Pentax 50mm f/1.8 DA
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Sample Images (more samples later in the review) top
This SMC Pentax 50mm f/1.8 DA is a small, light, inexpensive and sharp lens idea for any kind of shooting on any Pentax digital SLR.
Formats & Compatibility
This 50/1.8 DA lens is optimized for full-frame, and of course works great on all Pentax' digital SLRs.
It mounts, meters, manually focuses and shoots on Pentax's classic 35mm cameras, but since it has no aperture ring, it always meters and shoots at f/22 on my K1000. Viewing and focussing is wide open, but you have to imagine that it's always set to f/22.
Pentax calls this the SMC PENTAX 50mm f/1.8 DA.
SMC means Super Multi Coating; all Pentax lenses have been SMC since the 1970s.
DA means it works on Pentax' digital cameras.
Same optics as every other 50mm f/1.8 lens made in the past 40 years.
6 elements in 5 groups, unit focus.
Multicoated, branded as "Super Multi Coating" (SMC).
Pentax EF 50mm f/1.8 DA at f/22.
7 rounded blades.
Stops down to f/22.
Focal Length top
On Pentax digital cameras it will see angles-of-view similar to what a 75mm lens would see on a 35mm camera.
Angle of View
31.5º diagonal on Pentax digital.
46º diagonal, 27º vertical. and 40º horizontal on full-frame.
Close Focus top
1.5 feet (0.45m) from the image plane.
Maximum Reproduction Ratio top
1:6.7 (0.15x) at close-focus distance.
Hard Infinity Focus Stop? top
You have to let the AF system focus for you at infinity.
Focus Scale top
Depth-of-Field Scale top
Infra-Red Focus Index top
Filter Thread top
Pentax specifies 2.5" (63.5mm) diameter by 1.5" (38.1mm) long.
4.310 oz. (122.1 g) actual measured weight.
Pentax specifies 4.3 oz. (122 g).
Nice 52mm front cap.
Cheap push-on rear cap, not the usual Pentax bayonet rear cap.
Lens and caps; that's it.
Pentax Model Number top
Price, USA top
2015 July: $110.
Pentax 50mm f/1.8 DA.
SMC Pentax 50mm f/1.8 DA. enlarge.
The Pentax 50mm f/1.8 DA is sharp, small, inexpensive and handles very well.
Autofocus is via 1980s technology: a motor in the body connected via a screw coupling.
AF is as fast as most other cameras and lenses; no news here.
It's faster than I need for people and family photos.
You must move a lever on your camera.
The focus ring turns by itself as the camera autofocuses; keep your hands away!
If you turn the ring while in AF mode, you'll force the camera's motor to turn.
Manual focus is easy; just turn the ring. It's directly connected, just like a manual focus lens. No electronic foolishness or clutch systems here!
Bokeh, the quality of out-of-focus areas as opposed to the degree of defocus, is good and neutral.
Focus breathing (the image changing size as focused) is mostly of interest to cinematographers who don't want the image changing size ("breathing") as the lens is focused among different subjects.
The image from the Pentax 50mm f/1.8 DA gets larger as focused more closely.
The Pentax 50mm f/1.8 DA has some barrel distortion.
Many Pentax cameras can be set to correct for this.
Pentax EF 50mm f/1.8 DA. bigger.
This little lens handles fine, except for the focus ring turning by itself during autofocus.
The plastic 52mm filter threads are big enough that quite a few stacked filters won't cause any vignetting on full-frame or digital.
There is no need for expensive "thin" filters.
There are no visible lateral color fringes at 24MP, but there is some minor purple fringing visible on Pentax K3 II.
This is excellent performance, as expected for a normal lens.
It gets as close as every other classic 50mm lens:
SEIKO A829 at close-focus distance on digital at f/4.5.
It's super-sharp; here's a crop from 24MP at 100%:
Crop from above image at 100%. If this is 6" (15cm) wide on your screen, the full image would print at 40 x 60" (1 x 1.5 meters)!
Pentax EF 50mm f/1.8 DA. bigger.
The Pentax 50mm f/1.8 IS is well made, but it's all plastic except for the glass and electronics.
It's much tougher than other brands' 50mm f/1.8 plastic lenses because the optics move in and out inside the solid lens mount. Most other 50/1.8 lenses move the whole frit half of the lens in and out, and those are much more delicate. Of you hit the front of the lens, you probably won't break anything, while with other brands you may break their focus mechanisms.
Printed on the barrel.
I see what looks like all plastic.
Moisture seal at mount
Printed on a sticker glued into a recess in the bottom of the black plastic lens barrel.
Noises When Shaken
Vietnam, carefully hidden in black-on black around the outside of the rear element.
Image sharpness depends more on you than your lens, and lens sharpness doesn't mean much to good photographers. It's the least skilled hobbyists who waste the most time blaming fuzzy pictures on their lenses, while real shooters know that few photos ever use all the sharpness of which their lenses are capable due to subject motion and the fact that real subjects are rarely perfectly flat.
The Pentax 50 DA is super-sharp. It's just a little less contrasty wide-open at f/1.8, quickly improving to super-sharp as stopped down.
It's sharp way past the corners on digital because this is a full-frame lens.
It's sharp all the way to f/16, only getting much softer at f/22 due to diffraction.
Spherochromatism, misnamed "color bokeh" by laymen, is when out-of-focus highlights take on color fringes at full aperture.
Spherochromatism is a completely different aberration from lateral color fringes.
I see some spherochromatism; background highlights will have slight grren fringes as you can see at the Bokeh sample image. If anything it helps bokeh for outdoor portraits. Ignore this.
This is my favorite lens for Pentax' digital cameras. It's small, fast, light, tough and inexpensive.
Yes, it's all plastic, but it's designed so that the tough outer barrel protects the inner focus mechanism from shocks.
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