Pentax 16-45mm and 16-50mm compared

A comparision test of the Pentax SMC-DA 16-45mm f/4 ED AL and the smc PENTAX-DA* 16-50mm f/2.8ED AL[IF]SDM

A common dilemma raised on the Pentax User forums, and other forums around the globe, is whether to buy the Pentax 16-45mm lens or the 16-50mm. Another question surrounding these two lenses is when an owner of the 16-45mm isn’t sure whether it’s worth upgrading to the newer 16-50mm. So while Peter Bargh has both in his possession he thought he’d try and clear up the confusion.

The Pentax SMC-DA 16-45mm f/4 ED AL has been around since 2003 and currently sells for around £200, while the smc PENTAX-DA* 16-50mm F2.8ED AL[IF]SDM surfaced in 2007 and costs around £475*

Specifications

*prices on SRS web site as of 18 Feb 2009

The image circle in DA-series lenses, including the smc Pentax DA 16-45mm f/4 ED AL, is designed to perfectly match the 23.5 x 15.7mm size of the CCD used in Pentax digital SLRs, optimizing camera performance.

Features
As you can see from the spec list the 16-50mm has the advantage of a larger maximum aperture. Being a full stop faster means it’s better in lower light or at slower ISOs. It also provides a slightly brighter viewfinder image, although the difference is hardly noticeable, there’s slightly more clarity but it’s not enough to worry about.

The marginally longer focal length is also so small a difference that it’s really not an issue.

The 16-45mm has the edge on close focusing and one reason why its been my standard lens for nearly six years. Having a close focus as good as this means it’s a very versatile lens and is perfect if I stumble across a close subject and had decided not to take the macro lens. This lens has got me out of trouble on several occasions. The 16-50mm, while decent in its macro capabilities, is disappointing in comparison.

16-45mm closest focus	16-50mm closest focus

Because of the f/2.8 aperture, the 16-50mm is a bulkier then the 16-45mm and as a result has a much larger and more expensive to cater for 77mm filter thread. It’s also much heavier, but this does make it feel more like a pro spec Nikon competitor than a lightweight amateur model. If that’s an important factor the 16-50mm wins hands down.

Looking at the two lenses side by side you can see the 16-50mm (right) is a bulkier option, but not much longer. It’s the extra light-grabbing maximum aperture that makes the difference which can be clearly seen from the front view.

Around the back the lens mount is similar. You’ll see the usual range of electronic couplings, necessary for communication with the camera, along with two contacts on the inner mount of the 16-50mm (right). These are to power the Supersonic Drive Motor (SDM) and transmit modulation transfer function (MTF) data. They are not found on the 16-45mm.

Handling
As mentioned earlier, the 16-50mm looks and feels like a pro spec lens. The focusing ring is huge in comparison to the 16-45mm’s and is much better to control. The 16-45mm has a flimsy focus ring that sounds coarse when adjusting and feels plasticky. The 16-50mm focusing ring has a rubberized grip and smooth to adjust. Almost like an old quality manual focus ring.

The 16-50mm has weather seals so it’s safer to use outdoors in poor conditions.

Performance
Focusing in auto is precise from both models, but the 16-50mm does the job with more finesse. The sound is less squeaky and there’s less hunting and no clunking sounds.

Below is a series of comparison tests to check for sharpness, vignette, distortion etc. While these are not scientific, like those you’d get from an optical bench test they are more realistic and likely to indicate what you’d get from a day out shooting, rather than a day in the lab…which is not what we tend to do…or is it?

I did a series of tests that you can use to compare the lenses. All photos were taken using the Pentax K20D body.

Test 1 sharpness
Nothing beats a good old newspaper test - lots of small detail, high contrast, sharp text to test fringing, detail into the edges. And what I like is it’s not perfectly flat so you can see if the lens has a small amount of front or back focus as well as compare the two to see if depth-of-field is assisting the apparent sharpness. The newspaper was laid on the floor and the camera mounted on a tripod and positioned above. The tripod was adjusted twice - once for the wide setting and once for the longer zoom end.

Before looking at sharpness notice the differences in the subject coverage. Both claim to be same 16mm, yet the 16-50mm has a wider coverage. And at the longer end although the 16-50mm should show an extra 3.5deg coverage it looks less in the photos.

Three photos were taken at 16mm on each lens, one wide open at f/2.8 on the 16-50mm and f/4 on the 16-45mm, then one at f/8 and one at f/22 on each lens. The same series of shots was repeated at the 45/50mm foal length setting.

Pentax 16-45mm at 16mm and f/4	Pentax 16-50mm at 16mm and f/2.8
Pentax 16-45mm at 16mm and f/8	Pentax 16-50mm at 16mm and f/8
Pentax 16-45mm at 16mm and f/22	Pentax 16-50mm at 16mm and f/22
Pentax 16-45mm at 45mm and f/4	Pentax 16-50mm at 50mm and f/2.8
Pentax 16-45mm at 45mm and f/8	Pentax 16-50mm at 50mm and f/8
Pentax 16-45mm at 45mm and f/22	Pentax 16-50mm at 50mm and f/22

Each shot is reproduced small to keep the web page load low, but you can click on any shot to see a full size original. These were shot in AF mode and in RAW and sharpened slightly (50%) and have been saved as a jpeg high quality so you can download and compare.

I had to repeat the test on the 16-50mm as the f/2.8 shot was soft. It appears the AF ability of this lens at f/2.8 is suspect. The 16-45mm shots were all sharp but the 16-50mm clearly didn’t look right. So All the shots were redone using manual focus.

Test 2 Evenness of illumination
A photograph of an even neutral surface were taken with each lens at the wide and telephoto setting at maximum aperture to see how even coverage is and if there are any signs of vignetting.

Pentax 16-45mm vignette test at 16mm	Pentax 16-50mm vignette test at 16mm
Pentax 16-45mm vignette test at 45mm	Pentax 16-50mm vignette test at 50mm

The 16-50mm shows problems at the 16mm setting and also, surprisingly, has a small amount at the 50mm setting. The 16-45 shows much more even fall off. Uneveness of illumination like this is only going to be apparent when you're shooting something on an even background. You'll hardly see it when there's a variety of tones as you can see from the other sample photos. But it's worth knowing. Some software has a feature that allows you to even out the exposure so this can be corrected if you do see signs. Having said that, it's much better if the lens is doing the job it's intended to do.

Test 3 distortion
A brick wall is a good way to show any curvature of a lens. Use the straight lines of the brick edge/mortar to see if there’s any distortion. Shots were taken from the same point with each lens at the wide and then at the telephoto setting. 

Pentax 16-45mm distortion test at 16mm	Pentax 16-50mm distortion test at 16mm
Pentax 16-45mm distortion test at 45mm	Pentax 16-50mm distortion test at 50mm

Not much difference between the two, both have a small amount of barrel at 16mm and pincushion at 45/50mm. I would have hoped the 16-50mm would have been better at the wide setting. There’s clearly little advantage paying extra for this lens in this particular test.

Verdict
If the 16-50mm was only a £100 more than the 16-45mm it may be worth the money, but this lens is at least £200 more. It’s bulkier to carry around and the close focus capability isn’t as good. What you gain here is the one stop faster aperture, and for those shooting in low light that could be worth the price as increasing ISO on the current models can introduce too much noise. When Pentax produce a camera with superb low noise at ISO800 the advantage will become less advantageous, but until then the 16-50mm’s extra stop may get you out of a hole.

If you need a quiet lens the 16-50mm is also a winner, but for me I’m just after quality and prefer the lighter and lower priced 16-45mm which doesn’t disappoint when compared head to head with a lens twice its price. For me the clear winner is the 16-45mm and you'll have over £200 to spend on some other goodies!

Bellie
Member

Joined: 26/03/2008
Location: Sheffield

Link Posted 02/04/2009 - 09:47

Thats good to know Pete. My 16-45mm had an outing at the weekend and performed well, but you always wonder whether a DA* would have done better. Looks like I've got the right lens for the job - albeit like you said - a bit clunky.

loskeran
Pentax Pro Master

Joined: 08/01/2009
Location:

Link Posted 28/04/2009 - 07:53

A Very well done comparison, in plain English and with good graphical examples.
I to use the 16-45mm and had some very good shots with it on the K20 and my K200.
One thing that struck me when I first used it was the clarity and brightness of colours produced on what is a very reasonably priced lens. Far better than I expected.
Thanks

Kenny
New Member

Joined: 21/05/2009
Location:

Link Posted 21/05/2009 - 07:21

Very good comparison indeed. But how does the 16-45mm compare to the 17-70mm? I'm a beginner, so I suppose 17-70mm is a relative walk around lens to have. And what would be a good telephoto lens to complement it? 70-200mm? Thanks in advance!

Dwight-Morton
Pentax Master

Joined: 14/09/2006
Location: Hamilton, ON Canada

Link Posted 17/10/2009 - 00:37

Thanks, so saving up for the 16-45 mm still looks the route to go for an perhaps get one the fancy colour bodies from JAPAN to go with it.

vjacesslav
New Member

Joined: 14/01/2009
Location:

Link Posted 28/10/2009 - 11:06

Nice one. I´ve always knew that 16-45 F4 is exceptionaly good lens. 16-50 is not so much good, but still can keep doing good job. If you want to get nice sharp pictures even at f2.8, go to Tamron 17-50mm F2.8. This is another superior lens. Price is similar to 16-45, but you can use it directly from F2.8...