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SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW Review RSS Feed

SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW

Reviews Views Date of last review
2 47,272 Mon November 4, 2013
Recommended By Average Price Average User Rating
100% of reviewers $4,995.00 9.50
SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW


This ultra-wide-angle lens has a field of view that corresponds roughly to a 13mm lens on a Pentax APS-C DSLR or a 20mm lens on a full-frame 35mm SLR. Its image circle is big enough for use with current Pentax 645 film bodies.

It was launched in April, 2011 with an MSRP of $4999.95. It features all the latest technologies from Pentax, including SDM autofocus, quick-shift manual focus, super-protect and aero bright coatings, a drop-in filter slot, and 11 weather seals.

It uses the Pentax 645 AF2 mount, with support for SDM focusing only.

This lens was succeeded by the DA 25mm F4.

smc Pentax-D FA 645 25mm F4 AL[IF] SDM AW
©, sharable with attribution
Image Format
645 film
Lens Mount
Pentax 645
Aperture Ring
Automatic, 9 blades (rounded)
12 elements, 8 groups
Mount Variant
645 AF2
Check camera compatibility
Max. Aperture
Min. Aperture
AF (in-lens motor)
Min. Focus
40 cm
Max. Magnification
Filter Size
40.5 mm (Rear drop-in)
Internal Focus
Field of View (Diag. / Horiz.)

645 Digital: 95.5 ° / 82.6 °
645 Film: 109 ° / 96.7 °
Lens Cap
Dedicated metal push-on
Aero Bright,SMC,SP
Weather Sealing
Yes (AW)
Other Features
AF/MF Switch,Drop-in Filter Holder
Diam x Length
90 x 140 mm (3.5 x 5.5 in.)
1070 g (w/o attachments) (37.8 oz.)
Production Years
Engraved Name
smc PENTAX-D FA 645 1:4 25mm AL[IF] SDM AW
Product Code
User reviews
No autofocus on film bodies.
The CPL filter can be turned with a knob on the filter holder.
Two aspherical elements.
Supersonic AutofocusQuick ShiftWeather SealedInternal FocusingBuilt-in HoodAutomatic ApertureMedium-Format SupportAdapter needed for DSLRsDiscontinued
Price History:

Add Review of SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW
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Registered: January, 2009
Location: East Bay Area, CA
Posts: 6,448

8 users found this helpful
Lens Review Date: November 4, 2013 I can recommend this lens: Yes | Price: $4,995.00 | Rating: 10 

Pros: excellent IQ, internal filter capability, WR sealing
Cons: expensive, some CA, but normal for a lens this wide
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 10    Value: 9    Camera Used: 645D   

A truly exceptional lens, I am assigning this an overall score of 9.5, but rounding up in the absence of half point scores.

The focal length is what drew me in. That, and the luscious sample images posted here by Hark Lee. He really demonstrated the capabilities of the lens. That said, I purchased it and then found myself going through a phase of shooting longer focal lengths while this got left behind in the car. The times I have needed an ultrawide, it has performed marvelously as expected. Now that I am starting back up with seascapes, I will be subjecting it to the ocean spray, sand, fog, and other marine treachery.

The internal filter is very convenient and I have used it for my 9-stop ND as well as a circular polarizer. The finger wheel control for the CP is very nifty. In pixel peeping, the usual wide angle chromatic aberration is present and not unexpected. These are easily corrected in Camera Raw. I get the same amount of CA when shooting with my K-mount 10-17 fisheye, Sigma 10-20, FA77 limited, etc...

I definitely can recommend the lens if you have the funds and need something wider than the 35mm otherwise available for the 645D.

Here are some samples - click the flickr link to view large:

Isleton Bridge

Mossbrae Wood

Sundial Bridge III

Forum Member

Registered: October, 2010
Location: Sunnyvale, California
Posts: 57

10 users found this helpful
Lens Review Date: June 28, 2011 I can recommend this lens: Yes | Price: N/A | Rating: 9 

Pros: Resolution, view angle, build quality, built-in / pull-out filter holder.
Cons: Chromatic abberations, price, weight.

(1) At First Glance

The build quality of this lens is exceptional, everything feels very solid and well engineered. The entire body and even the lens cap are made
of aluminum (except for rubber/plastic rings, the knob and the dial). It's definitly on the heavier side at 1070g but understandable for its size.

(2) View Angle (82.70 horizontal / 66.85 vertical / 95.46 diagonal)

Corresponding to approximately 19.5mm on a 35mm full frame sensor, the view angle is good enough for most wide angle landscape shots.
Except for a handful of unusual occasions (i.g. Horseshoe Bend, AZ), I personally hardly go any wider than 16mm (on 35mm FF). Since this
lens will convert to a 15.5mm (on a 35mm FF) super-wide angle with a full-frame 645 sensor, I think this will remain as the wide end of my
work range.

(3) Optical Performance

The D-FA 645 25mm shows very impressive resolution across the frame, although it remains to be seen how it performs with a full-frame 645
sensor. With the current cropped sensor of 645d, even the extreme corners look very sharp and contain fine details. I would love to compare
this lens to Rodenstock Digaron-S 23mm, both of them seem to boast exceptional performances, but I am personally curious about how the
state-of-the-art 645 full-frame retro-focus superwide angle lens can stack up against high quality short-focus superwide angle lenses.

(4) Chromatic Abberations

This lens shows a substantial amount of CAs, which can mostly be fixed by using any lens correction software. Although Pentax has not
announced the newest version of RAW converter or a correction profile for ACR, you can still use lens correction filters of Photoshop to partially
correct them. At f/10-13, longitudinal CAs are not an issue (due to smaller aperture) and most of the CAs are lateral and therefore correctable.
I have no idea why Pentax didn't use any low-dispersion elements for a $5000 lens. I've yet to carry out tests at wider apertures, but I don't
think it would matter that much to a landscape photographer like me since I hardley shoot any wider than f/8.

(5) Filter Compartment

Creating an internal filter compartment in the mid-section of the lens was a fantastic idea and it works perfectly. Using the plastic dial, a polarizer
can be easily rotated and this saves you the trouble of purchasing a large (and very expensive) polarizer and sacrificing one slot of your filter
holder. You can also separately purchase a 40.5mm ND8 filter from Hoya, which can be very useful for shutterspeed control.

(6) Using GND Filters - Custom Filter Holder

Since nobody has manufactured a dedicated filter holder for this lens, I had to fabricate one from a cheap abs pipe and Cokin z-pro filter holder.
At Home Depot, I picked up a small end cap hub that has a slightly smaller diameter than the front section of the lens, cut off the cap part,
converted it into a short cylinder and glued it to the back side of the Cokin Z-pro filter holder. I had to bore the cylinder a bit for a proper
tolerance and lined it with black velvet. FYI, after wasting a fortune on a number of different materials, I settled down on fake adhesive velvet
that I picked up from Daiso. After cutting and grinding, spray painting is a must and now you have a custom filter holder. You can use one 4X6
rectangular filter without vignetting.

(7) Custom Focus Mirror

I also fashioned a custom focus-mirror that can be attached to the lens. For precise DOF control, I find myself focus-stacking quite often,
and if your camera is on your eye level and you are shooting horizontal, there is no good way of quickly changing the focus. So I purchased
a small inspection mirror at a hardware store, took off the handle and screwed it to a reusable rubber twist tie. This can also be used with
different lenses for the same purpose.

Mirror : General Tools 557 2 1/4-Inch Diameter Inspection Mirror: Home Improvement

Tie : Nite Ize GT18-2PK-01 Gear Tie Reusable 18-Inch Rubber Twist Tie, 2-Pack, Black: Home Improvement

(8) A Sample Image and 100% Crop (Processed with ACR, Sharpening : 75/1/50/30)

Alamere Falls, Point Reyes National Seashore, Bolinas, California

100% Crop #1

100% Crop #2

100% Crop #3

100% Crop #4

(9) More Samples
It has been a slow season for landscape photography, so I haven't got a chance to utilize the full-potential of this lens. I will add new pics
as soon as they are available.

Ano Nuevo State Park, Pescadero, California

Memorial Church, Stanford University, Palo Alto, California

Near Pigeon Point Lighthouse, Pescadero, California

Gray Whale Cove, Montara, California

Schwabacher Landing, Grand Teton National Park, Wyoming

Sutro Baths, San Francisco, Caifornia

Tioga Lake, Yosemite National Park, California

Dog Lake, Yosemite National Park, California

(10) Samples for Download (RAW)

Discuss: Pentax 645 25mm F4 review by forum member Hark Lee
Add Review of SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW

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