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SMC Pentax-M* 300mm F4

Reviews Views Date of last review
10 92,910 Thu November 15, 2018
Recommended By Average Price Average User Rating
100% of reviewers $460.37 9.70
SMC Pentax-M* 300mm F4

SMC Pentax-M* 300mm F4
SMC Pentax-M* 300mm F4

This compact 300mm lens is the only member of the M* series.

SMC Pentax-M* 300mm F4
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 8 blades
8 elements, 7 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
400 cm
Max. Magnification
Filter Size
77 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 5.5 ° / 4.6 °
Full frame: 8.2 ° / 6.9 °
Built-in, slide out
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Diam x Length
84 x 132 mm
825 g
Production Years
1981 to 1984
Engraved Name
smc PENTAX-M* 1:4 300mm
Product Code
User reviews
A separate, dedicated screw-in hood was available for use in connection with a 77mm circular polarizing filter since the filter would prevent the built-in hood from being pulled out
Manual FocusBuilt-in HoodAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-M* 300mm F4
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-10 of 10
New Member

Registered: February, 2016
Location: lake constance
Posts: 1
Lens Review Date: November 15, 2018 I can recommend this lens: Yes | Price: $300.00 | Rating: 10 

Pros: high technical quality, convinient, extreme sharpness
Cons: any, any, any
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 10    Camera Used: Pentax MX, Sony A7   

I had to wait for a long time to get this lens to an affordable price. It is not easy to get this lens at all - this is especially in finding a M version in good condition.
At last it can be over 35 years old. But I have experiences in collecting older M lenses, like the M 4/20mm or the M 1.7/50mm, so that I took the risk in buying it online. I didnīt get disapointed in any way. The body of this lens has some scratches, even on the scale, but the figures and marks are engraved and well painted, so that all looks clearly nevertheless. Mechanics are on a level, like on new lens.

The image quality is unbelievable. Instead of this lens, I former bought a Nikkor AF 4/300mm IF-ED lens, wich is 500g heavier than the Pentax. And it is longer, not so handy. The image quality is on top, so that I had great expectations to the Pentax. I thought, that because of the age of the Pentax, there is a lack of sharpness and contrast and the Nikkor had best recommendations on press. Until I saw the first images of The Pentax M 4/300mm green star. I took many pictures in comparison with the Nikkor. There isn`t a different to see, perhaps the Pentax has very light better color transmission. The Nikkor has a less saturation, is a bit cooler. The bokeh is similar to the Nikkor, perhaps not so quiet at all. But in the most cases it is not important, only visible in the direct comparison.
Sharpness is as good as the Nikkor. You have to consider, that the Nikkor is introduced to the market six to seven years later than the Pentax. The 4/300mm green star includes 3!!! lenses of ED - the Nikkor AF4/300mm IF ED includes only 2 of them. You can see the great efford of Asahi Pentax engeneers, to make the best and that in the beginning of the 80's! Chapeau!

Because as a family father I can`t keep both lenses, the Nikkor and the Pentax, I didnīt think for a long while. My expectations in relation of the Pentax where highly topped. So I sold the Nikkor. My Pentax lens collection is almost perfect - I love it more now, than any time before. Look at the picture of an Airbus A380 in a hight of 6-8 kilometers. It is made handheld with f8.The image is pure.

Forum Member

Registered: February, 2016
Location: Moab, Utah
Posts: 90

3 users found this helpful
Lens Review Date: January 31, 2017 I can recommend this lens: Yes | Price: $780.00 | Rating: 10 

Pros: Size, Bokeh, Coloring, Contrast
Cons: pricey
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 10    Camera Used: Sony A7ii   

A very unique lens. Perfect for use with the Rear Converter-A 1.4X-S for an extremely compact 420mm focal length. With my adapter to Sony this lens weighs 1000 grams or 34 ounces. With my teleconverter and adapter, it is just over 7" in my bag... and.... Incredible. Results with this combination blow away the SMC 400mm f5.6, especially with regard to aberrations and color fringing, not to mention being half the size. Aberrations not perfect, but I don't shoot into the sun often and I use the optional lens hood. This is THE compact long telephoto solution for premium image quality. M* for a reason. The images are phenomenal. Color density and microcontrast to the extreme. This lens has "pop" that none of the other 300's I tried have. I won't even mention how sharp it is but I often crop way in and the images are still clean. The only thing that compares is the autofocus Nikon 300 f4 ($2,000) and 1.4 TC-14E (over $500.) This costs half that and offers superior image rendering, but lacks autofocus. Possibly my favorite lens. Using this little lens with the rear converter and a high megapixel sensor blew my mind. It's nice. It's not quite the quality I got from Nikon 300 2.8 with tc-14, but it's darn close. And not even a quarter of the size/weight.

There is a separate metal 77mm lens hood available for use when using a polarizer. When using it, the built in lens hood goes unused. I would prefer if the separate lens hood used the built in lens hood and was an extension rather than a replacement to the built-in lens hood. It's hard to think of anything negative about this lens other than that. When using the rear converter in backlit conditions, aperture shaped bokeh appears. When using without or not in flaring conditions, bokeh is GORGEOUS and unique - preferable to the A* 300mm f2.8 IF in my opinion because of its characteristic swirlish effect toward corners.

This is a masterpiece from Pentax. Here are image samples on Sony a7ii using Pentax Rear Converter A 1.4-S, wide open, handheld in low and extremely backlit lighting conditions with 100% details.


When I die they will have to pry this lens from my cold dead hands.

More example images and talking about it in my video review.
Site Supporter

Registered: April, 2015
Location: Wisconsin, USA
Posts: 1,904

2 users found this helpful
Lens Review Date: June 5, 2016 I can recommend this lens: Yes | Price: $555.00 | Rating: 9 

Pros: Sharp, Sharp, Pentax colors, light weight
Cons: built in hood too short
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 8    Camera Used: K1   

I spent the day testing this old manual lens on my new Pentax K1 camera body.

Works great on the K1. Super sharp images.

The best aperture setting is F/13 (aka the half stop between 11 and 16).

Just thought you'd like to know that this old MF lens works just great on the full frame K1. If you don't mind MF and using the "green button" you might want to consider this lens for your telephoto needs.
Loyal Site Supporter

Registered: September, 2009
Location: Phoenix, AZ
Posts: 5,008

2 users found this helpful
Lens Review Date: November 8, 2014 I can recommend this lens: Yes | Price: $350.00 | Rating: 10 

Pros: Sharp, small, wonderful in the hand
Cons: Needs careful use to focus and avoid fringing
Sharpness: 10    Aberrations: 8    Bokeh: 9    Handling: 9    Value: 10   

I no longer own this lovely old lens but I hope to get another one some day. Once I learned how to use it properly it became one of my favorite lenses. It needs to be stopped down to avoid CA and manual focusing skill. All of this is fine since it just encourages the photographer to improve his or her skills. I have attached an example taken with the K3, focused with live view peaking - about 50 yards away.

Registered: September, 2006
Location: Millstone,NJ
Posts: 6,491

1 user found this helpful
Lens Review Date: May 1, 2013 I can recommend this lens: Yes | Price: $258.74 | Rating: 10 

Pros: Great low cost telephoto for full frame Sony NEX-VG900
Cons: none
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10    Camera Used: Sony NEX-VG900   

SMC Pentax-M* 300mm F4 on full frame Sony NEX-VG900

I use it mostly for video but here is a full frame 6000x4000 test shot :
click here

SMC Pentax-M* 300mm F4 on Sony NEX-3N
New Member

Registered: October, 2008
Location: Paris
Posts: 1
Lens Review Date: November 11, 2012 I can recommend this lens: Yes | Price: $500.00 | Rating: 10 

Pros: very light, very sharp, few abberation, very well built
Cons: None
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10    Camera Used: K10D   

No other Pentax 300mm lens is so light (825g). I have other telephotos lenses (even 6x7 400mm f:4) but the handling of this lens is very pleasant . Even with a 2X converter with natural loss of light (or loss of speed) it is very easy to shot without monopode. You have equivalent of a 600mm f:8 for less than 1kg. As there are very few defaults on the 300mm , quality is still very good with a converter

It is very well built (*star serie) and sharpness even at f:4 is excellent with very few CA

Bokeh is very good at f:4. Anyway a 300mm f:2,8 cannot be so handy

rather hard to find but it worth it if you find it
Inactive Account

Registered: April, 2009
Location: Massachusetts, USA
Posts: 48
Lens Review Date: February 8, 2012 I can recommend this lens: Yes | Price: $380.00 | Rating: 10 

Pros: short, sharp
Cons: mine has a little slop
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 9    Value: 10   

nice short lens. good build ( mine has a little slop but, didn't seem to affect sharpness UPDATE ! looking closer at the slop it is not in the lens but at the connection mount of my K5 ) . overall a very good lens. This was taken with it , hand held with K5. VERY SHARP ! CLICK ON THUMBNAIL IMAGE TO ENLARGE....these are all winter shots, not much in the way of greenery or colors.
Veteran Member

Registered: April, 2010
Location: Adelaide, South Australia
Posts: 795

4 users found this helpful
Lens Review Date: December 17, 2010 I can recommend this lens: Yes | Price: $540.00 | Rating: 10 

Pros: Compact, great image quality, easy to focus
Cons: some CA wide open, but gone by F5.6, large MFD, short lens hood
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 10   

For me, it is very compact, and image quality is outstanding, much much better than any consumer zoom tele lens.
Best for stationary objects, because its focus is slow-but-sure, great for an older person like me with slow eyes!

Compression of DOF, with outstanding bokeh really makes for great images.
Sharpness is superb, good enough to use with a 1.5x TC.
Contrast and colour rendition is typical for the Pentax "M" series of lenses, and build quality is very good (all metal body).

In very bright conditions, when pointing near the sun, it could do with a longer lens hood (you can buy a rubber one on ebay for under $5).
CA or PF is visible at wide apertures in high contrast scenes, but is virtually gone above F5.6, and easily fixed in imaging software.

A very good lens to use now, it shouldn't lose its value with time.
Highly recommended. I give it a 10 for sharpness!

Cheers from Jack.

Here's some sample shots:
Pentax K-r 1/640 ISO 100 F5.6

Pentax K-r ISO 200 F8.0 1/500s

Pentax K-r ISO 200 F4.0 1/640s - 100% crop

Pentax K-r ISO 200 F5.6 1/500s

K-r ISO 200 F8 1/200

La lune by Jackassp, on Flickr

Veteran Member

Registered: June, 2010
Posts: 737

1 user found this helpful
Lens Review Date: December 13, 2010 I can recommend this lens: Yes | Price: $540.00 | Rating: 9 

Pros: sharpness, compact body
Cons: purple fringing
Sharpness: 10    Aberrations: 7    Bokeh: 10    Handling: 9    Value: 10   

This is my first pentax star lens, purchased only two months ago, so please take my observation with reservation. Great thing about lens is that it is quite compact, great to carry around and even to shoot handheld - but for this you really need a lot of bright light. Centre sharpness seems to be very good already wide open, stopping down boosts the performance a bit. It isn't stellar, but telephotos of this lenght don't tend to be supersharp anyway. Metering with k20d seems to work fine without any drastic compensation - i usually used multiple exposure with plus/minus 0.7 EV compensation. My opinion is that lens is better working on shorter distances with rendering fine details. The best photos i got from it were focused on close distance with shortening the background perspective dramatically. Also for f4 lens it has quite shallow depth of field wide open and bokeh seems to be ok.
Main weakness of the lens seems to be quite heavy purple fringing. Another thing is that it lacks tipod mounting collar, which would be really helpful for better stability. Focusing throw is quite long so taking photos of moving objects is really a challenge.
For taking landscapes photos it requires a vast distances, but photos are quite striking. Overall i think it is very good performer for such an old lens - especially considering the price.

Inactive Account

Registered: November, 2006
Location: San Diego, California
Posts: 441
Lens Review Date: February 10, 2007 I can recommend this lens: Yes | Price: $400.00 | Rating: 9 

Pros: Very sharp, very compact size and well-built
Cons: Slow focus, no tripod collar, and hood too short

This was the first Pentax "*" lens. It is very compact for this focal length and very easy to handhold. It has some weight to it and all of the weight is in the front. On a tripod (which gives the best results in this focal length) the camera and lens combination is front-heavy. The focus ring is smooth but requires about 270 degrees from infinity to close focus (about 4 meters or 13 feet). There is a built-in lens hood but it is quite short and only extends about an inch past the front element. The lens has all metal construction and is beautifully made. The focus ring turns past infinity to allow for focus variations due to temperature differences.

In use, this lens gives great images. Wide open it is quite usable and the f4 aperture give decent blurring of the background. It is incredibly sharp stopped down to f5.6 or greater. The image quality is much better than any consumer-level zoom in this focal length and the sharpness and great contrast is readily visible in any comparison.

The shortcomings include the slow focusing, lack of a tripod collar, and the short built-in lens hood. Of course, the functionality on new camera bodies is limited by the lack of the "A" electrical contacts. The newer F* and FA* 300mm f4.5 lenses correct some of these issues.

The purchase price listed was for a used lens in mint condition about 15 years ago, and may not reflect the current market price.
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