Pentax 18-55mm f/3.5-5.6 AL II SMC DA
Lab Test Results
August 24, 2009
by Andrew Alexander
The Pentax 18-55mm ƒ/3.5-5.6 II is a ''kit'' lens sold with Pentax's current lineup of SLR bodies. It is designed to fit a camera with an APS-C (''subframe'') sensor, so while it will mount on Pentax film bodies, it will show obvious vignetting when set to any focal length wider than 24mm.
Small and light, the 18-55mm represents a field of view of approximately 28-80mm in 35mm terms. To economize and create a more efficient design, the lens is uses a variable aperture; as the zoom extends the focal length, both the smallest and the largest apertures change. The following chart represents the largest and smallest apertures you can expect at a given focal length:
The lens ships with a petal-shaped hood, and while it comes standard with several body packages, you could probably find it on its own for less than $200.
There's a definite improvement in the 'II' model of the Pentax 18-55mm ƒ/3.5-5.6: while the predecessor lens was fairly good, Pentax has managed to find a way to tweak the performance for sharpness where it was previously lacking.
Wide open at wide-angle (ƒ/3.5 and 18mm) is probably the lens' weakest point, and even here it isn't too bad. There's a sweet spot of sharpness in the center (~1.5 blur units), but the corners get just slightly soft, at around 2.5 blur units on average. Stopped down, performance doesn't improve until ƒ/5.6, where it's about as good as it gets at 18mm - stopping down further to ƒ/8 doesn't make a significant difference.
Wide open at 35mm to 55mm is very good, even exceptional for this class of lens, with results hovering around the level of 1.5 blur units across the frame. Stopping down only provides very slight improvement, meaning you don't have to worry too much about what aperture you need for maximum sharpness - when you're set to 35mm or greater in focal length.
Diffraction limiting sets in at ƒ/11, but we don't notice any real degradation to sharpness until ƒ/22. Even by ƒ/22, image sharpness is just shy of 2 blur units across the frame below 35mm, and just above 2 blur units at 18mm. Fully stopped down performance isn't as bad as we've seen from other lenses, reaching an apex of mediocrity at ƒ/40 and 55mm, where image sharpness is around 4 blur units on average, across the frame.
While Pentax may have found a way to improve sharpness, they haven't improved on the lens' tolerance to chromatic aberration. CA is fairly high below 35mm, outside a central region of sharpness. Above 35mm, resistance to CA is actually quite good, similar to the previous (non-II) model of this lens.
The Pentax 18-55mm II ƒ/3.5-5.6 does present some corner shading in certain situations. Set to wide angle (18mm) you'll get about 2/3EV darker in the corners when set wide open to ƒ/3.5, but this is about the worst it gets for this lens. At 18mm, corner shading never really goes away - it approaches 1/4EV at ƒ/22 - but set to other focal ranges, the effect is more tolerable. It's noticeable at any focal length below ƒ/8, but otherwise, the effect is negligible.
Happily, the lens seems to be optimized for the focal length of 35mm, so setting it here, even at ƒ/5.6, produces images without any light falloff.
Being a wide-angle lens, distortion comes with the territory when set to wider angles, and because of a simpler design, the distortion gets somewhat complicated when zoomed in greater than 35mm.
Beginning with the wide-angle picture, distortion approaches 1% barrel in the corners when set to 18mm. This is fairly typical of lenses with this focal range, and the distortion is uniform throughout the image. As the focal range approaches 35mm the distortion approaches 0%.
Zoomed in past 35mm, some pincushion (''squeeze'') distortion results in the corners, however this is complicated with some lingering barrel distortion re-appearing in the center. This effect is significant on our chart, but may be hard to see on a print, as the effect is less than 0.25% in the corners. However, if straight lines are important to you, than shooting outside of the focal length of 35mm will be asking for a bit trickier correction in your image processing software.
The Pentax 18-55mm ƒ/3.5-5.6 II isn't an SDM, so it still relies on a mechanical screw to conduct autofocus. The timing of autofocus depends largely on the body the lens is mounted to, as the lens is mechanically driven with a screw. On a K10D, the lens is surprisingly quick to focus, at less than one second to rack through the entire range. Being mechanically driven, the lens does make some noise while the lens does a full-range focus. Point to point focusing on the K10D is very quick, and comparatively silent.
The Pentax 18-55mm ƒ/3.5-5.6 II offers a magnification rating of 0.34x and a minimum close-focusing distance of 25cm (just under a foot); it's no dedicated macro lens, but it's not bad, either.
Build Quality and Handling
The 18-55mm ƒ/3.5-5.6 II is an upgraded version of the previous 18-55mm lens. Pentax has indicated it updated the lens with 'improved resolution to match higher resolution sensors.' In practice, this seems to have resulted in the removal of a single lens element.
At only 225 grams (7.9 oz), the 18-55mm II ƒ/3.5-5.6 is very light, but its construction is very solid. The mounting plate is metal but the filter ring is plastic. It has some nice finishing touches such as a distance scale, and Pentax's ''quick-shift'' system offers the ability to override autofocus and focus manually by just turning the focus ring at any time (you don't need to switch it into manual focus mode). The lens hood also gets special marks in my book for having a removable plate that lets you have access to, and turn, a mounted polarizing filter. The lens hood also mounts backwards for easy storage, though it's not easy to use the lens with the hood mounted this way.
Speaking of polarizers, mounted filters won't turn when the lens is zoomed or focused, which is always preferred. It's not a constant-length lens, in that as you select a different focal length by zooming the lens will extend its length. It's at its smallest at 35mm, and the lens will extend out at any other focal length from there. Zoom and focus rings take a little more than a quarter turn to run through their entire range, and the rings are well textured and smooth to turn.
Pentax 18-55mm ƒ/3.5-5.6 SMC P-DA ~$200
The predecessor Pentax kit lens was also a good lens, but has been slightly improved upon in the II version in the area of sharpness. Otherwise, it's essentially the same lens but 5 grams lighter.
Pentax 18-55mm ƒ/3.5-5.6 AL SMC DA WR ~$200
Pentax has released a weather-resistant version of the 18-55mm, which we haven't yet tested.
Pentax 17-70mm ƒ/4 AL IF SDM SMC DA ~$600
The Pentax 17-70mm is a bit more versatile, with a constant ƒ/4 aperture. It's also an SDM lens, making it faster and quieter to autofocus. Optically, it's the better lens in many ways: sharper, to be sure, and better tolerance to CA. Distortion is a bit odd, but not surprising.
Sigma 18-50mm ƒ/2.8 EX DC Macro ~$420
Sigma offers a constant ƒ/2.8 version in the 18-50mm focal length, compatible with the Pentax mount. We have not yet tested this lens. I specifically didn't put the newest 18-50mm HSM version here, mainly because it incorporates optical stabilization which the Pentax body already has built-in. Interestingly, Sigma calls this lens a Macro lens, but the Pentax 18-5mm ƒ/3.5-5.6 II actually has the same magnification rating (0.33x).
Tamron 17-50mm ƒ/2.8 Di II LD Aspherical IF SP AF ~$450
The Tamron lens is quite popular, and for good reason: a constant ƒ/2.8, and excellent results for sharpness and tolerance to chromatic aberration. Its low sticker price also makes it quite popular.
Most newer Pentax owners already have this lens, are potentially looking at upgrading to a more capable lens, and are probably looking at this page to see how ''much'' better a new lens might be. Optically, the Pentax 18-55mm ƒ/3.5-5.6 II is quite good, perhaps sharper than it should be for the price point. CA is a slight issue in the corners at wide angle, but set to 35mm and above, isn't much of a factor. The 'II' designation is more than cosmetic, there have definitely been some tweaks under the hood, primarily resulting in improved sharpness.
I don't see a compelling reason to upgrade to this lens from a previous version of the 18-55mm - the $200 is probably better invested in more capable glass. But existing users of this lens who aren't ready or interested in upgrading should be reassured that they've got one of the better kit lenses on the market.
The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.
As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.
Pentax 18-55mm f/3.5-5.6 AL II SMC DA User Reviews
9 out of 10 points and recommended by joe88 (37 reviews)very sharp if stopped down a fewvery small CA's
for a kit lens a very good lens. High contrast and nice colors,reviewed January 31st, 2014 (purchased for $50)
I tested it wide open and stopped down to f8. I compared
with a tree photo against the sky (without leaves).Between 24 and 55 corners are very sharp,too.
In combination with k-x CA's disappearing nearly totally.
8 out of 10 points and recommended by dugong5pm (52 reviews)sharp & contrast, build qualitynone
best lenskit, in the range of 18-55, compared to the other model. It has better image quality & build. period.reviewed October 13th, 2012 (purchased for $100)
8 out of 10 points and recommended by aldorp (2 reviews)Great Value, Great Image QualityNot a very fast lens
I got the Pentax K2000 Camera that comes with the cheap version of the Pentax DA 18-55mm f/3.5-5.6 AL. I say cheap because it uses the same glass but with a cheaper construction. Plastic mount and no lens hood.reviewed July 6th, 2009 (purchased for $90)
Pentax DA 18-55mm f/3.5-5.6 AL II upgrades in the following areas:
1) Better overall construction, metal mount
2) Hood is included
3) You get focus measurements on the focus ring for the manual "Quick-Shift Focus System"
4) Less Vignetting compared to Pentax DA 18-55mm f/3.5-5.6 AL (But still there wide open)
5) Sharper on center and boders compared to the Pentax DA 18-55mm f/3.5-5.6 AL on my Pentax K2000
Problems is still has
1) Has the very same Distortions as the Pentax DA 18-55mm f/3.5-5.6 AL common to zoom lenses. The distortion still makes the corners soft at 18mm.
2) Same speed (f/ stops) across the lens
3) Same 18 - 55mm short zoom range
4) Visible vignetting at 18mm wide open at f/3.5-4.5 and a little at long end 55mm wide open f/5.6. Better than before but still these. Goes away as you close down.
Pentax DA 18-55mm f/3.5-5.6 AL vs Pentax DA 18-55mm f/3.5-5.6 AL II
at 18mm F/3.5: The Pentax DA 18-55mm f/3.5-5.6 AL II has more contrast, sharpness, especially on the corners, but it is still soft. At F/5.6 both lenses improve in sharpness but the Pentax DA 18-55mm f/3.5-5.6 AL II stays ahead. At F/8 both are almost equally sharp at center but the The Pentax DA 18-55mm f/3.5-5.6 AL II still has sharper corners. The Pentax DA 18-55mm f/3.5-5.6 AL II clearly has less Vignetting at all apertures at 18mm.
at 35mm F/4.5: The Pentax DA 18-55mm f/3.5-5.6 AL II has more contrast, sharpness, especially on the corners. At F/5.6 both lenses improve in sharpness but the Pentax DA 18-55mm f/3.5-5.6 AL II stays ahead. At F/8 the The Pentax DA 18-55mm f/3.5-5.6 AL II is almost in a virtual tie with the Pentax DA 18-55mm f/3.5-5.6 AL, the closest I find both lenses to each other and the sweet spot for both lenses. The The Pentax DA 18-55mm f/3.5-5.6 AL II clearly has less Vignetting at F/4.5-6.3 apertures at 35mm.
at 55mm F/5.6.5: The Pentax DA 18-55mm f/3.5-5.6 AL is soft. On the other hand the the Pentax DA 18-55mm f/3.5-5.6 AL II is sharper and has a nicer bokeh (out-of-focus blur). At F/8 the The Pentax DA 18-55mm f/3.5-5.6 AL II clearly has a sharper and brighter image. The Pentax DA 18-55mm f/3.5-5.6 AL II clearly has less corner Vignetting at all apertures at 55mm.
In this version II of the lens it is very similar to the old Pentax 16-45mm f/4.0 SMC PDA ED AL wide angle lens in image quality and speed. The Pentax 16-45mm f/4.0 SMC PDA ED AL has less vignetting but the Pentax DA 18-55mm f/3.5-5.6 AL II has less chromatic aberrations. Sharpness is not that much different at the long end with both lenses with the Pentax 16-45mm f/4.0 SMC PDA ED AL having better center sharpness at the short end.
So the question becomes, is it worth the money? I got mine for $90.00 so to me it was a decent price and a decent upgrade. In the end I find the Pentax DA 18-55mm f/3.5-5.6 AL II a good buy. It is small, light and is nice to walk around.
9 out of 10 points and recommended by Simen1 (6 reviews)Build quality, fast AF, nice hood, cap, weight, priceNot water resistant
This is simply the best cheap kit-zoom around.reviewed May 19th, 2009 (purchased for $85)
Compared to Canon 18-55 f/3.5-5.6 IS and Nikon 18-55 f/3.5-5.6 VR this is by far the best of these. Here is why:
- Its smaller then the Nikon, about same size as the Canon.
- The Nikon feels vulnerable. Canon's lens feels better. Pentax feels quite solid. Pentax is the only one of these with metal mount.
- Focus ring is better on the Pentax. Simply turn it to focus manually. Even if the camera is in AF mode. The Nikon and Canon lenses need the AF/MF-switch to be at MF to focus manually.
- The front does not rotate. On Canon and Nikons offer the front does rotate and will be a problem with filters.
- AF is a lot faster on this then on Canon and Nikons kit-lenses.
- Flower shaped hood is included. With Canon and Nikons kit you must buy the hood separately. The hood is reversable for more compact transport. The hood even have a nice feature: a "window" to adjust filters without taking the hood of.
- The lens cap on Pentax and Nikons kit-zooms has a nice grip. Canon have a less practical cap.
- I have not noticed any significant different optical performance between the three lenses. Tests claims Pentax have slightly better optical performance.
- All three kit zooms are stabilized: Nikon and Canon in the lens, Pentax in the camera.
- Pentax and Nikon offers a tiny bit more wide angle and less tele then Canon because of different crop-factors.
- None of the kit-zooms are water resistant. That would be a nice feature with the weather resistant cameras it is bundled with. Rumors have it that a water resistant version are on the way.
Conclusion: This is simply the best cheap kit-zoom around. (Probably until the WR version is out)
9 out of 10 points and recommended by Hawki (4 reviews)Lightweight, Sharp for Price, Build better than I expectedManual focus ring not dampened, focus a little noisy.
This lens is a pleasant surprise. I had read a couple of reviews that had been everything but kind to this lens, but found them to be wrong, at least for my copy.reviewed November 3rd, 2008 (purchased for $109)
The colours are typical Pentax, the contrast is good, distortion is controllable and the CA's within reason. I have viewed several 100% crops with my K20D and it truly appears that the increase in resolution of this lens works. I plan to couple this with the 50-200 and then supplement with some of the limited primes for most of my critical work.
For the money, you just can't go wrong.