Pentax 43mm f/1.9 Limited SMC P-FA
Lab Test Results
March 18, 2008
by Andrew Alexander
The Pentax limited edition lenses show off a polish and refinement you don't see in average lenses. From the first moment you mount the 43mm ƒ/1.9 you can tell it's been manufactured with an eye to detail.
With a 35mm image circle, the 43mm is fully backward-compatible with all Pentax K-mount film bodies. On a subframe sensor body, the lens will give an effective field of view of around 65mm, a very unusual focal length. It's quite light for its construction, and makes a very compact camera package when mounted to a Pentax body. It takes 49mm filters, and is available now for around $470.
Update September 28, 2010: We've added a new shooter's report for this lens, which you can read here.
The 43mm ƒ/1.9 is a sharp lens, but only when you close the aperture down a few stops. Wide open at ƒ/1.9, significant softness can be found in the corner regions - the central third of the lens is fairly sharp at 1.5 blur units, but the corners hit upwards of 3 and 5 units. This softness reduces dramatically as the lens is stopped down to ƒ/2.8 and practically flattens out to an extremely sharp image at ƒ/4. Through ƒ/5.6 to ƒ/11 this sharpness trend is stable at 1.5 units, with diffraction limiting creeping in at ƒ/16. Even fully stopped down at ƒ/22, the lens is impressively sharp at a uniform 2 blur units.
So if you want your images to be uniformly sharp, this isn't a lens to be used wide open; by ƒ/2.8 you should get acceptably sharp results, with the best results showing up at ƒ/4 and above.
The lens has an issue with chromatic aberration, showing a relatively high average value of approximately 5/100ths of a percent of frame height at all apertures, and a maximum value of approximately 9/100ths. The chromatic aberration isn't the worst we've seen, but is noticeable enough in the corners to warrant comment.
Corner shading isn't a problem with this lens - only a third of a stop darker in the corners when the lens is set to anything below ƒ/2.8. By ƒ/2.8 and above, corner shading is negligible.
Distortion is also a non-factor with the 43mm ƒ/1.9, tending towards negligible barrel distortion (0.25% maximum, 0.125% average). These values are so small as to be almost negligible, and if it's vital to have your straight lines absolutely straight, the distortion isn't complex and can be easily corrected with image post-processing software.
The 43mm lens is mechanically driven, producing slower focusing results. A full rack through the focus is completed in 1.5 seconds on a K100 Super body, and produces a noticeable higher-pitched motor noise. Point-to-point focusing is not noticeably faster or quieter.
The lens is not a dedicated macro lens, with a maximum magnification of 0.12x and a close-focus distance of 45cm (just under 18 inches).
Build Quality and Handling
Pentax limited edition lenses are extremely solid and durable lenses, and the 43mm ƒ/1.9 is no exception. The lens is solid metal, our version being a silver model that feels like a precision-crafted device. Being silver, It does look a little out of place on the all-black K100 Super body.
The 43mm ƒ/1.9 is equipped with an aperture ring, a recessed distance scale and a depth-of-field indicator with infrared index. It doesn't have Pentax's ''quick-shift'' autofocus technology, meaning the focus is locked in place when set to autofocus and can only be turned when the body is set to manual focus operation. There is no autofocus/manual focus selector on the lens.
There's no denying the slick finishing touches inherent in the lens; even the lens cap is lined with green velvet for a classy and protective touch. The cap slides over the removable lens hood (also lined with velvet - black velvet). The lens accepts 49mm filters, though you'd need to remove the lens hood first and attach it onto the applied filter. As you might expect, any attached filters won't rotate during focus operation.
Being a fairly specific lens, there aren't direct comparisons to be made (no one else makes a 43mm ƒ/1.9 lens). However, there are a few options in the same ball park.
Pentax 40mm ƒ/2.8 Limited SMC P-DA ~$290
Another limited edition lens, the 40mm ƒ/2.8 ''pancake'' lens is probably as small and light as they come, with exceptional results for all of sharpness, chromatic aberration resistance, vignetting and distortion. Unless you really need an extra stop of light-gathering ability, or like a little softness in your corners when shooting wide open, the cheaper price tag and smaller size makes this a highly competitive alternative; however, it is designed with APS-C digital SLR bodies in mind, not having an aperture ring. However, the lens shows no signs of vignetting on a full 35mm frame.
Pentax 50mm ƒ/1.4 SMC P-FA ~$200
We haven't tested the Pentax 50mm, but it's also a full frame lens with an aperture ring which takes 49mm filters. It weighs slightly more, but costs slightly less, and is a half-stop faster.
There's no denying the sex appeal of the silver 43mm ƒ/1.9 - it almost evokes a feeling of nostalgia for bygone days of manual film cameras. It looks good, and performs well enough to buy as a walkaround lens that acts as a slightly-longer-than 50mm when mounted on a dSLR. I could have done with a more advanced focus system; oddly enough the smaller 40mm ƒ/2.8 pancake lens focuses faster and quieter, and is equipped with Pentax's ''quick-shift'' system to allow manual override of the autofocus at any time. Optically, it's better than average but not extraordinary: chromatic aberration is slightly pronounced, and corner softness is an issue when shooting wide open. But if you're into that look, and want to look good while getting it, then this is the lens for you.
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 43mm f/1.9 Limited SMC P-FA
Pentax 43mm f/1.9 Limited SMC P-FA User Reviews
10 out of 10 points and recommended by elho_cid (10 reviews)excelenent contrast and bokehlittle bit of CA
This lens is absolute gem.reviewed November 17th, 2009
I have both FA50 and FA35 and I was eager to see what will the FA43 be like.
It leaves the FA50 in dust and even has a bit edge of appeal against the FA35.
I already tried quite a lot of lenses with both Pentax and Canon systems, but never experienced the wow effect of FA43 before. The contrast it puts into slightest details of the image is unbelievable.
The CA is easier to correct than with other primes (such as FA50) and no problem at all.
And above all the Fa43 is a pleasure to use, it is more than just a great lens. It is a great lens with built quality to survive decades and still look like a jewel.
10 out of 10 points and recommended by ronen_we (7 reviews)looks, image quility, build, size
was hooked onto this lens due to its looks first time I saw it.reviewed November 15th, 2006 (purchased for $470)
a real charmer to use.
fast and extremely sharp.
all metal construction superbly built.
focus ring is a bit small may be a bit tricky if you have a large hand.
10 out of 10 points and recommended by Tubbie_GL (1 reviews)the lens is next to perfectnone
Well where to start, bought this lens as a walkabout lens, and because I wanted a fast lens when indoor situations demanded it.reviewed September 29th, 2006 (purchased for $400)
I have so far not been disappointed. This lens is among the best I have seen.
Crisp, excellent bokeh, fast and razor sharp.
Even a very smooth manual focus.
THe build quality is a chapter of its own. Outstanding, simply outstanding.
Aluminium all the way and the short full cone hood is linned with black felt. Lens cap is in aluminium as well and linned with a fine green felt that keeps the cap attached to the hood. very smooth.
I have acheaved excellent portraits and beautiful landscape photos with this one.
It has my strongest recommendation, excellent performance in every aspect and the it is a beauty on the camera:)