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I bought this lens after a trip abroad; I was getting incredibly frustrated with the frequency I had to change lenses and this lens has put an end to that.
The first thing I noticed upon opening the box was the weight of the lens. Despite it's frankly ridiculously low price, this lens is very solidly put together. Whilst not being necessarily attractive (is there an attractive lens?) it looks exactly as good as it needs to; the finishing is adequate and it's got a nice texture to it. The zoom ring has a good textured grip and turns without too much resistance, whilst retaining enough not to feel loose. There is nothing about the appearance or build of the lens that should lead anyone to doubt its quality.
Autofocus is snappy at 18mm and a bit slower at 200mm, but still far from problematically slow. It can sometimes hunt for focus a little bit at 200mm, but this is almost completely eradicated below about 180mm. When manually focusing, there is a slight grinding sound and turning the focus ring isn't entirely smooth. This can be a little off-putting, but it's more of a psychological thing and there really isn't any reason to worry about it.
The image quality of this lens is really the only area where its low price makes itself apparent, and even then, only really towards the 20mm end. Images taken at 18mm are as sharp as all but the best prime lenses, and this trend continues until about 100mm where the image quality does degrade slightly. This is not to say the images are horrible, just not quite as clear as at the wider end. There's no real noticeable distortion for the majority of the lenses available focal lengths, with the most distortion being visible at 18mm and dropping off sharply after that. This only notices when there are lots of straight lines towards the edges of the frame, and for day to day photography would barely notice. The lens hood is essential for almost any shot taken with this lens because it doesn't handle glare very well.
The maximum aperture is a paltry f/3.5 at 18mm and f/6.3 at 200mm, which means a steady hand or a tripod can often be a benefit. For the most part this lens is really a travelling lens, meaning most shots will be taken outside in good light, negating any problems with gathering enough light. In low light, a flash or a tripod is really the only option to obtain a good shot. High numbers can often worry people looking for narrow depth of field for a nice distinction between the subject and background, and although this lens won't give you the creamiest bokeh, it will do more than enough to emphasize the subject.
Overall, this is a fantastic general purpose lens at a great price; I paid £170 and would consider it to be worth twice that. Whether you're travelling or just don't like changing lenses, unless you're earning your crust from photography, this will not let you down.
When I first started out in SLR photography I wanted zoom, zoom and more zoom......A bit like a tech geek who wants more RAM for his PC as he thinks it makes it 'better' But as I became more involved with taking photos it turned out that I had an epiphany, that zoom wasn't the be all and end all of something especially if you wanted to take a wide angled shot of the pristine Snowdonian landscape in rubbish weather which involved taking that massive zoom lens off to put a smaller wide angled lens on, water and dust and dirt would creep into the sensor and before you knew it you had rubbish photos anyway.......Step forward the amazing utility lens which has both wide angled and telephoto capabilities all in one convenient lens.
The Sigma 18-200mm lens was the second telephoto lens that I had bought after my 55-200 lens which gave me a much larger range of photos that I could take with it. Having a Canon camera is ideal as so many third parties make decent products for them and although you cannot beat official Canon glass, this sure comes close as the price is amazing compared to Canons official offering.
The construction is fairly solid not feeling too plasticy but with a pretty decent weight behind it. Although this could be problematic when placed on a tripod at its maximum zoom, I have found that just by using your camera bag as ballast for the tripod your worries are soon overcome. Yes you do stick out like a sore thumb when you thrust out the zoom barrel at maximum zoom and the motor is hardly the most silent making wildlife photography pretty frustrating at times, but I use this lens when I go out travelling. Rather than miss a sunrise scene in a village of quirky culture in Tibet by having to swap over lenses you can take the wide angled mountain shot, capture that Tibetan Buddhist prostrating, capture the yak grazing and also that Tibetan shop keeper making trinkets to sell to tourists all in a twist of the wrist and a click of the finger. In my opinion one of the ultimate travelling lenses.
The aperture isn't fantastic though and only has an f stop rating of 3.5-6.3 which is pretty slow compared to other lenses but this is the compromise of having a zoom scope of 182mm...........Taking photographs in low light is OK not fantastic but passable and the quality of the photos produced by the lens are still way above anything you would get with a normal digital camera lens.
One annoying thing I have found with the lens though is that when you put your camera away or even have it facing the ground, the lens is succeptable to 'lens creep' which means that when you have put your lens in the exact place you want it but suddenly it slides out of the zoom you want and extends fully. What would have been better was if Sigma had made the lens lock available for all lengths and not just 18mm. A small gripe in an otherwise fantastic lens.
In a nutshell if you are looking for a budget lens that can do pretty much anything and can capture almost any image that you want when you are off seeing the world then I recommend this lens. It has been a permanent feature on my Canon 1000D for the best part of 2 years now and have not taken it off. It has seen 3 different continents and has even been licked by a panda, in Iceland I dropped it in snow and it still works like a charm, focuses pretty quickly and is just a gem.
My advice though is put a lens filter on it, either a polarising filter or a UV filter because the last thing you will want to do is get this baby scratched.
In my opinion a fantastic lens for a fantastic price, it will not disappoint.
I bought this lens after a massive amount of research, I wanted to find a lens that compromised of two possible lens into one big lens so it would be easier to carry around. I also was feeling very limited by the current lens I had which was Canon 18-55mm basic kit lens.
Most important thing I focussed on was the focal length; 18-200mm. It has an optical zoom of 11 times. This lens has a maximum aperture of F/3.5-6.3. One of the main issue with this lens is that when at 18mm, it has a maximum aperture of F/3.5 but move to 200mm, the max aperture increases to F/6.3. This is annoying as you have to control the lightning even more than you would have to. Also, at 200mm the picture quality tends to deteriorate whatever you're taking a picture of, the sharpness declines. This can be fixed in photoshop/ Lightroom, which is acceptable for an intermediate user but a bit unsuitable for a complete novice.
With the focal length this lens has, a person may get mistaken and think this is a suitable lens to do macro photography. It isn't. Because the lens has not been adapted to do close photography; the minimum focal distance is 0.45m. However, from my experiences so far, the optical quality of the lens has been very good, there is a lot of detail in my photos and I am able to focus on anything I want, making sure it's further away from 0.45m. At its lowest aperture, the lens performs wonderfully as it produces great 'bokeh' photos'; where the background is very blurry, making the focus of the picture stand out even more.
One of the main things about this lens is the quality of the build; even though it has rubber rings and such, it feels really solidly made and quite heavy; which has increased my confidence in using this lens. But however, it is not that heavy that you can't just travel with the lens; it is a travel lens.
I quite like the lock button where you can just lock the lens so the zoom doesn't change, sometimes when you're taking photos, the zoom may slide and mess up the overall focus of the photo. Sigma has found a way to prevent that.
I am a massive filter user where I just clip on the filters in the front. Previous lens I had, the front element would rotate and mess up the filter's angle, I would have to go back and do it again. The front element of this lens doesn't so it's a massive plus for those who love to use filters!
Even with the cons I may have presented here; I think it is worth the price I paid for it which was £220. I think it is a fantastic product for the price!
the sigma lens we have found as avey high quality product , we went round california and found this great as a travel lens, because it gives you huge focal options from one lens cutting down the need to carry another lens. not having to change the lens means less chance of getting dust on the camera sensor and also not missing that breath taking picture!
i find this lens as high quality as other more expensive brands, it is a good size and not too heavy and very easy to fit, sigma also make for a wide range of cameras but you have too make sure you buy the correct lens that fits your camera.
i would rate this lens very high as i say it has travelled along way and taken hundreds of pics and the quality is very proffesional, we are very pleased. a great all round product!