D7100 upgrading from 18-55 II kit lens

[SquarePeg]

Or are there other parts of the image quality that would improve with another lens, that doesn't come across as well without comparing images side by side?

Not IQ related, more about function, but a big advantage of the Sigma 17-70 is the short minimum focus distance. You can use it as a "macro" and get right up to your subject. Of course the 2.8 aperture is a plus over the kit kens, especially in low light situations. Also the background blur is easier to accomplish with the longer focal length and short focal distance. I don't know if the 17-50 has the same advantages...

 

[Marinlik]

Or are there other parts of the image quality that would improve with another lens, that doesn't come across as well without comparing images side by side?

Not IQ related, more about function, but a big advantage of the Sigma 17-70 is the short minimum focus distance. You can use it as a "macro" and get right up to your subject. Of course the 2.8 aperture is a plus over the kit kens, especially in low light situations. Also the background blur is easier to accomplish with the longer focal length and short focal distance. I don't know if the 17-50 has the same advantages...

Is this mostly because of the lens I'm looking at, and the price range? So if I where to get a prime lens for example, or a more expensive zoom with a lesser range, the IQ would improve? Or has the kit lens become so good that switching is more about getting better bokeh/low apeture, or just getting into other focal ranges than it is about actual image quality improvements?

 

[dannylightning]

the 17-50mm 2.8 lenses are better for low light and sharper than your kit lens, you should get better IQ with out of these

a wide angle lens is not really a every day lens, it is good for indoor shots where you want to get as much of the room in the photo as possible, its good for close up shots where you want to have the subject close to the lens and still get allot of background in the shot, or really close up to your subject get a unique looking photo,

check this link to see what people do with these wide angle lenses.

wide angle lens - Google Search

check out the sigma 17-70mm f/2.8-4 or the sigma 17-50 f/2.8 if your looking for a better lens than you kit lens that is not a ultra wide angel. the nikon 18-55mm VRII is really not a bad lens, image quality is good but there are lenses out there that are somewhat affordable and will give you better IQ like the 2 i mentioned. you can go to flickr.com and in the search bar type in sigma 17-70mm or sigma 17-50mm and you can see images that are taken with those lenses.

if you really want a ultra wide angle than go for it. just know wide angle lenses tend to have lots of barrel distortion and stuff like that when shooting wide so make sure that is really the type of lens you are looking for before you get one. there cool to have but most people i know that own one including my self do not use them that often. i am sure there are people out there that use them all the time but there not really your everyday type of lens for most people.

here are a few shots i took with my sigma 10-20mm f/4 lens the day i got it, i think i have used it twice since i bought it. as you can see some of them kind of warp the picture and make it look funny some look normal. i am not very good with this type of lens, you can get some awesome images with one if you know what your doing with it.