Matching lenses for my new Rebel XSi??

Neither one of those shots really contain bokeh... there are no points of light in the background. Bokeh is not just anything that is outside the depth of field in an image. It refers specifically to points of light.

http://en.wikipedia.or​g/wiki/Bokeh

Any way, I REALLY don't want to argue. I think people put too much weight on the low price of the nifty and forgive perhaps too many flaws.

PhatheadWRX wrote in post #8295809
The optics on the 17-55 are regarded as L quality. Its just the build quality that isn't up to L standards (also Canon does not have any EF-S [crop] lenses as Ls).

http://www.the-digital-picture.com …8-IS-USM-Lens-Review.aspx
look about half way down the page and there is a GMC picture where you can mouse over the quality difference between the two

The 18-55 IS has great optics for the price. But the 18-55 is variable aperature from 3.5 to 5.6
The 17-55 has constant 2.8 aperature (as fast as you get for current Canon zoom lenses)

Therefore, if your 18-55 @ 55mm wide open (5.6) needs a 1/30" shutter, the 17-55 @ 55 wide open (2.8) can shoot the same ISO at 1/120". Thats a huge difference in speed.

However, the 17-55 is almost 7x the price of the 18-55 (~$1000 vs $150). That's why I said, "if money was no object"

I see -- thanks for the explanation!

imahawki wrote in post #8295844
Neither one of those shots really contain bokeh... there are no points of light in the background. Bokeh is not just anything that is outside the depth of field in an image. It refers specifically to points of light.

http://en.wikipedia.or​g/wiki/Bokeh

I think that my examples include what most people consider (or look for in) bokeh. I don't have a lot of outdoor examples, but here is one with more light (yes, it's a bit overblown, but that's how I like this particular photo.) Also, you can see the sharpness and detail on my examples. The 50/1.8 is a good lens:

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imahawki wrote in post #8295844
Neither one of those shots really contain bokeh... there are no points of light in the background. Bokeh is not just anything that is outside the depth of field in an image. It refers specifically to points of light.

http://en.wikipedia.or​g/wiki/Bokeh

Any way, I REALLY don't want to argue. I think people put too much weight on the low price of the nifty and forgive perhaps too many flaws.

I DO want to argue here, because the wikipedia is incorrect here, and to me it seems the author did not necessarily read the references referred to in the Wikipedia piece in their entirety. It is about OOF blur, or rather, the quality of OOF blur, not only about the rendering of OOF points of light or specular highlights. And this is mentioned in those referenced articles more than once.

Yes, it is very easy to see the characteristics of OOF blur in OOF highlights, but that is all there is to it. OOF specular highlights are just part of the general concept of bokeh.

Kind regards, Wim

YankeeMom wrote in post #8295892
I think that my examples include what most people consider (or look for in) bokeh. I don't have a lot of outdoor examples, but here is one with more light (yes, it's a bit overblown, but that's how I like this particular photo.) Also, you can see the sharpness and detail on my examples. The 50/1.8 is a good lens:


Esp. for portraits:



I'm not trying to convince YOU to use yours, but the OP might want to seriously consider it, esp. if money is an issue.

You are entirely right. It is an excellent lens, and your photographs prove this (and that you are a good photographer). The only thing lacking in this lens is build quality. However, the latter is amply reflected in the price, so that, IMO, is completely acceptable.

The same is with all the focusing problems a lot of people seem to have. So far I have tested and/or owned 6 specimens of this lens, and 1 of the Mk I, and have never had a problem with focusing. And this is one lens I have used almost entirely for low light shots. The only thing that can be said is that focusing with this lens is a tad slow.

Kind regards, Wim

wimg wrote in post #8296790
You are entirely right. It is an excellent lens, and your photographs prove this (and that you are a good photographer). The only thing lacking in this lens is build quality. However, the latter is amply reflected in the price, so that, IMO, is completely acceptable.

The same is with all the focusing problems a lot of people seem to have. So far I have tested and/or owned 6 specimens of this lens, and 1 of the Mk I, and have never had a problem with focusing. And this is one lens I have used almost entirely for low light shots. The only thing that can be said is that focusing with this lens is a tad slow.

Kind regards, Wim

Thanks. Yes, I agree that the make of the lens is not heavy-duty at all. IOW, I wouldn't want to drop it. It feels like plastic on the outside. But that's a good compromise for the quality and price.

YankeeMom wrote in post #8295746
I'm just curious -- is the 17-55 IS much better than the 18-55 IS? What is the difference? Thanks!

I have both. There is very little difference in image quality between the two, which makes the 18-55 IS an amazing lens for the money.

But there's more to a lens than IQ:

- aperture at 17 or 18 mm is only a half stop difference, no big deal, but at 55 mm two stops is a big deal;

- the f/2.8 max. aperture allows many Canon DSLRs to use high precision focusing (available only at 2.8 and faster);

- the f/2.8 aperture allows quick focusing in very poor light;

- the ring USM focus motor allows manual touch-up of focus;

- the ring USM focuses very, very quickly;

- build is better.

So is it worth 8 times as much? It is to me, but certainly not to everyone.

-js