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Pentax 50mm f/1.8 DA
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Sample Images   Intro   Specs   Performance   Recommendations

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Pentax 50mm f/1.8 DA

SMC Pentax 50mm f/1.8 DA (35mm and APC-S coverage, 52mm filters, 4.3 oz./122g, 1.5'/0.45m close focus, about $110). enlarge. I got mine at B&H; I'd also get it at Adorama or at Amazon.

This ad-free website's biggest source of support is when you use those or any of these links to approved sources when you get anything, regardless of the country in which you live. Pentax does not seal its boxes, so never buy at retail or any other source not on my personally approved list since you'll have no way of knowing if you're missing accessories, getting a defective, dropped, damaged, returned, store demo or used lens. My approved sources ship from remote automated warehouses where no salespeople or lookie-loos can ever get their greasy fingers on your new lens before you do. Buy only from the approved sources I use myself for the best prices, service, return policies and selection. Thanks for helping me help you! Ken.


July 2015   Pentax reviews   all reviews


Sample Images   (more samples later in the review)      top

Sample Images   Intro   Specs   Performance   Recommendations


Pentax K3 II and 50/1.8 DA sample image

Palm, 25 June 2015. Pentax K3 II, SMC Pentax 50mm f/1.8 DA, f/5.6 at 1/500 at ISO 200, Perfectly Clear V2. Full resolution.


Pentax K3 II and 50/1.8 DA sample image

Corte Madera, 25 June 2015. Pentax K3 II, SMC Pentax 50mm f/1.8 DA, f/7.1 at 1/640 at ISO 200. Camera-original © LARGE basic JPG.


Pentax K3 II and 50/1.8 DA sample image

Palm, 02 July 2015. Pentax K3 II, SMC Pentax 50mm f/1.8 DA, f/7.1 at 1/200 at ISO 200. Camera-original © LARGE basic JPG.


Introduction       top

Sample Images   Intro   Specs   Performance   Recommendations

Adorama pays top dollar for your used gear.

B&H Photo - Video - Pro Audio

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.


Specifications        top

Sample Images   Intro   Specs   

Performance   Recommendations



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.


Optics       top

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).


Diaphragm       top

Pentax 50mm f/1.8 DA

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




Size       top

Pentax specifies 2.5" (63.5mm) diameter by 1.5" (38.1mm) long.


Weight       top

4.310 oz. (122.1 g) actual measured weight.

Pentax specifies 4.3 oz. (122 g).


Caps       top

Nice 52mm front cap.

Cheap push-on rear cap, not the usual Pentax bayonet rear cap.


Included       top

Lens and caps; that's it.


Pentax Model Number       top



Price, USA        top

2015 July: $110.

Pentax 50mm f/1.8 DA

Pentax 50mm f/1.8 DA.


Performance         top

Sample Images   Intro   Specs   Performance   Recommendations


Overall    Autofocus    Bokeh   Breathing

Distortion   Ergonomics   Filters

Lateral Color Fringes   Macro   Mechanics

Sharpness      Spherochromatism


Overall     performance      top

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     performance      top

Autofocus is via 1980s technology: a motor in the body connected via a screw coupling.


AF Speed

AF is as fast as most other cameras and lenses; no news here.

It's faster than I need for people and family photos.


Auto/Manual Switching

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

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     performance      top

Bokeh, the quality of out-of-focus areas as opposed to the degree of defocus, is good and neutral.

Pentax 50mm f/1.8 DA Bokeh

Pentax 50/1.8 DA shot on Pentax K3 II at f/1.8. Camera-original © JPG file.


Focus Breathing     performance      top

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.


Distortion     performance      top

The Pentax 50mm f/1.8 DA has some barrel distortion.

Many Pentax cameras can be set to correct for this.


Ergonomics     performance      top

Pentax 50mm f/1.8 DA

Pentax EF 50mm f/1.8 DA. bigger.

This little lens handles fine, except for the focus ring turning by itself during autofocus.


Filters, Use with     performance      top

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.


Lateral Color Fringes     performance      top

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.


Macro     performance      top

It gets as close as every other classic 50mm lens:

Pentax 50mm f/1.8 DA Macro performance

SEIKO A829 at close-focus distance on digital at f/4.5.

It's super-sharp; here's a crop from 24MP at 100%:

Pentax 50mm f/1.8 DA Macro performance

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)!


Mechanics     performance      top

Pentax 50mm f/1.8 DA

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.


Filter Threads




Printed on the barrel.


Focus Ring

Ribbed plastic.






I see what looks like all plastic.


Moisture seal at mount









Serial Number

Printed on a sticker glued into a recess in the bottom of the black plastic lens barrel.


Date Code

None found.


Noises When Shaken

Mild clicking.


Made in

Vietnam, carefully hidden in black-on black around the outside of the rear element.


Sharpness     performance      top

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     performance      top

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.


Recommendations         top

Sample Images   Intro   Specs   Performance   Recommendations

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.

If you find my work here helpful, my biggest source of support for this free website is if you get yours at B&H, at Adorama or at Amazon. When you use those or any of these links to approved sources when you get anything, regardless of the country in which you live, it helps me keep adding to this free website — but I receive nothing for these efforts if you take the chance of buying elsewhere. Unlike a bottle of milk or a CD, DVD or Blu-Ray disc, Pentax doesn't seal its boxes so you have no idea if you're actually getting a used product if you risk buying at retail. Never buy at retail.


Help me help you         top

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Mr. & Mrs. Ken Rockwell, Ryan and Katie.


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July 2015