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SMC Pentax-A 400mm F5.6

Reviews Views Date of last review
19 91,385 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
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 16-19 of 19
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:
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: 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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