This 40mm prime offering from Pentax can be placed in the classification of standard lenses. Designed solely for cropped sensor cameras of the *istDx series, it’s focal length works out at a slightly long standard rather than a short telephoto. It is also a very compact lens. We take a look at how it performs.
- Focal Length 40mm
- Max Aperture f/2.8
- Min Aperture f/22
- No of Blades 9
- Angle of view 39º
- Filter size 49mm
- Construction 5/4 elements/groups
- Focus type AF/MF
- Closest focus 400mm (0.13x)
- Weight 90g (ex hood)
- Dimensions 63x15mm
- Mounts available Pentax KAF
- Tripod bush No
- Price (SRP) £249.99p
Build and Handling
As you can imagine with a lens that is only 15mm thick not counting the lens hood, there is not a lot to describe! There is a distance window opening on the barrel, although this is obscured from view by the flash housing/pentaprism on the camera that protrudes almost as far as the lens. The scale is engraved and coloured in white for feet and gold for metres, the numbers being alternated. The front edge is the focus ring, which was nicely torqued and easy to use despite large fingers. When close focussed, the front of the lens extended, increasing the length of the lens by a huge 7mm, almost half as much again!
The lens is supplied in a neat draw-top pouch that takes up less room than a standard purse or wallet and, in fact, we have filters that take up more space. The lens comes supplied with a hood that we had to look twice to find. It was actually fitted to the lens and was initially mistaken for the lens cap. It is a screw-in type that is cone shaped and contains within it a screw-in lens cap about the size of a coat button!
Autofocus, which is switched on the camera, worked well being quick enough and quiet enough to cause any worries.
With the *istDx series of cameras being renowned for their small size, when fitted with this lens it becomes the first dSLR combo that you could happily carry in a jacket pocket without worry.
The simple optical design of this lens combined with modern manufacturing practice has come up with a lens that produces decent results. Yes, there is the tiniest amount of pincushion distortion and the chromatic aberrations are measurable, but certainly nothing that the majority of users would pick up and none with the Mk 1 eyeball. Contrast is good and colour rendition is pleasant. Resolution is maintained right across the width of the frame and all the way into the corners. Some lenses from Pentax have been accused of back focus on the *istDS but our tests proved that this was not the case, certainly with this lens even at the closest focus point and wide open.
At 40mm on a 1.5x crop factor camera, this lens is a good all round ‘standard’ lens proving useful in a number of situations.
All pictures shot at ISO200 and aperture priority on a Pentax *istDS
With a useful close focus distance of only 40cm it is a useful lens for indoor work and still life subjects. The front element does not rotate during focussing, so the use of filters is easily achieved.
Click on each of these two comparison photos to view full size versions
40mm f/2.8 at f/2.8
40mm f/2.8 at f/8
Below is our lens test data. To find out how to use this graph look at this article: How we test lenses
If you want a discreet, easily pocketable or lightweight lens then this is the one to have. With the metal lens hood and cap screwed into place, the build is up to knocking around in a handbag or glove compartment without worries. The fixed standard length means you will have to maybe walk a few more paces, but it will help you to think about framing your shots a little better too. The neat pouch makes it easy to carry in a trouser pocket too. There is no excuse for not having it with you.
In summary, the positive points of the Pentax SMC-DA 40mm f/2.8 lens are:
Size and weight are minimal
Hood/cap arrangement afford good protection
Cute little carry pouch.
The negative points are:
Screw-in lens cap is fiddly to remove
Optically good enough but not stunning.
Check the latest price of the SMC Pentax 40mm f/2.8 DA here
Test by Ian Andrews www.wildaboutkent.co.uk