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SMC Pentax 18mm F3.5

Reviews Views Date of last review
11 61,691 Mon August 20, 2018
Recommended By Average Price Average User Rating
100% of reviewers $454.38 8.73
SMC Pentax 18mm F3.5

SMC Pentax 18mm F3.5
SMC Pentax 18mm F3.5

This extreme-wide-angle lens is compact compared to the 15mm F3.5 and is very rare.

SMC Pentax 18mm F3.5
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 5 blades
12 elements, 11 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
25 cm
Max. Magnification
Filter Size
58 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 77 ° / 67 °
Full frame: 100 ° / 90 °
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Built-in Filters
Diam x Length
63 x 61.5 mm
328 g
Production Years
1975 to 1985
Engraved Name
SMC PENTAX 1:3.5/18 (early version), smc PENTAX 1:3.5 18mm (later version)
Product Code
User reviews
Built-in filters: Cloudy, skylight, yellow, orange. Screw-in filters cause vignetting.

Two variants were produced. The only difference appears to be in the engraved name:
SMC PENTAX 1:3.5/18 (early variant),
smc PENTAX 1:3.5 18mm (later variant)

Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax 18mm F3.5
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-11 of 11
New Member

Registered: January, 2015
Posts: 12
Lens Review Date: August 20, 2018 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: size & weight, center sharpness
Cons: flare, soft corners
Sharpness: 8    Aberrations: 7    Bokeh: 8    Handling: 10    Value: 9    Camera Used: K1   

Lovely full frame wide angle lens from the film era.
Small (filter size only 58 mm! Very small compared to the DFA 15-30).
Despite SMC a lot of flare (also reflections from the filter revolver?).
CA are present but easily correctable in post-processing.
Center is sharp from f 5,6, but the corners are a different story. At f16 only the extreme corners stay unsharp. Best aperture is f11-16.
Even small 58 mm Polfilters cause a litte bit vignetting. Four built in filters, two are useful (orange&yellow) for B&W

Veteran Member

Registered: September, 2013
Location: Sydney
Posts: 844

2 users found this helpful
Lens Review Date: May 9, 2015 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Sharpness: 8    Aberrations: 9    Bokeh: 10    Handling: 9    Value: 8    Camera Used: K2, K-3   

First off, if you are thing of getting this lens for APS-C I'd probably recommend getting the DA15 or DA21 instead. They're smaller, sharper, and can be picked on the second hand market for about the same price. If I was rating it solely based on apsc, I'd give it a score of 7.5 to 8 ish.

If however you are a 35mm film shooter, or have your eye on an FF camera, then it's worthy of consideration. The bokeh is actually remarkably good, but that's probably not why you're buying this lens! The inbuilt filters add to it's charm, but they are focussed somewhat towards B&W film. If you're an avid pixel peeper, then you might be a little disappointed (on the k-3 for example it can be a little soft in the corners, but it's still much sharper than the A20 f2.8!). The rendering of images, is however top notch. On 35mm film it's a fantastic lens, and there really aren't many better options that are so wide. You'll find some distortion there, but it's never bothered me too much.

So on FF it's great. On apsc, it's not that wide, it has great rendering and bokeh, but it is a touch soft at wider apertures. Worth picking up if you can find a good deal, but you might be better served with a DA limited. I'll report back when I get my hands on an FF pentax
Junior Member

Registered: February, 2014
Location: Nissedal (Goblin Valley)
Posts: 38

2 users found this helpful
Lens Review Date: February 18, 2015 I can recommend this lens: Yes | Price: $590.00 | Rating: 10 

Pros: Sharp
Cons: None
Sharpness: 9    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 10    Camera Used: K10D   

Read the other reviews, bought this lens anyway, worth every dollar! You see, even if this lens is a bit unsharp at the extreme edges (but not in the corners), it's not an unpleasent unsharpness. A lens can have high and low resolution in different ways. Leica lenses (whitch I've been using for the last 10 years) are very good examples of this. They have very high centre sharpness and contrast, and the low resolution areas are more like bokeh than like "unsharp" in a smudgy way. The K mount 18mm is like this. There are lenses with higher resolution, but this lens never renders objects ugly, in or out of focus, sharp or unsharp. It reminds me of my Leica R 21mm. I just can't wait to get this lens on a FF camera. Oh, and very low CA and fringing, just as good as the ltd 31mm, but with more ease. This lens is so far my best encounter with Pentax optics. Most lenses can be sharp and unsharp, but not always in a cool way.
New Member

Registered: October, 2009
Posts: 15

1 user found this helpful
Lens Review Date: July 31, 2012 I can recommend this lens: Yes | Price: $370.00 | Rating: 8 

Pros: Colors, focal length, handling
Cons: No interest on APS-C
Sharpness: 7    Aberrations: 8    Bokeh: 8    Handling: 9    Value: 9    Camera Used: LX   

The point of this lens is to be used on a large sensor (silver or silicon).
I used mine on a pentax LX and it is a good couple, very well balanced.

The feel is solid. It uses built-in filters, which are black and white oriented. (a tungsten to daylight filter would have been welcome).

About the results, colors are fine and pleasing. Distorsions are little but visible when you look at it (first picture). I think it is the counterpart of developping a light and small retrofocus wide angle.

To compare with what I own, I compared it to the 15 heliar which has practically no distorsions but is a so-so performer in color.

I gave a good rating in bokeh because when forcing it (focus at few cm , full opening) it is quite smooth and pleasing. But in the real life it is inexistant.
Aside from all that, wide angle are fun

Pentax LX / Fuji Superia 400

Pentax LX / Ilford XP2

Pentax LX / Fuji Superia 400
Senior Member

Registered: December, 2010
Location: Sydney, Australia
Posts: 114
Lens Review Date: December 8, 2010 I can recommend this lens: Yes | Price: N/A | Rating: 10 

Pros: Super wide angle, built in filters, great upclose..
Cons: Size and weight means it's often left untouched.

Lovely wide angle on the full frame 35mm. It's impact is lessend with the smaller DSLR sensors. Built in filters are useful but largely redundant (orange O56(O2)) and yellow(Y48(Y2)) filters for B&W, skylight and cloudy are the other choices. Great for sweeping landscapes, and well lit interiors. Mine focuses down to about 15cm on a ist DL2 Body. Great for distorted sizing effects. Not small or light means it oftens gets squeezed out of bulging camera bags. Still it's less imposing than it's 15mm F3.5 brother, well worth collecting now. (just imagine with a full 35mm sensor!). Definitely one of my 'TOP' 5 SMC Pentax Lenses.
Veteran Member

Registered: June, 2010
Posts: 737
Lens Review Date: September 26, 2010 I can recommend this lens: Yes | Price: $380.00 | Rating: 7 

Pros: distortion, full format, centre sharpness, small and compact.
Cons: edge sharpness could be better
Sharpness: 7    Aberrations: 9    Bokeh: 6    Handling: 10    Value: 7   

First of all - here is some old magazine test which puts this lens against some comparable lenses from other companies. Notice that Pentax is on top here with Olympus and Zeiss.

I purchased this lens when I missed oportunity to buy FA20mm. The lens comes with built in filters, but if you purchase step up ring 58to67mm you can mount any filter without vigneting on DSLR. The lens has very good control od distortion, not so significant in landscape photography but if you intend to make photos of architecture you'll surely appreciate this. Resolution in the centre of the frame is great from f5.6 to f16. Edges however are different story, softer below f8. I had the oportunity to compare the lens to Tamron SP17mm and Pentax DA16-45mm. SMC18mm easily outperforms Tamron, DA16-45 is tougher match, however i think older K lens is marginally better.
Cons: Avoid f22! Expensive.

In my opinion it is a very good UWA lens, if the resolution will be bit more even across the frame I'll give it 9.

Edit: Recently I purchased K20/4 and if you are considering UWA and you don't mind losing 2mm of focal lenght, I definitely recommend K20/4 over K18/3.5.
Site Supporter

Registered: January, 2010
Location: Calgary AB
Posts: 40
Lens Review Date: July 16, 2010 I can recommend this lens: Yes | Price: $550.00 | Rating: 9 

Pros: Built in Filters, Great IQ
Cons: Larger than the alternatives

I was originally looking for a 20mm F4 lens as a compact ultrawide, but was offered one of these lenses at a fair price. The built in filters are great, especially if like me you're shooting B&W film. The lens is very well built and has given me excellent results. Suprisingly resistant to flair.

This lens has been firmly fixed to my MX since I got it and I would highly recommend it.
Forum Member

Registered: April, 2010
Location: Santa Barbara
Posts: 60
Lens Review Date: April 4, 2010 I can recommend this lens: Yes | Price: $485.00 | Rating: 10 

Pros: Sharp, good color, fun to handle
Cons: not realy

It seems this lens may vary in quality throughout its production years.

My copy doesn't suffer any "pink hue", nor softness or other negative issues. This lens came as SMC and later as smc marked variant. My copy is the newer smc, renders very nice color, it's sharp 3.5-11 (my range of usage) from corner to corner and mechanically solid & pleasant to use.

One has to make sure the filter wheel is not accidentally set in off position, which could get in the way of performance. Mostly, I have dialed in the Skylight and 58mm UV Heliopan is protecting the glass. CA's are not any different than of my DA16-45mm (very minimal) and high contrast fringing is practically non-existent (on istD or K-x).

Will see if future digital FF body (hopefully one of these days) will like it as well. Very glad I was able to get this fun classic about three years back!
Senior Member

Registered: February, 2007
Posts: 151
Lens Review Date: April 26, 2009 I can recommend this lens: Yes | Price: $450.00 | Rating: 7 

Pros: low distortion, built in filters
Cons: a bit soft, built in filters

I must say, I was a little disappointed with this lens (sold it rather quickly). I heard so many glowing reviews about this cult lens and was very excited to use it. Long story short, it was noticeably softer than my M20/4 (although the m20/4 has quite a bit more distortion than the 18mm). Maybe my copy of the 18 was a dog (or maybe my copy of the 20 is better than average). If you are looking for a low distortion ultrawide this is the lens for you. If you are looking for a sharp ultrawide for candids I would pass. In any case, I think that the lens is overrated and does not deserve the price premium that it often fetches on the 2nd hand market.
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 6,627
Lens Review Date: January 18, 2009 I can recommend this lens: Yes | Price: $410.00 | Rating: 9 

Pros: Size, built in filters, dedicated hood and 100 degree angle of view.
Cons: If it were slightly faster like f2.8, I would give it a 10.
Camera Used: Pentax film bodies (K1000, KM, KX, K2, K2DMD, MX, LX, Super A, P50)   

The little brother to the 15/3.5, however the 18/3.5 is a far more practical lens for every day use. The 15/3.5 is more of a specialty lens like a fish-eye or shift, while the 18/3.5 is a lens that you will take with you on most outings.

This lens lies in the middle of the K series ultra wide angles, between the 15/3.5 and the 20/4. Compared to the 15/3.5 this lens is about half the size & weight and has a proper dedicated plastic clip on hood. The 20/4 does not have any built in filters and is slower at f4.0. I would select this as the best lens out of the three.

The 18/3.5 has a 58mm filter thread, but you will have a hard time finding a filter that does not cause vignetting. This problem is solved with the lenses four built in filters; Cloudy, Skylight, Y48 (Y2), O56 (O2). The 18/3.5 also has the ability to accept gelatin filters at the rear of the lens. The built in filters are selected with a dial on the top of the lens and cover most colour and b&w shooting situations. Unlike the 15/3.5 or fish-eye, you must select a filter at all times, there is not a none filter selection.

The 58mm rectangular plastic clip on hood is worth the extra cost if you can find one, its even more rare than the lens itself. It does a better job shielding the lens from stray light or damage, than the metal fixed hood on the 15/3.5.

I found f3.5 fast enough even when using slower daylight films. A faster film and a tripod will let you shoot city scenes in the evening. With the 100 degree angle of view you have the ability to capture an amazing amount of landscape in one shot.

The K 18/3.5 is definitely worth seeking out and is a perfect companion to any K series film camera, like a KX or K2. I have only had the 18/3.5 for a few months, but its rapidly becoming one of my favorite Pentax lenses.

Sample shots taken with the K18/3.5. Photos are medium resolution scans from original slides or negatives.

Camera: K2 Film: Fomapan R100 Processed in DR5 Chrome ISO: 160

Camera: LX Film: CineStill Film 50 ISO: 50

New Member

Registered: March, 2007
Location: Norway
Posts: 1
Lens Review Date: March 13, 2007 I can recommend this lens: Yes | Price: $400.00 | Rating: 8 

Pros: Solidly built, great FOV on film, great IQ
Cons: Built in filters, CA on digital

I bought this lens to use on a Pentax LX. Image quality is excellent, very well corrected and dramatic FOV. The lens is very solidly built.
On digital it looses some appeal as the FOV is covered by all normal zooms, it isn't particularily fast and it suffers from CA. It is still sharp and well corrected though.
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