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SMC Pentax-M 100mm F2.8

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50 215,795 Thu May 14, 2020
Recommended By Average Price Average User Rating
100% of reviewers $103.44 9.27
SMC Pentax-M 100mm F2.8

SMC Pentax-M 100mm F2.8
SMC Pentax-M 100mm F2.8

This is a compact non-macro 100mm telephoto lens.

SMC Pentax-M 100mm F2.8
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 6 blades
5 elements, 5 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
100 cm
Max. Magnification
Filter Size
49 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 16 ° / 14 °
Full frame: 24 ° / 20 °
Clip-on hood for 85mm/100mm lenses
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Diam x Length
62.5 x 55.7 mm
225 g
Production Years
1977 to 1984
Engraved Name
smc PENTAX-M 1:2.8 100mm
Product Code
User reviews
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-M 100mm F2.8
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Registered: January, 2011
Location: Skåne, Sweden
Posts: 467
Lens Review Date: January 11, 2011 I can recommend this lens: Yes | Price: $25.00 | Rating: 9 

Pros: compact, light, well built, precise focus, sharp wide open
Cons: lack of auto-focus (can't really blame the lens for that)

For the price I got this lens is not much room for objections.

Compact, solid feeling compared to new lenses, yet very light (about the same weight and slightly smaller size then the DA-L 18-55 kit-lens). Makes a very good companion on the K-x. The focus has a nice long throw, making it pretty easy to focus properly (I'm not used to manual focusing). It seems very durable as well, since my copy is looking like it has been used a lot (some dents on the body as well as some markings on the lens itself), but it still produces lovely pictures!

The images are sharp (even wide open), has a nice bokeh. Colors seems like a modern lens, not like some other older lenses I've used. I will have to use it more outdoors to give a proper evaluation of flare resistance etc.

All-in-all a lens that is fun to use, produces good images and you don't think twice to bring it because of size or weight. A bonus is that it looks very good on the K-x with it's polished metal details, black basis and white text (goes for both lens and camera).

Senior Member

Registered: July, 2008
Location: Milwaukee
Posts: 129

1 user found this helpful
Lens Review Date: December 6, 2010 I can recommend this lens: Yes | Price: $90.00 | Rating: 9 

Pros: Size, Sharpness, Bokeh
Cons: Flare, Softness and PF Wide-Open,

I snagged this lens off of ebay, and I've been in love ever since. It's a wonderful specimen, fantastic for a long portrait lens or even shortish sport lens. I've used to to shoot portraits, basketball games, concerts, and animals.

Handles as an M-series lens should: smooth as silk. I don't know why more modern lenses don't have such amazing focus rings. Literally every M-series lens I've used has a perfectly damped focus ring. The aperture ring is also incredibly smooth, stopping precisely at its detent locations. It is firm, but not so firm that it's hard to change the aperture. Perfect, in my opinion.

On a similar note, the build quality is outstanding, which is no surprise. This all metal and glass construction will probably outlive me. It continues to surprise me whenever I pick up one of these vs. a modern plastic lens. This guy just oozes quality.

Unfortunately, it is quite soft and prone to PF when shooting wide-open, but in some instances (portraits) the softness is a boon and PF can be eliminated by planning ahead and avoiding shots with lots of high contrast. The problems can also be handled via post-processing without too much difficulty.

Some folks would count the lack of automation to be a negative, and thus rate the lens accordingly. However, I argue that the ratings should reflect the lens' intended purpose, that is, a fully manual lens. As a result, I won't be taking any points off for not having auto-aperture or autofocusing. While these things would be very nice, they should not factor into the scoring of a fully manual lens.

Despite minor flaws in wide-open performance, its compact size, overall sharpness, bokeh quality, and overall handling characteristics garner it an easy 9/10. I highly recommend this lens to anyone looking for a manual telephoto prime.
New Member

Registered: May, 2010
Location: Ames, IA
Posts: 18

1 user found this helpful
Lens Review Date: December 5, 2010 I can recommend this lens: Yes | Price: $165.00 | Rating: 9 

Pros: Great feel, fast, good portrait length, but not unusable for other shots.
Cons: none really

This is a fantastic lens. It's got that great feel of the M series lenses, and it's pretty fast. Gives a nice shallow dof for portraits, and the bokeh looks good- not distracting at all. Also, it's got that legendary SMC sharpness and contrast, especially when stopped down a little bit.

Many say that the 100/4 is better for portraits, and that might be true from a technical standpoint. However, the usefulness of this lens makes it worth it to me. In addition to taking great portraits, it's fast enough that I can take it into a bar at night and take decent shots of the band playing. I've also used this lens for urban cityscapes, and landscape photography.

I think the 100mm length is about perfect for portraits anyway. It's short enough to give you an intimate portrait (and a more intimate portrait making session), yet it's long enough to give a good head and shoulders portrait without being right in someone's face. Like someone else said in their review- 135mm now feels "too far away."

The only con this lens has, IMO, is that the "wow factor" of sharpness and contrast is a bit less wide open. This should be expected with just about any lens, and I don't feel that it detracts from the quality or the value of the lens.

If anyone is thinking, "Man, I really need a decent portrait lens, but would like to use it for other things," Give the M100/2.8 a shot.

Registered: March, 2009
Location: Salt Lake City, UT
Posts: 509

1 user found this helpful
Lens Review Date: October 11, 2010 I can recommend this lens: Yes | Price: $80.00 | Rating: 9 

Pros: light, compact, well built, good IMQ-corner to corner
Cons: slightly low contrast and resolution at f2.8

In contrast to my other 100mm or so lenses, this is the lightest and smallest one. It is similarly well built as other M lenses. I would say that they are not as robust as the K lenses but much better than latter plastic lenses.

As similar to a couple of M lenses that I own, it has lower contrast and resolution at the largest aperture than its K counterpart. Minimization allows most M series lenses to have 49mm filters and shorter length than the K series . But it has taken its toll on image quality in some cases.

Is it worth it? Perhaps if you do not shoot too much at the largest aperture. Slow down a bit, IMQ increases steadily. One great advantage of a fixed focal lens is its corner to corner IMQ. This is no exception.

Overall, a good choice.
Veteran Member

Registered: January, 2010
Location: Montreal
Posts: 761
Lens Review Date: March 28, 2010 I can recommend this lens: Yes | Price: $160.00 | Rating: 9 

Pros: Fast, extremely sharp, size (so small)
Cons: nothing major

I got this lens about a month ago and I love it more and more each time I use it. I bought it mostly for indoor photography, concerts and stuff. Famous Marc Sab. was recommending it.

I mostly use this lens wide open and I find the lens very sharp. It's the sharpest wide open lens I have tried so far.
The lens is very small and well built. Focus is smooth and after some practice, it's very easy, and quick, to focus with.

I strongly recommend this lens, if you can get it at a good price. I could have waited a little bit longer and thus find a better deal but I really wanted to try it out. Now, I don't see myself selling it, until I get my hand on a A version... of course.

Just my two cents
Inactive Account

Registered: July, 2008
Location: Vancouver, Canada
Posts: 1,101

1 user found this helpful
Lens Review Date: March 18, 2010 I can recommend this lens: Yes | Price: $100.00 | Rating: 9 

Pros: Sharp, Bokeh, Contrast, Weight
Cons: nothing really

This is one of the sharpest lenses I have owned. f/2.8 is fast enough for me at this length. The bokeh is fantastic, very smooth and the contrast is excellent as well.

Set your aperture on the lens, focus, meter with Green button and fire, very easy.
Senior Member

Registered: October, 2008
Location: NYC
Posts: 258
Lens Review Date: April 18, 2009 I can recommend this lens: Yes | Price: $80.00 | Rating: 9 

Pros: Sharp, compact
Cons: Wish aperature can be wider

Very good portrait lens, very sharp image even at f2.8, small and compact for a 100mm lens, f2.8 wide open might is kind of slow for low light, but over all it's a great fast prime lens
Veteran Member

Registered: September, 2006
Location: Denver, CO
Posts: 10,686

3 users found this helpful
Lens Review Date: December 15, 2008 I can recommend this lens: Yes | Price: $118.00 | Rating: 9 

Pros: great combo of focal length, speed, IQ, size, build quality, and cost
Cons: much more purple fringing in very high contrast situations than other lenses

As I said in my summary above, this lens provides a fantastic value proposition - a really useful focal length (both on 35mm and APS-C, if for different reasons), decent speed, fine IQ, incredibly compact, solid build. And it's a bargain - I paid a little over $100 for mine, but also I bought one for my wife for a little *under* $100.

One of the things I do most is concert photography - digital - and I've decided this lens is as close to perfect a single prime lens as I could hope for. Wide open, I'm pretty sure it is outresolving what my (K200D) sensor can muster at the high ISO levels typical of concert photography. The focal length is pretty much ideal for isolating performers from a vantage point near to the front as you'd likely be if you're at least somewhat serious about it. It could work as a portrait lens outdoors or for really tight head shots, and it's just long enough on digital to feel like a "real" telephoto lens in other situations as well (if, obviously, not a wildlife lens). On 35mm, it would make a great portrait lens or for certain types of street candids, and would also work for concert photography if you like a little space around your subject or intend to shoot from right on stage.

So for me, it's pretty tough to beat on paper just based on specs, assuming it takes a picture at all. But I suppose most people will concentrate more on IQ :-).

Below, I'll link to a comparison against a couple of other M series telephoto lenses. But for now, I'll summarize that by saying it's the sharpest of the bunch at f/2.8. At high ISO, it's probably more resolution than my camera can use, and at lower ISO levels, I can clearly see my reflection in the eye of a portrait of my cat.

Stopped down, it's clearly at least as good as a consumer zoom like the 50-200 or Tamron 70-300. And comparisons posted by "Douglas of Sweden" on the SLR Lens forum show the optically-identical "A" version to hold up quite well against the extraordinarily well-regarded DA* 50-135 wide open. But I do suspect the 50-135 would win more clearly at f/5.6 or f/8, as the M100/2.8 doesn't actually perform dramatically better at these apertures compared to f/2.8. The resolution tests published by Yoshihiko Takinami show it not reaching maximum resolution until f/16, and while I haven't done any formal testing, this does seem consistent with what I've noticed.

Because I use the lens primarily for low light concert photography, I did notice the Achilles heel of this lens for quite some time. But shooting high contrast subjects wide open in bright sun, it has more purple fringing than any other lens I have used. Not that shooting high contrast subjects wide open in bright sun is a particular common thing to be doing. That fact that the lens lacks the built-in hood of the M120/2.8 and M135/3.5 is a disadvantage, too.

The bottom line for me regarding IQ is that at f/2.8, it's competitive with just about anything else, it seems, which is saying a lot considering the price and the size. At f/8, it's competitive (at least) with a consumer zoom, if perhaps not with a DA* or a macro. And at f/16, it's probably competitive again with any high end lens that started to become diffraction-limited at f/8 or f/11.

Here is my comparison against the M120/2.8 and M135/3.5:

My conclusion from a few posts later in the thread:

The 100 is the sharpest when comparing images at constant magnification (by a small margin over the 120 and a larger margin over the 135). And not that the others are particularly large or heavy (they aren't!), but the 100 is *noticeably* smaller and lighter. However, it has the most purple fringing by far, it lacks a built in the hood, and it can't blur a background to the same extent as the other two. It is the most generally useful portrait focal length of the three, but it has the least "reach". It is not too hard to find with a little patience, and it usually goes for $100-$150.
Again, given what you're getting for the money, it's a really great package!

Sample concert shot at f/2.8:


Registered: February, 2008
Location: Waterloo, Ontario
Posts: 4,462

1 user found this helpful
Lens Review Date: February 24, 2008 I can recommend this lens: Yes | Price: $150.00 | Rating: 9 

Pros: Sharp, contrasty, good portrait lens, light
Cons: Fully manual
Sharpness: 10    Aberrations: 10    Bokeh: 9    Handling: 10    Value: 10   

I had this lens for a number of years prior to purchasing the A-series 100 f 2.8 macro. I sold it with some regrets as I just couldn’t justify having two 100mm lenses. It may have been a mistake. Prior to the arrival of the macro the M 100 f 2.8 was one of my favourite pieces of glass. It was light, sharp, reasonably fast and balanced well on my MX. It was the first lens I reached for when taking people pictures. It wasn’t large enough that it scared people and it had just enough length to put the subject at ease. Many of my best portraits were a product of this lens. I actually kind of miss this aspect of the M 100mm f 2.8 as I look at its larger, heavier and much more expensive replacement. This lens did not have a flare problem but I bought the Pentax lens hood for the 100 just as I do for all my other optics. I believe lens hoods protect the front element and serve a useful purpose in keeping out stray light. In addition they look pretty cool. Boz Dimitrov provides techincal details:

(Non working link removed)

The Pentax M 100 f 2.8 would be an ideal fit mated to an LX or any of the K or M series cameras. For film I would highly recommend this lens to one and all. On digital I can only speculate but based on personal experience with several other M-series lenses I suspect it would still deliver the goods. There would be, however, all the limits to be expected when using a fully manual lens in this format. Metering will be stop down, no AF and no f stop information in the viwfinder.
New Member

Registered: January, 2008
Location: South of Sweden
Posts: 10
Lens Review Date: January 8, 2008 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Sharp, very solid metal built, small for a f2,8
Cons: autofocus!
Sharpness: 9    Aberrations: 8    Bokeh: 8    Handling: 10    Value: 9   

I bougt this lens for my ME Super for about 20 year's ago, i'm now using it on my K10D very often and even att 100% pixel peeping i find this lens very sharp and with good contrast. It's also very good in low light situations wide open i think.
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: $145.00 | Rating: 9 

Pros: Sharp and solid built
Cons: feels too light
Sharpness: 9    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10   

Its a good lens and the weight is comfortable as M series tend to be light, but feels well built.
A little test I ran back in 2002ish, but my choice of film made things less than clear so with a grain...
My little test rated the lens at about 74lpmm average @f4 and 81lpmm @f5.6 and 84lpmm @f8, is that good? My test is less than scientific lab perfect and the test lighting was not great, but the lens to my eyes is superb. Had the lens since 1999 with matching hood and case. Not found my test results for wide open, but regular use shots seem very good.

Also worth noting... GET A HOOD FOR YOUR LENS! I found a 8 to 14 lpmm jump in some tests due to glare being controlled. SMC is great, but not absolutely perfect.
Veteran Member

Registered: August, 2007
Location: Near Utrecht, Netherlands
Posts: 1,223

1 user found this helpful
Lens Review Date: September 22, 2007 I can recommend this lens: Yes | Price: $125.00 | Rating: 9 

Pros: Small, nice handling
Cons: none, really
Sharpness: 9    Aberrations: 8    Bokeh: 10    Handling: 7    Value: 8   

I bought this lens in 2002, I think, to go with my MZ-5N, for indoor portraiture. It met all my expectations from day 1 one. I like the feel of the lens; and I found that 100mm is a great focus distance for portraiture. I even got so used to it, that I think the 135mm is too close.

That's immediately why I do not use it very often, anymore. Since I have a DSLR, the crop factor turns this in a "feels-like-150mm-lens" and that is too close.

In my experience the lens makes very sharp images, even under pretty hard circumstances. A big pro is that it is so small.
Inactive Account

Registered: September, 2006
Location: Perth
Posts: 669

1 user found this helpful
Lens Review Date: September 15, 2007 I can recommend this lens: Yes | Price: $120.00 | Rating: 9 

Pros: Solid Build, relatively sharp wide open

I bought this lens for when my two hobbies come together (martial arts & photography) as I needed something relatively fast to take indoor shots and freeze the action. Not having the funds for one of the new DA* zooms (or even one of the F or FA variants) I decided to try an m series prime.

This lens performs its duties admirably pictures are sharp even at f2.8 I am very happy with this solid little lens. I do find I need to tweak the contrast up a little with this lens compared to my DA 16-45 - but that may just be a matter of my taste.
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 6,637

3 users found this helpful
Lens Review Date: February 18, 2017 I can recommend this lens: Yes | Price: $134.00 | Rating: 8 

Pros: Well built and good handling.
Cons: Could be sharper, minimum aperture of f/22
Camera Used: Pentax film bodies (K1000, KM, KX, K2, K2DMD, ME, MX, LX, Super A, P50)   

The M100/2.8 was released in 1977 and was a direct “miniaturized” replacement for the K105/2.8. The M100/2.8 was in production until 1984, when it was replaced by the A100/2.8.

Typical “M” series optics compared to the “K “series lens it replaced. Pretty good, but nothing outstanding at any aperture.

Focal Range:
100mm is a nice focal length on FF for portrait or short telephoto work. Though it’s sad with the release of the M100/2.8 Pentax stopped producing a 105mm option for the first time since the late 1950’s.

Excellent all metal build in a smaller size & weight than its K Series predecessor.

Excellent handling for an “M” series lens, mostly due to it being a short telephoto. The M100/2.8 also has a great distance scale and is easy to manual focus or adjust the aperture. Very nice compact telephoto lens to travel with.

The M100/2.8 uses a 49mm round plastic clip-on hood labelled: “SMC PENTAX 1:2 85mm 1:2.8-4 100mm”. This detachable lens hood will offer better protection than the smaller built-in hood on the A100/2.8. The M100/2.8 also had a dedicated hard lens case which also held the hood or you can use the shorter Pentax soft lens case from that period.

F2.8 is an average speed for a telephoto lens in the 100mm to 135mm focal range. The 85mm lenses tended to be faster and of course more expensive. The 100mm/105mm lenses were the slower more affordable portrait option.

The M100/2.8 vs my other similar FL short telephoto primes:
I also own the K105/2.8 which is sharper at every aperture compared to the M100/2.8. The M100/2.8 is as well built & handles the same as the K105/2.8 and has a slightly better minimum focusing distance of 1 meter compared to 1.2 meters for the K105/2.8. The K105/2.8 has a better minimum aperture of f/32 than the M100/2.8’s f/22. I rated my K105/2.8 a 9.5 and the M100/2.8 gets an 8.5.

Overall the M100/2.8 is an excellent short telephoto/portrait lens that is perfect for travelling due to its smaller size. But it’s not in the same league as its older brother the K105/2.8

I bought the M100/2.8 off eBay. It was in excellent + condition and came with the lens hood.

Sample shots taken with the M100/2.8. Photos are medium resolution scans from original slides.

Camera: KM Film: Fuji Velvia 50 ISO: 50

Camera: ME Film: Fuji Provia 100F ISO: 100
New Member

Registered: October, 2013
Location: Naples
Posts: 10

1 user found this helpful
Lens Review Date: November 1, 2013 I can recommend this lens: Yes | Price: $80.00 | Rating: 8 

Pros: Price/performance, 2,8, well bult, compact, good sharpness and resoution
Cons: Contrast a bit low, 100mm on apsc is a a bit too long for portrait
Sharpness: 8    Aberrations: 8    Bokeh: 7    Handling: 7    Value: 8    Camera Used: k5   

It's a good lens, The price, about 100 US dollars, makes it a good deal.

Sharpness is very good. But suffers from the low contrast. But resolution is very good so rising contrast or vibrance in post production is a way to get wonderfull pictures. If you can use ad adeguate lens hood (on apsc it should be for a 150mm focal... at least 135mm) things goes better. Anyway the smc coating resist from ghost and ray of light, even if the contrast goes down. Colours are good anyway, Bokeh is ok. Not one of the best in this kind of focal length. Abberations is ok, not to much, not noticiable at first sight and common size, to be a vintage lens. Manual focus is good.

On apsc digital sensors it' a great Black and withe lens, the a bit low contrast can catch a lot of gray tones. I love it for street and people ph. when I have to stay a bit far from the scene.

I'would not reccomend this lens for portrait. Even if at 2.8 the low contrast and center sharpness / border softness can make some good pics of faces, but in this focal lenght, at this price, you can get others lenses more specific for portrait, with a better skin rendition, better microcontrast and vibrance, better transition from focus to out of focus, and a more creamy bokeh. But I have to say that I would never buy a over 85mm lens to make headshot portrait on apsc... it's too much and press the elements of human face on the same plane, making it flat and not realistic.

It' a very good tele for general pourpouse on apsc. Fast, well built, sharp, and give result very easy to develop with just an increment of vibrance or contrast, so resolution and sharpness and colours become very very good. Great for b&w street ph. on apsc if you have to shot by 10 foots away.
Add Review of SMC Pentax-M 100mm F2.8

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