SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D) review

According provided by SIGMA ZOOM 18-50mm 1: 2.8 EX DC D lens (Nikon version) many thanks To sable Vladimir.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D). The lens is shown in film slr camera Nikon EL2

Navigation

1. Browse Navigation
2. In short
3. Main Specifications
4. Assembly
5. LOCK Button
6. Focusing
7. Image quality
8. Sample Photos
9. Alternatives
10. My personal experience with the lens
11. Results
12. User Comments
13. Add your review or question on the lens

In review lens SIGMA ZOOM 18-50mm 1: 2.8 EX DC D I will call in abbreviated form - Sigma 18-50 / 2.8 EX. This review shows the version for cameras Nikon DX Series, in its name, written on the lens barrel, it has an additional 'D' prefix (next to the gold lettering 'EX'). Lens versions for Canon, Pentax, Sigma and 4/3 cameras are deprived of this letter.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

In short

The Sigma 18-50 / 2.8 EX is a professional high-aperture zoom lens of universal directivity with a very convenient range of focal lengths. Sigma 18-50 / 2.8 EX - an alternative to the original super-lens Nikon 17-55 / 2.8G.

Please note that this review shows the very first version of the Sigma 18-50 / 2.8 class lens, announced in 2004, it is easy to distinguish from subsequent models Sigma DC 18-50mm 1: 2.8 EX MACRO и Sigma DC 18-50mm 1: 2.8 EX MACRO HSM by the name of the lens, which is written on the frame of the front lens for this model. The Sigma 18-50 / 2.8 EX dates back to the era of lenses, when it was customary to write the prefix 'ZOOM' in the names of Sigma lenses.

Choosing a versatile fast zoom lens is a very important step in the lives of countless photographers, especially those who have to shoot a variety of subjects. The Sigma 18-50 / 2.8 EX can be a budget solution for such tasks.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

Main technical characteristics of SIGMA ZOOM 18-50mm 1: 2.8 EX DC:

Sigma 18-50 / 2.8 EX is very similar to a lens Tamron Aspherical LD ​​XR DI II SP AF 17-50mm 1: 2.8 [IF], but still the Sigma 18-50 / 2.8 EX is much better. The difference in viewing angles between 17mm and 18mm focal length is not felt. Also, I would like to draw your attention to the fact that 50 mm of focal length for these lenses is available only during focusing to infinity, while focusing towards MDF, the angle of view increases, and the focal length decreases due to the 'Focus Breathing' effect.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

Assembly

Sigma 18-50 / 2.8 EX was made in Japan. To the touch the lens is pleasant, strong, weighty. The retractable frame of the case ('trunk') consists of one section, which is quite durable. The zoom ring has a small backlash that does not affect usability. This backlash is most likely constructive than acquired during use.

All parts of the body are covered with characteristic Sigma velvet, which has the property of quickly getting dirty and rubbing.

The design and body size of all similar Sigma lenses is the same or very similar. This makes it easy for Sigma to control production and reduce the cost of components.

The lens has metal bayonet mount. The zoom and focus rings are rubberized. Changing the focal length runs smoothly.

There is a bayonet mount mark and a mark on the case for quick installation of the hood. The lens uses a plastic hood, which is fixed in special grooves located near the front lens of the lens. The hood can be installed in the opposite direction for transportation. In this position, access to the focus ring at 18 mm focal length is lost. When you change the focal length, the lens hood moves with the front of the lens.

When changing the focal length, the rear lens moves in the middle of the lens body like a pump - it draws in and pushes out air. This behavior of the rear lens is called 'vacuum cleaner effect', which can increase the amount of dust that accumulates in the camera.

Number of petals aperture - 7 pieces. At the same time, they are weakly rounded and form an irregular heptagon on strongly covered diaphragms.

For Sigma 18-50 / 2.8 EX, the direction of rotation of the zoom and focus rings does not match the direction of the original Nikon 17-55 / 2.8G.

It is believed that this is a lens from a professional range of the highest quality. Unfortunately, the lens has no dust or moisture protection. Also, many professional lenses use classic 77 mm filters, 72 and 82 mm less often. Sigma 18-50 / 2.8 EX has filters with a diameter of 67 mm, which is not always convenient.

I want to separately note that despite the good assembly of the Sigma 18-50 / 2.8 EX, the overall reliability of the lens is much inferior to the original metal monster Nikon 17-55 / 2.8G.

It should be noted separately that the sample from the review has practically erased the golden 'EX' marking, real irony, since this abbreviation should be responsible for the highest level of quality of the lens. The 'Sigma DC' lettering is also pretty worn out. The lens from the review is a little buggy - sometimes it incorrectly indicates the value of the focal length in EXIF (most likely there are some problems with the indicator plates and their brushes, apparently they just got worn out and became less sensitive to the position of the zoom ring). And one more trifle - when changing the focal length, the zoom ring can rub against the focusing ring and rotate with it (critical during manual focusing).

It's important: Some lenses have the 'SIGMA DC' lettering in full gold, some have only 'DC' in gold lettering. I do not distinguish them in separate sub-versions. Drawing with differences.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

Lock 'LOCK ′

The frame (trunk) of the Sigma 18-50 / 2.8 EX does not spontaneously change its size under its own weight (perhaps this only begins with time). On the lens case there is a switch-lock focal length 'LOCK' (the so-called 'lock'), which tightly locks focal length at a value of 18 mm.

To fix the trunk of the lens, you must first set the 18 mm focal length. Near the button there is a drawn arrow that indicates in which direction the switch should be moved to lock the lens.

The switch is located in a convenient place - under the thumb of the left hand, so the lens can be quickly and comfortably 'removed from the lock' before starting shooting.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

Focusing

It's important: auto focus with this lens is available only when using him on cameras with built-in motor focusing.

Exact list Nikon DSLR cameras with a built-in focus motor, on which this lens will focus automatically:

• D1, D1h, D1x, D2x, D2xs, D2h, D2hs
• D3, D3x, D3s, D4, D4s, D5, D6
• Df
• D50, D70, D70s, D80, D90
• D7000, D7100, D7200, D7500
• D100, D200, D300, D300s, D500
• D600, D610, D750, D780
• D700, D800, D800E, D810, D810a, D850
• Fujifilm FinePix S1 Pro, S2 Pro, S3 Pro, S3 Pro UVIR, S5 Pro, IS Pro
• Kodak DCS PRO 14n, DCS Pro SLR / n

Exact list Nikon DSLR cameras without a built-in focus motor, on which this lens will not focus automatically:

• D40, D40x, D60
• D3000, D3100, D3200, D3300, D3400, D3500
• D5000, D5100, D5200, D5300, D5500, D5600
• Nikon z5, Z6, Z6 II, Z7, Z7 II , Z9, Z50... with adapter Nikon FTZ/ FTZ II

Only auto focus and sound confirmation of focus will not work with these cameras, all other important functions, such as automatic exposure metering and automatic iris control, will work well.

You will find a lot of useful information on the types of cameras and lenses Nikon here.

Nikon's first camera to not have inboard motor focusing has become Nikon D40introduced two years later than the Sigma 18-50 / 2.8 EX lens. Therefore, Sigma cannot be blamed for initially releasing its lens for Nikon cameras without inboard motor focusing. Later, Sigma 18-50 / 2.8 EX was updated to a version with a built-in focusing motor - Sigma DC 18-50mm 1: 2.8 EX MACRO HSM. I also remind you that even Nikon itself managed to release one (only one) camera lens Nikon DX Series (i.e. for crop) without a focus motor, it was an old man Nikon DX AF Fisheye Nikkor 10.5mm 1: 2.8G ED. Absolutely all other lenses for cameras Nikon DX have a built-in focus motor.

When used on a camera Nikon D90 with unpretentious Multi-CAM 1000 focusing system the lens behaves well. With precision and clinging focus, I had no particular problems. The lens clings well to captured subjects, rarely re-focusing. The number of focus misses is neither large nor systematic. In general, usually non-motorized lenses rarely have autofocus problems.

Auto focus speed average, comfortable for the vast majority of photo tasks. Focus speed is significantly lower than that of Nikon 17-55 / 2.8G. Let me remind you that Nikon 17-55 / 2.8G so far it is the fastest original lens in the Nikon DX series (it uses a large and powerful ring SWM motor).

Focusing on the Sigma 18-50 / 2.8 EX internal - when focusing, neither the front nor the rear lens rotates, and the lens itself does not change its size when focusing. Sorry, but during auto focus focus ring rotates and cannot be touched. In such Nikon lenses, the focus ring remains stationary during auto focus (focus modes M / A or similar).

In manual focus mode, the focus ring rotates approximately 45 degrees. Manual focus is quite inconvenient. When extreme positions are reached, the focus ring abuts and cannot be rotated further.

The minimum focusing distance is 28 cm (the distance from the camera’s sensor to the subject). With such an MDF, the maximum magnification factor is 1: 5 (exactly the same coefficient uses Nikon 17-55 / 2.8G). Shooting small objects is easy, but there is no need to talk about real macro photography.

Sigma 18-50 / 2.8 EX does not have a focus mode switch. To translate the lens into manual focus on cameras with motor For focusing, use the focus mode switching lever located near the camera mount. For cameras without motor Only manual focus mode will always be available for focusing.

Focus Features:

• There is noise from autofocus.
• There is a strong effect of 'Focus Breathing' (changing the viewing angle during focusing). During focusing towards MDF, the viewing angle increases.
• When changing the focal length, focusing is a bit confused.
• Unknown compatibility with teleconverters.
• Sigma 18-50 / 2.8 EX does not have hard stop (hard infinity mechanical stop) which allows you to accurately and quickly focus the lens at infinity under any external conditions.
• The lens has a focus distance scale with marks in meters and feet. The scale is plotted on the focus ring. The scale is very meager, on it there are marks for only 5 values ​​of the focusing distance (including 'infinity'). More advanced lenses usually use a scale in the form of a special window.
• Focus shift (shift-focus) was not noticed.
• Sigma 18-50 / 2.8 EX has no focus problems in Live View mode (tested on Nikon D90 ), but it focuses very slowly and uncertainly (the bigger problem is the Live View mode with focusing in contrast).
• The lens transmits the focus distance to the subject in the camera (analog Nikon D, Nikon G).
• The direction of rotation of the focus ring does not match the original Nikon 17-55 / 2.8G.
• Sigma 18-50 / 2.8 EX is a third-party lens. It may happen that it will not work correctly with some Nikon cameras. Details on this issue are considered by me. here.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

Image quality

In general, Sigma 18-50 / 2.8 EX, as for a lens of its class and age, is optically not bad, but still there are a couple of weak points.

Sharpness

• confident sharpness at open apertures in the center of the frame over the entire range of focal lengths
• no noticeable drop in sharpness during zoom
• poor sharpness at the edges of the frame at 18mm & f / 2.8
• very weak picture at the corners of the frame at 18mm & F / 2.8 (this major flaw optical qualities of this lens)
• good / excellent resolution in the center of the frame on covered apertures (in the F / 5.6-F / 10 region) over the entire range of focal lengths

Distortion

• the overall level of distortion is at a level typical for such lenses
• pretty strong distortion only visible at 18 mm
• distortion practically absent and imperceptible in the range of 24-50 mm
• in the wide-angle range, the nature of the distortion barrel-shaped
• the nature of distortion is unified, easily corrected in the editor

Vignetting

• general level vignetting is at the level typical for such lenses
• noticeable vignetting observed throughout the range of focal lengths and f / 2.8
• the strongest vignetting appears at 18mm & f / 2.8 when focusing on MDF
• vignetting amplified with focus towards MDF
• vignetting practically disappears at F / 4-F / 5.6
• vignetting easily fixable in the editor, especially when shooting in RAW

Aberration

• there is a noticeable amount of aberrations on F / 2.8
• the strongest chromatic aberration noticeable at 18mm & f / 2.8 at the edges and corners of the image (they also eat up most of the details)
• when closing to F / 4-F / 10 HA are slightly reduced
• general level HA slightly worse than similar lenses

Rest

• pronounced effect of a 14-ray star on strongly covered diaphragms
• a small amount of glare in the backlight, a slight drop in contrast in the side light. Immunity is at the level typical for such lenses.

Please note that this lens was released at a time when only Nikon D1 cameras existed on the market, D1h, D1x, D100, D2h, D70 with a very small maximum number of megapixels (not more than 6 MP, interpolated 10 MP with Nikon D1X not count). Most likely at that time, the Sigma 18-50 / 2.8 EX lens was not designed to work with cameras with 24 or more MPs. In the same time Nikon 17-55 / 2.8G It is an even older lens and works wonderfully with modern camera models.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

Sample Photos

Camera shots Nikon D90. The photos in the gallery below are shown without processing, converting the source RAW files with the original Nikon Capture NX-D utility without making any additional adjustments.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

My experience

Suddenly, one JPEG file with Sigma 18-50 / 2.8 EX, obtained by directly converting the original RAW file, weighs more than the original. Example. I occasionally see this, but very rarely, and the differences are usually not so big. There are several reasons for this: RAW compression, an excess of detail in the image, structure difference RAW and JPEG. Indirectly, this indicates a high resolution lens (for such conditions).

Sigma 18-50 / 2.8 EX appeared a year later than the original Nikon 17-55 / 2.8G. Unfortunately, the Sigma 18-50 / 2.8 EX is just a miserable semblance of a super lens Nikon 17-55 / 2.8G. I should note that despite the fact that Nikon 17-55 / 2.8G was the very first fast-moving universal zoom lens for cropped cameras; to this day it remains one of the best of its kind. In terms of build quality, he has no equal.

But the Sigma 18-50 / 2.8 EX should be given its due - this is the first such lens from a third-party manufacturer. Tamron, Tokina, Canon, Pentax companies have been slowing down for several more years with the release of such a solution (see the time of the announcement of this or that similar lens in the section 'Alternatives').

I am pursuing the idea that the photographer should have one good, high-speed universal lens for a wide range of tasks. In real life of a photographer, such a lens can often help a lot, especially at certain stages of the photographer’s development. The station wagon is the basis with which you can 'survive' in almost any photo task. To this basis, then it is worth adding other creative / artistic / special lenses of a narrower specialization.

Nevertheless, those who are looking for a fast wagon, I recommend that you first look at the original lenses. After them, look at the versions with a stabilizer from third-party manufacturers, and there are not many of them. At the time of this writing, these are only Sigma DC 17-50mm 1: 2.8 Zoom EX OS HSM (highly recommend this lens) and Tamron Di II SP 17-50mm F / 2.8 VC B005.

If you have to choose between inexpensive non-motorized lenses Tamron 17-50 / 2.8 A16, Promaster 17-50 / 2.8, Tokina 16-50 / 2.8, then I give preference to Sigma 18-50 / 2.8 EX or its subsequent updates.

The range of 18-50 mm is very convenient, it is not for nothing that it is used among whale lenses of the 18-55 class. Compared to whale lenses such as Nikon 18-55 / 3.5-5.6G VR AF-P, Sigma 18-50 / 2.8 EX is two steps lighter at the long end (F / 5.6 vs F / 2.8), which gives a gain in shutter speed 4 times. For moving lenses, this is a significant difference. Unfortunately, the range is 18-50 (EGF 27-75mm) is almost standard (in terms of set of focal lengths) and poorly suited for some creative photo tasks. Nevertheless, this range allows you to perfectly implement the daily routine work of a photographer, and from this range, with grief in half, you can shoot almost anything.

Questions regarding the torment of choosing a lens, leave in the comments, I will try to help.

Comments on this post do not require registration. Anyone can leave a comment. Lenses and promotions on them look at Moyo.ua.

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D)

All fast universal zoom lenses

Below is a list of all such aperture-type universal zoom autofocus lenses for SLR and mirrorless cameras with an APS-C sensor or less.

Tokina (DX, various mounts)

1. Tokina AT-X PRO SD 16-50 F2.8 DX Internal Focus, model AT-X 165 PRO DX, for Canon (C / EF version) and Nikon (N / AIS version), since July 2006. The optical design is similar to the lens Pentax SMC DA * 16-50mm f / 2.8 ED AL (IF) SDM

Tamron (DI II, DI III-A, various mounts)

1. Tamron Aspherical LD ​​XR DI II SP AF 17-50 mm 1: 2.8 [IF], model A16 N / E / P / S (under Nikon [N], Canon [E], Pentax [P], Sony / Minolta [S]), since February 2006. Produced in Japan, China and Vietnam
2. promaster DIGITAL XR EDO AF Ashperical LD ​​[IF] 17-50 mm 1: 2.8 MACROprevious lens under the brand Promaster
3. Tamron Aspherical LD ​​XR DI II SP AF 17-50 mm 1: 2.8 [IF], model A16 NII (only for Nikon cameras), since March 2008
4. Tamron Di II SP 17-50 mm F / 2.8 VC B005, model B005 E / NII (for Canon [E] or Nikon [NII]), from September 2009, Japan or China)
5. Tamron 17-70 mm F / 2.8 Di III-A VC RXD Model B070, Model B070, Sony E only, from December 2020

Sigma (DC, different mounts)

With constant maximum aperture (DC EX and DC ART series):

1. Sigma DC ZOOM 18-50mm 1: 2.8 EX (+ -D), since July 2004, for Sigma SA, Nikon F, Canon EFS, Pentax K. The version for the '4/3' system has been available since February 2006 (not mass-produced). The version for Nikon in its name includes the prefix 'D'.
2. Sigma dc 18-50mm 1: 2.8 EX MACRO, from September 2006, for Sigma SA, Nikon F, Canon EFS, Pentax K
3. Sigma dc 18-50mm 1: 2.8 EX MACRO HSM, since June 2007, for Nikon DX cameras only (Nikon F mount)
   
4. Sigma dc 17-50mm 1: 2.8 ZOOM EXOS HSM, from February 2010, for Sigma SA, Nikon F, Canon EFS, Pentax K, Sony / Minotla A
5. Sigma dc 18-35mm F1.8 A [ART, HSM], from April 2013, for Sigma SA, Nikon F, Canon EFS, Pentax K, Sony / Minotla A
6. SIGMA DC 18-50 mm 1: 2.8 DN C [Contemporary], since Oct 2021, for Sony E, Leica L

With variable maximum aperture (DC and DC Contemporary series):

1. Sigma dc 17-70mm 1:2.8-4.5, February 2006, for Sigma SA, Nikon F, Canon EFS, Pentax K, Sony / Minotla A
2. Sigma dc 17-70mm 1:2.8-4.5 MACRO HSM, from July 2007, for Nikon DX cameras only (Nikon F mount)
   
3. Sigma dc 17-70mm 1:2.8-4 MACRO HSM OS, from December 2009, for Sigma SA, Nikon F, Canon EFS, Pentax K, Sony / Minotla A
4. Sigma dc 17-70mm 1:2.8-4 C, [MACRO, OS, HSM, Contemporary], from September 2012, for Sigma SA, Nikon F, Canon EFS, Pentax K, Sony / Minotla A
5. Sigma dc 18-50mm 1:2.8-4.5 HSM OS ZOOM, from March 2009, for Sigma SA, Nikon F, Canon EFS, Pentax K, Sony / Minotla A

Nikon (DX, F mount)

1. Nikon DX VR AF-S Nikkor 16-80mm 1:2.8-4E ED N, Nikon F mount, from July 2015
2. Nikon DX AF-S Nikkor 17-55mm 1: 2.8G ED IF SWM, Nikon F mount, from July 2003

Pentax (DA, Q, K and Q mounts)

1. Pentax SMC DA * 16-50 mm 1: 2.8 ED AL (IF) SDM, Pentax KAF2 bayonet mount, since February 2007. Optical design similar to lens Tokina AT-X PRO SD 16-50 F2.8 DX Internal Focus (joint development of Tokina and Pentax)
2. HD PENTAX-DA * 1: 2.8 16-50 mm ED PLMAW, from July 2021, Pentax KAF4 mount
3. HD Pentax-DA 1: 2.8-4 20-40 mm ED Limited DC WR, Pentax KAF3 bayonet mount, black or silver, from November 2013
4. SMC Pentax 1: 2.8-4.5 5-15 mm ED AL [IF] [LENS 02], Pentax Q mount (with crop factor Kf = 5.53X or Kf = 4.65X)

Canon (EFS, EF-S mount)

1. Canon Zoom Lens EF-S 17-55mm 1: 2.8 IS USM (Image Sabilizer, Ulstrasonic, EFS), Canon EF-S mount, since May 2006

Sony (DT, A and E mounts)

1. Sony DT 2.8/16-50 SSM, Sony A mount (Minolta A), August 2011
2. Sony E 2.8/16-55G, Sony E bayonet mount, from August 2019

Fujifilm(X)

1. Fujinon Ashperical Lens Nano-GI XF 16-55mm 1: 2.8 R LM WR, Fujifilm X mount, since January 2015
2. Fujinon Ashperical Lens Super EBC XF 18-55mm 1:2.8-4 R LM OIS, Fujifilm X mount, September 2012

Samsung (NX)

1. Samsung lens 1: 2-2.8 S 16-50 mm ED OIS i-Function, Samsung NX mount, since January 2014

Olympus / Panasonic / Leica (4/3, Micro 4/3, Kf = 2X)

Mirrored 4/3:

1. OLYMPUS ZUIKO Digital 11-22 mm 1: 2.8-3.5since February 2004
2. OLYMPUS Digital 14-54 mm 1: 2.8-3.5since June 2003
3. OLYMPUS Digital 14-54 mm 1: 2.8-3.5 IIsince November 2008
4. OLYMPUS ZUIKO Digital 14-35 mm 1: 2 ED SWDsince January 2008
5. Panasonic Lumix LEICA D VARIO-ELMARIT 1: 2.8-3.5 /14-50 ASPH. MEGA OISsince July 2006

Mirrorless Micro 4/3:

1. OLYMPUS M.ZUIKO DIGITAL 12-40 mm 1: 2.8 PROsince October 2013
2. Panasonic Lumix Leica DG Vario-Summilux 10-25 mm f / 1.7 ASPH.since May 2019
3. LUMIX G VARIO 1: 2.8 /12-35 ASPH. POWER OIS, from June 2012, in March 2017 an improved version is released (outwardly no different)
4. Panasonic Lumix Leica DG Vario-ELMARIT 1: 2.8-4.0 /12-60 ASPH.since March 2017

SIGMA ZOOM 18-50mm 1: 2.8 EX DC (D). The lens is shown in film slr camera Nikon EL2

Results

Sigma 18-50 / 2.8 EX is an old fast full-time zoom with claims to a professional level of performance. May be the budget solution for Nikon's all-day crop lenses. Unfortunately, despite the fact that the Sigma 18-50 / 2.8 EX is a lens for the Nikon DX series, it lacks a built-in focus motor and will not fit the D3xxx, D5xxx, D40 / x series amateur cameras. D60 (for a detailed list, see the 'Focusing' section).

Advantages

1. low cost in the secondary market (especially compared to the original Nikon 17-55 / 2.8G)
2. convenient set of focal lengths
3. rear mount lens hood
4. metal mount, rubberized focus and zoom rings. Soul Warming Marking 'EX'
5. lock for fixing the lens in position 18 mm
6. compact sizes (significantly smaller and lighter than the original Nikon 17-55 / 2.8G)
7. special optical elements in the optical circuit (Sigma SLD, ASP)
8. focus type internal
9. constant maximum relative aperture of 1: 2.8 over the entire range of focal lengths
10. good optical performance (good sharpness on closed apertures in the center of the frame, normal sharpness on open apertures in the center of the frame, other parameters are within the normal range for this kind of lens), lack of focus-shift during aperture

Disadvantages

1. the direction of rotation of the focus ring and zoom does not match the original similar lens Nikon 17-55 / 2.8G
2. a slight backlash of the zoom ring, easily soiled velvet cover
3. small stroke of the focus ring, insufficiently convenient manual focus
4. not fast auto focus (but still quite comfortable)
5. lack of dust and moisture protection (critical for a professional lens)
6. absence inboard motor focusing (critical for users of amateur Nikon cameras without motor focusing)
7. noisy auto focus
8. rotation of the focus ring during auto focus. Lack of continuous manual focus control
9. no depth of field scale and tags for working in the infrared spectrum. The focus distance scale is not made in the form of a window, but is simply applied to the focus ring and is very small
10. rear lens movement while changing the focal length, small effect of a vacuum cleaner / air pump
11. not even enough hole aperture on covered diaphragms
12. lack of image stabilizer (appeared only in the model Sigma 17-50 / 2.8 OS, 2010)
13. there may be incompatibility with some cameras and / or teleconverters (no exact data)
14. lack of data about the lens in modern cameras, which makes it difficult to automatically correct some types of distortion (distortion, vignetting etc.), as well as the lack of a lens profile in most popular RAW converters
15. palpable barrel-shaped distortion 18 mm focal length, tangible vignetting 18 mm focal length, low resolution at 18 mm in the corners of the frame on open apertures

Material prepared Arkady Shapoval. Training/Consultations | Youtube | Facebook | Instagram | Twitter | Telegram.