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HD Pentax-DA 645 28-45mm F4.5 ED AW SR

Reviews Views Date of last review
7 40,341 Thu March 18, 2021
Recommended By Average Price Average User Rating
100% of reviewers $4,219.20 9.17
HD Pentax-DA 645 28-45mm F4.5 ED AW SR

HD Pentax-DA 645 28-45mm F4.5 ED AW SR
HD Pentax-DA 645 28-45mm F4.5 ED AW SR


The HD Pentax-DA 645 28-45mm F4.5 is a wide-angle zoom for digital Pentax medium format cameras, such as the 645Z and 645D.

This lens features the latest Pentax lens technologies, including HD and Aero Bright (nano) coating, DC in-lens autofocus, Super Protect front element coating, and in-lens Shake Reduction.

It corresponds roughly to a 22-36mm zoom on 35mm film and offers a diagonal field of view of 89-63 degrees.  You may wish to consider this lens if the SMC Pentax-DA 645 25mm F4 AL [IF] SDM AW is too wide or restrictive for your needs.

The US retail price is $4999.  In the UK, the lens retails for 3399 pounds.

HD Pentax-DA 645 28-45mm F4.5 ED AW SR
©, sharable with attribution
Image Format
645 digital
Lens Mount
Pentax 645
Aperture Ring
Automatic, 9 blades (rounded)
17 elements, 12 groups
Mount Variant
645 AF2
Check camera compatibility
Max. Aperture
Min. Aperture
AF (in-lens motor)
Min. Focus
40 cm
Max. Magnification
Filter Size
82 mm
Internal Focus
Field of View (Diag. / Horiz.)

645 Digital: 89-63 ° / 76-52 °
Lens Cap
F 82 mm
Aero Bright,HD,SP
Weather Sealing
Yes (AW)
Other Features
AF/MF Switch,In-Lens Shake Reduction,Internal Zoom
Diam x Length
99 x 151.5 mm (3.9 x 6 in.)
1470 g (w/o attachments) (51.9 oz.)
Production Years
2014 to present (in production)
$4996 USD current price
Engraved Name
HD PENTAX-DA 645 1:4.5 28-45mm ED AW SR
Product Code
User reviews
No autofocus on film bodies.
Two high-performance aspherical elements and two ED (Extra-low Dispersion) elements.

Supersonic AutofocusWeather SealedInternal FocusingAutomatic ApertureMedium-Format SupportAdapter needed for DSLRs
Purchase: Buy the HD Pentax-DA 645 28-45mm F4.5 ED AW SR
Price History:

Add Review of HD Pentax-DA 645 28-45mm F4.5 ED AW SR Buy the HD Pentax-DA 645 28-45mm F4.5 ED AW SR
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Junior Member

Registered: August, 2019
Posts: 25

2 users found this helpful
Review Date: March 18, 2021 Recommended | Rating: N/A 



Site Supporter

Registered: February, 2018
Location: NoVA
Posts: 635

4 users found this helpful
Review Date: December 10, 2018 Recommended | Price: $3,000.00 | Rating: 10 

Pros: Sharp, sharp, sharp. No aberrations that I could find.
Cons: It's a beast. Corners soft at f/4.5 and 28mm, but fine by f/5.6.
Sharpness: 10    Aberrations: 10    Bokeh: 7    Handling: 7    Value: 8    Camera Used: 645z   

I purchased a pre-owned lens from Adorama at a good price, and the lens turned out to be a problem performer. It was fine at some angles, but when level on the tripod, aimed at my test scene, it did not match the performance of either the 35mm prime or the 45mm end of the 45-85 zoom, and it missed by a mile. My suspicion is that something that is supposed to not be loose was, and fell out of alignment under certain conditions and into alignment at other times. Adorama took it back without a hiccup, and I sent that money to Australia to a forum member who offered me his lens instead. The beast was proving physically unmanageable for him, and I can understand that. It is indeed a beast, as all who have reviewed it will confirm. But compared to my Sinar P, it's light as a feather. And compared to a Zeiss Jena 180mm f/2.8 Sonnar (or, Heaven forbit, the 300), it's not particularly beastly. Put that Sonnar on a Kiev 60, and carry that around for a bit. Or a Pentax 67 with a 300mm lens and TTL finder. You'll never complain about the 645z again.

But I do consider carrying it around as part of my workout regimen. I warm up using my dumbbells, usually in the range of 35-50 pounds each, as a warm up for the big lift of carrying this puppy. Okay, it's not that bad, but it will still be favored by those who work out in the gym.

Today I made new test photos with the replacement lens, and conditions were a bit more like my original test in terms of lighting. It was a gray day just as it was in the late spring when I tested the other lenses in this series. But unlike that prior occasion, it never made it above freezing here so the camera got a bit of a cold-weather workout. The winter conditions also mean that the bushes and trees at Chez Denney are more leafless than in prior photos.

Here's a general view at 28mm:

As before, these are straight out of the camera, processed in DxO Photolab with the driest possible settings.


Here's a 100% crop from the middle of the image, at f/4.5. Remember that these 1:1 crops, when displayed on a typical monitor at 100 pixel/inch, are part of an image seven feet wide.

One of the tests of a zoom is whether it's better to carry a range of primes. The only good prime that competes at this end of the zoom range is the DA or DFA 25mm lens, which is of course no longer in production. The only lens I have in my collection that hopes to compete at this focal length is an Arsat 30mm Fisheye. So, what the heck, let's show the center crop from that lens (which is itself also a beast). Here is the image made at f/11, so we are comparing the best aperture of that lens with the wide-open aperture of the 28-45.

The Arsat doesn't stand a chance. But if you need a fisheye, and only a fisheye will do, then the Arsat is one.

But the real test of a wide-angle lens is in the corners. Is there field curvature? Does the sharpness hold up in the corners? Let's look. Here's the lower right corner:

This isn't curvature--it's just loss of sharpness in the extreme corner at f/4.5. But this IS just the very corner--compare this with the full image above. We're talk the four or five inches from the corner on that seven-foot print. This loss of sharpness in the corner nearly completely cleans up at f/5.6, and we'll look at f/8 further down and see that the effect is completely resolved once we've stopped down a bit.

What about curvature: Here's the upper left corner:

The branches you see are about in the focus plane, and they are sharp. The loss of sharpness that would correspond to the lower right corner is suffused into the bit of house that is quite out of focus. I don't see evidence of curvature here.

And here's the lower left corner, which was generally sharp with the FA35 (which is known for curvature). The field looks acceptably flat at 28mm.

While we are at 28mm, let's look at several apertures and see if we can determine the ideal aperture. Here's the center again at f/5.6:




And f/22:

There is no practical difference between f/4.5, 5.6, 8, and 11 in the center of the image and in the focus plane. F/16 starts to degrade slightly, though I may be imagining it, but not enough to keep me from using it even for a large print. F/22, though, would allow only a more subdued print size. But insufficient depth of field trumps diffraction.

Before moving away from 28mm, here's the lower right corner at f/8:

At f/8, it's sharp right to the corner.


I'll spend less time at longer focal lengths now that we know the basic behavior of the lens. Questions for 35mm: Does it out-perform the FA35mm prime lens? Are the corners better than at 28?

Here's the center at f/4.5:


And at f/8:

Here is the FA 35/3.5 at f/11:

This makes me want to check that f/8 exposure, which is very slightly softer than the f/4.5 image. F/5.6 is the clear winner of all of these, but the 35 may be diffracting a touch at f/11. The 35mm prime is very good in the center, but it's not better than the zoom. It is a LOT cheaper, though.

Here is the upper left corner at f/8:

Again, no sign of field curvature. The branches and dead leaves are close to the focal plane. The wood at left is only five feet from the lens, and the background pines are three times as far as the focus plane. There is a touch of movement blur here--shutter speed was 1/13 second. The camera was, of course, mounted on a tripod, but that river birch tree will move in not much breeze.


Center of the image at 1:1, F/4.5:

Here's the 45-85 zoom at 45 and f/4.5:

The 45-85 is stunningly good, especially at the short end. The 28-45 is a bit better.

Here's the same comparison at f/8:

Again, the 45-85 is outstanding, and the 28-45 is a bit better.

Finally, a word about focus accuracy. This lens front-focused very slightly, and I set the focus adjustmentment for this one to -3.

In conclusion, a good example of the 28-45 is an amazing performer. I tested the failed lens for details about shake reduction, but I did not test again here. I find that shake reduction is good for about a stop, but I did not use it in the above images that were made on a tripod using mirror pre-release.

But these lenses are not bullet-proof. If you buy one pre-owned, test it.

Rick "just about thawed out" Denney
New Member

Registered: September, 2016
Posts: 8

3 users found this helpful
Review Date: July 14, 2017 Recommended | Price: $3,500.00 | Rating: 9 

Pros: Sharp, good range at wide end
Cons: Heavy
Sharpness: 10    Aberrations: 9    Bokeh: 9    Handling: 8    Value: 9    Camera Used: 645Z   

I got his lens 2nd hand after trying to get the 25mm prime and failing! I already have a 35mm prime and I was looking for something a little wider for interiors and exagerated perspective/foreground detail

I finally got to use this lens for a full week attached to a 645z, leaving it attached most of the time. I spent a week walking about various locations with camera in hand for 3-6 hours at a time, it became tiring on shoulder strap, switch to carrying in the hand was better but at the end of the day some discomfort. The problem is that this is a lens you proably do want to leave attached. I need to look for a wider more comfortable strap.

You can read other reviews about the detail of the image quality all I will add is that Image quality is completely satisfactory for all practical usaes. A little less contrast than the 35mm prime, pretty flat field, surprising in the range. All images totally usable including those shooting with glare (since it showed as overall loss of contrast not patterns).

SR is very handy particlarly shooting inside without flash and seems to work well. It was also handy walking around a garden using a polarizer and ND grad, at ISO 100 f/8 I was shooting at about 1/30 but SR did cope with that fine.

One note about SR on the 645z though - when I previewed the detail info on my first few hours shots I noticed SR was "off" (and I couldn't make it come on), The root cause turned out to be that I often shoot with a tripod so I leave the camera configured for either IR remote or shutter release; it turns out that enabling IR/Timer etc. disables the Shake reduction. It sort of makes sense but it does mean that I have to get out of the habit of leaving the remote enabled. Turned of the IR function and the SR is back on!

I own the 35mm prime too, so an issue for me is if the added flexibility of a 28-45 zoom is worth the trouble? I reviewed the 400ish shots: I used 28 quite a lot, particularly for interiors, courtyards and to pick out the more sculptured parts of landscape gardens particularly lead-in lines, the rest at about 40-45, I am not realy using the part of the zoom range between 28 and 35, I think once you get that wide it is about style and perspective so you go to 28 and walk to get the composition! The downside is that I became a bit lazy when I needed something in the 70ish range, I simply shot 45 to crop! On more general landscape, people and lakes I only made occasional use of the 28mm end for added drama/ perspective. (Although about 100/400 shots were in the range 28-31mm, only 9 of the 60 "picks" were that wide, all the rest were longer than 35mm)

In conclusion then Is this a perfect walk-about lens for me? No, it is not long enough for that, but 45 is long enough that I am perhaps compromising in the 50-80 range instead of swapping lenses. I think this lens makes sense for some environments (interiors) but I shall proably use a lighter mid range lens and pull this out of the bag specifcally for those very wide angle needs. If there were a light prime in the 25-28 region I would us that instead

This lens does not add a lot of convenience unless you shoot in the wide to normal range, otherwise the range is not long enough, but it does mean no lens swapping in the wide-normal range (say 28-50mm). For me the bukiness seems to discourge lens changes and I seem to need a longer lens quite often so it is just like having another (big) lens to swap

Of course it does provide an upper body workout!
Forum Member

Registered: January, 2013
Location: Dallas, TX
Posts: 71

4 users found this helpful
Review Date: May 1, 2015 Recommended | Price: $4,600.00 | Rating: 10 

Pros: color, sharpness, 28mm is wide!
Cons: size, price
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 8    Value: 8    Camera Used: 645D   

Yes, it is large, but okay for handheld photography. SR is really effective, and stabilization effects in viewfinder is noticeable even for such a wide angle.

At 28mm it's much wider than I thought. Maybe because of 645 format rather than 3x2 format.

Upon initial inspection, sharpness is extremely high at the center as well as corner on 645D. CA is non present and minor distortion is there. Seems very uniform which is very easily corrected.
Junior Member

Registered: April, 2015
Posts: 47

3 users found this helpful
Review Date: April 28, 2015 Recommended | Rating: 9 

Pros: Incredible edge and corner sharpness
Cons: size, some distortion
Sharpness: 10    Aberrations: 9    Bokeh: 7    Handling: 7    Value: 8   

I was expecting a large lens and had read up lots in advance, but nothing prepared me for the sheer massiveness of it. It is genuinely enormous and every bit as large as a 35mm 70-200 f2.8 and much bigger than my 70-200 F4 lens. It handles fine in terms of what falls to finger, but the bulk is something to get used to. Tripod use will be interesting due to the lack of a collar, but I bought this lens for its range but also the fact that it can be used handheld, so very glad of the SR. I'm sure the tripod side will work fine.

Considering what the lens is doing (22-36mm equivalent, but on a larger sensor), image quality is nothing short of astonishing. Its tack sharp on centre from wide open and sharp right into the corners at close distances. Over long distances, it needs some stopping down, but is super-tight from f8 onwards at all focal lengths. It is so crisp that at f9.0, it is very hard to discern the edges from the centre.

Contrast is very good and viewed through the 645Z, the image is extremely bright, colourful and contrasty. I have not fully tested the SR in real terms, but it clearly works well and I can shoot at significantly lower speeds than my A7R with non-stabilised lenses.

This is a very complex lens and it changes character somewhat through the focal range and distances. I think there is curvature of the plane of focus towards the photographer at the edges, at distance, but very little up close. As I say, stopping down to f8 sort its out for landscape use and it is a no excuses lens. Simply amazing image quality that puts most prime lenses to shame. Diffraction comes into play by f11 on centre, but its very slight and f16 is still fairly respectable, so a lens I am happy to use anywhere from f8-f16 for landscapes, but with the aim of being around f8-11 if possible.

Its nice to see that it does not fall apart at one end of the range. I need to get to know it better, but from what I have seen it performs just as well at either end really (and in the middle).

CA is very well controlled, but distortion is quite noticeable at the wide end, though the profile in LR sorts that out nicely.

Massive and heavy, but it gives the sort of performance at landscape apertures I would expect from a Zeiss prime on full frame and clearly outperforms my 35mm f2.8 Sonnar for the A7R on a per pixel basis, around the edges and corners. It is closer to the 55mm FE Sonnar in sheer perfection, only it takes more stopping down to get there.

Mine was bought at a great discount with the 645Z and I cannot imagine what it would cost to have this sort of performance from Phase One or Hasselblad. Considering that even at the RRP it costs no more than a Leica 35mm f1.4, I consider it fairly good value for money.

Pentax have made the right decision making it big, because they have clearly ensured that it is optically astonishing and I have no doubt that this lens will still look very good on the next generation of sensors well in excess of 50mp. SR will have made it fatter, but for hand held work, it may be heavy, but can very clearly be used like a 35mm camera. Combined with the 645Z's ISO performance, its shooting envelope is huge.

I still can't get over the size of the thing, but I cannot stop looking at the perfect test frames it has delivered either.

Site Supporter

Registered: March, 2007
Location: Tucson
Posts: 292

2 users found this helpful
Review Date: January 15, 2015 Recommended | Price: $4,996.00 | Rating: 8 

Pros: sharp, good contrast, anti-flare coatings
Cons: large, heavy, narrow hood I.D.
Sharpness: 10    Aberrations: 10    Bokeh: 9    Handling: 6    Value: 7    Camera Used: 645Z   

This is a re-post from the Medium Format Forum, after renting the lens. The cost indicated is what B&H wanted at the time.

For me, this seems to be the ideal focal length range for landscapes on the 645Z, perhaps a little wider would be better, but this would do. Reading this forum, and people's comments on the size and heft of the lens, didn't prepare me for what I was about to experience.

It arrived Wednesday from Lens Rentals in a plain brown box. The box had a foam liner with a hole big enough for a Sigma Bigma, to fit. Inside that was the lens, with hood, inside its pouch. The lens cap looked like it came from a 1990's vintage Pentax lens, but the rest of the lens, and hood, looked new.

I put the lens on the 645Z and went out to the yard to take a few quick shots. I find the camera to be very nose heavy with this lens on it. The quick shots revealed the lens to be very sharp, and the new HD coatings do a nice job of reducing lens flare. Shots with the sun in them were very clean.

Back-lit Pomegranate Flower (28mm)

Since I'm a landscape photographer, and a big part of that is getting the equipment to the locations I want to shoot, I figured a good test would be to hike to a familiar spot. The spot I chose was a place known as "First Water", on the Mount Wilson Trail, in the Angeles National Forest here in Southern California. The hike to First Water is 1.5 miles with a a 980 foot ascent. It's not too bad if you're in reasonable physical health, but additional weight adds to the difficulty.

Mt Wilson trail Map

Once I got to First Water, I went down to the area I've shot before. I found the lens/camera combination less than enjoyable to use on slippery/unstable ground. It didn't balance well on a tripod. Perhaps the fact that the $5000 lens wasn't mine contributed to my uneasiness. Also, trying to use my Tiffen variable ND filter on this lens, with the hood, is impossible due the the close tolerances of the hood. There's little room to get your fingers in there to screw the filter on, and the hood doesn't have the little filter window some previous Pentax hoods have had. The result was I used the filter without the hood, which caused flare in the images.

First Water (28mm)

Heading back down the trail (28mm)

For me, to be able to use this lens, it would need: a) to be lighter, b) have a tripod collar so it feels better on a tripod, c) have a larger hood with provisions to use my variable ND filter. Also, I'd eliminate the optical stabilization. I don't think it's really that necessary for a focal length of this range, on a 'field camera'. That would also reduce the cost and most likely the weight and size.

A Weight Comparison:

645Z and SMCP-A 645 35mm

645Z and SMCP-FA 645 45-85mm

645Z and SMCP-DA 645 28-45mm

Wet brick (it was raining out, so a dry brick was not available)

I'm glad I rented the DA28-45 before buying one. I enjoy using the 645Z with the A35 and FA45-85, but I just could not find any pleasure in using the DA28-45, mainly because the 645Z becomes so unbalanced with that lens mounted on it. It does take nice photos though.

New Member

Registered: September, 2014
Posts: 6

2 users found this helpful
Review Date: October 21, 2014 Recommended | Price: $5,000.00 | Rating: 9 

Pros: SR and a zoom range I really like
Cons: weight and size
Sharpness: 10    Aberrations: 8    Bokeh: 8    Handling: 9    Value: 8    Camera Used: 645z   

Some corner sharpness gives me pause. Size is a bit of an issue but because of the SR I actually use it as my goto lens. Strangely the lens is inspires me to shoot much wider more often than before. Partially I think that is because of the inherent additional DoF associated with the wider end of the lens. I tend to shoot a bit from the hip so I don't love using a tripod but I have found that the great ISO performance combined with the SR and sometimes a monopod really gives me images I am pretty happy with.

CA is a bit of an issue with this lens especially in the corners. However I find lightroom zaps it with the auto check box. All in all it isn't perfect but it is good enough that it doesn't come off the camera really at all. Expensive but worth it.
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