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
38 160,964 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In 2006, it was superseded by an even smaller DA version, but that version did not feature an aperture ring.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
PEG Moderator

Registered: August, 2008
Location: Hielands o' Scootlund
Posts: 49,403

1 user found this helpful
Lens Review Date: September 12, 2018 I can recommend this lens: Yes | Price: $90.00 | Rating: 8 

Pros: She's wee
Cons: Green button use for exposure
Sharpness: 8    Aberrations: 8    Bokeh: 6    Handling: 6    Value: 9    Camera Used: K1   

Just purchased today on a wee whim, as she looked like an inexpensive bit of fun.

Planned to use as a more discrete "Street" lens, but married it up with Takumar 35mm rectangular hood, which is nearly twice as long (deep) as the lens.

Had her oot and aboot with me today, no initial problems apart from a little tricky to use as she is so wee, but got the hang of her now with Hyperfocal Focusing.

New Member

Registered: February, 2013
Posts: 20
Lens Review Date: December 29, 2016 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: size, size, size :)
Cons: 5-bladed iris ain't ideal (but better than 6)
Sharpness: 8    Aberrations: 8    Bokeh: 7    Handling: 7    Value: 7    Camera Used: Pentax MX, Fuji X-M1   

Nifty little lens which just got a new lease of life on my Fuji X-M1, just look/click at the following picture why:

Plenty sharp from F5.6, impeccable coatings (what else would you expect from Pentax), handling is a bit challenging because of it's size, but this lens IS about size...
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 6,711

2 users found this helpful
Lens Review Date: August 12, 2015 I can recommend this lens: Yes | Price: $93.00 | Rating: 8 

Pros: Excellent build, small size and focal length on film.
Cons: All the negatives associated with buying a manual focus pancake lens with no "A" setting.
Camera Used: Pentax film bodies (K1000, KM, KX, K2, K2DMD, MX, LX, Super A, P50)   

The M40/2.8 was released in 1976 and remained in production until 1984. It was the first Pentax pancake lens and the smallest in height.* A new digital optimized version the DA40/2.8AL, was released in 2004 and remains in production today. * Excluding the Takumar 18mm fisheye lens from 1963.

Decent optics and the M40/2.8 is sharpest at f/11 and pretty good at f/8 & f/16. At f/11 its center/edge sharpness can compete with any of the other M Series non macro 50mm lenses. Outside of f/8 to f/16 is where things are just average optically!

Focal Length:
On film this is a wider normal/standard lens and is perfect for street shooting. On APS-C you get the opposite, a long normal/standard lens. The 40mm FL on film is the main reason to buy this lens, as itís just about perfect.

Excellent all metal build in a very small package!

The M40/2.8 being a pancake lens, is pretty hard to focus and adjust the aperture. This however is pretty obvious when you buy a pancake lens, so the poor handling comes with the territory. I tend to use hyperfocal focusing & aperture priority a lot with the M40/2.8, to compensate for the small size. I leave the aperture ring at f/11, move the focus infinity mark to 11 on the distance scale and set the camera to the auto shutter setting. No metering and everything from 7 feet/2.1 meters to infinity will be in focus, so I only have to adjust for close-up shots.

There was one lens hood that was usable on the M40/2.8, the 49mm round rubber hood made for the other normal/standard M Series 50mm lenses.

F/2.8 is not very fast for a normal/standard prime, but again this is a pancake lens and if it was any faster its size would increase. So all things considered, f/2.8 is adequate for a pancake lens. Note the much newer DA version still has a maximum aperture of f/2.8.

The M40/2.8 vs my other similar FL normal/standard primes:
I also own the FA43/1.9 and the FA43 is better in all respects except for size (if you are looking for a small lens) and build, but thatís not really a surprise as one is an elite auto focus lens and the other designed specifically as a pancake. Both focal lengths are superb on film!

I would only recommend the M40/2.8 for a film shooter, as the DA40/2.8 is probably a better choice for digital. As I only shoot film Iím quite happy with the M40/2.8 and using it as a street lens in the fashion I indicated above. You just have to accept if you buy this lens you are getting poor handling, average overall optics and a slower speed.

I would rate the M40/2.8 Pancake lens an 8.5, rounded down to an 8.

I bought my M40/2.8 from a local seller I know on Craigslist and paid $120 CDN. It was in mint condition.

Sample shots taken with the M40/2.8. Photos are medium resolution scans from original negatives and slides. The first shot was taken around Vancouver, Canada and the second in NYC.

Camera: Super A Film: CineStill 50 ISO: 50

Camera: Super A Film: Fuji Provia 100F ISO: 100

Veteran Member

Registered: September, 2013
Location: Sydney
Posts: 844
Lens Review Date: September 15, 2013 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: Size, Sharpness.
Cons: Doesn't quite focus to infinity on digital.
Sharpness: 10    Aberrations: 9    Bokeh: 7    Handling: 10    Value: 8    Camera Used: P30T, K-x   

Awww, it's sad seeing this lens being marked so low! I picked up one of these in immaculate condition, and it's actually far better than the reviews here would have you believe. The bokeh when stopped down is nothing special, but my copy of this lens is actually sharper than my DA40 limited!

The only real issue I've found, is that on a DSLR, my copy doesn't quite focus to infinity. On film however, this isn't a problem at all. I don't have any problems focussing the 'M', the focus is nicely damped, and whilst the ring is smaller than most lenses, I've never found it to be difficult to get the right focus (Mind you, I tend to manually focus the DA version on DSLR most of the time, so it might just be something I've gotten used to)

The lens is so small, that you'll always be able to find space for it in your bag. Looking at some of the reviews here, and then looking at my copy, makes me wonder if a large number of copies have taken a fair few knocks in their time, having spent most of their life as 'the spare lens' bouncing about at the bottom of a camera bag?

If I was to give the lens a mark on it's own merit, it would be a firm 9. It's extremely sharp, extremely small, has a useful focal length on digital, and can be picked up fairly cheap. Sadly though, I'm going to have to give the lens an 8. The problem really is the DA40 limited. The DA40 outclasses the M40 in almost every way (except sharpness), is a bit smaller, and is much more enjoyable to shoot with. If you shoot manual film cameras, or are on a budget, then the M40 is nice little lens (if you get a good copy). If you only shoot digital, or shoot with an autofocus film body, then the DA40 is likely to be a better choice.
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:-)
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
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!
Site Supporter

Registered: March, 2007
Location: Los Angeles, CA
Posts: 462
Lens Review Date: May 5, 2007 I can recommend this lens: Yes | Price: $80.00 | Rating: 8 

Pros: light weight, super compact, good image quality
Cons: can be hard to use because of its size, not the sharpest lens

I really like this lens, even though it's not the sharpest and there's a good amount of purple fringing wide open.

It makes my K100D very compact and easy to carry around. I also like the 40mm focal length, which is a comfortable length for me to take pictures of people. A lot of Pentax users seem to like this lens for street photography because it makes their cameras look less invasive.

My copy of the lens is pretty worn, but it still works great. I liked it enough that I bought the DA 40mm Limited so I can have autofocus again. Comparing the two, I like the colors of the DA 40mm better, but it also seems to be worse with fringing in high contrast environments.
Junior Member

Registered: September, 2014
Location: United States
Posts: 35

1 user found this helpful
Lens Review Date: January 29, 2019 I can recommend this lens: Yes | Price: $95.00 | Rating: 7 

Pros: Super-Slim, great walk-around lens
Cons: focusing is a bit difficult due to size, okay bokeh, min. focus distance
Sharpness: 7    Aberrations: 7    Bokeh: 5    Handling: 7    Value: 8    Camera Used: Sony A7   

Got this lens with a bit of balsam separation. Fixed it and functions well. profile is super slim even with an adapter for the A7. It is a great walk-around lens, but other than that, you wont have too much creative license with it. The most disappointing aspect is the quite long min. distance focus. Other than that, I think it's worth the money, especially if you just want a lens to tack on and head out the door.
New Member

Registered: March, 2014
Posts: 1
Lens Review Date: January 14, 2015 I can recommend this lens: Yes | Price: N/A | Rating: 7 

Pros: Tack sharp from f/5.6
Cons: A tad soft wide open
Sharpness: 8    Handling: 8    Value: 6   

Judging from previous reviews, I only expected mediocre sharpness from this lens. And sure enough, at f/2.8 the lens is somewhat unimpressive.

However, when stopped down to f/4 the quality improves vastly, and by f/5.6 the lens is sharp across most of the (APS-C) frame, with an exceptionally sharp center.

Handling is similar to other M primes, although the focus ring is almost a bit too small.
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: 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...
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.
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.
Add Review of SMC Pentax-M 40mm F2.8

All times are GMT -7. The time now is 03:29 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]