Forgot Password
Pentax Camera Forums Home

Pentax Lens Review Database » Film Era Pentax K-Mount Lenses » M Prime Lenses
SMC Pentax-M 400mm F5.6 Review RSS Feed

SMC Pentax-M 400mm F5.6

Reviews Views Date of last review
10 64,385 Mon November 2, 2015
Recommended By Average Price Average User Rating
100% of reviewers $317.11 8.30
SMC Pentax-M 400mm F5.6

SMC Pentax-M 400mm F5.6
SMC Pentax-M 400mm F5.6

This extreme-telephoto lens has a an A-series counterpart with a different optical formula whereas the "K" version is optically the same as the "M".

SMC Pentax-M 400mm F5.6
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Automatic, 8 blades
5 elements, 5 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
500 cm
Max. Magnification
Filter Size
77 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 4.1 ° / 3.4 °
Full frame: 6.2 ° / 5.2 °
Built-in, slide out
Dedicated hard case
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Tripod Mount
Diam x Length
85 x 277 mm
1240 g
Production Years
1977 to 1984
Engraved Name
smc PENTAX-M 1:5.6 400mm
Product Code
User reviews
Manual FocusBuilt-in HoodAperture RingFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-M 400mm F5.6
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-10 of 10
New Member

Registered: August, 2015
Location: Stockholm
Posts: 15
Lens Review Date: November 2, 2015 I can recommend this lens: Yes | Price: $300.00 | Rating: 9 

Pros: Sharp, IQ
Cons: Slow, CA
Sharpness: 9    Aberrations: 7    Bokeh: 8    Handling: 9    Value: 10    Camera Used: Pentax K5 IIs   

I brought this to have a bit of extra reach for those certain moments. It is a big lens, not as heavy as it looks but it works best on a tripod. It is very sharp at f8-f16 and gives lovely colours. It is usable a f5,6 but just 1 or two steps down makes a lot of difference. It's easy to focus and the built in hood works well.

@ f8

@ f11
New Member

Registered: December, 2013
Posts: 15

2 users found this helpful
Lens Review Date: June 5, 2014 I can recommend this lens: Yes | Price: $475.00 | Rating: 8 

Pros: Good 400mm to start and learn the basics
Cons: Everything manual
Sharpness: 8    Aberrations: 4    Bokeh: 4    Handling: 7    Value: 9    Camera Used: K5-iis   

I think it is a good lens to start with..
I'm still practicing and trying to learn how to shoot without tripod or monopod,it's very hard to get good results with moving objects(in my world)
I have no experience with old school lenses thats why i have to spend more hours to learn the MANUAL FOCUS and try to make my techniq better, faster and more stable..
I love the 1970's style and the fact that was made in JAPAN..
Every beginner needs to learn how to use a fully manual lens like this
Senior Member

Registered: November, 2008
Location: The Cow Belt
Posts: 162

1 user found this helpful
Lens Review Date: November 13, 2013 I can recommend this lens: Yes | Price: $175.00 | Rating: 8 

Pros: sharp, lightweight, sturdy
Cons: fringing
Sharpness: 9    Aberrations: 5    Bokeh: 9    Handling: 8    Value: 10    Camera Used: MX; K200D; Samsung GX20   

Bought new in 1981. Sharp, particularly at f11 and better. Acceptable sharpness wide-open with film cameras. Compact for its focal length. Sturdy but lightweight metal barrel greatly resistant to shocks. Excellent tripod adapter but tripod hardly necessary as lens can be used handheld. In-body image stabiliser assists greatly (significant advantage when used with K-mount DSLRs).

Focusing difficult on both DSLR and film bodies mainly because of the shortcomings of Pentax viewfinders themselves, not the lens. Matte focusing screens were of some assistance in Pentax MX, none at all in DSLRs. Focus confirmation very useful for stationary objects. Pictures of flying birds require opening up two stops from the metered setting in film bodies, possibly more in DSLRs.

Significant chromatic aberration in high contrast shots.

Registered: September, 2010
Location: Northeast Philadelphia
Posts: 1,132

2 users found this helpful
Lens Review Date: June 27, 2011 I can recommend this lens: Yes | Price: $345.00 | Rating: 9 

Pros: Color, contrast, sharpness (when I nail the focus), light weight
Cons: Fringing, difficult to nail focus

This lens is a lot of fun — getting beyond 300mm (where consumer zooms generally end) is useful and exciting. I expected this lens to be very difficult to use — heavy, moderate sharpness and contrast, too long to hand hold — but I was wrong. It provides good contrast, nice colors, and it is possible to get impressive sharpness out of it. It's definitely an M-series lens in the quality of the images it produces. Plus, it's not as heavy as you would expect. I've used it successfully with both my K-7 and K-5, but I find the K-5 to be a better match because, in order to get proper exposure with sufficiently fast shutter speed (for me and this lens, 1/320 is as low as I can go without losing a lot of shots to hand shake; 1/400 is better), even in daylight, I have to use ISO 640 - 1600.

The ability to hand-hold this lens is very important to me, and it's why I gave it a nine instead of an eight. I don't have a nice tripod, and I don't like using what I have. So I hold this lens by hand, and I'm pretty happy with what I get. I did put it on the tripod once, and it seems to balance well because of the positioning of the tripod collar. I'm sure I'll use the lens with the tripod in the future, but I haven't yet.

It's usable wide open, but the closer to f/5.6 you get, the more fringing you will experience. This is really the only downside to this fully manual lens. Of course, it gets sharper as you stop it down too. I find myself using f/8-11 or thereabouts. But you will experience pruple and green fringing in high-contrast areas, and even in some moderate-contrast areas, particularly when the aperture is open.

Here are some recent photos:

That last one I include primarily because it's a high-contrast situation, and it illustrates that you can get usable photos in such a situation. Yes, I had to clean it up in ACR, but it wasn't tough.

Registered: February, 2009
Location: Perth, Western Australia
Posts: 2,437
Lens Review Date: December 20, 2010 I can recommend this lens: Yes | Price: N/A | Rating: 8 

Pros: light weight, build and focus feel, low cost, resolution
Cons: chromatic aberration on digital, flare

First of all, I must say that the previous review by Tom G is excellent and also lines up with my experience of this lens.

Immediately on purchase of this lens I was impressed by the build and feel. While this might have no direct effect on the final image quality delivered, such aesthetics are important in my opinion as the nicer a lens is to use, the more often I am likely to take it out to shoot with.
In this regard the M400 f/5.6 is a winner. Compact yet not too heavy for it's focal length, with fantastic damped manual focus and great metal build.

Using this lens, probably like most super telephoto lenses, demands a fairly sharp initial learning curve. The resultant depth of field is really very shallow even with smaller apertures (eg. f/16), so focusing needs to be precise. Exposure on digital means using the aperture ring and manual mode, but don't let that scare you off! With both of these considerations in mind, the lens is still easily usable but it does take practice to become efficient.

Exposure with stop down metering I find tends to be a little bit inconsistent with my K200D. This is not a big deal, but can result in a little bit of frustration if you are following a moving subject with changing light.
Now I will say that this lens does make you work relatively hard to get good shots. In addition to the usage points mentioned above, the M400 can be somewhat prone to chromatic aberation (particularly purple fringing) and sometimes flare. The presence and severity of these issues depends wholly on the light and your position to the sun. Keep the sun at your back and shoot in good light (not too harsh) and these issues will be completely managable. Shoot close to the sun at midday with a contrasty subject and you will have issues! Now it is important to note that with any lens you will get better results in better light conditions. With this lens it is just somewhat more obvious than with the newer "digital" lenses.

One of the positive features of the older M series lenses is their unique rendering. The M400 shows similarities to some of it's M series brothers like the M50 f/1.4 and M135 f/3.5 with similar rendering of colours. This works well on digital, with a pleasant slightly warm cast and unique blue tones that are particularly visible in skies. Sometimes this can be a nice refreshing change from the contrasty and saturated images produced by many modern lenses.

One last point about the M400 is regarding its optical resolution and sharpness. It is quite easy to fault the M400 for being soft, however with practice the fault is almost always found to be with technique. Once again I will defer to user Tom G here for a definition of excellent sharp results. I will also include some of my own examples from this lens for comparison.

In conclusion, I would recommend this lens. Great to use, good for building technique, much more affordable than other lenses, and capable of very good results when you put enough effort in. And really, a high fun factor!

And this is an example of the M400 on film, Fuji Superia 200:


Registered: February, 2008
Location: Waterloo, Ontario
Posts: 4,462

1 user found this helpful
Lens Review Date: February 16, 2009 I can recommend this lens: Yes | Price: $430.00 | Rating: 9 

Pros: Fairly light for a 400mm, very good build quality, sharp, relatively inexpensive
Cons: Prone to CA/PF in high contrast situations, no auto exposure, fully manual,
Sharpness: 9    Aberrations: 5    Bokeh: 8    Handling: 9    Value: 9   

In Feb. of 2009 I added the SMC Pentax M 400/5.6 to my collection. I had always wanted something in this focal length but brand name lenses in this range tend to be very expensive specialist optics. Finding one which wouldn’t break the bank or result in divorce was going to be a problem but this lens seems to fit the bill. Right up front on digital I must note there are issues with CA/purple fringing in high contrast situations. I have yet to shoot film with this lens so the CA/PF issues may differ in that format. The M 400/5.6 does not have ED (low dispersion glass) so these issues are no surprise with an optic almost thirty years old. We are talking about an "affordable super telephoto" after all. It should be noted several forum members report CA/PF issues are not nearly as pronounced in the film format for which this lens was designed. I have not shot a roll of film with this lens as yet but see no reason to doubt the observations.

Care must be taken when shooting into or towards the sun. Things improve significantly by stopping down to f 8-11. Whenever possible I try to shoot with the sun at my back. The minimum focusing distance of 15 feet is somewhat limiting and very annoying. This issue was evidently addressed in the A series 400/5.6 which will focus almost twice as close (2.8 m.).

There is a review of the successor to this lens in A series review area of this forum by Ben Edict. Ben notes that focusing is very slow with the A 400mm 5.6. This is also true with the M 400/5.6. At times one may have to turn through a full 270 degrees from infinity to the 15 ft. (5 m.) minimum focus distance to get a sharp image in the viewfinder. This longish minimum focusing distance can be frustrating when you manage to get close to an animal and just can't get it in focus because you are too close. This has happened to me on more than one occasion. Catching that bird on the fly will also be a challenge. OK - let's be honest. It's just not going to happen.

The lens is very well built, hefty (1220 grams/2.69 lbs) but not a lot heavier than my SMC Pentax K 300mm f4. It is possible to hand hold this lens but not advisable. There is a very sturdy built-in tripod collar and the lens balances well on the tripod/monopod with my K10. Tripod collar detents are located at the customary positions (zero degrees and ninety degrees) providing solid, secure stops. A large thumbscrew locks the collar firmly in place. Another thoughtful feature is the small thumbscrew, which holds the lens hood in place and acts as a handy gun sight. I find this sight is very useful with a lens of this length in finding, lining up and focusing on your subject. The hood also features a double set of knurled rings which helps sliding it in and out. Pentax seems to have paid a lot of attention to details with this particular optic. The focusing ring is decked out with typical M series square rubber checks providing a sure grip. The usual M series wealth of engraved data is to be found around the front retaining ring including: lens name, focal length, maximum aperture and serial number. Boz Dimitrov supplies technical details:

Update - Sept. 2009

I've now used this lens extensively for seven or eight months and I have mixed feelings about it. I love the extra reach of the 400mm. It is great for birding and the extra 100mm is a significant improvement over my K 300/4. As a sidebar it seems no lens is ever long enough when it comes to birding. I do wish it would focus closer than 15 ft. and have missed more than a few shots because of this. More than any of my other manual focus lenses, and I have a lot, I seem to miss the A setting with the 400mm. Perhaps because of the shallow depth of field it takes a while to focus this beast and auto exposure, while no panacea, would be a great advantage. It would be one less thing to think about. This is coming from a guy who successfully shoots manually almost all the time with lenses without an A setting. The SMC Pentax A 400/5.6 seems to have addressed these issues but it comes at a significantly higher cost. Depending on condition the SMC A 400/5.6 will run you at least twice the price of the M series model. As I update this review in September 2009 the A 400/5.6 is advertised on EBAY for over $1,000 US. I have seen it listed as high as $1,700.

So, where does this leave us? The SMC M 400/5.6 appears to be a good entry point for those seeking a reasonably inexpensive "super telephoto" lens. It will get you shots you just won't get with a shorter focal length and this is good but you will have to work for them. While I am recommending the lens to others in the forum it is a recommendation that comes with a caveat. You will have to be pepared for a lot of initial failures with this lens. Focusing a supertelephoto affords some getting used to and you may need to change out your stock focusing screen for a KatzEye with a split prisim. I can't imagine focusing this beast on a digital camera with the stock screen. Even with these issues in mind the M 400/5.6 can still be considered good value for the money. Depending on condition anything significantly better, the A 400/5.6 or the Tamron SP 400/4 LD for instance, won't leave you with much or any change from $1,000 in today's market.

As I look at this review it reads like a pretty thorough trashing of this lens. This was not the intent. In spite of its PF/CA issues in digital I am amusing myself with the old M 400/5.6 and that is the important thing. It is also possible some of the limitations I am finding in this lens are limitations in my own technique. In any case the M 400/5.6 has a very high fun factor rating due to its long focal length. I'm not sure how you put a dollar value on that but it is worth something to me. I had thought 300mm was a pretty long lens but 400mm is a whole new ball game. I would have given this lens a 7 1/2 on the rating scale if that were an option. It is closer to an eight than a seven so eight it is.

Update May 1, 2010

I have been using the SMC Pentax M 400/5.6 for a little more than a year now. I seem to be using this lens more than any other in my collection at this time. As I look at my favourite images from the past year or so most of them have been a product of this lens. I suspect as my technique improved so did the quality of the photos. Consequently, I think I may have been a bit harsh in my evaluation of the old 400mm. Yes, there are still CA/PF and close focusing issues but you can work around these limitations. As a result, based on prolonged use, I'm going to upgrade my rating on this lens from an 8 to a 9.

Here's a few images which demonstrate the best and worst of my efforts with this optic so far.

A couple of Common House Sparrows:

North American Robin - shows the great M series colours

and a Black Capped Chickadee. This is about as good as this lens gets, at least in my hands, with the K10. The colour rendition is very accurate and I was pleasantly pleased with the detail the M 400/5.6 was able to deliver in the image below.

And on the downside an example of the PF/CA you can expect in high contrast situations.

Green Heron - This is not the sort of thing one wants to happen when you finally get close enough for a good shot at one of these guys. Sadly, herons are usually found in marshy areas and the reeds tend to bring out the worst in the M 400/5.6. PF and CA shortcomings are clearly visible in this image. Things improve a little by stepping down and keeping the sun at your back. This is not always possible in a marshy area. Super telephoto lenses are not easy and you will have to work on your technique to get good results with this old timer. I find my best results with this lens come in early morning or late afternoon - much like any other lens as I think on it.

New Member

Registered: June, 2007
Location: Toronto
Posts: 12
Lens Review Date: December 6, 2007 I can recommend this lens: Yes | Price: $350.00 | Rating: 9 

Pros: sharp, inexpensive
Cons: slow, heavy, requires tripod

I use this telephoto lens only with a tripod and with much patience. Once the lens is stopped down to f5.6-f8-f11, it performs very well in terms of sharpness, contrast, and IQ. It does require a mono/tri-pod most of the time and lacks auto-aperture and auto-focus which makes this lens ideal for amatuers and hobbyists looking to improve their technique. This lens is highly recommended for the entry level photographer on a budget who would like to do extreme telephoto work.
Loyal Site Supporter

Registered: November, 2007
Location: Sparwood, BC, Canada
Posts: 10,866

2 users found this helpful
Lens Review Date: November 8, 2007 I can recommend this lens: Yes | Price: $300.00 | Rating: 7 

Pros: Sharp, not heavy, price was right.
Cons: Rear converters vignette, 5 meter minimum focus
Sharpness: 8    Aberrations: 3    Bokeh: 5    Handling: 7    Value: 8   

I use this lens for birding and other wildlife in the mountain parks here (and our back yard feeders). I often use if with the A 1.4xS - the L cannot be fitted inside the barrel. 8x10 format gets rid of the dark corners just fine, and I have a 560mm f/8 lens.

I use a 50mm extension tube (Pentax, of course) to allow me to focus closer.

Tested the lens today (2007/12/01) and it has serious color fringing on my K10D.

I have since retested on the K10D, not shooting into the sun, and got very good results. The lens must be used in manual exposure (and obviously, manual focus). Sunny 16 or metered at f/8 for a beginning exposure, the lens works very well. (2008/03/14)

[Edit] 2011-08-10. Updated ratings to meet new specs.
I have also tried this lens with the AFA 1.7X AF converter on my K10D, and with very careful handling, it will work satisfactorily, but it is much easier to use with the 1.4X - S.

New sample photos from a trip to Pacific Rim National Park Reserve, British Columbia, Canada

All these photos were taken with the lens set to f/11. This greatly reduced the chromatic aberrations and purple fringing. The black oystercatchers and the kids playing in the surf were taken with the AFA 1.7X at ISO 200. The seagull and wave were taken without the AFA 1.7X at ISO 400. All shots on tripod (Manfrotto 068) and ball head with 2" delay using a wired remote.
New Member

Registered: June, 2007
Location: Christchurch NZ
Posts: 3
Lens Review Date: June 30, 2007 I can recommend this lens: Yes | Price: $100.00 | Rating: 8 

Pros: Light weight, sharp
Cons: Tricky to use on digital body

I've hand held this lens all day for 4 days of an airshow. You need 1/500 for good looking prop blur, and at this speed camera shake is an issue. I have not tried the K10s shake reduction, but on the istDS I have have some great shots.

Using it on the tripod for birding has been OK too. The tripod mount is nicely balanced.

I got it for a steal on ebay (Buy it now), and have no regrets!
Veteran Member

Registered: September, 2006
Location: North Idaho
Posts: 665
Lens Review Date: January 8, 2007 I can recommend this lens: Yes | Price: $379.00 | Rating: 8 

Pros: exceptional build quality, outstanding optics, SMC
Cons: none really

I purchased this EX rated lens from KEH in February, 2005. It is my 'long gun' and has seen extensive usage when I shoot high school baseball. It was even my lens of choice when I shot a Dodger/Padre game from the press pit at Chavez Ravine.

Not sure what to say about this lens, except that I 'love' it. No complaints at all. Has a nice tripod mount, that balances the 'rig' nicely on a monopod. The lens includes a built-in slide-out sun hood that locks into position with a little curled thumb screw that also acts as an aiming aid, similar to older rifles and shotguns. Plenty fast enough that it produces excellent images wide open in low-light situations.

This lens will have to be used with some type of tripod/monopod support, but I suppose it could be handheld with Shake Reduction in bright sunlight conditions where you can have a decent shutter speed. Still, even though it is a miniaturized M series lens, it is not lightweight and you won't want to handhold it for very long.

Very Highly Recommended! Only rated an 8 because I reserve my 9 and 10 ratings for Limited, '*', and other outstanding Pentax lenses. This one comes close to a 9, and would be rated so if it were the A version with auto aperture capability.
Add Review of SMC Pentax-M 400mm F5.6

All times are GMT -7. The time now is 01:20 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]