canon/sigma f1.4 prime vs sigma 17-50 2.8?

[kin2son]

Canon 17-55 is overpriced. I vote for Sigma as well

[hazwing]

One other question that might sway be back towards the sigma 17-50. I take photos of smallish objects for a blog I do (generally ranging from ~5-15cm in size). At the moment I am using my compact camera's macro setting. The sigma 17-50 has a closer minimum focus distance and also has a longer focal length. Will the 17-50 be able to take close up shots such as this:

https://picasaweb.google.com/1131475...eat=directlink

[5W0L3]

^ those pictures aren't really macro to be honest.. they look like they were taken using a non-macro lens.

You can use both 17-50 or 30 f/1.4 and then crop out to make whatever you are shooting look that close.

[FEChariot]

http://www.the-digital-picture.com/R...mp=2&APIComp=0

Not a great comparison here because these examples are using different bodies, but from my own experience using both the 30/1.4 and 17-50 OS, the prime doesn't really gain sharpness over the zoom at the same apertures.

For corners, the 30/1.4 needs f8 to f11 to catch up with the center and by then it is starting to be limited by diffraction in the center. The 17-50 is sharp in the corners at f4 to 5.6.

Of the two I use the 17-50 more often, but the 30/1.4 is nice to have for when I want faster than 2.8. Most of the time for me the 30/1.4 is used 1.4 to 2.8 in good light where I am trying to get more blur in a loosely framed environmental portrait than I can get at 2.8 with the 17-50. I do use the 30/1.4 as a light pump for when I can't use flash in low light, but I expect a much lower keeper rate when I am doing this. Note that I don't see this as a lens fault but a limitation of the EOS focusing system needing enough light to focus in and having enough contrast. At f1.4 and ISO's of 3200ish, we are talking about low lighting levels and this is what limits the EOS system. In good to medium light, but the 17-50 and 30/1.4 are quite accurate in AF especially in one shot mode.

How happy are you with the 18-200? If you are happy with it, the 30/1.4 might be the ticket because it gives you more aperture options. Having said that, either of the 17-50 or the 30/1.4 are going to blow the 18-200 out of the water in IQ.

[hazwing]

Well after a bit of consideration and looking at sample images, I'm probably going with the sigma 30mm 1.4. I'll keep the sigma 18-200mm II as my walk-around lens for now... to my untrained eyes, the images in the 18-100mm range generally seem sharp enough for my purposes.

If I decide I need to upgrade to another walk around zoom that is sharper, I'm thinking about the canon 15-85mm (orpossibly the sigma 17-50)