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SMC Pentax-M 40mm F2.8

Reviews Views Date of last review
38 159,619 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In 2006, it was superseded by an even smaller DA version, but that version did not feature an aperture ring.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 1-15 of 38
Forum Member

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

1 user found this helpful
Lens Review Date: January 15, 2018 I can recommend this lens: Yes | 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:
Senior Member

Registered: November, 2011
Location: Los Angeles
Posts: 167
Lens Review Date: November 23, 2014 I can recommend this lens: Yes | Price: $90.00 | Rating: 10 

Pros: Vibe, usability
Cons: Vignetting, if you dislike vignetting
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 10    Camera Used: MX, ME Super, K01   

I don't understand people who dislike this lens.

Mine is sharp. Very sharp. I shoot mostly film with a little digital on my K01. I've also owned the DA40XS, which I sold because I didn't like it any better than this lens. I've owned this one for maybe two years now, and ran tons of film through it.

The M40 has a lot of "mojo" or "vibe." Maybe the vignetting is part of its unique look. The focal length is nearly perfect; 40mm is such a natural FL. The amazingly smooth bokeh is definitely part of this lens's personality.

I should say that I have owned Super Tak 50/1.4 and 105/2.8, M 50/1.4, /1.7, and /2, K 35/3.5, M 20, M28/3.5, M28/2.8, and the M35/2. I also own a Minolta system with a bunch of glass. I would sooner stick this lens on my camera and go shoot than almost any of the above (except maybe the K 35).

Its handling is quirky, but soon becomes transparent. As a lens that you can use every day, it is a very good value.
Forum Member

Registered: September, 2013
Posts: 62
Lens Review Date: December 28, 2013 I can recommend this lens: Yes | Price: $130.00 | Rating: 10 

Pros: very compact and sharp
Cons: not detected
Sharpness: 9    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 10    Camera Used: LX, ME-super, K-30   

good lens, with ME-super is very light kit to travel.
sharp and easy-to-use.
Little slow? yes, but at the day light You never open more than f/5.6.
this lens is not for "bokeh-hunters", but for travel and indoor it is great.

I was sold it last month, because now I'm using only DSLR K-30, and obtain auto-focus DA40Lim instead.

there is a BIG pros for M40 and DA40Lim - so small lenses not "scaring" children and other peoples, they never taken seriously so small lens and filling free and naturally.
only one thing - for my big hand tiny focusing ring is to thin
but in any case - it is a very good lens.
New Member

Registered: February, 2012
Posts: 15
Lens Review Date: December 6, 2019 I can recommend this lens: Yes | 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.
New Member

Registered: October, 2011
Posts: 9
Lens Review Date: March 31, 2017 I can recommend this lens: Yes | 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: June, 2016
Posts: 1
Lens Review Date: December 9, 2016 I can recommend this lens: Yes | Price: N/A | 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

1 user found this helpful
Lens Review Date: July 12, 2016 I can recommend this lens: Yes | 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: 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.
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

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.
New Member

Registered: April, 2009
Location: Poland
Posts: 1
Lens Review Date: April 16, 2009 I can recommend this lens: Yes | Price: $150.00 | Rating: 9 

Pros: Great on film camera
Cons: Do not use with a DSLR

I love the pancake lens when I use it with an old ME Super for BW photography. I find the 40mm focal length very useful on film as it is wider than the 50mm standard and yet it has little distortion, less than other wider angle primes (28, 35).
It is so small when attached to my ME Super body that I can carry it with me most of the time.
I wouldn't recommend using it with DSLR though. It is hard to get accurate focus with small viewfinder of a DSLR (compare K10 and ME Super's viewfinders and you'll know what I mean).
Because of the crop factor it's great focal length is not an advantage on DSLR's
I often shot stepped down to f 8 or so and the photos are really sharp.
Built quality is great and after so many years of usage it still works like a charm.
Giveaway winner!

Registered: December, 2007
Location: beantown
Posts: 944

1 user found this helpful
Lens Review Date: December 14, 2007 I can recommend this lens: Yes | Price: $118.99 | Rating: 9 

Pros: Small, fits in most of my pockets, sharp enough.
Cons: not as good as my 50mm, element delaminated.
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 8    Value: 9   

LpMM nit-pick... nonsense:
The test I ran long ago scored about 46lpmm at average in f4. The corners only 37lpmm and the high of 48lpmm... What does that mean? Nothing in real life.... the lens seems to do well enough and sure, not a stellar lens, it still get the job done.

Rear element Issues:
The original test was on my pre-repaired lens. Soon after the lens test it developed a de-lamination problem and grew from the sides in on the rear lens group.

Post repair:
I started to use it again and with newer emulsions as well a the digital (K20D) and found that the pictures were much better than I recalled. The cement was a recommended type for lenses and claimed not to change the dynamics of the lens to any degree that could be noticed. On the plus sides I'll disagree!

Originally a so-so score, I've found it seemingly a bit more higher.
The center was about 55-56 and the corner on a full-frame is 39-45lpmm, this is from the Ektar and TMax film in the test... sorry, no Tech-Pan.
On a APS-C format, the test is a little tricky to compute for results, but the numbers are similar at center... 52-55 lpmm and the corners 49-52. Using film style test on a digital is difficult to do and I don't have the standard digital targets so take this with a grain of salt.
(compared to: M50/1.4 @ f2.8 and a top score of 61-64lmpp @center / 52-54 @ corner)
And now, what does these numbers mean? ...nothing... It still is a nice lens for its size.

Wide open the lens is good for most applications and still is a bit mushy, at f4.0 the lens is as good as many lenses, at f8 it is harder to tell one from another lens in sharpness. I tested at up to f8 and it seems to hugged near the acceptable results and it seems that f11 to f22 your getting less contrast.

What is really important in all?
Post repair, a better utility lens than one would think.
Original form with no de-lamination problems, it is a good value due to the size. A slip into the rain coat or any medium large pocket or narrow bag.

Colors are very good and the glare resistance is very good in more general situations, but you should shade in high brightness situations.

The one big gripe is the weak rubber grip. One thin strip of rubber prone to damage and near impossible to replace with the same. A nice suggestion of using an equivalent size rubber O-ring.

The DA 40mm is a sort of successor, but only in the APS-C format... not had the chance to test it.

Summing it up:
Reality is that most versions out there will not have a major optical repair applied to it. So the thing to remember is that this lens is mostly a small handy lens and it is a super match to any of the M-Series film bodies when small is what you need. Remembering that it functions much like a "Snap-Shot" lens, I'll forgive the short comings because its the compact size that I am happy about. Similar or smallish might be a M28 or M30, but the M40 fits in my pocket... jacket pocket.
Add Review of SMC Pentax-M 40mm F2.8

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