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SMC Pentax-M 24-50mm F4

Reviews Views Date of last review
5 33,022 Mon August 22, 2016
Recommended By Average Price Average User Rating
60% of reviewers $106.67 7.50
SMC Pentax-M 24-50mm F4

SMC Pentax-M 24-50mm F4
SMC Pentax-M 24-50mm F4

The M 24-50mm is a fixed-aperture, manual focus zoom lens with 2 separate rings for zooming and focusing. On an APS-C camera the range is a versatile moderate wide angle to short tele.

SMC Pentax-M 24-50mm F4
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 6 blades
12 elements, 10 groups
Mount Variant
Max. Aperture
Min. Aperture
Min. Focus
40 cm
Max. Magnification
Filter Size
58 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 62-32 ° / 53-27 °
Full frame: 84-47 ° / 74-40 °
RH-B clip-on
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Diam x Length
64 x 67 mm
380 g
Production Years
1980 to 1984
Engraved Name
smc PENTAX-M ZOOM 1:4 24-50mm
Product Code
User reviews
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

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New Member

Registered: August, 2016
Location: Pittsburgh
Posts: 5
Lens Review Date: August 22, 2016 I can recommend this lens: No | Price: $130.00 | Rating: 5 

Pros: Small and lightweight, good built and handling
Cons: Very soft when wide open -almost unusable at f/5.6 and f/4
Sharpness: 3    Aberrations: 8    Bokeh: 8    Handling: 10    Value: 6    Camera Used: MX, LX (both film)   

I have read the excellent reviews of this lens posted by other users, but my experience is very different. My example of this lens is so soft that it is almost useless when wide open or at f/5.6, independently on the focal distance. I've had it for a while now and never shot more than a dozen rolls of film with it. However, when stopped down at f/8 or f/11, it performs extremely well an all focal lengths... But then, almost any lens does well at f/8 or f/11. In general, I only use it in very bright/sunny days.
New Member

Registered: August, 2009
Location: Quebec
Posts: 6
Lens Review Date: April 11, 2014 I can recommend this lens: No | Price: N/A | Rating: N/A 

Cons: Flare
Camera Used: Pentax LX   

This lens has a pronounced flare problem. I noted a strange color balance with this lens sometimes. So I did a test. On a sunny day in winter, I took a photo of the white snow, excluding everything else around but snow. I did a shot at f8 with a SMC-Takumar 28mm f3.5 and another one with the M24-50. On the first one the snow was white, on the second one it was green. Why? I had green firs all around me. The 24-50 picked up the reflection of the firs. This is one way flare can affect a lens. To give such an effect the lens must have a design flaw (baffles, optical design). It has been corrected in the A version of the lens, a rather good zoom.

I'd llike to know if anyone having the lens could reproduce this kind of experiment, as my slides from the test are not around and I don't have the lens anymore.
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 5,522
Lens Review Date: April 30, 2012 I can recommend this lens: Yes | Price: $90.00 | Rating: 8 

Pros: Focal range on film, constant aperture.
Cons: A bit slow & bulky, two touch zoom design.
Camera Used: K Series film bodies (K1000, KM, KX, K2, K2DMD)   

The M24-50/4 was released in late 1980 and was replaced in 1983 with the optically different A series version. The M version has one more lens element (12 vs 11) than the A and F version.

Pretty good optics but I found the M24-50 to have more distortion that the M24-35. Just donít take straight on shots of brick walls with this lens!

Focal length:
A great zoom range on film, which covers the wide to standard focal lengths. This lens, along with the M24-35, are great street lenses on film.

The M24-50 is basically a beefed up bigger version of the M24-35, with similar looks and build. The M24-50 has a dedicated set-screw type lens hood with a 58mm filter thread, that Iíve never come across. Instead I use the push-on RH-B 60mm or the screw-on RH-RC 58mm rubber hoods for the A or F series 24-50/4. The zoom is a two touch design which I donít like as much as the one touch push/pull. The M24-50 also does not have a DOF scale which is missed on a wide angle lens.

F4 is on the slow side for the standard FL range and ok for the wide range. This is also a constant aperture zoom, which I like much better than the variable ones.

The focal range on film is the best thing about the M24-50. However the lens is too bulky to use when I travel and the optics/speed are not good enough to replace a standard prime in the 40-55mm range. Iíd rather take my M24-35 & FA43 lens in place. Iíll use the M24-50 mostly around town, when the size/speed/optics are less of an issue.

Sample shots taken with the M24-50/4. Photos are low resolution scans from original slides or negatives

Camera: K2 Film: Adox Silvermax 100 processed in DR5 Chrome ISO: 160

Camera: MX Film: Ilford SFX ISO: 200

Forum Member

Registered: March, 2010
Location: Norfolk
Posts: 83
Lens Review Date: July 4, 2011 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: Rugged build, nice handling, sharp, good colour
Cons: Too large for its zoom range

MY 24~35 was fine for film but didn't make much sense on a 1.5 crop dSLR, so when I recently saw a 24~50 I swopped. The extra reach (effectively 36~75) makes it far more useful as a walkabout lens and the constant aperture takes some of the hassle out of the manual stop-down metering.

My copy (on a K-r) provides crisp images at the wide end even wide open but needs to be stopped down to f8 at the long end. IQ not quite up to the 28~50 in my opinion and it's a little too chunky to qualify as a travel lens. Mixed feelings about this one.
Senior Member

Registered: December, 2006
Location: Lincoln, UK
Posts: 229
Lens Review Date: June 5, 2011 I can recommend this lens: Yes | Price: $100.00 | Rating: 9 

Pros: Constant Aperture. Performance Zoom Range
Cons: Lack of A setting

This used to be one of my favourite lenses on the LX if I needed wide and didn't have the luxury of using primes.

One of the better and early M lenses which featured a constant aperture. I try to use incident light meter readings and so I didn't have to worry abiut losing a stop in speed as I went from one end to the other.

If you need an extra 1/2 stop or size is important the the 24-35 might be an alternative.

If you are looking for such a lens for the DSLRs, the A version would be better as it has the auto setting but little difference otherwise.

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