17-55 f/2.8 IS..should I buy one?

If you decide on the 17-55IS, get the lens hood for it. There are certain situations which can cause some flare, (like most other lenses) this lens works better in those situations with a hood.
I've had mine for about 1 year, no dust issues to date - and no filters other than polarizer when needed. I clean out my 20D regularly, a while back I had a 17-40 with some dust from inside my camera, since I started regular cleaning (dusting really) i have had no issues.

I've no dust in mine, but I did put a filter on as soon as I opened the box.

bacchanal wrote in post #3833439
I'm not saying the Tamron isn't a great value, but it doesn't have USM and it's more like 1/2 the cost (in the US). The new version of the Sigma 18-50 is supposed to be pretty good too....and if you like playing the waiting game, there is the Tokina 16-50.

when I got my 17-50 it was $390, and currently the 17-55 is $999 (and the Tamron is $409). not quite 1/3 but definitely less than 1/2. have loved mine, and while I would have gotten the Canon if I had the extra $600, it wasn't worth it to me at the time. the only thing I miss is the IS, as my indoor shots have to have the ISO bumped, as 2.8 doesn't quite cut it. not sure whether it's worth the extra cash to me, though, but that's where your mileage may vary (YMMV).

I keep the 30D because I decided to keep the 17-55/2.8IS as there is no alternative in the market for this lens for FF ( I have a 5D). Mine has no dust issue as I have put filter on from day one. But I did see some copies out there got quite dusty inside.
The AF is very fast, accurate and very quiet. Image produced from this lens is VERY sharp! Only contrast and saturation may lag behind the L's. I would replace it with 24-70/2.8L IS or 24-105/2.8L IS without a blink if canon eventually made those lenses. But for now , I will have to keep this lens.

This is the lens to have for a crop body. The first week I had this lens I took over 1k shots. Absolutely wonderful lens. I would recommend putting a UV filter on it but get a good one like a B+W MRC. Fantastic addition to this lens.

Here was my first duck shot with the 17-55 IS.

HTTP response: NOT FOUND | MIME changed to 'image/png' | Redirected to error image by ZENFOLIO PROTECTED

Dust we dont see no stinkin dust
yah man its a good lens

As noted, there have been a few copies with dust problems. Also as noted, the dust doesn't seem to affect image quality.

I've looked carefully at my two Canon zoom lenses (24/105L and 17/55). The quality of the build is not the same; the 24/105 is obviously better built.

As for the dust situation, the major difference in the two lenses can be seen when one attempts to slip a thin piece of cardboard between the zoom ring and the barrel. On the 24/105, the cardboard stops very quickly against what feels to me like an O-ring, whereas on the 17/55, there is no seal, and the cardboard slides in easily.

A simple test was done by pushing a 1/4" (6mm) wide strip of light cardboard (really heavy paper) between the zoom ring and the barrel: On the 17/55 I was able to push it 1 3/4" (45 mm) into the lens. On the 24/105, the strip of cardboard won't even go in 1/8 of an inch (2 mm).

The most significant difference in the two lenses is that the position of the zoom and focus rings is reversed, meaning that going from one lens to the other is confusing.

The image quality of the 17/55 is at least as good as the 24/105, and the colour to me seems identical.

I have no dust whatsoever in the 17/55, but I'm one of the idiots that puts a UV filter on every lens. However, considering the lack of a seal between the zoom ring and the barrel, I highly suspect that a major point of entry for dust is at this point. Having always been aware of the potential dust problem, I always wipe the exterior of the lens with my fingers or a cloth to remove any dust that has collected on the barrel at the juncture with the zoom ring as I feel it could be sucked in when the lens is zoomed out (the increase in length results in an increase in volume which can only be made up by incoming air).

IMO, this is a killer lens. Photozone tends to agree:

http://www.photozone.d​e …s/canon_1755_28​/index.htm

Look at the MTF charts for this lens compared to other lenses; very few lenses even come close to, and even fewer exceed, the IQ of this lens. In the centre, it tests better than my 100 mm f/2.8 macro.

One other comment: I use this lens for indoor people shots (birthday parties, etc.). With the fast f/2.8 and the IS, I don't use flash; just set the ISO to 1600, and in a reasonably lit room, flash isn't necessary. One can get a lot of good candid shots with this lens.

Glenn NK wrote in post #3838044
...I have no dust whatsoever in the 17/55, but I'm one of the idiots that puts a UV filter on every lens. However, considering the lack of a seal between the zoom ring and the barrel, I highly suspect that a major point of entry for dust is at this point. Having always been aware of the potential dust problem, I always wipe the exterior of the lens with my fingers or a cloth to remove any dust that has collected on the barrel at the juncture with the zoom ring as I feel it could be sucked in when the lens is zoomed out (the increase in length results in an increase in volume which can only be made up by incoming air)....

This has always been my suspicion as well. It doesn't quite jive that dust is entering via the seal between the front element and zoom barrel. However, the point between the zoom barrel and lens housing seems the culprit, if for no other reason than it just makes sense. As the zoom barrel moves in and out, it has to suck air in and out to compensate for the vacuum it creates.

The front element seal, not so much. It doesn't seem to have a gap anywhere along the perimeter.

However, I'm not about to chance it and the Hoya Pro 1 is never coming off.

Dekka wrote in post #3838331
This has always been my suspicion as well. It doesn't quite jive that dust is entering via the seal between the front element and zoom barrel. However, the point between the zoom barrel and lens housing seems the culprit, if for no other reason than it just makes sense. As the zoom barrel moves in and out, it has to suck air in and out to compensate for the vacuum it creates.

The front element seal, not so much. It doesn't seem to have a gap anywhere along the perimeter.

However, I'm not about to chance it and the Hoya Pro 1 is never coming off.

I believe that dust IS entering through the front. I had a huge issue with dust in my copy - I complained to Canon and had them clean it under warranty. After that it came back clean, and while I was fooling around with a new UV filter, it got a couple of huge flecks in, but since then I haven't taken it off, and it has hardly accumulated anymore.

This seems to be corroborated by the guy who took apart a copy he had and noticed large 'ducts' that came in from behind the front seal.

There is definitely a channel from the front, as you can feel air there when you zoom, that disappears when you have, say, the cap on.

Anyway, I will always recommend this lens - 2.8 with IS, high image quality, and a very versatile zoom range makes it nearly the perfect lens (for 1.6x). However, I will also recommend a UV filter for it too - and I'm generally in the camp of 'don't use a filter unless you need it' (some copies of the 17-55 needs it).

Looks like I will have to get one....

mrkgoo wrote in post #3838495
I believe that dust IS entering through the front. I had a huge issue with dust in my copy - I complained to Canon and had them clean it under warranty. After that it came back clean, and while I was fooling around with a new UV filter, it got a couple of huge flecks in, but since then I haven't taken it off, and it has hardly accumulated anymore.

This seems to be corroborated by the guy who took apart a copy he had and noticed large 'ducts' that came in from behind the front seal.

There is definitely a channel from the front, as you can feel air there when you zoom, that disappears when you have, say, the cap on.

Anyway, I will always recommend this lens - 2.8 with IS, high image quality, and a very versatile zoom range makes it nearly the perfect lens (for 1.6x). However, I will also recommend a UV filter for it too - and I'm generally in the camp of 'don't use a filter unless you need it' (some copies of the 17-55 needs it).

It's not actually a "seal" on the front - I believe "label" would be more accurate.

This front label has a self-adhesive backing and can easily be pried off with a finger nail.
The label OD is considerably smaller than the body ID and if this label IS applied dead centre then you'll have one that IS NOT prone to dust ingress.

With a UV filter fitted I expect that more dust will likely be drawn in at the slip-joint and this dust will reside deeper inside the lens, not just behind the front element where the dust can be seen that enters through the big gaps in the front element mount (past the label).

Ron1004 wrote in post #3839327
It's not actually a "seal" on the front - I believe "label" would be more accurate.

This front label has a self-adhesive backing and can easily be pried off with a finger nail.
The label OD is considerably smaller than the body ID and if this label IS applied dead centre then you'll have one that IS NOT prone to dust ingress.

With a UV filter fitted I expect that more dust will likely be drawn in at the slip-joint and this dust will reside deeper inside the lens, not just behind the front element where the dust can be seen that enters through the big gaps in the front element mount (past the label).

Interesting and enlightening comments that make some sense.

Being able to slide the paper "feeler gauge" 45 mm into the lens, would suggest that dust through this path would get deeper into the lens.

The bottom line though is that the lens is certainly worth getting - it will surely satisfy the most demanding "IQ nut" even with some dust.

Ron1004 wrote in post #3839327
It's not actually a "seal" on the front - I believe "label" would be more accurate.

This front label has a self-adhesive backing and can easily be pried off with a finger nail.
The label OD is considerably smaller than the body ID and if this label IS applied dead centre then you'll have one that IS NOT prone to dust ingress.

With a UV filter fitted I expect that more dust will likely be drawn in at the slip-joint and this dust will reside deeper inside the lens, not just behind the front element where the dust can be seen that enters through the big gaps in the front element mount (past the label).

Interesting...thanks for the comments. Does new adhesive need to be reapplied after removing the label? If so, what is the best? If not, maybe I'll even chance my own hand at taking it apart...

mrkgoo wrote in post #3841505
Interesting...thanks for the comments. Does new adhesive need to be reapplied after removing the label? If so, what is the best? If not, maybe I'll even chance my own hand at taking it apart...

I didn't apply new adhesive, but if needed, I would use that real thin mirror tape, which is what the original stuff looks like.

I'm just going to add to what others have already said. It's a fine lens. Very nice quality and I have to agree with someone else in here who said that you buy lenses to take photos, not to break them.

I am a casual shooter and every now and then I shoot weddings. I don't shoot in the rain forest or the desert. I don't take the lens and throw it at moving animals. Therefore, I don't need "BUILT LIKE A TANK" quality. I care a lot about image quality and the 17-55 delivers.

The 17-55mm and the 70-200mm L is an awesome combination. ENJOY!!!!