| Sigma 120-300mm F2.8 EX DG HSM Review |



   
 

Intro

I owned a Canon 100-400mm L IS lens which I used for motorsport and wildlife but with an aperture of F5.6 at 400mm and a tendency to produce slightly soft images at this aperture I began researching possible replacements.

The Canon 300mm F2.8 L IS is the obvious step up but with a cost of over £3k it was out of my budget. This got me looking at lenses from Sigma which I thought I would never do (Canon L lens addict) but I figured it's the end result that matters and not the gear used to take it with!

Initially the Sigma 300mm F2.8 prime lens seemed the one to go for; it's sharp, has quick focus and importantly it was within my budget, but whilst reading through some photography forums the Sigma 120-300 F2.8 lens kept being mentioned as a better performer. I found it hard to believe that a zoom could outperform a prime lens so decided to do some research.

I located the MTF resolution charts for both lenses and they revealed that the center of the image on the 120-300 was sharper with better contrast than the 300 prime. Performance on the 120-300 does drop off towards the edge of the frame but as I was going to use the lens on a Canon 20D edge softness wasn't going to be an issue.

Sigma MFT Charts

Sigma 120-300mm F2.8

  Sigma 300mm F2.8


Key

X Axis
0 Center of Frame,
20 Edge of Frame

Red line = Contrast
Green Line = Sharpness

  



Y Axis
Higher up the chart the better the lens


Auto focus speed was reported to be quicker that any other telephoto zoom lens (Source : Motorsport photographers on Photography On the Net forums) so it was beginning to look like this was the lens to buy so I took the plunge and ordered one.

First impressions

The lens is big !!! The front element is 105mm and it weighs 2.6kg.
It comes in a fairly large box; also containing an over the shoulder carry case, tripod collar and a cover for the front lens element.

One of the things I was expecting to be an issue was the weight; 2.6kg is approximately twice as heavy as the Canon 100-400L but when lifting the lens out of the box for the first time it didn't feel as heavy as I was expecting it to be. I guess being a regular gym user helps :)  More on weight later in this review.
The big rubber ribbed rings for manual focusing and zooming have a good grip, are easy to operate, well damped and both are within fingertip range when supporting the lens with the left hand under the tripod collar.
Both zooming and focusing takes place internally so the length of the lens does not change. Therefore there is pretty much no change in the center of gravity which makes the lens very well balanced. Focal lengths are marked at 120, 150, 180, 200, 250 and 300mm. There is the option to screw on 105mm type of filters.
  Moving onto the lens hood; this must be locked with an adjustable knob and mounting it takes some getting used to - you have to look carefully on how to slide it into the bayonet fitting. When attached it is solid and you can put the lens and camera on it in a vertical position. The hood can be reversed fitted for storage. It lacks the soft anti-reflective inner lining that the Canon examples have. The hood is much smaller than ones found on 300mm prime lenses because it is constructed not only for an 8 degree view angle at 300mm, but also for a 20 degree view angle at 120mm. This to prevent vignetting at the short end of the range.


The tripod collar on the newer DG version of this lens is much better. The plate where you attach a tripod or monopod is much bigger and it can also be used as a carrying handle. If you buy a non DG model then I would advise you to buy the new collar as it improves the handling characteristics, but it expensive; around £100.

Lens test and comments

Sports photography is the primary market for the Sigma 120-300mm F2.8 but there are other good uses for it. On a full frame body, compressed portraits are one. On a 1.6x crop body or with extenders, wildlife is another.

 












DG and non DG Tripod Collars

At 300mm F2.8 depth of field is very shallow; this is one of the plus points of this lens. It allows subjects to 'pop' out of the frame and gives very creamy backgrounds. Stopping down the aperture (F4) will increase the sharpness even

more and also increase the depth of field. Shooting at 2.8 at close range demands a perfect auto focus technique as the margin of error is very limited because of the shallow depth of field. For example : at 300mm F2.8 with a subject distance of 10 meters depth of field is just 1.2cm (On hundred and twenty millimetres.

Minimum focus at 300mm is 2.5 meters moving down to 1.5 meters at 120mm.

I intend to use this lens with a 1.4x extender (168-420mm F4) and a 2x extender (240-600mm F5.6).

The test shots below show how the lens stacks up with the extenders fitted. Click on any of the images to view a larger size.

  

300mm F2.8
Click to view a 50% Crop of the full image

A major plus of the Sigma is the ability to attached a 2x extender for a focal length of 600mm and still achieve auto focus on all Canon camera bodies; aperture of F5.6. Image quality and auto focus speed will suffer a little but as this photo shows it's still possible to get very high quality images of fast subjects using this setup.
 
1.4x
420mm
1/800
F7.1
ISO 400

Click to vew larger

Click to vew larger
 2x
600mm
1/320
F11
ISO 400
     

A slight downside is the lens weight; coming in at 2.6kg it requires strong arms for continued use or a support. This is the same across all long telephoto F2.8 lenses though.

I've found I can use it handheld for several hours without fatigue but I will be buying a monopod to help support when shutter speeds start to get down to the 1/focal length rule.

     

Conclusion

Comparing this lens to the Canon 100-400mm L IS the Sigma wins easily in both sharpness and focus speed. The constant 2.8 aperture means the Sigma can be used at much quicker shutter speeds compared to the Canon F5.6 aperture from 280mm and this really helps when shooting sports events indoors or under dull light.
Even with a 1.4x extender fitted to the Sigma aperture is F4 at 420mm and the image quality is at least equal if not better.
 
I preferred the push-pull zoom design on the Canon as it makes changing focal length very quick indeed but adjusting to a twist zoom shouldn't take too long to get used to.

The build quality on the Sigma is also better; it feels much more robust.

One downside to the Sigma lens is there is no Image Stabiliser (IS). Having owned the Canon for over 4 years I had got used to getting sharp images at 400mm right down to a shutter speed of 1/80 and clearly the Sigma won't be able match this. However with the F2.8 or F4 (420mm) aperture the shutter speed can be bumped up 2 or 3 stops above what the Canon could stuck at F5.6. Also IS is not really essential when shooting motorsport subjects.

Overall I highly recommend the Sigma 120-300, though not a cheap lens, it is a decent value.

I will be using the lens at events throughout 2008 so check back for more images.