Introduction

Sigma APO 50-500mm f/4-6.3 EX DG HSM is one of those extreme zoom lenses that many lens manufacturers started to introduce to the market in hopes of appealing to those photographers who cannot or don't want to carry and change different lenses during a photo-shoot. However, building a lens that is capable of producing high quality results across such an extreme focal length range is not trivial and the market is now full of rather mediocre lenses covering everything from 18mm ultra wide all the way to 200mm and even 300mm telephoto ranges. It remains to be seen whether Sigma's extreme (is this what EX stands for? just kidding...) zoom has finally succeeded where so many others failed.

The optical construction of the lens consists of 20 (yes, 20!) elements in 16 groups, with four SLD glass elements designed to reduce various forms of aberration. A 10x zoom ratio offered by this lens obviously introduces challenges in the lens optical design, which in turn affects the physical characteristics of the lens - it weights a whopping 1,840g (4.16lb) and measures 95 x 218mm (3.7 x 8.6in) when collapsed, but the lens inner cams extend during zooming and practically double the overall length of the lens. No wonder that many web forum users call this lens BigMa!

Image

The overall build quality is exceptional - Sigma's EX finish in general rivals that of Canon's L lenses, and APO 50-500mm f/4-6.3 EX DG HSM is no exception. Both focus and zoom rings are rubberized and easy to grip. There is no wobbling, even with fully extended inner cams. The lens provides 1:5.2 maximum magnification at 200mm focal length, has the minimum focusing distance of 1m (39.4in) at 50mm focal length and has the minimum aperture of f/22 (like with most modern lenses, aperture is camera controlled, so there is no dedicated aperture ring). The filter size if 86mm. Sigma included a zoom lock switch, which locks the barrel with collapsed cams to prevent it from accidentally extending during transportation. The lens sports a HSM-type AF as well as full-time manual focusing mechanism controlled by an AF/MF switch on the side of the barrel.

The lens is compatible with optional APO tele-converters (tele-converters can be used in 100-500mm focal length range only through). With a 1.4x EX converter, the lens becomes a 140-700mm f/7.3-8.8 ultra zoom and with a 2x EX converter it turns into 200-1000mm f/10.4-12.6 ultra zoom. In both cases you would loose auto-focusing. The factory box includes Sigma APO 50-500mm f/4-6.3 EX DG HSM lens, front and rear caps, LH935-01 lens hood, soft lens case, detachable tripod mount, manual and warranty card. The lens is priced at about US$900 (as of July 2007), making it more or less affordable for serious amateurs.

 

Summary
Lens Composition 20 elements in 16 groups
Angular Field 46-5 degrees
Minimum Focus 1m/39.4in
Focusing Action AF/MF, HSM-type
f-stop Scale f/4-f/22, camera-controlled
Filter Size 86mm
Lens Hood LH935-01 (included)
Weight 1840g/64.9oz
Dimensions 95x218.5mm/3.7x8.6"
Lens Case Soft case (included)

 

Field Tests

I loved the extreme zoom coverage of this lens! Think about it - 50mm to 500mm. This is the extreme of extremes and for wildlife photographers Sigma 50-500mm should be a dream lens. Or something like that. While the zoom coverage is pretty convenient, the image quality of this lens leaves room for improvement. The lens was quite capable at the close end of the zoom range, producing images with very good center and border quality with stopped down aperture. Unfortunately, image quality degrades towards longer end of the zoom range, and stopping down the aperture does not help much. At 500mm the images were still OK in the center, but borders were noticeably soft.

With the extreme zoom, comes extreme weight - the lens is a monster. Not that it is the heaviest lens or the largest, but shooting it off hand was tedious (mildly put). Using a tripod is pretty much mandatory in my opinion.

 

Vignetting @ f/4 - full frame vs 1.6x crop (50mm)
Vignetting @ f/4 - full frame vs 1.6x crop (50mm)

 

Vignetting @ f/6.3 - full frame vs 1.6x crop (500mm)
Vignetting @ f/6.3 - full frame vs 1.6x crop (500mm)

 

The lens produced mild levels of vignetting throughout the zoom range on a full-fram Canon 5D, which is somewhat surprising for a telephoto lens. Vignetting was non-existent on an APS-C body. The lens did not produce any major color fringing. Ditto for barrel distortion across the zoom range.

 

ISO 100, 1/400, f/4, 50mm
ISO 100, 1/400, f/4, 50mm

 

Lab Tests

Please note that MTF50 results for APS-C and Full-Frame cameras are not cross-comparable despite the same normalized [0:1] range used to report results for both types of cameras.

 

Canon APS-C: The lens performance was somewhat mixed. Center performance was very solid from 50mm through 300mm range, but only with stopped to f/8-f/11 aperture. Center performance with wider apertures (f/4 at 50mm and f/5.6 throughout the zoom range) was slightly worse but still quite decent. Border performance trails performance in the center throughout the zoom range - at 50mm border quality is outstanding fromf/8 to f/11, is decent at f/5.6 and plain average at f/4. This trend continues once you start moving towards the longer end of the zoom range - border performance at f/5.6 (f/6.3 @ 500mm) is average at best and towards 500mm becomes plain mediocre. Border quality fares somewhat better with stopped down aperture, but also degrades towards 500mm. At its best (f/5.6-f/11, 50mm through 200mm), the lens is capable of producing outstanding 16in prints. Conclusion? There's no doubt that this is not the sharpest telephoto lens that is currently available on the market, but the question that we should probably be asking instead - are there any other lenses with similar zoom coverage that are any better? Let me know if you find one...

 

MTF50 (Line Width/Inch on the Print) @ 50mm
MTF50 (Line Width/Inch on the Print) @ 50mm

 

Normalized raw MTF50 @ 50mm
Normalized raw MTF50 @ 50mm

 

MTF50 (Line Width/Inch on the Print) @ 100mm
MTF50 (Line Width/Inch on the Print) @ 100mm

 

Normalized raw MTF50 @ 100mm
Normalized raw MTF50 @ 100mm

 

MTF50 (Line Width/Inch on the Print) @ 200mm
MTF50 (Line Width/Inch on the Print) @ 200mm

 

Normalized raw MTF50 @ 200mm
Normalized raw MTF50 @ 200mm

 

MTF50 (Line Width/Inch on the Print) @ 300mm
MTF50 (Line Width/Inch on the Print) @ 300mm

 

Normalized raw MTF50 @ 300mm
Normalized raw MTF50 @ 300mm

 

MTF50 (Line Width/Inch on the Print) @ 400mm
MTF50 (Line Width/Inch on the Print) @ 400mm

 

Normalized raw MTF50 @ 400mm
Normalized raw MTF50 @ 400mm

 

MTF50 (Line Width/Inch on the Print) @ 500mm
MTF50 (Line Width/Inch on the Print) @ 500mm

 

Normalized raw MTF50 @ 500mm
Normalized raw MTF50 @ 500mm

 

The lens produced minimal level of CA in the center, generally not exceeding ~0.5px. Chromatic aberration around borders was somewhat higher (~0.9px across the zoom range), but still under control.

 

Image borders @ 50mm (100% crop): f/4 vs f/8
Image borders @ 50mm (100% crop): f/4 vs f/8

 

Canon FF: The lens did not fare very well on a full-frame camera. As with an APS-C camera, overall performance degrades towards longer end of the zoom range. Performance in the center remains solid from 50mm through 100mm, but starts to give up ground at 200mm and beyond. Border quality is decent at 50mm and 100mm but only with stopped down aperture. From 200mm and on, border quality is rater average at f/8-f/11 and mediocre at f/5.6. Conclusion? Performance-wise, there's nothing spectacular here, which (unfortunately) is expected from lenses with such an aggressive zoom coverage.

 

 

Normalized raw MTF50 @ 50mm
Normalized raw MTF50 @ 50mm

 

Normalized raw MTF50 @ 100mm
Normalized raw MTF50 @ 100mm

 

Normalized raw MTF50 @ 200mm
Normalized raw MTF50 @ 200mm

 

Normalized raw MTF50 @ 300mm
Normalized raw MTF50 @ 300mm

 

Normalized raw MTF50 @ 400mm
Normalized raw MTF50 @ 400mm

 

Normalized raw MTF50 @ 500mm
Normalized raw MTF50 @ 500mm

 

Like with an APS-C, chromatic aberration on a full-frame Canon 5D was well under control. CA did not exceed 0.6px in the center and ~1px around borders.

 

Image borders @ 50mm (100% crop): f/4 vs f/8
Image borders @ 50mm (100% crop): f/4 vs f/8

 

Alternatives

There are not that many ultra long telephoto zoom lenses available on the market, and Sigma is dominating this segment, at least for now (of course having a wide selection is one thing and having a wide selection of high quality lenses is completely different story). Currently Sigma offers four ultra long telephoto zooms - APO 80-400mm f/4.5-5.6 EX DG OS, APO 135-400mm f/4.5-5.6 DG, APO 170-500mm f/5-6.3 DG and APO 300-800mm f/5.6 EX DG HSM. The first three are priced about the same level as APO 50-500mm f/4-6.3 EX DG HSM, while the 300-800mm telephoto zoom costing about 5x/6x times as much. Canon offers EF 100-400mm f/4.5-5.6L IS USM (review), which unfortunately seems to be suffering from production problems. Finally, Tamron offers SP AF 200-500mm f/5.6-6.3 Di LD.

 

Recommendation

Sigma APO 50-500mm f//4-6.3 EX DG HSM does not really grab any stars from the sky (metaphorically speaking), but for an ultra long zoom lens this does not come as a surprise. What you get is a decent 50-200mm and an average (or subpar, depending on your demands) 300-500mm zooms in one package that sports outstanding build quality and does not break your bank account. While the lens cannot really compete with dedicated ultra telephoto primes, it clearly stands out in the ultra zoom category and as such might be a suitable choice for some.