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SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW Review RSS Feed

SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW

Reviews Views Date of last review
13 73,112 Mon May 29, 2023
Recommended By Average Price Average User Rating
100% of reviewers $819.00 9.75
SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW


This lens was introduced in 2010 with the PENTAX 645D camera and incorporates a high-performance, hybrid aspherical optical element in its optics. On the 645D its field of view is that of a standard lens; on a 645 film camera it will be a wide angle lens. According to PENTAX this lens offers exceptional image-resolving power with outstanding brightness levels even at the edges, while compensating various aberrations to a minimum. All lens characteristics are optimized for digital photography: for instance, flare and ghost images are minimized by applying exclusive lens coatings to optical elements and employing anti-reflection materials for the interior of the lens barrel. As the result, this lens can bring out the full potential of the PENTAX 645D medium-format digital SLR camera.

The lens covers the full 645 format and can thus be used on 645 film cameras as well as on 645 digital cameras.

The lens has a built-in motor (SDM) for the autofocus function. On a 645 film camera the lens can be used in manual focus mode only, and only in P and Tv exposure modes due to the lack of an aperture ring.

smc Pentax-D FA 645 55mm F2.8 AL[IF] SDM AW
©, sharable with attribution
Image Format
645 film
Lens Mount
Pentax 645
Aperture Ring
Automatic, 9 blades (rounded)
9 elements, 7 groups
Mount Variant
645 AF2
Check camera compatibility
Max. Aperture
Min. Aperture
AF (in-lens motor)
Min. Focus
50 cm
Max. Magnification
Filter Size
67 mm
Internal Focus
Field of View (Diag. / Horiz.)

645 Digital: 53 ° / 44 °
645 Film: 65 ° / 54 °
Lens Cap
Plastic clip-on
Aero Bright,SMC,SP
Weather Sealing
Yes (AW)
Other Features
AF/MF Switch
Diam x Length
81.3 x 68.2 mm (2.7 x 3.2 in.)
416 g (w/o attachments) (14.7 oz.)
Production Years
2010 to present (in production)
$999 USD current price
Engraved Name
smc PENTAX-D FA 645 1:2.8 55mm AL[IF] SDM AW
Product Code
User reviews
No AF on film bodies.
AL lens elements.

Supersonic AutofocusQuick ShiftWeather SealedInternal FocusingAutomatic ApertureMedium-Format SupportAdapter needed for DSLRs
Purchase URL: Buy the SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW
Sample Photos: View Sample Photos
Price History:

Add Review of SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW Buy the SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW
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amateur dirt farmer

Registered: December, 2014
Location: probably out in a field somewhere...
Posts: 39,896

1 user found this helpful
Review Date: May 29, 2023 Recommended | Price: $395.00 | Rating: 9 

Pros: color, clarity, bokeh, rendering - all amazing...
Cons: MFD is a bit long...
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 9    Value: 9    Camera Used: 645D   

this is an epic lens that mates perfectly with the 645D, and brings out everything that I love about working with the 645D

as expected for a 'modern' medium-format lens, it's sharp, contrasty, makes beautiful bokeh, the AF is reasonably quick...

the lens' MFD is a bit long at 18" or so, but it's so sharp you can crop as much as needed...

I carried this combo all over this past month and it's been a joy, every time I pick it up...

some of my favorites this month:

sunset by Pepperberry Farm, on Flickr (this one hit 'explore')

ornate tortoise by Pepperberry Farm, on Flickr

cottontail by Pepperberry Farm, on Flickr

thistle by Pepperberry Farm, on Flickr

daisies by Pepperberry Farm, on Flickr

wildflowers, abandoned lot by Pepperberry Farm, on Flickr

and the rest of my flickr album for this lens:

simply put - if you are shooting with either a 645D or Z, this is the walk-around lens to have....
Loyal Site Supporter

Registered: October, 2018
Location: Quebec City, Quebec
Posts: 6,294

1 user found this helpful
Review Date: October 13, 2021 Recommended | Price: $550.00 | Rating: 10 

Pros: Very sharp, light, natural FOV
Cons: Expensive
Sharpness: 10    Aberrations: 10    Bokeh: 9    Handling: 10    Value: 9    Camera Used: 645Z   

A couple of weeks ago, I went to take pictures on the western tip of Isle d'Orleans with a view towards Quebec City. I used my old A 55 mm f/2.8 manual-focus lens and was disappointed with the results. The lens seemed weak at gathering far-away details, despite being on a solid Manfrotto tripod, stopped-down to middle apertures and carefully focused at infinity. When I saw this offering on eBay in Japan, I could not resist and ordered it. It took a week for it to reach Canada from Japan via FedEx because of our Thanksgiving weekend. As soon as I received it, I inspected it carefully. All seemed perfect, AF working silently and precisely, the glass glowing bright and impeccable and the diaphragm closing as expected. I set out to test it on the Ste Anne River, which I had not yet visited this year.
I mounted the 645Z on the tripod, set the ISO at 100, put the camera in Av mode and took a series of 7 images, starting at f/2.8 and going down to f/22. Here are my findings : f/2.8 and f/4 are usable but resolution is not at its best for landscapes; performance is pretty much uniform between f/5.6 and f/22 with, IMHO, f/16 providing the ultimate edge-to-edge resolution. Contrast and sharpness are a joy to observe and colors are typical warm Pentax rendering. I then turned the head of my tripod about 45 degrees to the right and captured an aspen in yellow autumn garb, its leaves trembling quietly in this year's unusually warm wind. Great colors and very high resolution, AF reaching correct focus without any problem. All in all, an excellent lens no landscape artist should be without.

I toured Isle d'Orleans in mid-october and gathered a few additional colorful pictures with the DFA 55 mm f/2.8 AL :

Two more images of the Sainte Anne River :

And three of the St Lawrence at sundown :

I should have bought one sooner !!

New Member

Registered: January, 2021
Location: Pianezza (Torino -Italy)
Posts: 23

4 users found this helpful
Review Date: January 23, 2021 Recommended | Rating: 10 

Pros: Resolving power, three-dimensionality
Cons: None
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 10    Camera Used: 645D   

I've been trying it for a few days "in the real world" and I must say that (even if I come from full-frame reflex), I was amazed at the results especially on A3+ prints.
The image is truly three-dimensional and the colors very realistic.

Junior Member

Registered: August, 2019
Posts: 25

1 user found this helpful
Review Date: December 18, 2019 Recommended | Rating: N/A 


Site Supporter

Registered: February, 2018
Location: NoVA
Posts: 635

3 users found this helpful
Review Date: May 15, 2018 Recommended | Price: $439.00 | Rating: 10 

Pros: Surgically sharp without being harsh
Cons: None
Sharpness: 10    Aberrations: 10    Bokeh: 8    Handling: 10    Value: 9    Camera Used: 645z   

Exceptionally good lens. I test images based on the default raw processing settings of DXO Photolab, and this lens is in their database, so distortion and lateral color are automatically corrected. I tested this on a 645z. My test scene is not flat, so field curvature may work to my advantage, as in the real world.

My testing is nowhere as rigorous as doing star tests at f/2.8 in the corners. But I would be happy to make a 16x20 print from an image made at f/2.8, and I would have confidence that it would retain my required sense of endless detail at any viewing distance. 1:1 on the screen matches the full image quality of many smaller format lenses. A 60"-wide print would reveal pixels to the close-up viewer, but not lens faults.

I bought this lens primarily to have a weather-resistant lens for my new 645z, but this lens really delivers and I will look for opportunities to use it even when it is not raining. Mine is a bit knocked about, and I bought it used in "V" condition from Adorama.

Focused details are sharp to the pixel at any aperture down to f/16, after which diffraction has its effects. Bokeh is typical for double-gauss lenses. But it doesn't matter--like a really good plasmat on a 4x5 camera, this lens will want you to make the image sharp.

Edit: Here are some images:

Test scene, full frame, at f/11. Lighting was very flat, and I've done nothing to make these images look better.

1:1 center crop, f/2.8:

1:1 center crop at f/11:

In those crops, the only thing that improved was the depth of field.

Rick "seeing large-format-worthy results from this lens" Denney
New Member

Registered: October, 2016
Posts: 2

3 users found this helpful
Review Date: October 13, 2016 Recommended | Price: $1,047.00 | Rating: 9 

Pros: Superb overall optical performance from 5.6
Cons: Not quite up to wide-open star capture work, hard to focus for wide open at infinity
Sharpness: 9    Aberrations: 9    Handling: 8    Value: 9    Camera Used: 645Z   

I just carefully examined the optical performance of three copies of the 55 D-FA lens on a 645Z body. By any traditional, fussy standard, all three copies were exceptionally fine lenses, in my tests being essentially perfect from corner to corner from f/5.6 on up.

But my hope for these lenses was to find one which would serve as a fine lens for super low light capture (stars), being actually capable of a strong performance in all four corners wide open at f/2.8. All three of the lenses had at least two sharp corners wide open. Two had, arguably, three sharp corners. All showed a fairly modest loss of contrast wide open, what one might call a smeary effect, but it wouldnít, I think, prove to be problematic for stars. Dark wires against a blue sky turned blue from sky light spread around, but that effect went away by 5.6 when stopping down.

Wide open, specular highlights in the corners showed obvious coma, changing a small spot into a little triangular spaceship pointing toward the optical axis. With each successive stopping down, that improved, to the point where it was gone at 5.6. It may be the case that only brighter stars would show any coma, as some of the specular reflections showed less of it, but note that my 35A lens shows none of this wide open at f/3.5. My better of two copies of the 35A lens (which is much sharper in four corners on a 645Z than one 35 FA lens I tested recently) is much more smeary in the corners wide open than the 55 D-FA lenses are (design is), but Iím hoping that wonít hurt too much with stars. The 35Aís falloff wide open is about 1.3 stops but Iím leaning toward using it wide open the next time I have a chance with stars, instead of using it at between 4.5 and 6.8. It is fully sharp and well-behaved starting at 6.8.

Itís important to note that these lenses, designed to cover a 70mm film image circle, are very well-behaved in the corners when illuminating the 55mm diagonal of the 645Z sensor with respect to both falloff and optical aberrations, which is great and quite distinct from the overwhelming majority of lenses built for full-frame cameras. Even so, working at f/2.8 is more or less asking the impossible, yet that is what night sky photography more or less demands, as itís not far from a million times darker than daytime outdoor work.

I had hoped that using one of the 55mm lenses would give me closer to 2 stops of net speed in star photography than the 35A lens, but given the corners of these three samples, I couldnít achieve that. A perfect copy might do it, but only with some coma issues. Most likely I would use stitching to combine multiple 55mm exposures, and/or sets of perhaps 8 exposures per frame, used for averaging to reduce noise from exposing at 1600 to 3200 ISO. I may use an equatorial mount, but if not, exposures with the 35A lens will be 8 seconds apiece to limit star trails. (Eight exposures at 8 seconds each) With an EQ mount, exposures might be 1 to 5 minutes instead, or they might still be eight exposures at somewhere between perhaps 8 and 30 seconds. I donít know yet whatís the best way. With the 645Z, it seems to work better to leave Long Exposure Noise Reduction (LENR) turned off (Firmware v1.22).

I actually observed some corners have quite mild curvature of field and others not, within the same lens. And even more surprising was that I saw opposite corners doing this, which is something Iíve never seen before with other aberrations. De-centering defects seem to always cause only adjacent corners to be degraded, never opposite ones. And cornersí being cruddy is by far the #1 optical defect class that I look for when testing lenses. I donít worry about on-axis sharpness, as sharpening readily overcomes any on-axis issue that Iíve ever seen (ignoring axial CA, which Iíve not found troubling, in general). None of the observed curvature was very significant, mildly so wide open, but perhaps only a tenth as strong as Iíve seen with some lenses. This issue may depend on spacing errors between elements, but it does also seem to vary from copy to copy, sometimes in a large way with some lens designs. A Rodenstock 35 HR lens, at one point the best wide angle ever built according to the specs, had severe curvature, in focus at infinity in the center but 30 feet in the corners wide open, and some lenses are worse than that. The 55D-FA curvature was perhaps 200 feet in the center and 160 feet in the corners, when it was present at all. Iíve not once seen curvature in the corners that puts the plane of focus further away, always closer. There have been reports of severe curvature with some copies of this lens, so just be on the lookout for it, but in the sample images Iíve seen from five copies now, Iíve not seen anything beyond very mild curvature if any (again, varies by corner, by lens).

I also found it remarkably difficult to focus with adequate precision, using Live View zoomed in to 16X, focusing on the top of a telephone pole about 200 feet away, my favorite lens testing subject matter (often handy, take five shots, center-focused on the pole top in the center, then re-aim to place the pole top in each corner in turn, with no change in the focus setting. The Live View image just isnít sharp enough for nailing it at 2.8 reliably.

The slight movement of the plane of ideal focus behind the pole top when itís in the corners (think about the geometry) is always overwhelmed with other issues so this works out OK with short or long focal lengths, even at f/2.8, when your goal is to have superb infinity corner to corner sharpness). These D-FA lenses do not have an infinity stop (being AF lenses) but the A, fixed focal length lenses do, and those which I own have all shown their infinity stops to be dead on accurate. The two A and FA zooms that I use are a bit off that way and a tiny bit variable too, but basically I can use barrel mark alignment to focus at infinity for non-starry sky work. I really donít know whether a D-FA lens can be reliably focused in near total darkness. I have not been able to do enough testing to verify that, because my own 645Z body has experienced an electronic failure which had made Automatic aperture control malfunction, stopping the attached lens down all the way for every exposure, regardless of aperture setting. I therefore use the manual aperture ring on the lens for all work. The camera repair would be over $800 and likely take many weeks (ship to Precision Camera in Connecticut, ship to Japan, repair, back to the east coast, then back to me). Their flat fee for all 645Z body repairs (or they may increase the cost, depending) strikes me as excessive, and their phone support is frightful. No email responsiveness either. Perhaps if itís true that all 645Z body repairs go back to Pentax in Japan, we can at least trust that repairs will always be done well.

I would focus with the Live View, carefully, only to find that I was 20 or 30 feet shy of the 200-foot correct distance fairly frequently. Not a lot under most circumstances, but when shooting at 2.8 for this kind of test, a big enough error to mess up the test and to mess up stars. I donít expect AF could possibly be useful in the dark, but the infinity mark on the barrel might.

Perhaps somewhere in the world I might find either a 45A or 55A lens that is actually sharp in all four corners wide open. I think itís unlikely, but if so, Iíd like to have it for the occasional night sky picture, to get more speed, which in star photography comes from both the f-number and the clear aperture (meaning that the longer the focal length, the brighter a star will be recorded with the same f-number, because itís almost a geometric point, which is all rather strange). Failing that, Iíll stick to my 35A and make do with the combination of a not-very-bright lens and perhaps the worldís greatest sensor. With the right technique, it can produce pretty good quality night sky noise and detail levels at high resolution.

After writing that I realized that I should consider using my 75A lens, another 2.8. I had dismissed the possibility since itís so long, but if one is going to stitch an image which isnít super wide, that could be fine, especially when one has an EQ mount (clock drive), which I recently acquired, the Sky Watcher Star Adventurer Photo Package. It turns out the 75A is a real champ. By varying the degree of sharpening for different parts of the image, itís pretty darn good wide open and really beautiful, not quite perfect, at f/4.0 (first click down). Falloff wide open is only 0.85 stops and only a third of a stop at f/4. Distortion is close to zero, FWIW. And the ďclear apertureĒ is huge, 27mm or so, which should make it great for seeing lots of stars, brightly. Stars are weird that way. Semi-geometric points. Were it not for the atmosphere and the camera, they would be geometric points, essentially. The actual disks of stars are on the order of 50,000X smaller in diameter than they appear. I digress, but this and the prospect of compromised performance of the 35A when wide open is why I held out hope for the 55 D-FA to be effectively two stops brighter than the 35A.

So, the 55 D-FA is great, but as always, immediately, carefully check the corners with contrasty subject matter and expect them to all be superb on the plane perpendicular to the optical axis at 5.6 and smaller, focused at more than 20 feet away, or send it back. Not exactly the same as the center but beautiful. Most lenses can only dream of being that good. Usually to have that be true at f/8 is excellent.

Here is a 100% section from the center of one of the lenses, with no sharpening and accurate focus, wide open:

And here is a 100% section from the top right corner of the same lens, with no sharpening, also wide open:

Finally, here is that same top right corner, sharpened (hopefully these last two are not mixed up, it's hard to tell with the posting system since they look the same as a thumbnail and the file names are changed...):

This corner was typical of the better corners of this lens. I find it likely to be usable for stars (at 2.8), though we can see that the roundish spots of specular highlight on the insulators have been morphed into curvy triangles from coma and the darker shapes are tinted blue from the surrounding sky. The worst corners were unsalvageable when exposing wide open. Again, all four corners looked great at 5.6, no more blue shadows, no more coma, contrast way up there, corner sharpness quite uniform. Minor focusing errors are overwhelmed with more DOF as well.
New Member

Registered: November, 2015
Location: Walnut Creek, California
Posts: 23
Review Date: January 31, 2016 Recommended | Price: $840.00 | Rating: 10 

Pros: Great Performer & Lightweight
Cons: None that I can find
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 10    Camera Used: 645z   

Great lens and the second most used lens in my kit. Great image quality, and well balanced on the 645z.

Discovered a bonus with the lens hood by accident, and I thought I had broken a piece off - then realized the tab that had come off in my hand allowed a polarizer to be adjusted with the hood attached. Nice touch.

Senior Member

Registered: May, 2011
Location: Hanoi
Posts: 213
Review Date: August 27, 2015 Recommended | Price: $1,000.00 | Rating: 10 

Pros: fast autofocus, lowlight; sharpness
Sharpness: 10    Aberrations: 10    Bokeh: 9    Handling: 10    Value: 10    Camera Used: Pentax 645Z   

I totally amazed with the speed autofocus, I got positive experience with the autofocus of 645D, but when DFA 55mm f2.8 SDM combined with 645Z it becomes the better combo.

Nadia by mujahideen's, on Flickr

Nadia, on Flickr

Alexandra, on Flickr

Alexandra, on Flickr

Thuy Linh, on Flickr

Thuy Linh, on Flickr
Loyal Site Supporter

Registered: January, 2009
Location: East Bay Area, CA
Posts: 6,570

6 users found this helpful
Review Date: July 2, 2013 Recommended | Price: $1,000.00 | Rating: 10 

Pros: stunningly sharp and compact size
Cons: price
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 9    Camera Used: 645D   

wow, I was not prepared to be so impressed with this lens. Everything about it seems to be well considered and executed. Sharpness is wonderful as is bokeh and contrast. The 9-blades make lovely 18-pt stars too. I find no detectable CA issues and though I am not an AF user for the most part, when I need it, the AF is smooth and silent via SDM. Lens is well constructed and lightweight. highly recommended.

single exposure, single frame:

single exposure, single frame

This is a 4-frame pano shot with the D-FA 55/2.8
Forum Member

Registered: July, 2011
Posts: 72

2 users found this helpful
Review Date: August 11, 2011 Recommended | Rating: 10 

Pros: light weight, nice bokeh, sharpness, fast
Cons: maybe the price
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 10   

I think the built quality of this lens is really great. It feels very light but durable. The performance is also very good even wide open. Here it outperforms the 75mm A easily with better sharpness and bokeh. Stopped down to f/8 both perform very similiar.
The price is pretty high compared to the older Pentax lenses. But compared to the Canon lineup this one is a bargain.
This was my first lens for the 645D and I still love it.
New Member

Registered: July, 2011
Posts: 5

3 users found this helpful
Review Date: August 11, 2011 Recommended | Price: $1,100.00 | Rating: 10 

Pros: bokeh, fast
Cons: price, agree..big lens hood for this focal length
Sharpness: 9    Aberrations: 8    Bokeh: 10    Handling: 10    Value: 9   

Solid. Beautiful beatiful bokeh, that's been the most pleasing thing. Fast and good results wide open. Some very minor chromatic aberration in very high contrast, magnified shots. Expensive, but highly recommend. A touch more flaring than I expected for a modern lens, but minor and manageable, I'm nitpicking. My 9 rather than 10 on sharpness is probably more 645d system than lens. I've done no technical testing. Practical shooting, tripod, monopod, handheld, keep in mind this is a heavier system with a big mirror.
Veteran Member

Registered: February, 2011
Posts: 573

2 users found this helpful
Review Date: April 25, 2011 Recommended | Price: $1,000.00 | Rating: 9 

Pros: Sharp, fast, and weatherproof
Cons: Big lens hood

This is a nice lens and matches the 645D body very well. The AF is quiet and manual focus is easy. There must be use of polycarbonate materials in the design because Pentax has kept the weight down, which is good. Solid construction.
New Member

Registered: April, 2010
Location: London, UK

3 users found this helpful
Review Date: August 8, 2010 Recommended | Rating: 10 

Pros: Standard lens for 645d. F2.8. SDM AF. Sharp and smooth.
Cons: No aperture ring.

This is the normal/standard lens for the 645d. It produces images just like the FA 43/1.9 for 35mm. Extremely sharp, lovely colours, smooth bokeh. Fast for a medium format lens. AF virtually silent. Has quick shift / manual over-ride of AF. Weather proofed. Balances nicely with 645d. Feels well built. Useful close focus of 0.5m What's not to like? No aperture ring - may be missed by some.
Add Review of SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW Buy the SMC Pentax-D FA 645 55mm F2.8 AL [IF] SDM AW

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