 is better. Even then you will lose a few to moving mouths and hands.

Sleeping babies can be shot down to 1/15 or even slower if you like.

People who are posing and holding still might be OK to 1/40.

I've had both. Had the 24-70 first then sold it to get a 17-55. The 17-55 is not an L but if you can get over being in the lowly Non-L crowd, I think you'll be fine. I think the image quality of the 17-55 matches that of the 24-70.

24mm was just too wide for me on a crop body. Especially if you're primarily shooting a lot of indoor shots....chasing the little one's around. 17mm is awesome for indoor shots. My 17-55 is my everyday/walk around lens. Wouldn't be caught without it. BTW, I have 4 and 5 year old kids that move around a lot faster than those newborns!

Maybe rent the 17-55 for a week to see if it helps your decision.