Like all super zoom lenses, the Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens features a to-die-for focal length range. Sigma packages this 13.9x (250mm divided by 18mm) focal length range in a very well built, modestly-sized, reasonably-priced APS-C-only lens with quiet, fast AF and optical stabilization. Image quality is, as usual for a super zoom lens, sacrificed. How much is the pertinent question.
She was pleased with her first fishbone braids - and I thought she looked especially cute (of course). So I quickly moved her to one of my go-to locations in the house (all good photographers should have one or many of these) for a quick indoor ambient daylight portrait.
The Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens was already mounted on my Canon EOS Rebel T2i/550D DSLR. The 95mm telephoto focal length, short focus distance and long background distance allow the background (carpet) to be nicely blurred beyond distraction even at the moderately narrow f/5.6 aperture. Another moment in life preserved.
While extremely convenient, putting the equivalent FLR (focal length range) of two normal zoom lenses into a single, small lens usually involves an image quality sacrifice. "Complicated" is the best word I can think of to describe the Sigma 18-250 OS' overall image quality.
At 18mm with a wide open aperture, expect the center portion of the frame to be reasonably sharp. The right side is a bit soft while the left side is decent. Stopping down the aperture to f/5.6 brings a nice improvement in sharpness in the center and left side, while f/8 continues to help the right side - which never becomes real sharp at 18mm.
At 24mm through 35mm, wide open, the center and right side are reasonably sharp while the left corners are soft. Stopping down to f/5.6 produces a very sharp image with the exception of the left side - which becomes reasonably sharp at f/8.
I have been using this lens off and on for almost a year and have been generally satisfied with the image sharpness from most of my shots taken between 18mm and 50mm - especially those shot at f/5.6 through f/8. This is the typical FLR for a kit lens or general purpose lens, so the rest of the focal length range could be considered pure advantage over one of these kit-grade lenses.absolute; left: 240;" However, at 50mm and beyond, image quality begins to break down.
At 50mm, the center is reasonably sharp wide open (which is now f/5.0) and quite sharp at f/8. All corners are somewhat soft wide open. The left side becomes very sharp at f/8 while the right side remains soft.
By 80mm wide open (f/5.6), there is a small area of the frame to the left of center that is sharp wide open. The rest of the frame, and especially the corners, are soft. With the exception of the right side, the image is sharp at f/8. The right side remains noticeably unsharp even at f/8.
By 150mm wide open (f/6.3), the small area of sharpness to the left of center covers about 1/4 of the frame (left to right and top to bottom) and is centered about 1/3 of the way into the left side of the frame. Stopping down the aperture to f/8 expands this sphere of sharpness, but the corners remain soft. At f/11, the results are decent.
At 250mm wide open, the entire image is soft and the corners are very soft. At f/8, there is a noticeable improvement - the middle-left portion of the image again becomes reasonably sharp. So, if you can position your small-to-mid-sized subject (like a person's head) into this area of the frame and shoot f/8, 250mm can indeed be usable. Here is a 250mm example:
The above Amish field scene (shot with a Canon EOS 50D at f/8) shows three pair of corn shocks. The center corn shocks are approaching the bottom-right of the area of sharpness I am describing. The left-most corn shock is about the left-most limit of this area of sharpness. The right-most corn shocks are not as far out on the image circle radius as the left-most corn shocks, but they are obviously blurry even with moderately strong sharpening applied.
It is not unusual for lens image quality to worsen as the outside of the image circle is approached with the corners of the frame typically having the worst image quality. When there are inconsistencies in image quality between the sides of a lens, I am less confident in lens-to-lens variances as a misalignment defect is likely being observed.
CA (Chromatic Aberration) is somewhat strong in the corners at 18mm, improves until it is mostly gone at 35mm, begins to show again around 150mm and becomes very strong at 250mm. As seen in the above example, at 250mm, CA is very strong in the mid and corner areas of the frame - making Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens image quality evaluation difficult without CA removal being performed (DPP is not able to remove CA from non-Canon lenses). The CA characteristics of this lens are in-line with the other currently available super zooms.
Distortion begins as moderate bulge-in-the-middle barrel distortion (good for this class of lens) that becomes mild pincushion distortion by 21mm. Pincushion distortion becomes strong by 35mm through 50mm and lessens to mild again by 80mm. Only mild pincushion distortion is present between 150mm and 250mm.
Though some vignetting is apparent, I don't consider it a weakness of the Sigma 18-250 OS. Some vignetting is visible at 18mm f/3.5 but is mostly cleared up by 30mm or so. Vignetting again becomes apparent at 150mm through 250mm.
Bokeh (OOF foreground and background blur quality) appears decent.
The Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens is moderately prone to flare - more so than the other brand 18-2XXmm super zoom lenses. It delivers some very interesting flare patterns at f/11.
Like the rest of the super zoom lenses, the Sigma 18-250 OS is not a fast (wide aperture) lens. Utilizing a narrow max aperture opening keeps the size, weight and cost down. Also like the rest of the super zoom lenses, the Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens is a variable max aperture lens. Here is a table showing the focal length ranges for the max aperture of various 18-something mm zoom lenses.
|Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens||15-17mm||18-26mm||27-37mm||38-60mm||61-85mm|
|Canon EF-S 18-55mm f/3.5-5.6 IS Lens||18-23mm||24-28mm||29-38mm||39-46mm||47-55mm|
|Canon EF-S 18-135mm f/3.5-5.6 IS Lens||18-21mm||22-30mm||31-40mm||41-63mm||64-135mm|
|Canon EF-S 18-200mm f/3.5-5.6 IS Lens||18-23mm||24-39mm||40-49mm||50-89mm||90-200mm|
|Sigma 18-125mm f/3.8-5.6 DC OS HSM Lens||18-27mm||28-40mm||41-72mm||73-125mm|
|Sigma 18-200mm f/3.5-6.3 DC OS Lens||18-20mm||21-30mm||31-50mm||51-77mm||78-153mm||154-200mm|
|Sigma 18-250mm f/3.5-6.3 DC OS HSM||18-23mm||24-34mm||35-49mm||50-79mm||80-146mm||147-250mm|
|Tamron 18-200mm f/3.5-6.3 XR Di II Lens||18-30mm||31-46mm||47-59mm||60-72mm||73-124mm||125-200mm|
|Tamron 18-270mm f/3.5-6.3 Di II VC Lens||18-29mm||30-45mm||46-58mm||59-90mm||91-237mm||238-270mm|
There are a lot of differences between lenses in the above chart, but I'm not sure any of them are significant as there is generally a 1/3 stop difference at most between lenses.
Holding a narrow aperture lens steady enough for sharp pics in low light becomes a problem - unless the lens has some form of image stabilization built in. Optical Stabilization (OS) is Sigma's answer for this lens. This OS implementation is extremely quiet and very well behaved (viewfinder image does not jump when engaging, disengaging or during use).
Many hundreds of test shots determined that I need a shutter speed of 1/6 second for a high percentage of sharp shots at 18mm with a slowly diminishing keeper rate down to .5 seconds. That compares to my needed 1/25 - 1/30 shutter speed without OS.
At 80mm, 1/13 to 1/15 second was my handholding limit with OS assistance. This speed was a somewhat-hard floor to what I could handhold at 80mm, though I have sporadic sharp images down to 1/8 second. Without OS, I need 1/125 - which was also a solid figure.
And at 250mm, my Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens handholding limit is 1/20 second with a slowly diminishing keeper rate down to 1/15. I have sharp 250mm images taken at 1/6 second, but plan on shooting a lot of shots for each sharp one at this setting. Without OS, I am getting some sharp results at 1/125, but 1/3 stop faster setting gives me a better percentage of sharp shots.
So, as usual, OS is a great help. Though it is rated for 4-stops of assistance, I personally am seeing about 3 stops of help from OS on this specific lens. Still, I'm very happy with 3 stops of assistance.
Focus matters - an OOF (Out of Focus) shot is usually worthless to me. As I have mentioned in other Sigma reviews, I have had a great deal of trouble with Sigma lens autofocus accuracy. I am very pleased to report that the first copy of the Sigma 18-250 OS I purchased retail focuses accurately - consistently. And with HSM (Hypersonic Motor) AF, it does so quickly, quietly and internally. The 18-250 focuses at least as fast as the non-USM Canon EF-S 18-200 and is slightly quieter. I found AI Servo AF performance to be good.
FTM (Full Time Manual) focusing is not enabled. Manual focusing requires the AF/MF switch to be positioned to the MF setting and the focus rings turns when autofocusing. You will want to keep your fingers clear of the MF ring to prevent damage to the internal gears while autofocusing, but the layout and size of the zoom ring makes this easily accomplished.
Filters attached to the front of this lens do not rotate (helpful when using certain types of filters including circular polarizer filters). This is not a parfocal lens - changing the focal length requires refocusing.
All of the compatible APS-C Canon Digital SLR cameras require a max aperture of f/5.6 for autofocus to function. Fortunately, the Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens autofocuses at all focal lengths including those with an f/6.3 max aperture on these cameras.
The manual focus ring is very smooth with no play, but as is common with the 18-2XXmm super zoom lenses, the MF ring has a short rotation between MFD (Minimum Focus Distance) and infinity. This can make manual focusing at longer focal lengths touchy.
Here is a comparison table showing the MFD and MM (Maximum Magnification) of some comparable lenses.
|Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens||13.8"||(350mm)||.21x|
|Canon EF-S 18-55mm f/3.5-5.6 IS Lens||9.8"||(250mm)||.34x|
|Canon EF-S 18-135mm f/3.5-5.6 IS Lens||19.3"||(490mm)||.21x|
|Canon EF-S 18-200mm f/3.5-5.6 IS Lens||17.7"||(450mm)||.24x|
|Sigma 18-125mm f/3.8-5.6 DC OS HSM Lens||13.8"||(350mm)||.26x|
|Sigma 18-200mm f/3.5-6.3 DC OS Lens||17.7"||(450mm)||.26x|
|Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens||17.7"||(450mm)||.29x|
|Tamron 18-200mm f/3.5-6.3 XR Di II Lens||17.7"||(450mm)||.27x|
|Tamron 18-270mm f/3.5-6.3 Di II VC Lens||19.3"||(490mm)||.29x|
Another great spec for a lens that attempts to be a one-lens solution - a .29x MM value is one of the best available from a non-true-macro lens. That is not the end of the story though as the 18-250's MFD value is Sigma's specification - which is apparently for autofocus (which tests at about 16.7" / 424mm). As you will notice in the Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens Specifications page, the true MFD range of this lens (using manual focus) is 11.65” - 12.76” (296mm - 324mm) over the focal length range - significantly increasing the MM to about .40x. Unfortunately, image quality remains weak at 250mm (the focal length the maximum magnification is reached at).
None of these lenses are compatible with extenders/teleconverters.
The Sigma 18-250 OS is a very nicely built lens. The lens feels solid and there is no play in the extending barrel. Like the focus ring, the zoom ring is smooth (especially for this focal length range) with no play in it. As usual with a long-extending lens, gravity has an effect on the rotational force required to change focal lengths. Extending the lens when pointed downward is much easier than when pointed up - and vice-versa.
The included hood size is small - and as usual with this class of lens, will not offer much protection against flare at longer focal lengths. Protection from damage is always a good reason to keep it installed. I often mention my personal dislike for Sigma's matte lens finish - mostly because I do not like how it shows dust and marks so easily (it looks great when new). The hood continues to have this property, but the rest of the lens is mostly zoom ring with the balance being mostly focus ring.
A zoom lock switch is available to hold the retracted lens position (only), but the zoom ring is firm - tight enough to prevent gravity-zooming while being carried around. I have heard a couple of reports of loose 18-250mm lenses though - so there may be some variances in this regard.
The Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens' size and weight are very nice for take-with-you-everywhere use, Though it weighs more than any other lens in the list below, the additional weight is not a differentiating factor between it and the other image stabilized 18-2XXmm super zoom lenses in my opinion.
|Model||Weight||Dimensions w/o Hood||Filter||Year|
|Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens||20.3 oz||(575g)||3.2 x 3.4"||(81.6 x 87.5mm)||72mm||2009|
|Canon EF-S 18-55mm f/3.5-5.6 IS Lens||7.1 oz||(200g)||2.7 x 2.8"||(68.5 x 70mm)||58mm||2007|
|Canon EF-S 18-135mm f/3.5-5.6 IS Lens||16.1 oz||(455g)||3.0 x 4.0"||(75.4 x 101mm)||67mm||2009|
|Canon EF-S 18-200mm f/3.5-5.6 IS Lens||21.0 oz||(595g)||3.1 x 4.0"||(78.6 x 102mm)||72mm||2008|
|Canon EF 28-135mm f/3.5-5.6 IS USM Lens||19.1 oz||(540g)||3.1 x 3.8"||(78 x 97mm)||72mm||1998|
|Sigma 18-125mm f/3.8-5.6 DC OS HSM Lens||17.8 oz||(505g)||2.9 x 3.5"||(74 x 88.5mm)||67mm||2008|
|Sigma 18-200mm f/3.5-6.3 DC OS Lens||21.5 oz||(610g)||3.1 x 3.9"||(79 x 100mm)||72mm|
|Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens||22.2 oz||(630g)||3.1 x 4.0"||(79 x 101mm)||72mm||2009|
|Tamron 18-200mm f/3.5-6.3 XR Di II Lens||14.0 oz||(398g)||2.9 x 3.3"||(73.8 x 83.7mm)||62mm|
|Tamron 18-270mm f/3.5-6.3 Di II VC Lens||19.4 oz||(550g)||3.1 x 4.0"||(79.6 x 101mm)||72mm||2008|
The Tamron 18-200 is the only notably smaller/lighter 18-2XXmm lens, but it lacks image stabilization. The 18-55mm kit lens weight is hard to beat of course. Pictured below from left to right (ordered by extended size with lens hoods) are the:
1. Canon EF-S 18-55mm f/3.5-5.6 IS Kit Lens
2. Tamron 18-200mm f/3.5-6.3 XR DI II Lens
3. Sigma 18-200mm f/3.5-6.3 DC OS Lens
4. Canon EF-S 18-200mm f/3.5-5.6 IS Lens
5. Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens
6. Tamron 18-270mm f/3.5-6.3 Di II VC Lens
Click on the image below to take a look at 5 super zoom lenses mounted to a Canon EOS 50D.
Again, I don't feel that size and weight are good differentiators between these lenses. The focal length range is of course the most compelling reason to buy a super zoom lens.
Though it will physically mount on a full frame or APS-H sensor body, the Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens is a "DC" (Digital Camera) lens. This means the lens image circle will only cover an APS-C (1.6x FOVCF) sensor. Thus, the 18-250's 35mm-equivalent AOV (Angle of View) equates to a 28.8-400mm lens. Here are a couple of examples of what this incredible focal length range looks like (use the mouseover links below the image).
Pictures shot at 18mm will give the viewer a sense of presence in the scene and it just keeps going and going from there. 250mm will bring distant subjects in close - compressing the details in the image - potentially blurring the background. From moderately wide landscapes to portraits to short distance wildlife photography, the right focal length is available in one lens.
This focal length range is in-arguably excellent, but as we saw in the Canon EF-S 18-200mm f/3.5-5.6 IS Lens Review, all lens focal lengths at less-than-infinity focus distances are not necessarily equal. Focal lengths are rated at an infinity focus distance, but here is a table that shows the moderate distance required to frame a 47.25" x 31.5" (1200 x 800mm) test target at maximum focal length when mounted on an EOS 50D.
|Canon EF 200mm f/2.8 L II USM Lens||424.9"||(10792mm)|
|Canon EF 200mm f/2.0 L IS USM Lens||425.1"||(10798mm)|
|Canon EF-S 18-200mm f/3.5-5.6 IS Lens||369.9"||(9395mm)|
|Sigma 18-200mm f/3.5-6.3 DC OS Lens||369.6"||(9389mm)|
|Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens||476.0"||(12,090mm)|
|Tamron 18-200mm f/3.5-6.3 XR Di II Lens||384.7"||(9771mm)|
|Tamron 18-270mm f/3.5-6.3 Di II VC Lens||500.3"||(12708mm)|
Calculations based on the two prime lens figures indicate that 250mm should have a distance of about 531.1" (13,490mm) and 270mm should have a distance of about 573.6" (14,569mm). So, all of the zoom lenses seem to be similarly short of their named max focal length at this test distance, but the 250mm and 270mm variants do indeed have longer max focal lengths than the 200mm variants - which are similar to each other.
Due to popularity, the super zoom lens market is a somewhat crowded one. And the extra 50-70mm max focal length is a product differentiator. Here is a visual max focal length comparison between these super zoom lenses.
The above images were shot from a stationary EOS 50D with each lens set to the maximum focal length. They are listed from left to right in the order they were taken. Interesting is that the Sigma 18-250 presents a lower view of the scene.
The difference between 200mm and 250/270mm is noticeable, but not dramatic when looking at the overall range covered by these lenses. And regardless of their true maximum focal lengths at any distance, all of these super zooms have an awesome focal length range (FLR).
If you decide the irresistible focal length range is what you want, your next decision is - which is the best super zoom lens, overall? I spent far more days than I want to think about trying to create a set of outdoor image quality comparisons to show you in addition to the ISO 12233 Chart Tool results. But thus far, I am not satisfied with how my test shots compare the complex image quality from these lenses. I may still add an outdoor comparison to this review, but in the meantime, I'll leave you with my personal preferences.
Cost aside, I would give up the Sigma 18-250 OS' additional 50mm of focal length on the long end as well as some of the build quality, and select the Canon EF-S 18-200mm f/3.5-5.6 IS Lens over the rest of the 18-2XXmm super zoom lenses. The main reason for my choice is better image quality. This choice, at review time, will set you back $100 more than the Sigma 18-250 and will have more barrel distortion at 18mm.
The Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens would be my second choice. The Tamron 18-270mm f/3.5-6.3 Di II VC Lens is the third on my list, but I like the Sigma 18-250's build quality, AF and OS better. The Tamron has slow AF and a less-well-behaved image stabilization system. Image quality ranking between these two lenses is not easy - the Tamron has an advantage in my testing, but the difference is not dramatic.
The Sigma 18-200 OS and the Tamron 18-200 would bring up the bottom of the group I have in front of me right now. The newer lenses are definitely showing improved optical characteristics. The Tamron is a really small, light and inexpensive lens - and has a really low price. This is one advantage it holds.
I could easily see others deciding that the Sigma 18-250 OS is the best super zoom lens for them. It is a very nice lens with great build quality and AF, a nice OS implementation and a reasonable price.
With a huge 13.9x focal length range and OS, the Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens is like two lenses and a tripod in the package of a medium-small lens (great for travel). While the Sigma 18-250 OS' image quality in the 50-250mm focal length range is not ideal, it can deliver a lot more than an 18-55mm lens can in that range. And if you are willing to give up the ultimate image quality a multi-lens solution will provide - for the convenience of a super zoom lens, the Sigma 18-250 OS should be near the top of your consideration list.
The Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens is available in Canon (tested), Nikon, Sigma, Pentax and Sony mounts and comes with a 1 Year International Warranty plus 2 Year Sigma U.S.A. Extended Warranty.
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