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SMC Pentax-M 28-50mm F3.5-4.5

Reviews Views Date of last review
14 55,205 Fri November 29, 2019
Recommended By Average Price Average User Rating
93% of reviewers $62.50 8.14
SMC Pentax-M 28-50mm F3.5-4.5

SMC Pentax-M 28-50mm F3.5-4.5
SMC Pentax-M 28-50mm F3.5-4.5
SMC Pentax-M 28-50mm F3.5-4.5
SMC Pentax-M 28-50mm F3.5-4.5
SMC Pentax-M 28-50mm F3.5-4.5
SMC Pentax-M 28-50mm F3.5-4.5

This lens succeeded its original K version. The two versions have the same optics.

SMC Pentax-M 28-50mm F3.5-4.5
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 6 blades
10 elements, 10 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
60 cm
Max. Magnification
Filter Size
52 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 55-32 ° / 46-27 °
Full frame: 75-47 ° / 65-40 °
PH-R52 clip-on
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Diam x Length
65 x 52 mm
310 g
Production Years
1979 to 1985
Engraved Name
smc PENTAX-M ZOOM 1:3.5 28mm-1:4.5 50mm
Product Code
User reviews
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-M 28-50mm F3.5-4.5
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-14 of 14
New Member

Registered: March, 2019
Posts: 2
Lens Review Date: November 29, 2019 I can recommend this lens: Yes | Price: $45.00 | Rating: 7 

Pros: size, good focal range, nice colours
Cons: sharpness at infinity and in the corners
Sharpness: 7    Aberrations: 8    Bokeh: 7    Handling: 8    Value: 9    Camera Used: Sony a6000 and Pentax me super   

This is not a sharp lens. Even using it on an apsc sensor which uses the best central bit of the lens elements, sharpness is lacking, both in the corners and at infinity. Conversely, up close (within 10m) sharpness is acceptable. This is the only real negative for me.
The colours are nice and vibrant straight out of the camera. The size and weight of the lens is more in keeping with Pentax m lenses rather than the bulky 35-70mm m zoom. I also like the more modern zoom function meaning it has a third ring. It is noticeably stiffer on my copy in comparison to the focus ring meaning you're unlikely to change focal length when focusing.
28mm on a apsc sensor (42mm equivalent) is just about my favourite walk around focal length. Wide enough for street photography and catching the whole scene, narrow enough to be able to pick out detail. This is the main reason I picked up this lens; I look forward to getting the best out of it.
Site Supporter

Registered: June, 2013
Location: Utrecht
Posts: 27
Lens Review Date: May 25, 2019 I can recommend this lens: Yes | Price: $40.00 | Rating: 8 

Pros: Well build, compact, nice to handle, sharp stopped down
Cons: Flare, corner sharpness wide open at 28mm
Sharpness: 8    Aberrations: 8    Bokeh: 7    Handling: 9    Value: 9    Camera Used: K1-II   

Another old zoom in my cabinet, still looks brand new with clear and nice coated glass in it. This lens always was (and is) very useful on my ME-super, this is a compact combo. I now compared this with the 40 years younger DFA 28-105 kit lens. Full open at 28 mm the center sharpness already is very good, towards the edges and corners it gets a bit blurry. This lens has strong field curvature, the focus in the corners is much further away than it is in the center. The DFA also has some curvature, but opposite to the M lens the corners just are sharper more nearby. At F8 the lens is sharp on the whole frame at all focus lengths and delivers perfect pictures. This lens is rather sensitive for flare, so always use a cap or cover strong backlight with your free hand. Full open the corners suffer a bit for blue/yellow CA and fringe a bit purple in harsh conditions. At F8 most of this is gone. The DFA anyway is the better one full open, more stopped down there is fewer between them.

Full open 28 mm:

F8 50mm:
Forum Member

Registered: April, 2014
Posts: 61
Lens Review Date: January 7, 2018 I can recommend this lens: Yes | Price: $80.00 | Rating: 8 

Pros: build quality, size, focus throw, image quality
Cons: slight vignetting.
Sharpness: 8    Aberrations: 9    Bokeh: 7    Handling: 9    Value: 10    Camera Used: sony a7r   

I use the sony a7r and have had great results with the m35-70 f2.8-3.5, m75-150 f4 and A70-210 f4.

The 24mm focal length for this camera is problematic, potentially reflecting sensor thickness and I have found the 24mm end of the m24-34 F3.5 and A 24-50 f4 to be disappointing.

To that end, I decided to take a punt on this lens to determine if it could be a useful travel compact zoom.

This is the first review of this lens on a FF 36MP camera.

The lens has excellent build quality and contrary to other reviews, I like having separate zoom and focus rings. Some reviewers talk of a "stack of primes" and with this double ring arrangement one feels as though one does have a stack of primes to hand, easily setting the zoom to one's preferred focal length. The photos included in the link below were taken at 28mm, 35mm and 50mm and at f8.

In concordance with the other m series lenses, it produces deep vibrant colours, excellent contrast and images with good clarity.

The lens is "plenty sharp" at f8 or below, at all focal lengths. Only at f3.5 do the edges suffer somewhat what the images are still pleasing to the eye..

The lens suffers slight vignetting which is easily corrected with lightroom.

There is no significant distortion, CA or defringing.

The camera / lens combination feels pleasantly balanced and is a comfortable one either to carry by hand, or around one's neck whilst sightseeing.

In conclusion, this lens offers a cheap solution for a travel compact zoom, that produces images of pleasing quality at all focal lengths and I recommend it to those using a FF sensor
Veteran Member

Registered: October, 2006
Location: Belgium
Posts: 471
Lens Review Date: August 7, 2017 I can recommend this lens: Yes | Price: $25.00 | Rating: 10 

Pros: Compactness, feel, performance
Cons: None worth mentioning
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 10    Value: 10    Camera Used: MX, K-5   

This is by far my most used lens on film (either MX or LX.)

What I like best about this lens is that it is basically a 28-45 f/3.5 + 50 f/4.5. That is, as long as you don't zoom all the way it is quite bright (extremely bright I might add given its' compactness.) Wide open it is more than usable, stopped down it is sharp. I haven't noticed any distortion of note. I am not a bokeh man, so I leave that to others. The 42-75 it becomes on an APS-c camera makes it a little desirable, but even then it is a pleasure to use.

This lens is very compact, just a little longer than a standard 50mm and very light, so it is always with me.

If you find one, just buy it! You won't regret it...

Sample photo @ 28mm (K5 RAW unaltered Lightroom.) Distortion? Where distortion?
New Member

Registered: February, 2013
Posts: 14

1 user found this helpful
Lens Review Date: April 2, 2014 I can recommend this lens: Yes | Price: $150.00 | Rating: 9 

Pros: Small, nice handling, good snap to color photos.
Cons: variable aperture
Sharpness: 8    Aberrations: 9    Bokeh: 7    Handling: 10    Value: 10    Camera Used: MX, ME Super   

This is my "standard" lens on my MX. Like almost all M lenses, this thing is built to excellent craftsmanship. The zoom barrel is smooth as is the focusing ring. I usually have one finger on the focus ring and other on the zoom ring and a third on the aperture ring. I don't remember how long it took me to embed that technique into my brain, but its like second nature to me now and operating this lens is smooth and fast. Its funny that what we considered to be standard quality then is now regarded to a Premium or Limited editions today.

As has been said before, its not the sharpest lens in my collection, but its not bad. Around 5.6 things start sharpening up considerably. Slight barrel distortion at 28mm but mostly gone by 35mm.

Previous to this lens, I owned the CPC Phase 2 28-50mm which is said to also be made by Pentax. (although I didn't know that at the time, kinda explains a lot about that lens.) That lens handled exactly the same and had similar image quality, but lacked the SMC coating of the Pentax.The main difference is the "snap" that the Pentax has over the CPC with my color images. Everything seemed to be slightly more contrasty, and more saturated than with the CPC. So SMC really does make a big difference.

The range covered is good on film and the lens looks great on the classic cameras.

Registered: January, 2013
Location: Kansas City, MO
Posts: 1,566

2 users found this helpful
Lens Review Date: December 25, 2013 I can recommend this lens: Yes | Price: $50.00 | Rating: 8 

Pros: Nice range, enjoyable to use, well-built, painfully sharp
Cons: Heavy, slow
Sharpness: 10    Aberrations: 10    Bokeh: 7    Handling: 9    Value: 8    Camera Used: K30, K-S2   

I wanted a manual lens with my most-used focal lengths and I found a copy for a reasonable price online. My copy is in beautiful condition, well-cared for and functions smoothly and perfectly.

I absolutely LOVE the handling of this lens. There are a couple of reviews below that find fault with the handling, but I disagree completely. The zoom and focus are intuitive and pleasant. However, I use manual lenses 99.99% of the time, so maybe I am just in a comfort zone.

The aperture ring is manual-only, obviously. It clicks happily and is easy and comfortable to use, in my personal opinion. It is pretty darn soft wide open, but one or two stops down is ridiculously, mind-blowingly sharp. I haven't noticed any remarkable CA at any setting. My first iteration of this review said the lens was OK. I was grossly wrong. After more experience, I can say that this might be the sharpest lens I own.

The zoom range is great on APS-C and film.

The focus is smooth, BUT I will gripe that I have found this lens to be rather difficult to focus. I can only assume the reason for this is the darkened viewfinder, since the lens is not fast. It performs best in bright daylight. When you land the focus, be sure you're wearing eye goggles to view the image, because it will slice your eyeballs right open. So sharp.

I do wish the lens had a hyperfocal distance scale, particularly since I seem to have such a hard time focusing through the viewfinder.

It's a bummer that the lens does not have a constant aperture, however, it does have constant focus. What you focus on at the 50mm end stays in focus at 28mm.

This lens is a HEAVY MUG and it is noticeable when I lug it around and when I clunk the body/lens assembly down on a surface. It is NOT too heavy when in use and I don't notice the weight at all when I am using the lens.

The closest focusing distance is around 2 feet, which sounds fine in theory, but in practice, you'll wish you could get closer. ;-)

Since the lens is totally manual, it doesn't communicate its focal length to the camera and you have to take care with the Pentax in-body shake reduction to maximize image clarity. This can be a chore with a manual zoom like this.

Overall, I like it, but the hit-and-miss game I play with focusing, and the relatively "slow" speed turn me off a little
Veteran Member

Registered: November, 2011
Location: ON, RH
Posts: 2,170
Lens Review Date: November 19, 2013 I can recommend this lens: Yes | Price: $10.00 | Rating: 9 

Pros: Cheap, well built, great portrait lens
Cons: not the sharpest in the world, might be awkward to handle
Sharpness: 7    Aberrations: 8    Bokeh: 7    Handling: 8    Value: 10    Camera Used: ME Super, K-5, K-01   

I got these lens for $10 from Henry's store in Canada. Great little thing and works very well on any of my film K mount cameras and gives great results on my k-01.

Not the sharpest lens in the world but I like the softness if gives especially when doing portraits.
For the price I got it for, is a good lens to have. I haven't found any issues with the image quality from my point of view.

The zoom / focus rings combination might be a little awkward to work with for some, but personally I find it OK... quite entertaining. Everythings works smooth. Not bad for an old lens .
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 6,351
Lens Review Date: November 30, 2012 I can recommend this lens: Yes | Price: $130.00 | Rating: 7 

Pros: Small size and focal range on film.
Cons: Variable aperture and two touch design make it cumbersome to use. Too slow at the 50mm end.
Camera Used: K Series film bodies (K1000, KM, KX, K2, K2DMD)   

I also have the original K Series version of this lens and have done a review. Since the K & M28-50/3.5-4.5 are the same lens you can read my K28-50 expanded review for more details.

Summary of what I like and donít like about this lens.

Focal range on film

Two touch zoom
Focal range on APS-C

Variable aperture
No DOF scale

Note the higher price I paid for this lens was due to the lens being mint and having the lens case, lens hood & lens hood case included.

Sample shots taken with the M28-50/3.5-4.5. Photos are low resolution scans from original negatives.

Camera: KM Film: Expired Ilford HP5+ ISO: 400

Camera: KM Film: Expired Ilford HP5+ ISO: 400

New Member

Registered: March, 2012
Location: Sydney, Australia
Posts: 5
Lens Review Date: March 29, 2012 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Colours, sharpness, handling
Cons: a little sensitive to exposure metering
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 9    Value: 10    Camera Used: ME-Super, SF7, K100D, K5   

I am really surprised at some of the other reviews of this lens. I have had my copy since 1983 and although it fell into a little disuse for about 10 years in the early 2000's I have used it both on film and more recently with digital.

I recently started using this on my new K5 and am able to compare this with my F series 28-50 zoom and my sigma 18-50 DC zoom (both Auto-focus).

The real difference with this lens is the colours and the 3D nature of the photos it produces which are far and away better than my other two lenses. Once you get the hang of using a manual lens on the K5 it is quite easy to get great sharp results. I have however noticed that in tricky lighting situations, (e.g. long shadows in late afternoon with a descending sun) it is a little sensitive to exposure when spot metering. See my photos below taken in exactly that type of situation.

The handling is typical of an M series lens (although my copy needs a service as it is a little loose at the 50mm end of the zoom).

At the current prices this is a real bargain hence my high rating. See my sample shots below as examples of what I am saying.

Site Supporter

Registered: August, 2009
Posts: 387
Lens Review Date: February 9, 2012 I can recommend this lens: Yes | Price: $20.00 | Rating: 6 

Pros: appearance
Cons: handling, aperture
Handling: 3    Value: 8    Camera Used: ME Super   

Handling is awful. The throw is too short, and the aperture is simply too slow through the viewfinder. Pentax M series lenses look great, as did this, but after a quick handling of it, I popped it back up for sale. I already have the range covered with primes, and would suggest that for the short focal lengths, this is the way to do it. Particularly when the primes are such great value
New Member

Registered: August, 2007
Location: Madrid
Posts: 1
Lens Review Date: August 12, 2011 I can recommend this lens: Yes | Price: N/A | Rating: 10 

Pros: sharpness at 5,6 - 8 among the best
Cons: variable aperture ?
Sharpness: 10    Aberrations: 8    Bokeh: 9    Handling: 8    Value: 10   

I own this lens since 80 or 81. I used it with the KX, ME Super and SFX in the analogic era, and now with the K10D. I don't remember how much I paied for it - it was pre-owned - but in any case a pittance - and always worked very well. Last year I decided to repair because some free movements of the rings and the lens is again su. Go for it it if you have the ocation thru the e-bay.

Pentax K 10 D; M 28-50 at 40mm, ISO 200; f 8,0; 1/160 seg

Pentax K 10 D; M 28-50 at 50 mm, ISO:100; f 5,6; 1/250 seg

Pentax K 10 D; M 28-50 at 40 mm, ISO:100; f 8,0; 1/200 seg
Senior Member

Registered: December, 2006
Location: Lincoln, UK
Posts: 229
Lens Review Date: June 5, 2011 I can recommend this lens: No | Price: $75.00 | Rating: 6 

Pros: Can be quite cheap
Cons: Variable aperture. Zoom Range

Of the 3 wide angle M zooms, this is the one I would avoid.

It doesn't have the constant aperture of the 24-35 or the 24-50 and loses nearly a full stop through it's short zoom range. Not too much of a problem on a ME Super on Auto but slows things down when metering manually.

The 24-50 has a wider zoom range and is constany aperture. The 24-35 also has the constant aperture and is more useful at the wider end of the scale.

Forum Member

Registered: March, 2010
Location: Norfolk
Posts: 83

1 user found this helpful
Lens Review Date: March 15, 2010 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: compact, good build quality
Cons: none

This has been a good friend for 25+ years, doing duty on an MX, ME-F, Rocoh XR7 and now an MZ-M. An excellent walkabout and travel lens thanks to its small size - not much bigger than a standard 50 - and reassuring build quality. As a wide-end zoom it's fast enough at f3.5~4.5 in most situations.

I use it mainly for colour slide work and it has always produced crisp, contrasty results thoughout its range. If it was a PKA fit it would probably be a permanent fixture on my *istDS.

Not a lens I would willingly part with.

Registered: April, 2009
Location: South Central Nebraska - USA
Posts: 1,511

1 user found this helpful
Lens Review Date: January 22, 2010 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: Nice little lens for a walk around lens in daylight
Cons: Rather slow

This is the lens that I had on my ME Super most of the time. I used it for landscape photography and liked it a lot. It had reasonably good sharpness and contrast and was a very versatile lens. I liked it on my ME Super and my MX and it would be comparable on those cameras as the 18-55 kit lens is on the Pentax digital cameras.
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