Sunday, 20 February 2011

Lens Comparison: Canon 100-400mm Vs Sigma 150-500mm

I've recently bought myself a new lens, the Canon EF 100-400mm f4.5-5.6L IS USM, to use instead of my trusty Sigma 150-500mm f5-6.3 DG APO OS HSM.  I love the Sigma lens, so why the desire to change ...??

I've recently been shooting more wildlife as a result of my wife's interest in all things nature, and her (sorry, "our") desire that we do more together.  She's using my old 350D body and a Tamron 28-300mm lens I bought her.  I've been shooting with my new 7D body and the Sigma lens which, although a fine lens for my more traditional motorsports subjects, has a few restrictions when shooting live animals.

Sigma 150-500mm f5-6.3 DG APO OS HSM
Firstly, animals don't follow a track - they can appear from anywhere and head off any which way they like.  This is particularly the case with those small feathery things which I'm told are called 'burds'!  They're little buggers - they have no respect for the patient photographer who, having sat quietly for half an hour or a little more (I have my limits) appear where you don't expect them and fly off just before focus lock!  So problem #1 - need faster focus.

These 'burd' things also have the annoying habit of sitting in trees, often constructed with a confusing array of branches, which plays havoc with the autofocus - and they won't wait for you to focus manually.  So problem #2 - need better focus with branches.

Canon EF 100-400mm f4.5-5.6L IS USM

Although it's one of the oldest Canon lenses (first released in 1998), it's still on sale for around £1,200 new and is the biggest zoom offered by Canon getting consistent good reviews for image quality.  The only negatives appear to be the weight (but hey, it's a well built big lens so what do you expect!) and, more importantly, a few comments on its propensity to suck dust into the lens and body as it's a push/pull zoom ('trombone' as some people refer to it) rather than the more common twist zoom (as an aside, in my early photographic days my favourite lens was a Tamron 70-210mm push/pull zoom - and I have found this action better on the Canon, but more of that later).

Now, my biggest concern was comparable image quality - by losing 100mm in focal length I would have to crop images smaller like-for-like when using the Canon, so does the reported increase in image quality offset the increased crop?  To find out I did a little experiment ....

Here's the view from my garage at maximum zoom with both Sigma and Canon ....
Straight away you can see the difference in image size due to the 100mm difference in focal length.  I then shot a series of images at different zoom lengths and apertures, all shot in RAW with identical post processing in Lightroom, and then looked at a cropped section from each image; these are both at f8  (click on the image to see a larger version) ....

As you can see, the more heavily cropped Canon image is still better than the Sigma!

How does it perform in other respects?

Problem #1 - Fast Focus:  MUCH faster than the Sigma, that's not to say the Sigma is slow, but the Canon does perform a lot better (but then for the price you would expect it to!).

Problem #2 - Better Focus:  The Canon can certainly focus in lower light/contrast than the Sigma, how much of this is due to it being a slightly faster lens I don't know, but it's definitely better achieving focus lock where the Sigma would not.  It still gets confused by too many branches but it does seem to be better than the Sigma, though this is more perception than side-by-side comparison.  My wife agrees with this (did I mention she bolted it onto her camera as soon as it arrived, and bagged a shot of a Kingfisher before I'd even had a chance to see how it felt!  See it on her Blog if you're interested).

Other considerations:  It's a faster lens, not by that much but every bit helps.  It's a bit lighter and more compact, so my wife prefers it (lovely!).  It's white, and you know what that means!  And I find the push/pull zoom helps me to acquire moving targets (especially those burd things again) and zoom in while tracking the critter much more successfully than I could with the Sigma (you may put that down to bad technique, and you'd probably be right!).

So the Sigma is going to be sold! :(  But no rush on that one!!

I guess only time will tell if the 'dust sucking' reputation is justified.  The lens I bought is a 2003 built lens so it’s been around a while, but is in immaculate condition with absolutely no signs of any dust; does this mean it’s not a problem, or that it hasn't been used very much?!!  I'll let you know how I get on.

August 2011 Update:  Still love the lens, no problems with dust despite plenty of use, one bit of advice I've followed is NOT to 'lock' the zoom to keep the slide action smooth - this does seem to make a difference.  Also found that wide open my example is a bit soft at maximum zoom as some people report, but at f8 it's pin sharp (so my comparison above might differ if you're shooting wide open all the time).  And the Sigma was sold - eventually!