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| p.1 #1 · p.1 #1 · Sigma 45mm f/2.8 DG DN Contemporary Review | |
Order the Sigma 45mm f/2.8 DG DN Contemporary:
B&H Photo
Review quick links:- About the lens
- Infinity Performance
- Infinity Performance vs Sony FE 35/1.8
- Infinity Performance vs Voigtlander 40mm f/1.2
- Field Curvature
- Close-up performance
- Specular Highlights
- Sunstar rendering
- Rendering
- Lateral CA / Longitudinal CA / Purple fringing
- AF speed and accuracy
- Final thoughts
- Samples 1
- Samples 2
- Samples 3
- Samples 4
- Samples 5
About the lens:
The Sigma 45/2.8 Contemporary E-mount is an intriguing lens and a welcome addition to the E-mount system. It's compact, light and delivers great optical performance without neglecting rendering.
The lens features an electronic aperture ring and a manual focus ring with a linear response. I like the design of the lens with the hood on - It’s all metal and well-built. The lens itself weighs a mere 212g without caps but the hood adds another 44 grams and extra bulk which negates the compact design when attached. There is also a MF/AF button.
Optical Design: 8 elements (2 aspherical)
Main Features
Infinity Performance:
The Sigma 45/2.8 Contemporary is optimized for infinity distance and it's already sharp from wide open (f/2.8) while showing noticeable improvement stopped down to f/3.2:
At center, it achieves optimal resolution/contrast at f/4:
Moving off-axis, the mid-field area benefits from f/5.6 for maximum resolution/contrast, although it's very similar to f/4.
The same can be said for the extreme corners where f/5.6 seems to be the optimal aperture. (f/2.8 and f/4 not too far behind)
Field Curvature:
The Sigma 45/2.8 has low field curvature but it's still noticeable at pixel level, especially at mid-field. The curvature is slightly wavy but the corners are also affected to a smaller degree.
Here are three crops from images shot at f/2.8 showing the center area of a scene at infinity distance:- Left crop: Center area focused at center
- Mid crop: Center area focused at corner
- Right crop: Center area focused at mid-field
As you can see from the crops above, the mid-field are shows the most curvature, although there is a slight curvature at the corner as well.
Same as above but now stopped down to f/5.6: Field curvature gets masked by depth of field:
For landscapes, I would stop the lens down to least f/4, making field curvature less relevant in the field.
Close-up performance:
As mentioned earlier, the Sigma 45/2.8 is not optimized for close focus and does not feature a floating element system. From MTF until about 0.6m, it greatly improves when closing the aperture to f/4. After 1m, resolution and contrast improves greatly and from 3m to infinity it's already great from wide open.
Here are 1:1 crops comparing f/2.8 vs f/4 at various distances. (0.2m, 0.6m, 1m, and 3m)
Thumbnail at MFD (0.2m) showing the full image:
1:1 crop comparison from f/2.8 to f/4 at MFD (0.2m):
Spherical aberration is very noticeable
1:1 crop comparison from f/2.8 to f/4 at 0.6m:
SA still noticeable
1:1 crop comparison from f/2.8 to f/4 at 1m:
At this distance, the lens improves greatly and looks good even wide open
1:1 crop comparison from f/2.8 to f/4 at 3m:
From 3m to infinity, the lens performs optimally
Specular Highlights:
The inner structure shows slight traces of onion ring pattern. However, it's not very noticeable in real world images.
Bokeh balls look good at close distance but its cat-eye shape is noticeable away from center. Here is an example showing f/2.8 (top) and f/4 (bottom) at about 0.5m. After f/5.6, specular highlights are no longer rounded.
Here is the same scene at 5m:
Sunstar rendering (14-point)
I could only manage to get somewhat defined sunstars at f/22 but it's still a bit fuzzy. I much prefer the sunstars from the Loxia and Voigtlander line. Ghosting flare is hard to avoid.
Rendering
Out of focus rendering is the Sigma 45/2.8's biggest strength despite its slow aperture. I have a feeling Sigma optimized this lens for high resolution and contrast at long distance and rendering at close and mid-distance. Transition zone and overall rendering is very smooth from wide open.
Here are a few samples:
Lateral CA / Longitudinal CA / Purple fringing correction
The f/2.8 aperture gives this Sigma a big advantage in color aberration correction. I can only see traces of magenta/green in defocused areas (LoCA) and no visible lateral CA towards the corners. Overall excellent performance.
Samples 1:
Thumbnail showing full image:
Focused area:
Defocused area:
(only traces of green color error)
Samples 2:
Thumbnail showing full image:
Focused area:
Defocused area:
AF speed and accuracy
The Sigma 45/2.8 Contemporary has fast and quiet (not silent) auto-focus under good light. In low light it hunts depending on the subject but nothing out of the ordinary for a f/2.8 lens.
However, my copy has issues with focus accuracy. I'm not sure if it is a widespread problem but others have reported similar problems with AF-C (PDAF). That includes Eye-AF as well.
I tested this today at various distances (0.5m, 1m and 3m) and got consistent issues with AF-C and back-focusing at 0.5 and 1m. At 3m, AF-C seems more accurate but still not as good as AF-S.
The test below shows AF-C (left crop) vs AF-S (right crop) at different distances. 5 images were taken with each mode and they were consistent on the results presented here:
AF-C vs AF-S at 0.5m
AF-C vs AF-S at 1m
AF-C vs AF-S at 3m
All my close-up tests in this review were done in MF for this reason. However, this does not affect AF-S (contrast-detect).
Final Thoughts:
The 45/2.8 Contemporary gets many things right but what makes it unique is the butter smooth rendering.
It's well-built, compact and light. The aperture ring stops down in one-third increments with great precision. The manual focus ring has linear coupling and is a joy to use. Optimized for mid and long distances, it is capable of high resolution across the entire image field. The f/2.8 maximum aperture restricts the amount of blur and subject isolation, however, starting at the transition zone, rendering is smooth and pleasant. It's refreshing to see Sigma focus on rendering with their latest mirrorless designs for the E-mount.
Another strength is color aberration correction. I struggled to find color fringing in any of my test images even under high contrast lighting. Slight traces of longitudinal CA are still present - but overall, the lens is well corrected for CA.
The aperture mechanism is equipped with seven 'rounded' blades which prevents the lens from rendering defined sunstars at mid-range apertures. However, when stopped down to f/18-22, it still produces defined 14-point sunstars.
Rounded blades are very popular with AF lenses because it maintains circular specular highlights at smaller apertures. In the case of the Sigma 45/2.8, bokeh is still circular at f/4.5. (This would not be possible if it was equipped with straight blades)
On the negative side, flare resistance is average with good retention of contrast while ghosting is visible under backlit situations. AF is a mix bag. It's fast and quiet but there are issues with phase detection (AF-C). It consistently back-focuses and hopefully this is an easy firmware fix for Sigma. AF works great in AF-S mode (contrast-detection). The lens is not equipped with a floating element system so expect image degradation at close distance.
For those looking for a light and compact walk-around AF lens with superb rendering and color correction, the new Sigma 45/2.8 Contemporary may be what you're waiting for.
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Order the Sigma 45mm f/2.8 DG DN Contemporary: B&H Photo
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https://www.fredmiranda.com/forum/ufiles/01/1856701.png
I agree though, sunstar rendering is not a strength but in exchange we have very rounded bokeh balls at f/4.