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SMC Pentax-A 400mm F5.6

Reviews Views Date of last review
19 91,387 Mon August 31, 2020
Recommended By Average Price Average User Rating
100% of reviewers $395.89 8.58
SMC Pentax-A 400mm F5.6

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

The SMC Pentax-A 400mm F5.6 lens is a compact extreme-telephoto lens featuring a tripod collar and built-in hood. Manual focus, auto aperture.

SMC Pentax-A 400mm F5.6
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (A setting)
Automatic, 9 blades
7 elements, 6 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
280 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
Hard case HE-330
Lens Cap
Plastic clip-on
Weather Sealing
Other Features
Tripod Mount
Diam x Length
85 x 277 mm
1240 g
Production Years
1984 to 2004
Engraved Name
smc PENTAX-A 1:5.6 400mm
Product Code
User reviews
Manual FocusBuilt-in HoodAperture RingAutomatic ApertureFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-A 400mm F5.6
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Veteran Member

Registered: July, 2007
Location: Hong Kong
Posts: 431

7 users found this helpful
Lens Review Date: October 22, 2010 I can recommend this lens: Yes | Price: N/A | Rating: 7 

Pros: Build quality, sharpness and good contrast.
Cons: Slow focusing and some purple fringing.

This is a slow lens in term of focussing speed and the aperture.
Although, it does suffer from purple fringing, nevertheless, the image quality is rather good and sharp.
Weight is not too heavy and reasonable for a 400mm tele lens. Handheld is possible.
All the sample pics below were indeed taken without a tripod or monopod.
I agreed to Ben Edict's review of this lens. If speed, fast tracking of moving object is not the primary concern (possible but not easy), this lens can be a very good choice.

Samples from this lens:

Loyal Site Supporter

Registered: August, 2011
Location: North Carolina, USA
Posts: 5,123

6 users found this helpful
Lens Review Date: February 16, 2012 I can recommend this lens: Yes | Price: $550.00 | Rating: 8 

Pros: Sharp; short MFD; handles well for a 400
Cons: Some CA
Sharpness: 9    Aberrations: 7    Bokeh: 7    Handling: 9    Value: 10   

A good sharp super-tele that is easily hand-holdable, although of course with a 400mm lens a tripod is necessary to get the best results. While it's true you can't instantly change focus between near and far objects, the long focus throw and solid focus damping help to achieve precise focus, and are a good match for a MF super-tele.

The short minimum focus distance is excellent for those occasions when you can get really close to your subject. This is a slight crop:

High-contrast subjects can produce some purple fringing. Another mild crop:

A busy high-contrast background can result in nervous bokeh with bokeh CA -- here's a 100% crop from the above image, showing both purple fringing on the subject, and bokeh CA (green and purple background highlights):

I think that is something of a worst-case scenario, and in practice this is very manageable. Another example showing strong backlighting, first uncropped and then a 100% crop:

Loyal Site Supporter

Registered: February, 2014
Location: Pennsylvania
Posts: 1,365

4 users found this helpful
Lens Review Date: August 27, 2019 I can recommend this lens: Yes | Price: $385.00 | Rating: 8 

Pros: Build quality, IQ at middle apertures, Bokeh
Cons: Not sharp until F 8-11, Slow focusing
Sharpness: 8    Aberrations: 8    Bokeh: 9    Handling: 8    Value: 8    Camera Used: K-5iis, K-3   

I’ve owned two almost mint condition copies of this lens, both performing nearly identically.

The SMC-A 400 f5.6 has a number of things going for it. The build quality, typical of all A series lenses, is impeccable. Reasonably compact, with a built in tripod collar and lens hood, it travels well. Colors are saturated and warm, Another A series trait. No green button metering either, this lens communicates fully with modern digital Pentax bodies. Image quality and sharpness can be very good to excellent if you hit the “sweet spot” of close to medium distance and apertures between f9 to f13 or so. Flare is very well controlled, even when shooting a strong point light source.

I really wanted to love this lens, unfortunately it just doesn’t deliver the goods in these areas. Focusing is quite slow. The focus throw is very long and somewhat heavily damped, great for tripod use on stationary subjects but far from ideal handheld or for fast moving subjects. Performance at f5.6 to f8 is so-so at best.
Frame filling close subjects which require minimal enlargement in PP can look reasonably good. Subjects more than twenty yards or so away often look very soft, showing little fine detail. Not an ideal birding lens. Some color fringing is also evident in strongly lit, high contrast situations, though at f11 this is minimized.

The deciding factor to wether you will like the A 400 f5.6 comes down to cost vs. performance. Pentax doesn’t give one many viable options when it comes to long telephoto lenses. The excellent but exceedingly expensive and rare f2.8 400 mm lenses and the D FA 150-450mm which is also expensive are there for well heeled photographers. The older Takumar, SMC K and SMC M 400’s are less expensive but suffer from many more performance comprises and often have hazing or fungus issues. Third party 400mm’s are hard to find and usually aren’t particularly good. This leaves the A 400 f5.6 in a zone all by itself. Purchased between $300 to $425 or so, the lens represents a pretty good value in price vs. performance. Plus, you will never wear one out.
Site Supporter

Registered: June, 2013
Location: Montreal, Canada
Posts: 537

4 users found this helpful
Lens Review Date: October 22, 2017 I can recommend this lens: Yes | Price: $270.00 | Rating: 10 

Pros: Very sharp, easy focus for a manual lens
Cons: CA, contrast

An affordable very sharp long lens. I bought it for shooting the eclipse and wasn't disappointed. I find making focus is easy with this lens. On my K-5 focus confirmation signal is very precise so I can even risk taking birds in flight! ... with about a rate of succes of 1 in 20. But for a slower moving subject I get really good results. The star field below was taken at f/5.6 and shows virtually no coma in the corners. It is a stack of several frames so it is slightly cropped. Without ED elements in the lens, you have to deal with a fair amount of purple fringing in PP and work on improving contrast

The lens sure packs a lot of bang for the bucks.

Veteran Member

Registered: October, 2008
Location: Albuquerque NM
Posts: 9,830

4 users found this helpful
Lens Review Date: February 21, 2016 I can recommend this lens: Yes | Price: $400.00 | Rating: 9 

Pros: Sharp, works with all automation modes, not huge
Cons: Focus emphasizes accuracy rather than speed
Sharpness: 9    Aberrations: 9    Bokeh: 8    Handling: 7    Value: 10    Camera Used: Pentax K3, Sony A7R   

The lens is a long, skinny, sturdy metal package with a handy tripod mount and built-in lens cap. The focus feel is excellent, but the throw is long, making a fast focus on moving objects more of a challenge, but allowing very precise focus on stationary subjects.

I have used this on Pentax film and APS-C bodies, and now the Sony A7R. I can't say I really saw what this lens could do until I mounted it on the full frame 36mp A7R body. It is sharp all the way across, but a little PP is needed to punch up the contrast.

The Photos below are full frame, and show best when viewed on Flickr, rather than the small version which displays here with the link.

The last photo of the small bird below was taken with the A400 plus the 1.4x-L converter of similar vintage for an effective 560mm. These two were made for each other, and they work very well either on cropped or full frame sensors. The detail on the small bird is amazing given the converter.

New Member

Registered: April, 2015
Posts: 1

4 users found this helpful
Lens Review Date: April 8, 2015 I can recommend this lens: Yes | Price: $550.00 | Rating: 8 

Pros: lightweight, high PQ ratio, easy to find in second hand market
Cons: not internal focusing, not sharp at wide open, not physically balance when mount on tripod
Sharpness: 8    Aberrations: 7    Bokeh: 7    Handling: 9    Value: 10    Camera Used: K5iis   

This lens is not designed for tracking fast moving object in view of its long range of focusing distances and f/5.6 maximum aperture. It does suffer from purple fringing with strong backlighting.

Considering its relatively light weight, it is a good handheld lens for snapshot and birding.

Image quality will greatly improve when stop down to f/8 or below. When stop down to f/11, the image quality is superb and sharp.

Samples @f/11 are attached below:


Registered: August, 2011
Location: Langwarrin Australia
Posts: 382

4 users found this helpful
Lens Review Date: August 13, 2013 I can recommend this lens: Yes | Price: $390.00 | Rating: 9 

Pros: Sharpness,contrast, short minimum focus,build,value
Cons: Long slow focus
Sharpness: 9    Aberrations: 8    Bokeh: 9    Handling: 9    Value: 10    Camera Used: K5IIs   

This lens surprised me it just doesn't get the same recognition as the 300mm f4, yet it out performs it with better sharpness and contrast. Its short minimum focus also surprised me, something rarely seen in lenses of this focal length. This lens is far better than the price I paid for it, great value for money and a real sleeper.
Senior Member

Registered: October, 2015
Location: Washington
Posts: 267

3 users found this helpful
Lens Review Date: July 16, 2016 I can recommend this lens: Yes | Price: $400.00 | Rating: 10 

Pros: Sharp, Handling, IQ, Price
Cons: none
Sharpness: 10    Aberrations: 8    Bokeh: 9    Handling: 10    Value: 10    Camera Used: K-3, K-1   

I always wanted this lens. I got it on E-Bay.
Lens came with carrying case. It is built solid. Good old Pentax metal body lens..built to last.
It is light enough for handheld shooting. That was the main reason I bought it. I have much larger
SMC 500mm f/4.5 and that one require tripod. With this SMC A 400mm f/5.6 I have more freedom to
walk around and shoot. Image quality is very very good. Better than I expected. It is a "A" lens, so shooting is pretty simple , especially in TAV mode (Aperture and Speed priority). All you have to do is focus.
Focusing ring is silky smooth. I just love older Pentax lenses.
I highly recommend this lens for someone looking for a nice prime lens with decent range and don't mind manual focus.
Here are some samples.

IMGP8823 by Ludovit Tatos, on Flickr

IMGP8880 by Ludovit Tatos, on Flickr

IMGP8738 by Ludovit Tatos, on Flickr
Site Supporter

Registered: June, 2013
Location: Utrecht
Posts: 53

2 users found this helpful
Lens Review Date: December 11, 2019 I can recommend this lens: Yes | Price: $300.00 | Rating: 9 

Pros: Very sharp at F8-11, sturdy build, tripod, close focus
Cons: As it is manual focus, so not very fast in handling
Sharpness: 9    Aberrations: 8    Bokeh: 10    Handling: 8    Value: 9    Camera Used: K1ii and K-01   

The A400 is a very nice and solid lens. I bought it as an upgrade for my K300 F4 and RMC Tokina F5.6. The A400 has better IQ then the K300 for aberrations and is a little bit sharper overall then theTokina is. All three lenses are sturdy build, the K300 has the nicest looks and the most attractive coatings. I had some fungus in the center between the front elements and I had to do some small destructive cutting to get it unscrewed, but it is fully operationalnow and very clear and bright. See also my post how I managed that.

K-01 shots both taken at F8, 1/180 sec (bright moon) resp 2 sec (blood moon). The latter is less sharp due to the movement of the moon...

Dec 2019 addition: I use it now on Full Frame K1ii,this lens even shines more on it then on APS-C. APS-C shots in fact are physical crops of what this lens was intended for. On full frame this lens delivers real nice equally sharp pictures on your screen.

Shot taken on 225 meters distance at F8 ISO 1600:

Cropped x5:

Senior Member

Registered: December, 2008
Location: Oxford, UK
Posts: 276

2 users found this helpful
Lens Review Date: April 21, 2010 I can recommend this lens: Yes | Price: $100.00 | Rating: 9 

Pros: Good IQ, good bokeh
Cons: Heavy
Sharpness: 8    Aberrations: 8    Bokeh: 8    Handling: 6    Value: 10   

I got it at an auction, so the $100 is an equal share of the price of the lot it was in.
I really, really like this lens. For me, it is definitely a tripod or mono-pod lens. As others have said, it gives sharp results and good colors. I like the bokeh.
This is one lens that I will keep until one of us can't take pictures anymore...

Shot was F8, ISO 100, 1/90.
New Member

Registered: November, 2009
Location: Temuco
Posts: 13

2 users found this helpful
Lens Review Date: November 9, 2009 I can recommend this lens: Yes | Price: $470.00 | Rating: 5 

Pros: Real long lens, at accessible price
Cons: Very soft at 5.6 and 8

On my search for something better than an 80-200mm zoom with 2x teleconverter for shooting birds, I finally decided on this lens. Indeed it's better than the above combination, as was to be expected, but at least the sample I got does not live up to the excellent reviews I have read before purchasing it.
My quality standards for any 35mm lens call for a resolution of at least 40 line pairs per mm, all over the frame. Below that level, slides look blurry when projected. This lens meets that standard, just barely, only at f/16. At f/11 it falls slightly short of this, but with some goodwill it's still acceptable. At f/8 and f/5.6, instead, it's totally unsharp. So, its rated 5.6 aperture is useful only for easier and more precise focusing, but cannot be used for actually shooting the picture - at least when good resolution is required.
At f/22 and further, of course diffraction becomes a problem, as with any lens. So, basically, use this lens always at f/16, or when there is very little light, f/11. The other aperture settings are basically decorative.
Given the very high cost of better quality long teles, I would still recommend this lens, but only to people to whom the above restrictions are acceptable.
Site Supporter

Registered: August, 2011
Location: Kansas City
Posts: 183

1 user found this helpful
Lens Review Date: May 20, 2013 I can recommend this lens: Yes | Price: $550.00 | Rating: 10 

Pros: Very sharp, comfortable handling, excellent image quality
Cons: None
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 10    Camera Used: K-5, MX   

I bought this lens from a fellow Pentax Forums member over the winter, and I have only recently had the opportunity to use this lens. I like to use a long lens to really throw the background out of contention when I want to isolate people at events and such. This weekend, I finally had my first opportunity when our city held its annual festival. With this lens, it was a piece of cake getting far enough away that people had no idea they were being photographed. I will admit at times it was nice to have this lens mounted on a monopod, mostly because I got a little tired after two or three hours of hand-holding it. That said, the built-in tripod mount collar provided a well-balanced mount. Whether hand-held or mounted, the lens was very easy and comfortable to work with. I was surprised to find that the focus ring was actually about as smooth as that of an internal-focus lens, and it made it very easy to focus precisely.

Since it is an A-series lens, it works great on my K-5 as well as on my MX. And the images are, in my opinion, pretty nice with decent bokeh and contrast and lovely color rendition. I was only able to detect the slightest chromatic aberration (see inset of picture below) from the hundred or so images I shot. Considering this lens does not boast ED glass, it's impressive that it out-performs my former Nikkor 300mm ED(IF) with regard to purple fringing (as well as overall image quality).

In short, this is a truly fun lens to use, and the image quality is excellent in my opinion.

Here are some shots from this weekend's festival. The first two shots were at f/6.3.

This next shot reveals a high-contrast area with purple fringing --

The rest of the shots, however, were just fine under close examination. This was shot wide open at f/5.6 --
Forum Member

Registered: August, 2007
Location: Cambridge, United States
Posts: 57

1 user found this helpful
Lens Review Date: January 6, 2010 I can recommend this lens: Yes | Price: $400.00 | Rating: 9 

Pros: Price for performance, build, contrast and colours, manual focus (good to learn on!)
Cons: Soft below f8, some purple fringing, manual focus (obviously)

I bought this lens paired with a 1.4x Pentax L converter (a magnificent piece of glass), principally for birding. The combination gives me great, fairly sharp, fairly slow, reach at a decent price.

I am pleased I bought it - I spent ages testing it and it was a close call based on sharpness, but with my tripod (Velbon CF 530 and Kirk Bh3 head - so a strong setup) I get images I like.

What I like:
It's a 400mm, and at f5.6 it's not terribly slow.
It's sharp from f8 onward, and can produce some seriously sharp images.
Manual focus means you have to work hard for good results. I like that in a lens because it means I practice good techniques (like checking focus before shooting).
The colours are beautiful (like so many Pentax lenses). I love how it renders green... a pretty important colour in wildlife photography.
It's well built and strong, all metal and glass.

What I dislike:
I wish it was a bit sharper wide open. But hey, don't we all.
There's purple fringing with strong backlighting. I don't really mind but it's something to think about.
Hit to miss ratio is pretty low, but that is down to technique as well as sharpness.
Manual focus!

The bottom line:
If you are patient and work hard this lens can deliver great results. Don't go tripod-less!

Some pics:
Site Supporter

Registered: June, 2008
Location: Florida Hill Country
Posts: 17,298

1 user found this helpful
Lens Review Date: July 7, 2008 I can recommend this lens: Yes | Price: $425.00 | Rating: 9 

Pros: sharp, good contrast, well made
Cons: long and heavy
Sharpness: 9    Aberrations: 8    Bokeh: 8    Handling: 8    Value: 9   

This is one of my 2 favorite Pentax lens (that I own anyway). If I didn't own a Tokina A 400mm f5.6 that was a bit shorter and lighter, I may not have given this lens a 10 because it deserves a 9.3 rating imho. Now that I have a k200d, I need to do a side by side comparison of these two lenses. This lens is tough to master hand holding but long lenses require practice in general. This lens features the F.R.E.E. arrangement.

Edit: A sample image.

I think the person above me's overall rating of 5 is ridiculous for this lens.
Veteran Member

Registered: July, 2007
Location: SouthWest "Regio"
Posts: 3,309

1 user found this helpful
Lens Review Date: April 4, 2008 I can recommend this lens: Yes | Price: $400.00 | Rating: 9 

Pros: high build quality, excellent sharpness and contrast
Cons: long, focusing slow

This lens is sharp and contrasty - in fact even more so, than the A* 4/300 I also use. So the optical parameters are really top notch. The build quality is typical for A-lenses: massive and made to last. Pentax for once decided to include the much needed tripod collar, though it should extend farther. As is, some tripod heads get in the way, if you use a camera + battery pack.
Despite the too basic tripod collar (which nevertheless is rigid enough), the only, but even more noticeable, drawback of the lens is its focusing mechanism. You have to turn the focusing collar nearly a full 360 degrees from infinty to the closest distance of 2.8 meters. That makes focusing slow.
If speed is not your primary concern, the lens is an excellent choice.
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