The medium telephoto Sigma 105 is long and fast enough to make a good portrait lens and at the same time gives the photographer enough working distance for macro compared to the shorter lenses where lighting can be a problem due to the front of the lens blocking light to the subject. The Sigma 105 is actually one of my favorite lenses, 100% dependable, sharp and very good color correction and an excellent value from a price/performance ratio.
It competes with the image quality from Canon EF 100mm f/2.8 USM L IS and the Nikon AF-S VR Micro-NIKKOR 105mm f/2.8G at a cheaper price, maybe 20% less. It doesn't have weather sealing like the Canon 100 but in years of using the Sigma 105 professionally I have never missed it honestly.
TECHNICAL DETAILS
Type: Macro lens Focal length: 105mm at infinity Aperture: 9 blades
Magnification range: 1X - infinity
Coverage: Full frame Working distance: Good.
Chromatic Aberration (CAs): No problems here, CAs are well controlled.
Lens mount: The lens tested here was in G-type Nikon F-mount.
Optical design: 16 Elements in 11 Groups, including 2 SLD elements.
Coverage: Full frame.
Filter threads: 62mm.
Cost: Easy to find new and on the used market. Street price for a new lens is currently $569.
RATING
What I like about the lens
Image Quality
CA correction
Compact size
Focal length
Price
Things I can live with
Lack of a tripod collar.
Things that I dislike about the lens
Nothing at all.
Things I don't need
Image stabilization for macro photography.
Weather sealing.
After more than 10 years of experience photographing wildlife professionally in all kinds of weahter, I think the need for weather sealing is really more of an internet myth, than a true professional feature.
Image Quality: This lens has very good overall performance without any real weaknesses.
Sharpness Test
This 6 inch silicon wafer was shot at 1X, Nikon D810 ISO 64 Nikon MM-11 stand. Image shown are 100% or actual pixel crops. Be sure to click on an image to see larger version.
A highly detailed, high-contrast test target like the wafer used here, will tend to reveal sharpness differences and chromatic aberration much more strongly than a real-world image.
Test setup notes
-The Nikon D850 camera was vertically mounted on a Nikon MM-11 stand for this test.
-For each lens and each aperture setting focus was bracketed and the sharpest image was chosen at 100% view in photoshop.
-Manual mode was used at ISO 64.
-To avoid any sharpness loss due to vibration a Nikon SB-R200 flash was used at 1/16th to 1/2 power. -The flash remained in place for the entire test to avoid changes in light angle, the flash was mounted on a flash bracket bolted to an optical breadboard.
-RAW NEF files were processed in Photoshop CC with all noise reduction and lens correction turned off, all settings were zeroed out and the same white balance setting used for all the images.
-All crops are shown here at 100% actual pixel view.
-All of the test result images are single frames.
-To avoid focus shifts with aperture changes, 10-15 shots were made at 40 micron steps at each aperture.
-The sharpest images were chosen at 100% actual pixel magnification, cropped and saved in Photoshop.
-Although the sharpest aperture is shown, each lens was shot in full stops from wide open down to f/8 or f/11.
-Results of the other apertures will be posted on the individual lens pages (coming soon).
The target is a silicon wafer shot at 1X, the un-cropped full frame image is below with the crop target areas highlighted in blue.
Center crop at 100% magnification view below. Click on an image to see larger version in a new window.
Sigma 105 OS center crop at f/2.8
Sigma 105 OS center crop at f/4
Sigma 105 OS center crop at f/5.6
Sigma 105 OS center crop at f/8
100% magnification actual pixel center crops, f/2.8 to f/8, left to right. All of the center crops are sharp, I think the peak is at f/4.
Edge crop at 100% magnification view. Click on an image to see larger version in a new window.
Sigma 105 OS edge crop at f/2.8
Sigma 105 OS edge crop at f/4.
Sigma 105 OS edge crop at f/5.6
Sigma 105 OS edge crop at f/8.
All edge crops are clean and sharp.
Corner crop at 100% magnification view. Click on an image to see larger version in a new window.
Sigma 105 OS corner crop at f/2.8
Sigma 105 OS corner crop at f/4
Sigma 105 OS corner crop at f/5.6
Sigma 105 OS corner crop at f/8
The Sigma 105 shows great corner sharpness at f2.8, and f/4, with a slight falloff in sharpness at f/5.6, and a noticeable drop-off at f/8. The drop-off at f/8 was a surprise since I had never noticed it in-the-field, but this test is far tougher than a real-world subject so I don't think the drop-off would be noticeable with normal photography. Lateral chromatic aberration, absent at f/2.8, increases as the aperture is closed, becoming noticeable at f/5.6.
Sigma 105mm f/2.8 EX DG vs Nikon AF-S VR Micro-NIKKOR 105mm f/2.8G at 1X
The Nikon 105 VR is a very popular lens and has been around for what seems like forever. How does it compare to the Sigma 105, a much less expensive lens? Lets compare some image crops at 100% and find out.
Click on an image to see larger full-size version in a new window.
Center sharpness on the Sigma 105 is best here at f/4, on Nikon 105 VR sharpness peaks at f/5.6 . The Nikon looks very good but the Sigma shows more detail. No surprise here since the Sigma is a much newer design, the Nikon design is 10+ year old by now and was optimized for 12 MP sensors.
Corner sharpness with the Sigma at f/4 is very good really, with only the slightest trace of lateral CAs. On the other hand the chromatic aberrations are really excessive in the corners with the Nikon 105 VR, the pink fringing is really noticeable and worse yet, this is stopped down to f/5.6, the fringing was even worse at f/4. In the corners the Sigma 105 OS is much sharper and with much better CA supression.
Longitudinal Chromatic Aberration 1X test
What are LoCAs?
Longitudinal chromatic aberrations or LoCAs are ugly purple and green fringing seen in the out of focus areas in front of and behind the focus point of an image. LoCAs are common, especially with fast lenses, so chances almost all of your lenses have at least a trace, you just never noticed. The problem is that LoCAs are extremely difficult to correct with complex designs using special glass to fully correct the aberration, the Scanner-Nikkor for example has 14 elements, 6 of those being ultra low dispersion.
Test Setup
D810 camera was mounted on a Newport PRC-3 rail carrier and Arca Swiss style quick release clamp and moved back and forth to accommodate the different focal length lenses set at 1X. The Newport PRL dovetail rail system was bolted to a Thorlabs aluminum breadboard with a printed target set at 30 degrees on a tilt head. A single Nikon SB-R200 flash and the tilt head remained in place during the test.
Lateral chromatic aberration 1X test
What are Chromatic aberrations (CAs)
Chromatic aberrations (CA) are one of several aberrations, or imperfections, that degrade image quality. These occur because glass bends different colors by different amounts. This phenomenon is called dispersion, and this is why you see some high performance lenses have labels such as, SD, UD, ED, SLD, ULD. These acronyms all refer to different types of low-dispersion glass types used in the lenses.
Lateral CAs appear in images as purple and green fringing, mostly seen on near-vertical hard edges on the left and right corners of the image. This results in softening of edges in the corners of an image. CAs occur because the different wavelengths of light are magnified by slightly different amounts by the lens.
CA correction
Minimizing chromatic aberration is one of the most important goals of a lens manufacturer. Lens design correct for CAs by combining different lens elements with different dispersion properties, or different refractive indexes. But CAs remain a big problem for lens manufacturers in ultra-wide lenses, long telephoto lenses, and extreme zooms. Most manufacturers offer some level of correction, some can completely correct CAs, with in-camera correction. Over the last few years some manufacturers have become really sneaky with the use of Opcodes.
Opcodes
According to Adobe, Sony, Olympus, Leica, and Panasonic have an agreement in place with Adobe to allow automatic chromatic aberration correction (and distortion correction) before RAW file conversion by tagging the RAW files with Opcodes. The sneaky part is that Opcode force corrections in Lightroom and Adobe Camera Raw before you even even open the image. Opcodes cannot be disabled but you can delete the codes with certain apps. Opcodes also corrects for distortion (and vignetting) which means the image will be enlarged slightly then cropped to correct for distortion so there could be some effect on sharpness.
Lateral chromatic aberration is reduced by the lens design to a certain degree by combining different lens elements with different refractive indexes. There are lenses that use very complex designs using expensive low-dispersion glass to completely eliminate CAs. Examples of these types of lenses would be the Printing Nikkor, Scanner Nikkor and Schneider Macro Varon.
Test Setup
D810 camera was mounted on a Newport PRC-3 rail carrier and Arca Swiss style quick release clamp and moved back and forth to accommodate the different focal length lenses set at 1X. The Newport PRL dovetail rail system was bolted to a Thorlabs aluminum breadboard. The laser printed test target was taped to a Newport 460P XYX micrometer controlled setup. A single Nikon SB-R200 flash was used for lighting and has bolted to a articulating flash arm.
Sigma 105mm f/2.8 EX DG at 1X and f/5.6
Nikon AF-S VR Micro-NIKKOR 105mm f/2.8G at 1X and f/5.6
External Site Links for more info:
The Sigma 105mm f/2.8 EX DG OS on the Sigma USA website: https://www.sigmaphoto.com/105mm-f2-8-ex-dg-os-hsm-macro
Sigma 105mm test at Objektivtest.se : http://www.objektivtest.se/tester/test-sigma-105-mm-f28-ex-dg-os-hsm-macro/
Sigma 105 tested on a Canon full frame DSLR, at Photozone, now called Optical Limits.com:http://www.photozone.de/canon_eos_ff/743-sigma105f28oseosff
Sigma 105 tested on a Canon APS-C DSLR, at Photozone, now called Optical Limits.com: http://www.photozone.de/canon-eos/747-sigma105f28oseosapsc
Lenstip.com Sigma 105mm test: https://www.lenstip.com/318.1-Lens_review-Sigma_105_mm_f_2.8_EX_DG_OS_HSM_Macro-Introduction.html