Forgot Password
Pentax Camera Forums Home

Pentax Lens Review Database » Film Era Pentax K-Mount Lenses » K Prime Lenses
SMC Pentax 300mm F4 Review RSS Feed

SMC Pentax 300mm F4

Reviews Views Date of last review
33 143,661 Mon June 22, 2020
Recommended By Average Price Average User Rating
94% of reviewers $205.16 7.82
SMC Pentax 300mm F4

SMC Pentax 300mm F4
SMC Pentax 300mm F4
SMC Pentax 300mm F4
SMC Pentax 300mm F4
SMC Pentax 300mm F4

This original K-Mount 300mm lens is much heavier than its M* counterpart which was introduced later.

SMC Pentax 300mm F4
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 8 blades
7 elements, 5 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
85 x 188 mm
1020 g
Production Years
1975 to 1981
Engraved Name
SMC PENTAX 1:4/300 (early version), smc PENTAX 1:4 300mm (later version)
Product Code
User reviews
Like many other K-mount lenses: Introduced in 1975 with the early K-mount naming style: SMC PENTAX 1:4/300. Later, when the M series lenses came out, lenses were either replaced with an M lens, or, like this one, renamed to follow the new neming style: smc PENTAX 1:4 300mm
Manual FocusBuilt-in HoodAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax 300mm F4
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-15 of 33
New Member

Registered: November, 2017
Location: Lake Worth, Florida USA
Posts: 3

1 user found this helpful
Lens Review Date: June 22, 2020 I can recommend this lens: Yes | Price: $127.00 | Rating: 9 

Pros: Very high quality for an excellent price. Terrific results if you work with it's limits.
Cons: Soft wide open
Sharpness: 8    Aberrations: 7    Bokeh: 9    Handling: 10    Value: 10    Camera Used: Pentax K1   

I bought my lens for only $127 and didn't use it much initially. I use it on a Pentak K1 and lately started experimenting again with it.

It is fairly soft wide open, but stopping the lens down will result in some sharp photographs.

Purple fringing is obvious under certain circumstances, but that's easily remedied in post production.

The construction is built like a tank and will be working long after I leave this place. The focus is smooth. The overall feel is well balanced with my K1.

If you have a K1 or other similar camera with excellent high ISO capabilities and image stabilization then this lens is a no brainer and should be part of your collection.

New Member

Registered: December, 2019
Posts: 11

1 user found this helpful
Lens Review Date: December 31, 2019 I can recommend this lens: Yes | Price: $70.00 | Rating: 8 

Pros: handling, simplicity, build quality in-hand
Cons: no tripod ring
Sharpness: 8    Aberrations: 7    Bokeh: 9    Handling: 8    Value: 10    Camera Used: MX, 5dmkII   

Bought along with a M 50/1.4 for $110 combined; asking price was $80 each. Purchased copy was in decent condition optically and externally but had a relatively stiff (though smooth) focusing ring and a dented lens hood that takes some finesse to extend.

I think the people who don't like it either have unrealistic expectations for MF film-era lenses or paid too much for it.

-Not ultra sharp at F4
-weighs more than a modern plastic/composite/computer-designed 300/F4
-focus throw is very long
-No tripod ring
-300mm prime is too long to be very useful on a crop-sensor
-Fringing, especially at F4

-Sharpens up nicely by F8 (aberrations stay somewhat)

-incredibly sturdy
-focus throw is very long (useful for fine-tuning focus)

-surprisingly good in-hand, especially with a modest-sized film camera attached (paired kind of wonderfully with my MX)
-300mm is great on a full-frame sensor or film

300/F4 at F8, 1/250th on a Pentax MX. Portra 800 in EV11-ish (maybe more like 10.5-10) conditions.

It's not a good sports lens. Hunting for focus across its full focus range is not fun. It's a nice budget complement to more "normal" lenses, but it's definitely not a replacement for them. it's also just small enough that I can fit it into my camera bag as part of my typical carry; I like how it gives me a completely different perspective on subjects from what I get from, say, a 50mm, and at F4 it's bright enough for mixed light situations, though it really does shine only during the day (largely because of the lack of a tripod mount). I've also used it with a 50mm screwed on front for a 6:1 macro, which is a unique look.

All told I'd probably be disappointed if I'd paid $300 for it today but I wouldn't own it if it was a $300 lens.
Site Supporter

Registered: June, 2013
Location: Utrecht
Posts: 58
Lens Review Date: October 26, 2019 I can recommend this lens: Yes | Price: $100.00 | Rating: 8 

Pros: Superb build quality, manual focussing, sharp, bokeh
Cons: Abberations, only hand hold shots
Sharpness: 9    Aberrations: 7    Bokeh: 10    Handling: 7    Value: 9    Camera Used: K2 to K1ii   

This lens feels so solid, beautiful crafted lens. It is real sharp when you focus with live view, the DOF is very narrow. Water shots in bright light have to be corrected because of the green/magenta aberations in front and behind your object. In that sort of situations the aberations help you in pin point focussing, the narrow area without aberations is in focus... . Aberations are easy to correct on post btw. Stopped down this lens is very sharp. Very nice focus throw also.

On K-01 :

On K1ii :

Edit Feb 2021: I compared K300 / A400 / Tokina RMC400 in ideal situation on 24 MP Pentax KP. Resolving power is quite good, only aberrations around blinking objects are an issue.

New Member

Registered: February, 2016
Posts: 2

1 user found this helpful
Lens Review Date: October 11, 2018 I can recommend this lens: Yes | Price: $35.00 | Rating: 8 

Pros: Solid, good focus throw, very sharp when stopped down
Cons: CA to f8,
Sharpness: 8    Aberrations: 5    Bokeh: 6    Handling: 7    Value: 8    Camera Used: k-3   

I love these legacy lenses! I have the 200 f4, 300 f4 and the 500f4.5. I just need the 400 to complete the tele collection.

It's not super fast but the focus throw is really good.

I got it at a church sale for $50CA and it is in new condition. I'm loving this lens!
Forum Member

Registered: February, 2015
Posts: 93

1 user found this helpful
Lens Review Date: August 7, 2018 I can recommend this lens: Yes | Price: $140.00 | Rating: 9 

Pros: Build quality, IQ
Cons: A bit large, but still acceptable
Sharpness: 10    Aberrations: 10    Bokeh: 9    Handling: 8    Value: 10    Camera Used: K2dmd   

Don't listen to the so so reviews of this lens if you're shooting film, which is what this beautiful thing was made for.
I just picked one up and ran a test roll of HP5, tortured it and I don't see any weaknesses at all.
This wasn't made for digital so you can't expect it to behave like it was. After seeing what it can do I'll never sell it.
It is large but the images it produces nullify that particular shortcoming. I found the focus throw to be about right also.
I'd give it a 9.5 but there's no provision for that
New Member

Registered: June, 2017
Posts: 3
Lens Review Date: June 17, 2017 I can recommend this lens: Yes | Price: $110.00 | Rating: 7 

Pros: Good value, included hood
Cons: bad aberrations, slow, somewhat heavy
Sharpness: 8    Aberrations: 6    Bokeh: 7    Handling: 7    Value: 9    Camera Used: Samsung NX1   

Very bad aberrations and purple fringing can occur with this lens. Don't shoot toward the light. Even if you shoot with light behind you, in some apertures, you still can get very bad purple fringing. Manual focus with no stabilization can be a challenge with any lens 300mm+. Lens has long focus throw on my copy.

I used Samsung NX1 with the official Samsung NX to PK Adapter. Photos edited to taste in Lightroom.
Senior Member

Registered: May, 2011
Location: Marseille Provence
Posts: 142

2 users found this helpful
Lens Review Date: April 1, 2015 I can recommend this lens: Yes | Price: $200.00 | Rating: 9 

Pros: Full-Frame, Full-Metal, Easy Focus, Sharp, Colors, Price, No AF issue, Eternally Sustainable !
Cons: Green / Magenta fringes in OoF High-Contrast zones, far Close Focus, No Tripod Mount
Sharpness: 9    Aberrations: 7    Bokeh: 9    Handling: 8    Value: 10    Camera Used: Pentax K-5   

Hi All !

The 40 yrs old SMC Pentax 1:4/300 is a * bargain * as long as you avoid shooting against the light !

Sat. March 28 at circuit Paul-Ricard = first practice session of the 2015 WEC :
- LMP1 Audi R18 #8 - GTAm Ferrari #66 - LMP2 Morgan-Sard #43
( Right Click + View Image to pixel-peep it at full size ! )

Focus is on ~the front of the Audi, 1/800s, f/8, ISO-200, pp DCU4 as is, No CA Correction !
= you can see some fringing on the slightly OoF air intake of the blue Morgan...
this picture is ~1/4 of the area of the original PEF (logos=100%)

Here is a rare Review of this SMC Pentax 1:4/300 :
+ the way to read it all around the world :

- LMP2 Alpine Nissan #36 - LMP1 AER ByKolles #4 - LMGT Aston Martin Vantage V8 #99
Right Click + View Image to pixel-peep this one up to 2048 1408 pixels !

Focus is on ~the front of the Bykolles, 1/800s, f/7, ISO-200, pp DCU4 as is, No CA Correction
This Large picture is ~2/3 of the area of the whole Original PEF frame...

Both photos : K-5 - Manual Exposure setting + Manual Focus + Single Shot mode !

Good Luck to find your own SMC Pentax 1:4/300 !
Loyal Site Supportaxian

Registered: September, 2013
Location: Texas
Posts: 501

1 user found this helpful
Lens Review Date: July 20, 2014 I can recommend this lens: Yes | Price: $172.00 | Rating: 7 

Pros: Cost, Not too heavy considering vintage 4/300
Cons: Significant Magenta in high contrast OOF areas.
Sharpness: 9    Aberrations: 5    Bokeh: 8    Handling: 6    Value: 8    Camera Used: Canon Crop and FF   

Great performance on a budget. Sharp, but does have significant magenta in high contrast OOF areas when shooting under f8.

Correction. I previously stated that this had the same optical formula as the M42 S-M-C-Takumar-300mm-F4. It does not.
Veteran Member

Registered: January, 2012
Posts: 1,972

2 users found this helpful
Lens Review Date: May 3, 2014 I can recommend this lens: Yes | Price: $190.00 | Rating: 9 

Pros: sharpness, focusing and overal handling
Cons: color fringing and no tripod mount !!!
Sharpness: 10    Aberrations: 6    Bokeh: 10    Handling: 10    Value: 9    Camera Used: K-01   

I bought it to accompany or to replace my massive Meyer Orestegor 300mm and I did a comparison of those two - which you can see from the following link here on Pentax Forums :

Just to quickly sum up - the lens is having a really good sharpness - I was surprised that even wide open the details was there - even in very contrasty situations ( like in the comparison linked ) - so basically i rate this lens fery high on sharpness.

The aberrations on the other hand ARE the problem and on certain situations they will ruin your shot. Meyer is performing much better in this area. The worse news is that Pentax doesn't quite stop color fringing even when I stop the lens down - after f8 it is nearly gone - but not fully, so watching out for this flaw is important and this lens will not deliver in every situation.

Handling is superb - lens feels very solid, focusing is superb and aperture flawless . The only gripe is the lack of tripod collar or mount - and that is making using this lens on tripod a bit awkward. Shame Pentax !!

I went through several cheap 300-400mm lenses and the very first one that I was very happy about was Meyer. Now I can see how Pentax will take its place for hand-held use and Meyer will stay at home or be only used with tripod .

Very happy with this lens and I would recommend it to every Pentax user. If you can live with / or fix in PP this awful color fringing -you will be very happy with what this lens is capable of - a very competent performer indeed !

I would personally rate this lens 8 for digital and 9 for film use - as the color fringing is less of an issue there . Since we don't have 0.5 marks here I went with 9 for it - although for both digital/film use I would rate it 8.5.

if it had a tripod collar - that would be a solid 9 - and if fringing was not that prominent - that would be a solid 10 for the money- but then the lens would be selling for much more I guess :P

Below several shots from this lens - at f4 f8 and the bokeh wide open :

Pentax K 300mm f4.0
SMC K 300mm - bokeh @ f4.0

PS: here is how SMC K 300mm looks against my Meyer Orestegor 300mm f4.0

SMC K 300mm against Meyer Orestegor 300mm
Junior Member

Registered: December, 2012
Location: Sydney
Posts: 49
Lens Review Date: March 10, 2014 I can recommend this lens: Yes | Price: $160.00 | Rating: 8 

Pros: Well Built and decently sharp
Cons: Bad CA and quite heavy
Sharpness: 8    Aberrations: 6    Bokeh: 8    Handling: 7    Value: 9    Camera Used: Pentax K-30   

I bought this lens from a friend from the forums and it was in excellent condition!

The lens is sturdy, very well built. I prefer the metal body of the old pentax lenses than the plastic ones.

Using it with my camera I found it quite heavy and tricky to use but not too difficult (And its a good workout for your arms!).

Overall the Images were decent except for the CA which as previous users have said is somewhat of a problem. But then again it can be removed through post-processing.

I would recommend this lens as more of a backup rather than your primary telephoto lens.
Inactive Account

Registered: March, 2014
Posts: 3

2 users found this helpful
Lens Review Date: March 6, 2014 I can recommend this lens: Yes | Price: $340.00 | Rating: 10 

Pros: built quality, colours, sharpness
Cons: Slow maximum aperture of f4, a little heavy
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 10    Camera Used: Pentax K-01   

At 300mm on film and 450mm on digital the Pentax K 300/4 is my second longest lens as I recently added a SMC Pentax M 400/5.6 to the collection. While it is not a lightning fast 300/2.8 it is no slouch either. When you put a 2x converter on the back of this beast and you have a 600mm film/900mm f8 on digital! How is that for an extreme telephoto? For those of us to whom photography is just a hobby it is unlikely we will ever be able to afford or justify that 600mm f4 lens.

Overall a good well built super telephoto lens that is somewhat portable, but on the slow side.
New Member

Registered: November, 2010
Posts: 5

3 users found this helpful
Lens Review Date: April 15, 2013 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: Build, IQ
Cons: Weight
Sharpness: 9    Aberrations: 7    Bokeh: 9    Handling: 8    Value: 10    Camera Used: K5   

This is my longest lens. I primarily use it for birding. I routinely mount it to the Sigma APO 2X AF Teleconverter and get good results. It takes a lot of practice and some luck to get birds in flight due to the shallow DOF. It is built like a tank. I dropped it once onto a carpeted floor from a height of five feet. One of the lens mount's flanges was bent, but I replaced that myself using a spare mount I had. The only other damage was to the aperture mechanism, and that was fixed by a minor readjustment which was done by a repair shop. Nothing else was broken. The tech said one of the newer mostly plastic lenses would have had broken lens mounts from such a fall.

It is a sharp lens, and when I get the focus right, it produces excellent images. Below is a hummingbird photo I took at my backyard feeder. The bird was about 10 feet away and I used a 24mm extension tube to get the lens to focus at this closer then normal distance. 300mm, F8, fill flash, 500 ISO, K5 on X setting. Some noise reduction and exposure adjustment was done in Photoshop Elements. This is a cropped image that is as close to 100% in size as I can approximate.

I took one of the previous reviewers advice and purchased a Canon aftermarket Tripod Ring on eBay. On the ring it says A(W) Micro 100 F2.8. It fits the 300 4 perfectly and I have kept it on the lens ever since. It mounts securely to the lens between the aperture ring and the focus ring and it balances the lens and my K5 perfectly. I no longer have to worry about this heavy lens damaging my camera body when mounted on a tripod, especially when I have the 2X converter attached.

I would like to add that I use a Katzeye focusing screen in my K5 and would highly recommend it when using MF lenses. I once tried to get a photo of a Redtail Hawk in a tree, using this lens and the Sigma teleconverter, and only one out of a dozen photos was in focus. On that same outing I found a Heron hunting frogs in a tidal canal. Only a couple of my photos turned out, no matter how hard I tried to get the focus right. That was when I out and acquired a K5 with a Katzeye. I now wouldn't think of using this lens without it. I believe a Katzeye is a mandatory requirement when using long MF lenses.

Another thing I discovered that when taking a photo at 600mm, you need a quality filter. I tried one of those cheap UV Vivitar filters you find on eBay for less than ten dollars. At 600mm, you could see wavy lines in the viewfinder. The image was so distorted, it was impossible to take a useable photo. I immediately put a quality B&W UV filter on this lens and now get great results.

New Member

Registered: January, 2012
Location: France
Posts: 9

1 user found this helpful
Lens Review Date: April 14, 2012 I can recommend this lens: Yes | Price: $270.00 | Rating: 9 

Pros: sharpness, color,used without tripod
Cons: application knowledge in post processing, minimal focusing
Sharpness: 10    Aberrations: 5    Bokeh: 9    Handling: 9    Value: 10    Camera Used: K-5   

Hello all,
I possess a K300mm f4 for a week.
I usually to wait longer before giving my opinion on a lens, but I think I can bring some information on this post.
First a 300m f4 manual is never very easy to use, again, it is true that this old lens is not optimized for digital camera.
For someone who want a JPG ready, and not doing a post-processing, ignore my comment as a DA 55-300mm may be more suitable.
1) the build quality is uncompromising.
2) the weight of this lens is similar to that of DA 300mmF4. I use it without tripod on my K-5.
3) focus takes a little practice, but the ring is very precise.
the minimal focusing distance of 4m is a little weak
4) the k-5 viewfinder remains luminous because F4 is a good compromise (300mm f2,8 is probably too big and heavy).
5) the sharpness is very good has F4, extraordinary by closing the diaphragm.
6) The contrast is very good, and asked to be adjusted as usual cases.
7) the colors are balanced and faithful to reality.
8) the bokeh is superb (silky and soft).
9) the chromatic aberrations beings are often corrected, good softwares of Treatment solve the problem very often (I developed my SILKYPIX RAW DSP DSP 4 or 5.)
In conclusion, for an affordable price, here's a lens that give exceptional results. You need a little practice to master the subject and some knowledge in post processing.
New Member

Registered: March, 2011
Location: West Sussex
Posts: 11

1 user found this helpful
Lens Review Date: December 3, 2011 I can recommend this lens: Yes | Price: $156.00 | Rating: 8 

Pros: Sharpness, colour, bokeh
Cons: Lack of tripod collar
Sharpness: 8    Aberrations: 7    Bokeh: 8    Handling: 5    Value: 10   

I bought this lens when I had a Samsung GX10 and was pretty disappointed by the amount of CA. Purple, red, green - you name it, the lens produced the CA in high contrast situations. Since buying a K5, the CA situation has improved dramatically in my tests so far, so the new CMOS sensor really is a big plus. I reckon this is a bargain lens at this money - not perfect, but then, what is? Best results come with tripod mounting the K5 with this hefty lens.
New Member

Registered: April, 2009
Posts: 4

1 user found this helpful
Lens Review Date: November 12, 2011 I can recommend this lens: Yes | Price: $300.00 | Rating: 10 

Pros: Sharp / Solid / Build-In Hood
Cons: No tripod mount
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 9    Value: 10   

Extremly sharp on my little K-r - i just fall in love with this lens. I was surpised about the moderate rating here, but im only looking only for the IQ and that is a clear 10.
Yes, a tripod mount would be better and yes - it is heavy - but the image quality of my copy is great !
Add Review of SMC Pentax 300mm F4

All times are GMT -7. The time now is 11:58 PM. | See also:, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]