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SMC Pentax-M 40mm F2.8 Review RSS Feed

SMC Pentax-M 40mm F2.8

Reviews Views Date of last review
42 210,903 Sun October 29, 2023
Recommended By Average Price Average User Rating
79% of reviewers $94.21 7.87
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In 2006, it was superseded by an even smaller DA version, but that version did not feature an aperture ring.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 1-15 of 42
Site Supporter

Registered: January, 2009
Location: Champagne Ardennes, France
Posts: 8
Review Date: October 29, 2023 Recommended | Price: $90.00 | Rating: 9 

Pros: Small, build quality, IQ
Cons: Focus ring to small..not A
Sharpness: 8    Aberrations: 10    Bokeh: 9    Handling: 7    Value: 10    Camera Used: Pentax *IstdL   

Lens to make a "pocket camera" with your DSLR. Nice picture rendering. I think this M40 is not so far from my DA40 ltd in terms of optical quality...
Site Supporter

Registered: February, 2017
Posts: 1,864
Review Date: July 9, 2021 Recommended | Rating: 9 

Pros: Punchy images from f4 onwards, Nice and compact. Good build quality
Cons: Aperture ring on Pentax DSLR's is not easy to operate. Softness wide open
Sharpness: 9    Aberrations: 8    Bokeh: 7    Handling: 8    Value: 9    Camera Used: Pentax film and APSc, Fujifilm cameras   

This is the second time I have reviewed this . The first time I reviewed it solely with film cameras in mind. This time I will do so with a mind to APSC use.

I have tried the lens out now on my K3, KP, and Fujifilm cameras. It produces sharp, contrasty images from f4 onwards. Black and white images are particulary good. It is a bit soft at f2.8, an aperture I would avoid using unless one wants that effect. It makes a nice compact "long" standard lens. It handles very well on Fujifilm cameras via an adapter. The adapter seems to give you extra space to operate the aperture ring more easily and it is also easier to see the aperture ring than it is on a DSLR. Handling on both my K3 and KP is not so great. The bulge around the cameras' lens mounts (film cameras lack this bulge) mean the aperture ring is not easy to turn. Focusing can be difficult also with the relatively poor (compared to film cameras) DSLR viewfinders.

I have four 40-45mm f2.8 film era pancakes, this one, an Auto Revuenon 45mm f2.8 and 2 copies of the Zeiss Tessar 45mm f2.8, one standard and one a limited edition. In terms of IQ the Zeiss lenses are the best of the group, being slightly better than the Pentax wide open. Stop down and you are hard pushed to see much difference. The Auto Revuenon is the weakest. Build wise the limited Zeiss and Pentax are prety much the same, both excellent. The Auto Revuenon is a bit plasticky, but not in a bad way. The standard Zeiss is not very well put together at all, but seems to function OK. I would not call it a joy to use in any sense though. I also have a HD DA 40mm f2.8 Ltd. A cracking little lens which matches the Zeiss optics but loses the functionality on many cameras.

I would not recommend this lens for DSLR use, basically the Ltd or XS 40mm's are better options. However, for film or as an adapted lens on a mirrorless system its pretty damn good. Nice, small and compact
New Member

Registered: February, 2014
Posts: 7
Review Date: May 2, 2021 Not Recommended | Price: $100.00 | Rating: 6 

Pros: small, light, nice focal lenght, sharp stopped down
Cons: soft wide open, weird bokeh sometimes, needs good hood
Sharpness: 7    Bokeh: 4    Handling: 8    Value: 4    Camera Used: ME   

Long story short: I'd rather take one of the great 35 or 50mm lenses with me.

A 40mm prime is nice and useful, shame there aren't more of them!

I really wanted to like this one as it's such a cool little thing, but in the end, for me, there are too many flaws -
I agree with the others here that say it needs to be stopped down to f8 to really become sharp.
The lens does not like stray light at all, so you need a good hood in scenarios where the sun isn't behind you.
When you're ok with shooting soft wide open you still have to watch busy backgrounds as the lens doesn't render those too nicely I'd say.
For what it delivers it really is expensive right now.

That being said it can give you nice, contrast-y images when there's lots of light and you can stop down. Colors are also nice.
But still, as mentioned above, I'd just rather take a 50 or 35 instead, they're just better performers overall.

Attached there are some shots, straight from the scanner..



f8 - that one's actually really sharp, yet it seems the gallery function of this forum further compresses / softens the images unfortunately..
Unoriginal Poster

Registered: November, 2016
Location: Espoo
Posts: 3,089

1 user found this helpful
Review Date: September 1, 2020 Recommended | Rating: N/A 


The pancake. One really canít make manual focus lens with aperture ring smaller. Thereís barely room for focus ring. Still itís nice to handle. Especially if you add collapsible hood on it. Put you pay the price from small size with long minimum focal distance. Itís clearly longer than in 35ís or 50ís. I must say that this isnít chart monster. Again both 35ís and 50ís are sharper. But this lens has great rendering. It makes wonderful photos both on APSC and FF bodies. So good that some of my all time favorites are taken with this.

This makes great travel companion, if you want to go light. Iíve done some trips with only this lens on K5 and didnít miss anything. Itís so small that I had to try to put my K1ii with it in pocket. Didnít quite fit, but I had to try.

Reasonably priced fun lens that doesnít take much space in camera bag, thought maybe most fun when you leave that bag home.

APSC SIC album:
FF SIC album:
New Member

Registered: February, 2012
Posts: 17

1 user found this helpful
Review Date: December 6, 2019 Recommended | Price: $25.00 | Rating: 9 

Pros: Very sharp from f5.6 onwards, good colours, super-compact, good standard lens of APS-C
Cons: Ntot great at f2.8 so hard to judge manual focus, flare can be a problem
Sharpness: 9    Aberrations: 9    Bokeh: 9    Handling: 8    Value: 10    Camera Used: GX10, GX20, Kx   

I paid £19 for this online; don't ask me why it was so inexpensive.

It is very compact. It's not very good at f2.8, and this makes precise manual focusing tricky, but it is pretty much as sharp as the Pentax 50mm offerings across the APS-C frame when stopped down to f8 and f11.

The bokeh is inobtrusive.

The colours are great.

The minimum focus is 60mm, so not great, but sufficient for an arms length selfie.

It isn't weatherproof, but it is so small it is partially shielded from the elements by the DSLR bodies, and I have confidence it is as rugged as they are.

40mm on an APS-C is equivalent to about 60mm on full frame, so it's very similar to using the Helios/BIOTAR 58mm on a 35mm camera. I prefer the perspective of the 40mm to the 35mm.

I use it, a lot, when hiking, skiing, dog-sledding; any activity where I want to take my camera, but I want to minimise weight and it might be exposed to physical abuse. For views, I can just set it to infinity and f11 and they turn out well.

Unless you are actively seeking veiling flare, do not include the sun in your frame!

I like to boost the contrast out of the camera, but it's a matter of taste. As others have noted, the images from this lens are quite distinctive.

Well worth my rating of 9, I reckon.

Registered: November, 2018
Posts: 535

3 users found this helpful
Review Date: October 3, 2019 Recommended | Rating: N/A 


Junior Member

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

1 user found this helpful
Review Date: January 29, 2019 Recommended | 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.
PEG Moderator

Registered: August, 2008
Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake
Posts: 57,296

3 users found this helpful
Review Date: September 12, 2018 Recommended | 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.

Forum Member

Registered: February, 2016
Location: Moab, Utah
Posts: 90

2 users found this helpful
Review Date: January 15, 2018 Recommended | Price: $140.00 | Rating: 10 

Sharpness: 7    Aberrations: 9    Bokeh: 7    Handling: 10    Value: 10    Camera Used: Sony A7s, A7ii   

This lens is incredible and unique. One of my favorite Pentax-M lenses. I use it on full frame bodies. It's not razor sharp like the M 50 f2 until about between 4 and 5.6 (at which point it is very sharp.) However, it has more pop than the smc Takumar 35 3.5 in my opinion. I did a side by side comparison in overcast low light. In bright light, it flares extremely easily, and that is it's weakness/character along with some minor vignetting. This lens has a unique glow about it. It's known for being a street photographer's lens, but I think it's more than that. It's just a great lens. I like it so much, I think it's one of the 5 best M series lenses, and also represents the M series really well being the smallest "Pentax" lens up until the DA. This lens is slightly larger than the fisheye takumar 18mm 1:11 though. I have a video talking about this lens with example images for anyone interested:
New Member

Registered: October, 2011
Posts: 9

1 user found this helpful
Review Date: March 31, 2017 Recommended | Price: $70.00 | Rating: 9 

Pros: Small, solid, easy to use, fun, interesting results, great for close up photography.
Cons: Not so good for landscapes
Sharpness: 9    Aberrations: 8    Bokeh: 7    Handling: 10    Value: 10    Camera Used: K5   

Interesting little lens. I can see why some people give it negative reviews. For landscapes on an over cast day it is pretty crap. I am presuming this is because of it's design (I could be wrong) which seems to give it an abnormal shallow depth of field. The first pictures I took were on a very grey day and appear somewhat all soft. However, when photographing close ups, it is tack sharp and has wonderful contrast and colour. As you can see below, the station shot is a bit dreary and soft at the edges whilst the flowers are sharp but have a quick fall off and the bug hotel holds focus all over the frame. I was only messing with it in the sun this morning so I'm not posting award winning pics, but I hope you agree, the latter three pictures do have a lot of charm.

New Member

Registered: February, 2013
Posts: 20

1 user found this helpful
Review Date: December 29, 2016 Recommended | 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...
New Member

Registered: June, 2016
Posts: 1

1 user found this helpful
Review Date: December 9, 2016 Recommended | Rating: 9 

Pros: size and field of view
Cons: cost
Sharpness: 8    Aberrations: 8    Bokeh: 8    Handling: 8    Value: 8    Camera Used: ME Super and MX   

I bought mine from Ffordes in 2007 for £90 in excellent condition as I wanted a small versatile lens for my ME Super for a holiday I was going on. I was only taking 1 camera and lens. Previous experience has taught me that the ideal focal length for a single lens/camera combination on 35mm is the range 40-45 for general scenic shots in the UK. On the continent I prefer a longer FL, say 55mm. This is because of the scale of the land/cityscape here is smaller than continental Europe or northern America. For outdoor photography the max aperture is plenty adequate.
I have not done any tests on this lens' optical quality. In my experience this lens produces perfectly acceptable images on 35mm film at all apertures in general walk around photography. In part, a reason I wanted one is that several years ago I remember an "opening shot " double spread image taken with one in Photography Monthly which was stunning. It was a picture of somewhere in the Lake District with sun breaking through clouds.
In terms of handling, it is not so easy to focus as a more normal sized lens but its not a significant problem. You can either use zone focusing as the DOF is quite deep or just take a fraction of a second longer to focus.
The build quality is as good as all other M series lenses I have used, certainly a lot better than the newer FA or DA series,excluding the special edition models. Its a lot better built than my Zeiss 45mm f2.8.
I've played around with it on my KM and KX bodies but it just feels and looks all wrong, but on my ME Super and MX its lovely and balanced. I can't see the point of using this lens on digital at all.
If you think small is beautiful, you really want one of these lenses in good condition for your ME Super or MX.
I paid top price for mine back in 2007, but I haven't regretted it one bit!
New Member

Registered: November, 2014
Posts: 3

2 users found this helpful
Review Date: July 12, 2016 Recommended | Price: $50.00 | Rating: 9 

Pros: really flat
Sharpness: 8    Aberrations: 8    Bokeh: 8    Handling: 8    Value: 9    Camera Used: K-30 and film   

Great little lens. I use it often for 35mm film, and is a nice light general purpose on DSLR.
Put it on f/8, 250th ISO 100 and its a simple walk-around point and shoot.
At 40mm it is a "nearly wide angle", with great depth of field. The image quality is very good.
It seems quite resistant to flare, and colours are as one would expect from an SMC lens.

This shot is taken with Pentax ME Super, XP2 film, scanned at 2100dpi.

This shot is taken with K-30.

New Member

Registered: December, 2013
Posts: 11

1 user found this helpful
Review Date: November 28, 2015 Not Recommended | Rating: N/A 


I've owed my MX from new when it first came out and still going strong. It came with the standard f 1.7 50mm. Some years ago I purchased a f1.4 50mm , although excellent , it made the camera front heavy and unbalanced. Recently I began to use again an old f2 I had neglected .[All the above are manual SMC.] I find the f2 excellent in terms of lightness and compactness and seems to suit the design of the camera body . This lens I think is a better alternative to the pancake.I remember when the pancake came out I was warned off it by my camera shop . Now it seems popular. Times change. As an aside , I purchased the MX as a first SLR because of it's very compactness being used to rangefinder cameras all the hitherto SLRs , FTb , Nikon F2 , were monsters to me . [ Small hands.] And so the pancake attracted me but I was persuaded instead to buy the F2 . Quite right I think looking back.
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 7,967

3 users found this helpful
Review Date: August 12, 2015 Recommended | 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

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