Forgot Password
Pentax Camera Forums Home

Pentax Lens Review Database » Film Era Pentax K-Mount Lenses » M Prime Lenses
SMC Pentax-M 40mm F2.8 Review RSS Feed

SMC Pentax-M 40mm F2.8

Reviews Views Date of last review
38 159,622 Fri December 6, 2019
Recommended By Average Price Average User Rating
79% of reviewers $94.15 7.86
SMC Pentax-M 40mm F2.8

SMC Pentax-M 40mm F2.8
SMC Pentax-M 40mm F2.8

Also known as the "pancake," this is the smallest SLR lens that Pentax ever produced. It includes all the features of any other M lens.

In 2006, it was superseded by an even smaller DA version, but that version did not feature an aperture ring.

SMC Pentax-M 40mm F2.8
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 5 blades
5 elements, 4 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
60 cm
Max. Magnification
Filter Size
49 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 39 ° / 33 °
Full frame: 57 ° / 48 °
Hard case HA-90B
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Diam x Length
63 x 18 mm
110 g
Production Years
1976 to 1984
Engraved Name
smc PENTAX-M 1:2.8 40mm
Product Code
User reviews
Lens was sold without hood. The folding rubber hood RH-A49 fits
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-M 40mm F2.8
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 16-30 of 38
New Member

Registered: January, 2012
Posts: 15
Lens Review Date: June 20, 2013 I can recommend this lens: Yes | Price: $100.00 | Rating: 9 

Pros: Very compact & light weight, sharp, Good looking when fitting on DSLR
Cons: Hard to focus
Sharpness: 9    Aberrations: 8    Bokeh: 8    Handling: 10    Value: 8    Camera Used: K10D   

Super compact and light weight. Fitting on DSLR is very good looking.
Cons : Focus is difficult & hard to use, more difficult in low light condition.
Forum Member

Registered: August, 2012
Posts: 54
Lens Review Date: April 7, 2013 I can recommend this lens: No | Price: N/A | Rating: 7 

Pros: Small, well built
Cons: Mediocre optically, very small focusing ring
Sharpness: 7    Aberrations: 8    Bokeh: 8    Handling: 5    Value: 6    Camera Used: LX, ME Super, *ist DL, K-01   

This lens has only one claim to fame - its size. The downside of this was that the focusing ring is very narrow. Optically it is not stellar although good enough for most purposes, especially when shooting film. I used it a bit back in the film days but it never was one of my most used lenses, I mainly used it when I wanted a compact package. The ME Super with this lens was as compact as you could get with a film SLR. The focal length makes more sense on film than on APS-c digital cameras.
Junior Member

Registered: June, 2012
Location: Prague, Czech Republic
Posts: 36

1 user found this helpful
Lens Review Date: November 14, 2012 I can recommend this lens: Yes | Price: N/A | Rating: 8 


As the other reviewers stated, its problem is a mediocre performance but above average price. I have nothing more to say than that the stated is truth. It doesn't mean it's an optically bad lens. It isn't. But its true potencial is in its size. Put it on a small manual film body and marvel at the size of the combo. Its IQ suits 35mm film better than APS-C digital, as well as its focal lenght. Use it as it is meant to be used and it's worth the money:-)
Junior Member

Registered: November, 2012
Location: Cosenza
Posts: 42

1 user found this helpful
Lens Review Date: November 11, 2012 I can recommend this lens: No | Price: $90.00 | Rating: 6 

Pros: compact, nice tonality in b/w
Cons: not too sharp
Sharpness: 6    Bokeh: 8    Handling: 8    Value: 6    Camera Used: Canon Eos 5D Mark II, Pentax ME Super   

I had it for a year or so (I love the 40mm focal length), as it made a really nice and compact package on my 5d mk II and, better still, on the ME Super. But I ended up selling it. It has two flaws:

1st flaw (this one only for Canon users)
To use it on a full frame camera you need to remove (better, less messy) or file down the rear fin that commands the aperture, otherwise it will hit the mirror, and badly. I seems to recall that someone ended up with a lens jammed on the camera, too, from what I read elsewhere.

Once removed the fin there is not a problem whatsoever. From what I understand there are no problems in using it on a 1.6x camera, even unmodified (but I didn't try).

2nd flaw
It is a good lens, just not exceptional. And given that you can buy, for a tenth of its money, a Pentax 50mm f/1,7 that not only will be almost the same weight and size but it will be faster, and probably will beat it to death, this pancake it's not a smart buy.

Please, though, take this with a grain of salt: my copy had the focus ring jammed after the previous owner let it fall, and I was able to repair it in a crude but effective way. So maybe my sample was in desperate need of a collimation . But what I read about his lack of sharpness mirrors my own experience with it.
Junior Member

Registered: November, 2012
Location: East Coast, Canada
Posts: 26

1 user found this helpful
Lens Review Date: November 4, 2012 I can recommend this lens: Yes | Price: $25.00 | Rating: 7 

Pros: Compact, Lightweight, Color rendition
Cons: PF wide open, Soft wide open, Fiddly to focus for someone with large hands
Sharpness: 7    Aberrations: 7    Bokeh: 8    Handling: 7    Value: 7   

Got this lens paired with a Pentax MX (yes.... for $25 ) Quite a compact lightweight combo. Great for street photography because of its small size and unobtrusive looks and the color rendition is also pretty decent. However compactness and good looks come at a price. This lens gives a "normal" FOV, being 40mm and f/2.8 it doesn't give a wide enough angle of view to really use it over the much sharper (and faster) M 50mm f/1.7 or even the f/2. The 40mm exhibits more purple fringing than both 50's, and is much softer wide open. This lens does have a cult following and prices have managed to stay heightened despite its sub par performance compared to other M lenses of similar "length".
Veteran Member

Registered: July, 2010
Location: Yorkshire
Posts: 1,501
Lens Review Date: July 15, 2011 I can recommend this lens: Yes | Price: N/A | Rating: 7 

Pros: Small... Stopped down it's sharp-ish...
Cons: Thin focus ring... Bokeh not amazing... Colour rendition
Sharpness: 7    Aberrations: 7    Bokeh: 5    Handling: 5    Value: 5    Camera Used: K-x - MEsuper - MG   

Like others I'm not keen on using this on a digital camera (K-x in my case)

The bokeh isn't great and at 2.8 it isn't too sharp (read soft)... The centre does sharpen up at f5.6 but edges and corners do remain slightly soft at all apertures...

Edit: the use of a standard metal screw-in hood has dramatically improved sharpness... It's still no razor of a lens but no longer a slouch

It's normally paired up to my black MEsuper and using Ilford XP2-400 I've obtained some cracking shots... Enough contrast for good B&W street shots...

Its size on the MEsuper make a pretty damn perfect 'inconspicuous street shooting rig'... Nobody ever seems to notice me with this combo...

On my K-x shooting RAW I can't use AWB with this lens... Everything comes out a bit yellow... Set the WB manually and colour rendition is much improved... A longer process...
If you're a DSLR only shooter... Maybe not for you...

If you want it for a 35mm camera its worth what I paid... I will make a profit when I sell as prices on this lens are simply crazy... So if you can pick one up... (NB: I've noticed a few attached to MEsupers that ebayers tend to miss go very cheaply)

I may sell at some point but it does raise conversation among my shooting buddies when it comes out...

(I have made a few edits to my original review and dropped the score to a 7... It is a lens with character and although not 'stellar' in terms of IQ it is not a dog of a lens however much I appear to have slated it...
Veteran Member

Registered: June, 2011
Location: Chester
Posts: 719

2 users found this helpful
Lens Review Date: June 23, 2011 I can recommend this lens: Yes | Price: $40.00 | Rating: 9 

Pros: Size, Sharpn, Colours
Cons: Bit slow, bit dire wide open, odd focal length

Admittedly, I paid a fairly small price for this, and that came with a flash unit, an ME, and a case, but it was totally infested with fungus. Considered throwing it away because it was soft and unusable, but after scratching the front to a ridiculous degree, I took it apart and cleaned it, because I loved the size, and there's just something enjoyable about it. This was the first time I'd ever taken a lens apart mind you.

And now, for $40, I have what is possible my sharpest lens, with ridiculously vibrant colours, in a tiny package, and I love it. I can see where it's bad rep might come from, as it blooms like flowers in spring wide open and it's soft at the edges, but stop it down and it's incredible, beautiful for flower or general outdoor use.

Lookie here: for an example, this thing is worth looking at. If you can get hold of one cheaply, even with fungus, I'd snap it up. Take it apart and clean it, it's really easy, and you'll have an excellent little lens, that's a conversation starter too!
Forum Member

Registered: April, 2011
Location: Gwynedd
Posts: 93
Lens Review Date: June 14, 2011 I can recommend this lens: Yes | Price: $60.00 | Rating: 9 

Pros: Size, Weight
Cons: Min Focussing Distance, Speed, usual price.
Sharpness: 9    Aberrations: 10    Bokeh: 7    Handling: 8    Value: 6   

Some people seem to have quite a downer on this lens and I have no idea why! Personally I think it makes the perfect standard lens due to it's size, especially on an ME body.

Optically it's nice, I find it more than sharp enough wide open. There are the smallest hints of Purple fringing, nothing at all to worry about. Bokeh is OK, not the best, not the worst. Quite swirly, once stopped down a bit the aperture shape can be quite distracting as it's pentagonal.

Ideally it would have been nice to have an f1.8 version, and minimum focussing distance could be lower, but these things would all have compromised the small size, so in that respect you can't really fault it.

I didn't pay a lot for my copy, £42 including an ME body which is well below the current going rate for a lens on it's own. They do tend to be pretty expensive, and not as common as the 50mms. If you prioritise size, then I would definitely reccomend one, however there is no denying a 50mm would be a tad more versatile and cheaper to boot.

Some test samples can be seen (Non working link removed)
New Member

Registered: June, 2008
Location: Pune
Posts: 2
Lens Review Date: October 1, 2010 I can recommend this lens: Yes | Price: $80.00 | Rating: 9 

Pros: pan cake, light, sharp

Lens is very light, sharp, nice bokeh, nice colours
Inactive Account

Registered: March, 2009
Location: Australia
Posts: 207
Lens Review Date: August 16, 2010 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: Small
Cons: Very small

I bought this lens on a whim and have only recently had a good chance to use it (with an MX body).

So far, my main use has been on "scenics", using it in hyperfocal distance focusing mode.

After having read some less than complimentary reviews on this lens, I was very pleasantly surprised by the results, which were more than satisfactory IMHO.

I'm not a "pro" and not a "pixel peeper", so I was more than happy with it.

It is TINY and somewhat fiddly to adjust, however, using it in hyperfocal distance focusing mode, it is faster to use than autofocus would be.

As to a lenshood, I found a "standard" (screw-on circular rubber) lenshood designed for a 50mm lens worked perfectly (no vignetting).

BTW, used with colour print film, it is amazing the amount of small detail it will resolve. For example: bare twigs, a duck's feathers and beak, both 20m distant, giving not just the shape but also the subtle shade of colour.

Very satisfied
Veteran Member

Registered: June, 2010
Location: Tromsų, Norway
Posts: 886
Lens Review Date: June 13, 2010 I can recommend this lens: Yes | Price: N/A | Rating: N/A 

Pros: small, light, sharp focus
Cons: the focus dial is fiddly

I got this lens along with my father's old Pentax LX camera, and i have had fun using it. along with a 13mm extension tube, it makes an awesome macro lens, but it is also very nice to use on its own, because of its small size. i haven't had much success taking closeups with it (alone), but it is a good lens to use for longer range portraits. I look forward to using it with my new K-m!!
Forum Member

Registered: August, 2009
Location: Toronto, Ontario
Posts: 61
Lens Review Date: December 9, 2009 I can recommend this lens: Yes | Price: $150.00 | Rating: 7 

Pros: Size; "Perfect" aspect ratio on film
Cons: Tiny focus ring

I love this lens for its size, and it is pretty good value when you weigh in the size of the lens, weight, speed, and field of view. 50mm is a little "too" normal for me personally and I feel that 40mm is the ideal normal lens. For most daytime shooting f/2.8 is plenty of speed, and mounted on a small body such as a SuperProgram, with zone focusing, it's a great setup.

That said, the focus ring is tiny, so tiny that I now only rely on zone focusing for the lens. I've shifted the aperture ring more than once instead of focusing. While others have complained about image quality, I haven't noticed anything very negative about it -- but I might not be making as large prints.

I do wish that they made an SMC-A version.

Registered: March, 2009
Location: Salt Lake City, UT
Posts: 509
Lens Review Date: November 7, 2009 I can recommend this lens: Yes | Price: $100.00 | Rating: 9 

Pros: Small, light, and decent IMQ
Cons: Focusing ring is a bit small.

I had this pancake 10 some years ago when I used it on my ME super. It was not on my camera for very long, since the focal length was a bit odd on a 35mm camera. I was not a street photographer by any stretch of the imagination. So the importance of convenience was not valued. I sold it and have not used it for close to 10 years.

I bought another one recently to take pictures of my kids. It works well on my K10D (which is not very good at AF), even though it does not support P-TTL. It is not good for using with flash. The image quality was much better than I expected and remembered. Contrary to what have stated above, I am quite pleased with the image quality. While the contrast and the resolution are ever so slightly lower at f2.8, it is quite usable wide open. It clearly fares better than my zoom lenses. Since there are fewer glass elements, the IMQ is good. It would be better to use with a lens hood. However, the hood would reduce the meaning of a pancake.

No regret what so ever. But I suspect that the DA would be better in terms of value (performance/ price).
Junior Member

Registered: April, 2008
Location: Hayward, California
Posts: 40
Lens Review Date: October 22, 2009 I can recommend this lens: Yes | Price: $85.00 | Rating: 9 

Pros: very compact.
Cons: focus ring hard to use. so thin it is hard to mount/unmount.

I actually liked this lens. Bought it recently for my Italy trip. Very small to carry with my DL; great travel lens. Not necessarily pocket-able but reduced the bulk quite a lot. Feels like you are wearing a range finder around your neck.

Effective angle of view for the 40mm focal length on the DL is a little narrow for my taste for shooting in close quarters.

The pictures it produced at f/5.6 were very good. Color rendition is good too. Better than I expected, after having read other reviewers' comments about this lens. It is a keeper for me for portability purpose.
Inactive Account

Registered: December, 2008
Location: Tasmania, Australia
Posts: 7
Lens Review Date: July 6, 2009 I can recommend this lens: Yes | Price: $50.00 | Rating: 8 

Pros: size, ease of use on film and dslr, ideal diagonal size for film.
Cons: focus/ aperture rings cramped

I have used this lens on both film and digital. It's sharp across the frame at f5.6 -f9.
It has great flare resistance and in my experience a lower contrast. This makes it seem less 'punchy' but is great for shadow detail.

I like the colour rendition very much on film and digital.
Its main attractions are the ideal focal length for 35mm film, a natural perspective which combines the best attributes of wide angle and normal view, and it works really well on digital. My k100D is a much more portable when needed, and gives an almost normal perspective.
Its 2.8 aperture makes focussing reasonable on digital's smaller viewfinder.

Compared to exotic glass like 50mm 1.7 or 1.4 which I also have, its not razor sharp. But it's pin sharp, which means why worry about it?
All pancake lenses have similar attributes and have some compromises optically to make them so small. But colour rendition is great. I'm never selling mine!
Add Review of SMC Pentax-M 40mm F2.8

All times are GMT -7. The time now is 11:34 PM. | See also:, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]