The Pentax 31mm lens is one of the best lens that Pentax has ever made. You can get the best price from Amazon
You might be surprised to see the price on those store. That’s completely normal. When you are done reading my review below you will know why.
They really offers superb package on this glass. The optics are very sharp and has very good distortion, vignetting and chromatic aberration control.
On top of that, this glass has the best build quality that I have ever seen on any prime lens.
All of those come at a price and it is a very costly one.
If you are new to the photography world, then put this glass on your wish list and get a cheaper glass first.
After your photography skill improves, then you might consider getting this glass.
For professional photographers though, this glass is definitely one of the glass that you would want to put in your bag.
See the complete Pentax 31mm review below.
Specs • Performance • Sample Image • Conclusion • Where to Buy
Pentax 31mm Specs
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Official Name:
Pentax SMC FA 31mm f/1.8 AL Limited
Focal Length Markings:
31mm
Features:
SMC – Super Multi Coating – Minimizes flare in the glass.
FA – Compatible with both full frame and cropped sensor DSLR camera.
AL -Aspherical Elements – Minimizing chromatic aberration by installing aspherical elements on the glass.
Limited – A Limited Edition glass. Label that is put for great performance in a compact package.
Full Technical Specs
| Technical Specifications | |
| Groups / Elements | 7 / 9 |
| Angle of View | 70° |
| Number of Blade Diaphragm | 9 |
| Minimum Aperture | f/22 |
| Minimum Focusing Distance | 12in. |
| Filter Thread | 58mm |
| Weight | 12.2oz. (345g) |
| Dimension (Diameter x Length) | ø2.6 x 2.7″ |
| Macro Magnification Ratio | 0.16X |
| Available at | Amazon, B&H Photo, Adorama |
Optical Performance
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Pentax 31mm Sharpness
Center is very sharp at any aperture. The same goes with the borders.
To get maximum sharpness on this glass, shoot at f/4.
Sharpness Scale (from Best to Worst):
(5) Excellent
(4) Great
(3) Good
(2) Fair
(1) Poor
Center Sharpness
| Focal Length / Aperture | f/1.8 | f/2.8 | f/4 | f/5.6 | f/8 |
| 31mm | Great | Excellent | Excellent | Excellent | Excellent |
Border Sharpness
| Focal Length / Aperture | f/1.8 | f/2.8 | f/4 | f/5.6 | f/8 |
| 31mm | Great | Great | Excellent | Excellent | Great |
Distortion
Distortion is very well controlled on this glass and will not be a problem on the field.
See the distortion grid test below.
Pentax 31mm Distortion
Vignetting
Vignetting is visible at f/1.8. Stop down to f/2.8 to completely reduce the vignetting to an unnoticeable degree.
See the vignetting test result below.
Pentax 31mm Vignetting
Chromatic Aberration
Chromatic aberration is very low, even at the widest aperture of f/1.8.
On the other apertures, it can be safely ignored.
See the test table result below.
Chromatic Aberration Scale (from Best to Worst):
(5) Negligible
(4) Very Low
(3) Low
(2) High
(1) Very High
Chromatic Aberration
| Focal Length / Aperture | f/1.8 | f/2.8 | f/4 | f/5.6 | f/8 |
| 31mm | Very Low | Very Low | Negligible | Negligible | Negligible |
Build Quality
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Materials
Being a Limited Edition lens, this glass is made from top notch, very high quality parts made all from metal.
Focusing
Autofocus is fast and accurate, although it produces some noise due to the lack of internal autofocus motor (it relies on the Camera’s screw drive).
The focus ring operates smoothly. The lens extends just a bit during focusing.
The hood on this lens is a flower shaped one and cannot be removed.
There is still a dedicated aperture ring on the glass (typical of FA glass).
Image Stabilization
The Image Stabilization feature is installed in the camera body, not on the lenses. Check your DSLR camera if it has Image Stabilization feature.
Compatibility
The FA designation means that this lens is compatible with both full frame, cropped sensor DSLR and old film SLR camera.
Sample Image
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Below are some sample shots that I took using this lens. Click on any thumbnail to open the image.
Get the best price online from these sites: Amazon
Conclusion
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Here’s the summary of this Pentax 31mm lens.
As I’ve mentioned at the beginning of this review, this lens is their best prime lens.
This is not a new lens by any means, but the optical perfection and build quality is very tough to beat even for a new lens.
It is very sharp at any aperture, both on the center and on the borders, have great distortion, chromatic aberration and vignetting control.
On top of that, it has top notch, superb build quality that is simply exceptional for a prime lens.
The downside would be the slightly visible vignetting at f/1.8 (which is common for a prime lens) and the costly price.
Is this lens worth it?
Considering the price, build and performance, I would say yes. This lens can easily belong to the “Pentax Dream Lens” category.
Just make sure you have the money to spend.
See my conclusion below for the summary:
Drawbacks
- Slightly visible vignetting at f/1.8
- Costly price
- Moderate autofocus noise
Positives
- Very sharp on the center and borders
- Superb, top notch build quality
- Excellent chromatic aberration control
- Good distortion control
- Great vignetting control
- Fast and accurate autofocus mechanism
Good For
- Normal lens for cropped sensor DSLR
- Moderate wide angle lens for full frame DSLR
- Anyone wanting to get the best image with their Pentax DSLR or Film SLR
Not So Good For
- Anyone on a tight budget
What Others Are Saying…
by “LFLee”
This is ‘The lens’ that every Pentaxian (well, this is what Pentax user called themselves) wants. It is a ‘legendary’ lens in the Pentax lens line up. Currently, Pentax have 3 FA limited lens: 31mm, 43mm, and 77mm…
Click here to see the full review
by “Finn Pillsbury”
Greatest lens I have ever used, period. This is the most incredible lens I have ever used. Razor sharp even wide open, with silky bokeh and beautifully rendered color transitions. There is a luminosity to images that I have never seen with any other lens…
Click here to see the full review
Where to Buy
Support this site, buy the Pentax 31mm lens from these sites (best price online):
Amazon (Best Price + FREE Shipping)
See the following related post below to see more options.
Thanks for reading my Pentax 31mm review and I hope you’ll get some value out of this.
| Lens Score | |
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| Optical Quality | |
| Build Quality | |
| Value for Money | |
| Overall | |
