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SMC Pentax 50mm F4 Macro

Reviews Views Date of last review
12 59,909 Tue December 3, 2019
Recommended By Average Price Average User Rating
100% of reviewers $167.56 9.50
SMC Pentax 50mm F4 Macro

SMC Pentax 50mm F4 Macro
SMC Pentax 50mm F4 Macro

The SMC Pentax 50mm F4 macro lens was succeeded by an M version, and later by faster A, F, FA, and D-FA versions.

SMC Pentax 50mm F4 Macro
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 5 blades
4 elements, 3 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
23 cm
Max. Magnification
Filter Size
52 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 32 ° / 27 °
Full frame: 47 ° / 40 °
Not needed
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Diam x Length
63 x 54 mm
241 g
Production Years
1975 to 1977
Engraved Name
smc PENTAX MACRO 1:4/50
Product Code
User reviews
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:

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Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-12 of 12

Registered: March, 2008
Location: North Carolina
Posts: 973
Lens Review Date: December 3, 2019 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Sharp across frame, well made, nice focus, size
Cons: None...It's a manual lens
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 9    Value: 9    Camera Used: K5IIs   

I am a big fan of this lens and the K series lenses in general. Great K series construction. Glass is set deep in lens, so doesn't really require a hood. Works well as a walk around lens in addition to macro. I use it wide open at f4 most of the time, so no green button metering required, and great bokeh at f4. Kinda hard to find the K series one, but they show up from time to time. See my flickr album for a picture of my lens and some samples images. If you like well made, manual focus, sharp lenses, you will not be disappointed with this one!
Site Supporter

Registered: February, 2017
Posts: 592
Lens Review Date: December 31, 2018 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: focal length on APSc, Overall general performance, K colours
Cons: rarity
Sharpness: 10    Aberrations: 9    Bokeh: 8    Handling: 8    Value: 8    Camera Used: K3   

Came across this lens looking for something else. It is a rare item and usually goes for the £100 I paid including postage from Japan to UK. This is the reason I got my copy - the knock down price - I did not need it as I already own the A 50 f2.8 macro which is one of my desert island lenses. So now I have the K 50mm I am truly spoilt for choice.
The older K model is even better constructed than the newer A one. Beautifully smooth focusing and aperture control, though one loses the convenience of the A setting of course. Although relatively big for a 50mm, it is light due to the small front element and low element count. Sharp enough wide open for general walk about use and once stopped down to 5.6 and smaller, up there with modern lenses. As for colours - beautiful as I have come to expect from the K range, again comparable with my HD Ltd's. Typical for an old macro lens the front element is deeply recessed so no need for protective hood or UV filter, though if I wanted to use a polarizing filter I would choose a different lens and add a hood.
I have scored it at a 9 for the following reasons:-
1. It usually goes for a lot more than I paid so value would normally be an 8
2. One may not be entirely comfortable using it in manual mode compared to the enhanced compatibility of the A series and later lenses ( I am OK with this, though)
If you stumble across one you should buy it, if at a reasonable cost. It is a stunning piece of photographic history, which still delivers in the modern digital age
Site Supporter

Registered: April, 2015
Location: Winterthur
Posts: 854

1 user found this helpful
Lens Review Date: January 23, 2017 I can recommend this lens: Yes | Price: $248.00 | Rating: 10 

Pros: supersharp wide open, great to focus
Cons: no A-Setting but one knows about this
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10    Camera Used: K5IIs, K3, K-01   

I was able to buy an almost new copy of this fantastic lens. built quality is up to the best limiteds.
Allthough just a 1:2 macro, this isn't really a problem, just add a Canon D240 close-up 52mm lens which is not hard to find at all and you have at least 1:1 if not even slightly larger.

But just as a 50mm walk-around (if one is fine using the green button) this is a fantastic lens.
Surprisingly nice bokeh for a 5-blade design, but can become busy when stopped-down.

Just F4? Not good enough? I don't think so because the special design of this lens is as somebody mentioned already designed for flatness of field (Tessar Design) . So this lens is wide-open super sharp right into the corners. Amazing. So not for low-light where I use the A50/1,4 or the F50/1.7 if Autofocus is needed or my 8-Element Takumar 50/1,4.

I had the chance to compare it to the A50/2,8 macro which is also a great lens as well as to the F50/2,8Macro and the M50/4 Macro.

The M50/4 Macro is a similar Zeiss Tessar design but shorter (42,5mm) and with a 49mm filter. The K50/4 Macro is 54mm long and takes 52mm filters (and thus works great with the mentioned Canon D240 close-up lens). The focusing is longer, smoother and much more precise, it is easy to focus infinity, which can be a problem with the M50/4 Macro. The K50/4 Macro has more contrast wide open. The A50/2,8 Macro is as good as the F50/2,8 macro (similar design but AF), but both are different, not sharp wide open to the corners, so for different use.

The focusing of this lens is that smooth (well, it is almost new) which I have not even found on limited lenses.

This lens deserves a healthy 10. One of my best lenses for sure.
New Member

Registered: April, 2010
Location: Gulf Coast
Posts: 22

2 users found this helpful
Lens Review Date: May 18, 2013 I can recommend this lens: Yes | Price: $75.00 | Rating: 10 

Pros: Super Sharp....Classic Glass!
Cons: None
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 9    Value: 10    Camera Used: Pentax K-x and K-30   

I acquired this lens in a lot of camera equipment that I purchased on eBay. All I can say is WOW! Focus is smooth and easy and build quality is excellent. I must have a very good copy, because It seems like I get "the shot" on the first try nearly every time with this gem. I do a lot of macro shooting, I've owned and used SMC Pentax-FA 50mm F2.8 Macro and the Sigma 105mm F2.8 EX DG Macro. As far as IQ....the SMC Pentax 50mm F4 Macro is certainly on par, if not better! I can say, without hesitation, this is definitely one of the best Macro lenses I have ever used. Other than full crop, the pics below have no post-processing.

New Member

Registered: January, 2013
Posts: 1

1 user found this helpful
Lens Review Date: January 25, 2013 I can recommend this lens: Yes | Price: $130.00 | Rating: 10 

Pros: IQ and built quality
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10   

Very sharp lens. The build quality gives a lot of pleasure.
New Member

Registered: March, 2012
Posts: 3
Lens Review Date: April 2, 2012 I can recommend this lens: Yes | Price: $225.00 | Rating: 10 

Pros: Sharp as a razor, Amazing contrast, Performance will embarrass most newer lenses.
Cons: None
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10    Camera Used: K1000, ME Super   

Outstanding lens performance. Can be used as a walk around lens or do serious macro work, it is a great all around normal lens. Sharp and Contrasty when shot wide open and delivers a pleasing bokeh. This lens has a rugged metal build that just makes you feel good about its durability, this lens will last a lifetime if you get a good copy.

The only drawback is that they are so rare, If you see one go up for sale, just buy won't be sorry.
Veteran Member

Registered: November, 2009
Location: Strand
Posts: 1,366
Lens Review Date: March 3, 2011 I can recommend this lens: Yes | Price: $200.00 | Rating: 10 

Pros: Size, build, sharpness. Walking-in-the-wood-lens

Always with me when I heading out for a walk. Very light, very good sharpness, very good color, perfect focal for touring, but no action, less bokeh. It is good when I have time to enjoy the moments with family, teaching kids to see in macro world. Only one lens needed.

For real macro, I use M28 with reverse ring.

Highly recommended.
Lens Review Date: January 30, 2011 I can recommend this lens: Yes | Price: $200.00 | Rating: 10 

Pros: Very very sharp, metal construction and...beautyful !
Cons: Not a real macro lens (x2 only)

As all the "M", this lens has a exemplary construction, all in metal. The focusing ring is well dumped and the aperture ring well notched.
The image quality is exceptional wide open, so well as on my DA70mm Limited. Its magnification factor of 2X forbids him the literally "macro" without bellows or extension rings. But it is grand for the small objects, or for reproduction of documents and slides on a reproduction stand.
In all these applications (macro included), the AF is no usefull. So, this lens has really no one defect, in my opinion...
You can see on this photo a figurine 20 cms height of pottery (a "Santon" of Provence), shot wide open for the best bokeh.

(Hight resolution here : h ttp://

New Member

Registered: November, 2010
Location: Oegstgeest
Posts: 4
Lens Review Date: December 5, 2010 I can recommend this lens: Yes | Price: $80.00 | Rating: 10 

Pros: High IQ, reliable, very goud built quality
Cons: manual focussing

I bought this lens at the same time as my new Pentax K-r. That is about for 5 weeks. I am very happy and made some nice macro's and pictures, all handheld. I tried to post some examples, but I did'nt succeed.
Site Supporter

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

2 users found this helpful
Lens Review Date: July 2, 2009 I can recommend this lens: Yes | Price: $200.00 | Rating: 9 

Pros: Size, build and sharpness.
Cons: Maximum aperture of f4, only 0.5x magnification.
Camera Used: K Series film bodies (K1000, KM, KX, K2, K2DMD)   

The K50/F4 Macro is one of my favorite lenses. It’s very small and easy to carry around, so it’s perfect for traveling when you want to pack light. It’s also very sharp and easy to hand hold, even at slow shutter speeds. The K50/4 macro is similar in size to the other K series primes. This lens has its front element so far retracted that a lens hood is not required.

The K50/4 is designed for “flatness of field” (no distortion), so it’s sharp from corner to corner. This is also the reason why it has a maximum aperture of f4.0, a larger aperture would have resulted in edge distortion. The K50/4 is hands down the sharpest K Series lens.

The K50/4 has .5x magnification and by adding a #3 Auto Extension Tube, it will give you 1.0x magnification. You can also reverse the lens and when used with a Bellows Unit, get almost 3.5x magnification. The only draw back is that you have to get really close to your subject, so a 100mm macro is a better bet if you are trying to shoot insects.

As with all Pentax K series lenses, the K50/4 Macro is well built and will last generations. I originally owned the M50/4 Macro and sold it when I finally found the rarer K50/4. Both versions have the same optical formula, but I found the “K” version a lot easier to focus due to its larger size and focusing ring. The “K” version also has a 52mm filter thread compared to 49mm for the “M”. The M50/4 was a bit too small for my taste and I much prefer the “K” version.

Overall I rate the K50/4 Macro a 9.5.

Sample shots taken with the K50/4 Macro & the Auto Extension Tube #3. Photos are medium resolution scans from original slides.

Camera: KX Film: Kodak Ektachrome E100VS ISO: 100

Camera: KX Film: Kodak Ektachrome E100VS ISO: 100

Veteran Member

Registered: June, 2007
Location: British Columbia, Canada
Posts: 753
Lens Review Date: March 19, 2008 I can recommend this lens: Yes | Price: $150.00 | Rating: 8 

Pros: Competent little macro lens f4 - f32

This is the type of lens that you can quickly develop a soft spot for. It always seems to deliver results that exceed my expectations. I have used this lens on bellows and extension tube with good results. It is reasonable sharp wide open at f4, and performs well closed down at f32. It is a good working lens that always gets the job done. Being small it is great to take on hikes to capture flowers, textures, and insects, etc. It works well with close up lenses. It is built solid.
Senior Member

Registered: January, 2008
Location: Bondi, Australia
Posts: 206

2 users found this helpful
Lens Review Date: January 29, 2008 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Superb resolution up to f/16, compact
Cons: only goes to 1:2, f/22 starts dying badly , f/32 worse than wide open

Many years ago I tested this lens with Paterson lens testing cards along with a huge swag of other lenses on tech pan film, reviewed with a microscope. Performance wide open was actually very good - the best of all of my Pentax lenses. At f/5.6 it was already excellent. In the f/8 to f/13.5 it hit over 80 lines per millimeter up to a dizzying 88 lpmm- excellent in anyone's language. F/22 started to suffer badly from diffraction. F/ 32 performance awful. Bit of a pain for a macro, where DOF is critical. Sold this lens when I picked up an f/2.8 macro. Great little macro for general purpose, should be able to pick one up cheaply.
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