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SMC Pentax-M 100mm F2.8

Reviews Views Date of last review
45 168,290 Fri June 16, 2017
Recommended By Average Price Average User Rating
100% of reviewers $106.05 9.24
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
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
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
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-M 100mm F2.8
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New Member

Registered: June, 2017
Posts: 3
Lens Review Date: June 16, 2017 I can recommend this lens: Yes | Price: $100.00 | Rating: 9 

Pros: Nice bokeh and usability
Cons: none really
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 10    Value: 10    Camera Used: Samsung NX1   

I'm using this on a Samsung NX1 with the official NX to PK adapter. Fully manual, but works great. Great lens for outdoor portraits and landscapes. Photos come out sharp enough and very adjustable in lightroom. I also have the 135mm, but prefer using this 100mm more. Photos edited to taste in Lightroom.

Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 5,443

1 user 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
Site Supporter

Registered: January, 2015
Posts: 71
Lens Review Date: February 9, 2017 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Sharp wide open, small & light, nice bokeh
Cons: Mega PF
Sharpness: 10    Aberrations: 6    Bokeh: 10    Handling: 10    Value: 10    Camera Used: K-5, K-50   

I bought my copy at a bargain price because it is stuck wide open and has a scratch on the front element but otherwise clean and good mechanically (hence no price listed to throw off the average). I used to own the "A" version and can confirm that sharpness improves as you stop down, but the real draw here is that IQ is very very good wide open at f/2.8. I have some pixel peeping tendencies and while f/8 is certainly sharper, I cannot in good faith knock the wide open IQ at all. This is especially true if you consider the diminutive size, ease of MF, buttery bokeh and price/value.

I use this M lens exclusively in Av mode on the K-5/K-50 since it won't stop down anyway.

Purple fringing.....if you shoot a tree against a bright sky at f/2.8 you may find that entire branches turn purple. It is borderline comical in some situations, but still easy to remove in PP. You can spend a bunch more and get a modern lens with similar specs that doesn't exhibit PF, but personally I'll suffer through a few mouse clicks on my keepers to get where I need to be.

I recently took some test shots comparing this lens to the Kiron 105mm f/2.8 Macro (mint copy). At portrait distances this SMC-M 100mm f/2.8 is noticeably sharper, easier to focus, and has smoother bokeh. Interestingly, the Kiron seemed to have a shallower DOF at the subject yet did not blur the background as smoothly. All comparisons were made wide open at f/2.8.

This lens can produce pro-quality (or close, at least) portraits and won't break the bank.
Site Supporter

Registered: September, 2016
Posts: 3

2 users found this helpful
Lens Review Date: October 30, 2016 I can recommend this lens: Yes | Price: $50.00 | Rating: 10 

Pros: Quality through and through
Cons: Can't think of any
Sharpness: 10    Aberrations: 9    Bokeh: 8    Handling: 10    Value: 10    Camera Used: K-30   

Metering and auto white balance is spot on with my K-30, which isn't to take for granted with legacy lenses. No need to dial in any + or - EV.

So much fun to shoot with this lens, so small for this focal length, yet so well constructed. Focuses like a dream and focus throw is not too long which makes for fast shooting even though it is a manual lens. Focuses close enough that it's even usable indoors in spite of the long focal length.

Still sharp enough wide open but with some very slight PF in harshly lit areas. Immaculate image quality stopped down from F4 onwards. Great contrast and rendering. Very nice out of focus areas. Faultless prime. Price I paid for an excellent copy is laughable. Some lenses you know you will never get rid of, and this is one of those for sure.

Downscaled original sample + 100% crop, shot at F5.6 if I remember correctly. Impressed with the sharpness which can be seen in the rendering of the window frame, where the finely corrugated stone border is resolved without any issues.

New Member

Registered: June, 2013
Posts: 18

2 users found this helpful
Lens Review Date: October 6, 2016 I can recommend this lens: Yes | Price: $50.00 | Rating: 10 

Pros: Great image quality in small package
Cons: I wish it has more aperture blades.
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10    Camera Used: Sony a7   

This is my main portrait lens on my a7. My copy is in great condition, like new, the glass was incredibly clean and cosmetically in perfect condition. The focus grease was a bit dry, so I relubed it and now it really is a joy to use. The lens is very small, with is a big plus.

I was astonished when I saw the first portraits. I didn't expect such a great image quality. At f2.8 is very sharp, but not excessively sharp, and contrast was a bit flat. But microcontrast is at a very good level at this point. It vignettes a bit. Very good for portraits. At f2.8 it has a bit of purple fringing, but not so much! When stopped down it becomes great. At f5.6 sharpness in incredibly high, and focusing at infinity gives excellent sharpness across the frame on a FF camera. Very impressive. Bokeh is very beautiful and smooth at all apertures and seems to resist flare very well.

The six aperture blades make a smi-circular shape until f5.6, but I really wish it had more of them. 8 blades would be perfect.

I recommend this lens!

Registered: July, 2014
Location: Nagoya
Posts: 577

2 users found this helpful
Lens Review Date: July 31, 2016 I can recommend this lens: Yes | Price: $180.00 | Rating: 10 

Pros: Sharpness/clarity, size, build, handling
Cons: None worth mentioning

Sharp and contrasty pictures from f2.8, compact, classic M series quality, ideal for portraits, flowers and longer street shooting (I use it for street with black and white film a lot, and it really shines).
Even for £100 in Exc+ condition I think it's a bargain. Definitely recommended. Get a cheap 49mm tele hood for best results.

K1000, Fomapan 100, f4:

New Member

Registered: June, 2015
Posts: 1

1 user found this helpful
Lens Review Date: July 5, 2015 I can recommend this lens: Yes | Price: $80.00 | Rating: 10 

Pros: Value, Sharpness, IQ
Cons: Contrast
Sharpness: 9    Aberrations: 9    Bokeh: 9    Handling: 8    Value: 10    Camera Used: NEX-5R   

Outstanding lens for the value. If you can snag this for under $100, you'd be hard pressed to find a better option at a similar price (but that's true for most of the M-series'). Around $175-ish the max for what I would pay for this lens.

Build quality is excellent, as is form factor.

Bokeh is quite good, and the 100mm is not too large on a APS-C that still makes for a very affordable portrait lens. Sharpness can actually be a bit too much for a portrait lens stopped down, but is wonderful wide open.

The only down side is I almost always have to PP the color and contrast (but that's true for most legacy lenses).

Bottom line is this is one of the best values out there.
New Member

Registered: March, 2014
Posts: 1

1 user found this helpful
Lens Review Date: January 14, 2015 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Excellent sharpness across the frame stopped down
Sharpness: 9    Aberrations: 9    Handling: 9    Camera Used: Sony A7   

The SMC Pentax-M 100mm f/2.8 is a very good M prime. Very compact for a 100mm, smooth focusing and solid construction.

The lens is usable from f/2.8, but stopping down to f/4 boosts the contrast and sharpness noticeably, even in the center. From f/5.6 the lens is very sharp all the way to the full frame corners. CA is very low.

All in all, an excellent performer
New Member

Registered: March, 2009
Location: Copenhagen
Posts: 8

4 users found this helpful
Lens Review Date: January 12, 2015 I can recommend this lens: Yes | Price: $90.00 | Rating: 9 

Pros: Small, light, well built, sharp, nice bokeh, cheap
Cons: Purple fringing at full aperture against the light, a bit long for portraits on digital camera
Sharpness: 9    Aberrations: 7    Bokeh: 10    Handling: 10    Value: 10   

Despite this lens doesn't have automatic aperture (for those using it on a digital body) I have given it a 10 for handling due to the fact that it's diminutive size combined with light weight and the buttery-smooth focus ring makes the handling exquisite and for me I like to use it on 2.8 due to the great bokeh for portraiture, so I havn't really missed the "A"-setting. Suprisingly I havn't been able to find many images online taken with this lens so I have attached some images that I have shot with a K5 - making it a 150 mm effectively but still with the size of a 50 mm standard lens! This lens though, is abit challenged from purple fringing when shooting against strong light. This lens is a very inspiring little gem! Enough words, I will let the images will speak for themselves

New Member

Registered: December, 2014
Posts: 2
Lens Review Date: December 8, 2014 I can recommend this lens: Yes | Price: $120.00 | Rating: 9 

Pros: IQ, Solid build, small, light
Cons: purple fringing
Sharpness: 10    Aberrations: 8    Bokeh: 10    Handling: 10    Value: 10    Camera Used: K200D   

I own this lens for more than 3 years now and it is still my favourite one. It is build like a tank, fun to use. I love the imagy quality and the colours of this lens. If you have the chance do not hesitate to buy a copy. I think it is a bit underestimated beside the 85mm f2 but it is almost as good, but for a much better price.

The only thing you have to be aware that this lens, as many of the old ones, does not tolerate when the light comes directly to teh lens. In this case you will get solid purple fringing. All the other cases it is an excellent choice.

New Member

Registered: November, 2014
Posts: 13

1 user found this helpful
Lens Review Date: November 24, 2014 I can recommend this lens: Yes | Price: $100.00 | Rating: 10 

Pros: sharp, fast, beautiful image color
Cons: nothing I can think of
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10    Camera Used: K2000   

I bought this lens used with my K2000 back in 2009 and it's been my favorite since then. I've used it on many occasions, but mainly for portraits. The color and sharpness I manage to get out of it nearly every time I use it blow me away. Without a doubt it produces the finest images I've made with my limited experience. I just barely upgraded to the K3 and can't wait to try it out on that.

Here's a portrait I took last December. f2.8. That bokeh!

Senior Member

Registered: March, 2010
Location: Texas
Posts: 195

1 user found this helpful
Lens Review Date: September 19, 2014 I can recommend this lens: Yes | Price: N/A | Rating: 10 

Pros: sharpness every aperture, bokeh, size, color and contrast
Cons: nothing of note

I didn't go looking for this lens. I just came across one somewhere years ago at a very minimal price and in mint condition. I took a few sample shots and thought they looked very good but didn't understand just how fine the lens was. Now, I often find myself thinking this is my best lens. It covers for an 85 and 135. It's easily in league with the best of those focal lengths. Superbly sharp at 2.8 and already producing perfect color and nice bokeh. Takinami is right-@ f16, this lenses sharpness is in the top tier of the best of the best. What a combination. It's a great portrait lens and a great landscape lens in a small package. I don't mind that it's only 2.8 because of the total dependability at all apertures. It's just about a perfect lens for what it is. How many lenses are this good?

I give a 10 in review to lenses that are most nearly the best so that they won't become underrated in comparison to other lenses, even very good ones. So, this one has to receive a 10. I only review lenses I've used extensively and that stick out from the rest of the pack.
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.
Forum Member

Registered: July, 2008
Location: Sheffield, England
Posts: 63

1 user found this helpful
Lens Review Date: June 16, 2013 I can recommend this lens: Yes | Price: $120.00 | Rating: 9 

Pros: Lovely build, light, fast, capable
Cons: Soft wide open, some fringing (on APS-C)
Sharpness: 8    Aberrations: 8    Bokeh: 7    Handling: 9    Value: 9    Camera Used: K10D   

On a K10D my comparators for this lens are the Pentax DA 35mm f2.8 Macro Limited and Voigtlander Nokton 58mm f1.4, in which company the 100mm does pretty well (as far as I can tell, only had it a short while). Even though it is a recent purchase, this is a lens I can already see no reason ever to part with (unless I ever find a mint 'A' version)

It was purchased primarily for portrait shooting with increased working distance over the 58mm Nokton and came up at a price too good to ignore (mint £79 in spring 2013). An 'A' variant would have been nice but certainly wouldn't crop up near that price these days in the UK. An 85mm would maybe have been a nice choice but they usually cost considerably more. So in terms of value the 100mm M is very good indeed

I use it mostly used at f2.8 / f4 where it offers shallow depth of field and okay (fussy, definitely not outstanding) bokeh. Resolution is lovely for portraits but I would say this is not a high resolution lens in the terms I am used to, not even at f8. Strong contrast does cause some minor fringing issues, especially wide open but for portrait use it isn't an issue

couple of early images at f4 (note shallow depth of field in both and fussy bokeh in forest floor image) Some post process here as I messed up M exposure (RAW not on AND Green button not pressed - doh!)

Function on the K10D is fine, manual focus is usually good (with split screen, not sure how it would be with plain screen or AF confirm as I don't use them) and exposure using M and the green button in RAW rarely causes any real issues. Best of all, it looks like it belongs on the front of a K10D and just 'feels' right when it is in use
Junior Member

Registered: August, 2012
Posts: 35
Lens Review Date: April 7, 2013 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Solid, decent optically
Cons: Manual focus and aperture
Sharpness: 9    Aberrations: 10    Bokeh: 9    Handling: 8    Value: 8    Camera Used: LX, ME Super, *ist DL, K-01   

This is a very decent film-era lens. Well built and optically not bad. Handles very well but of course there is no autofocus and no auto aperture. Quite useful as a portrait lens on film but a bit too long for that on APS-c digital cameras.
Add Review of SMC Pentax-M 100mm F2.8

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