Pentax-FA 43mm F1.9 Limited (APS-C)
Aberrations and Color
On this page, we will be taking a look at how the Pentax 43mm Limited is able to suppress ghosting, flare, and color fringing (chromatic aberrations). We will also examine contrast and color.
Fringing
For this test we shot a backlit roof top with our K-3:
The thumbnails below are 100% crops (no scaling) of JPGs right out of the camera. Click a thumbnail to enlarge and browse.
F1.9 | |
F2 | |
F2.8 | |
F4 | |
F5.6 | |
F8 |
Color fringing (chromatic aberration) is well-controlled with this lens except wide open (F1.9 and F2.0). At F2.8 we see a dramatic improvement, and the size of the fringe continues to diminish as you stop down. Above F2.8 fringing is not an issue, except when examining a photo at 100%.
Below let's look at another example, shot with a K-3 in heavy backlight - a scene in which many lenses would produce pronounced chromatic aberration, but the 43mm Limited only exhibits faint traces of CA:
The scene, F9.5, shot in RAW, developed with ACR |
Upper left corner (click to enlarge) - Link to full-size jpg |
Ghosting and Flare
All test shots in this section were shot with a Pentax K-3 in JPG. No post processing was applied other than scaling.
The first test was a night scene with a good selection of light sources. The 43mm Limited did not exhibit any significant flare in this test. There is a little bit of ghosting at F11 from the street lamp, but that's about it. Click on any thumbnail to enlarge and browse.
F1.9, 1/4s | F2.0, 1/4s |
F2.8, 1/2s | F4, 1s |
F5.6, 2s | F8, 4s |
F11, 8s |
It is, however, possible to provoke pronounced flare and ghosting with this lens as the next set of tests illustrates. Here we shot with a very bright lamp inside of the frame. Click a thumbnail to enlarge and browse.
F1.9, 0.5s | F2, 0.5s |
F2.8, 1s | F4, 2s |
F5.6, 4s | F8, 8s |
F11, 15s | F16, 30s |
As seen from the test photos above the 43mm can be quite prone to flare and ghosting when there is a strong nearby light source within the frame. The least amount of ghosting in this test is at F8. Then at smaller apertures reflections from the diaphragm becomes visible - this could be caused by light bouncing back from the sensor.
Our conclusion is that the 43mm Limited can be used successfully even with pointed light sources in the frame as the first set of test photos shows, but you need to watch for flare and ghosting and be prepared to recompose to avoid it. Shooting into nearby and extremely strong light sources should be avoided with this lens.
With our third set of images we illustrate what happens when the light source is just outside the frame, but not shielded by the lens hood. Since the lens hood is designed for the 24 x 36 mm (full frame) format it doesn't offer any protection in this case.
F1.9, 0.7s | F2, 0.7s |
F2.8, 1.5s | F4, 3s |
F5.6, 6s | F8, 8s |
F11, 15s | F16, 30s |
Flare is much better suppressed in this case. As the aperture gets smaller we see part of the star pattern reflected from the diaphragm blades even though the light source is outside of the frame. This is caused by the lens being full frame: Even though the light is outside of the APS-C frame, it still enters the lens and forms an image.
As a side note, the 43mm produces a nice starburst effect when stopped down, thanks to its straight octagonal aperture.
Contrast and Color
The FA 43mm produces good contrast and pleasing colors, even at night night and when the scene is heavily backlit.
Check out the samples page for more images to evaluate color rendition and contrast.
Verdict
The 43mm can produce images with little or no flare even when pointed at direct light sources, but it requires some experience with the lens to achieve good results. Shooting into a very or nearby strong light source should be avoided since this produces pronounced flare from reflections within the lens and camera, as well as some ghosting.
The lens generally produces pleasing colors and maintains good contrast and color in backlight as well as when flare is provoked. Also, a pleasing starburst effect can be observed at small aperture settings.