Kit lens vs Sigma 18-125 in-store comparison

Started Apr 2, 2005 | Discussions thread
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Kit lens vs Sigma 18-125 in-store comparison
Apr 2, 2005

I've been torn for a long time now between either getting the kit lens (which I loved on my 300D) or the Sigma 18-125 to accompany my upcoming 350D. after reading the pro's (sharpness, contrast) and con's (autofocus noise and accuracy) here, I decided to order the Sigma online and later buy a body only 350D. but just before I placed my order, I decided to walk into a local store to try out the real thing myself. since I have no camera myself at this point, I used the store's 300D.

first I weiged both lenses in my hand - I don't know the exact specs, but the sigma was almost twice as heavy. in my book, that is a minus. I much prefer a light camera and a light lens. I usually shoot 4, sometimes up to 6 hours straight (at events) and those are the times when you really start to appreciate the lightness of your setup. consequently, a 300D with the 50mm F1.8 is my favourite combo. for extended shooting, I'd definetly prefer the kit over the sigma as far as weight goes.

then I mounted the kit and tried focusing at objects around the store and through the window. half-press/focus, half-press focus, the kit focused almost instantaneously and accurately (at least as far as I could see in the viewfinder) every single time. just like I was used to with my 300D/kit combo.

then I mounted the sigma and did the same. half-press/zzzzzzzzzm/out-of-focus. whoa! first of all, focusing seemed like two or three times slower than that of the kit lens and secondly, when it locked focus, it was quite often very obviously OUT of focus! tried focusing around the store and the only thing consistent about the focus was its inconsistency and slowness compared to the kit. half-press/zzzzm/almost-in-focus, half-press/zzzzzzzm/way-out-of-focus, half-press/zzzzzzzzzm/in-focus, half-press/zzzm/way-out-of-focus, half-press/zzzzzzzzm/almost-in-focus etc.

I now tried constantly re-focusing on a single contrasty item without moving the camera. first I tried this with the kit lens. as before, the kit nailed the focus correctly the first time and when refocusing, didn't either move at all or refocused just a tiny bit. taking my eye off the viewfinder to see what the focus ring was doing, I saw it was hardly moving with every new refocusing. the kit was pretty sure where the focus was and stayed at it.

trying the same with the sigma, it sometimes focused, sometimes almost focused and sometimes completely missed focus, all while I wasn't moving the camera at all and was just refocusing on the same object. taking my eye off the viewfinder I saw the sigma's zoom ring twisting left and right quite violently each time I refocused on the same item. it was clear the sigma had only a very vague idea where the correct focus should be and was playing a hit-and-miss game. the store was fairly well lit - I dare not think how the sigma would have pefrormed in even less lighting.

I know this is not an image quality comparison and it was hardly scientific. and I know I may have ended up with a real bad copy of the sigma to test. nevertheless, I'd never know what kind of copy I get from ordering online. and since I do a lot of split-second spontaneous action photography, a combination of both slow and unaccurate autofocusing is the LAST thing I need (but please no advice on getting USM lenses then, it is still just a hobby for me:). even if the resulting pictures with the kit lens are less sharp and contrasty and have less reach, I'd take the fast and accurate focus of the kit over the much slower and very iffy focus accuracy of the sigma any time of the day.

...or maybe I just got a REALLY bad sample of the sigma? still, it scared me enough to decide to buy the 350D with the kit lens instead once the 350D is available where I live.

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