Pentax D FA★ 50mm f/1.4 Review

For Astro - Worth the Investment?

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The Pentax D FA* 50mm f/1.4.
The Pentax D FA* 50mm f/1.4.

Released in 2018, the Pentax D FA 50mm f/1.4 marked Pentax’s official jump into modern, fast full-frame primes. Made for all applications, including Milky Way Photography, the lens was quickly praised by the community and lens reviewers alike.

Its fast f/1.4 aperture makes it great for low light photography, it has little to no distortion, and its rugged build means it is just as notoriously tough as the rest of Pentax’s camera gear.

I initially bought the lens with one thing in mind: shooting the Milky Way.

DISCLAIMER: The item in this review was purchased with my own money and was not gifted to me, nor lent to me by any third party. No payment was received for this review.

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Why Did I Buy the Pentax 50mm f/1.4?

The Pentax D FA* 50mm f/1.4 first started shipping in mid-2018.

The lens was on my wish list from the day it was announced and I planned on buying it once I saw the results of someone using it for night photography.

I was eagerly waiting for images of the Milky Way to flood all of the Pentax forums and Facebook groups, but that day never came. I waited for almost 10 months.

I had a decision to make. Do I continue to wait for the photos that may never come, or do I take that leap for the good of Pentaxains across the globe?

With the click of a mouse, I took a leap… for science!

I have owned the lens for about seven months at the time of writing this and have used it for everything from portrait photography, street photography, and photojournalism to travel photography, commercial photography, and the all-important night photography.

About The Pentax D FA★ 50mm f/1.4

The Pentax 50mm f/1.4 D FA*
The Pentax 50mm D FA f/1.4

Before getting into my thoughts and observations, first some technical jargon and a breakdown of the name.

The full name is the Pentax D FA* 50mm f/1.4 SDM AW. The name is quite the mouthful, but it’s important nonetheless.

First is the D FA* marking, “D” meaning digital, and “FA” meaning the lens is designed for a 35mm full-frame sensor.

The star on the lens means the lens is part of the Pentax star-series lens lineup which are defined by their, “excellence in three categories: exceptional image quality, large aperture, and a lens barrel design with excellent strength and outdoor protection performance,” the Ricoh Imaging site says.

The “SDM” in the name refers to the lens ultra-quiet and powerful autofocus motor and the “AW” is reserved for Pentax’s lenses top-of-the-line “all-weather” lenses.

Handling

My first impression of the lens is that for a 50mm prime, it is huge and its all-metal and glass construction means it is heavy. At 910 grams or slightly over 2 pounds, it is by no means a light lens.

For reference, that is 95 grams more than Sigma’s 50mm f/1.4 Art or the weight of almost six Canon “nifty fifties.”

However, I personally like bulky lenses because they feel rugged, and this lens is no exception. It balances very well on the front of my Pentax K-1.

I’d give the lens five stars based on feel alone, especially compared to the competition.

Other 50mm Options

The competition for this lens is almost nonexistent if you’re looking for a fast K-mount 50mm with autofocus. There is an older designed Pentax 50mm f/1.4, but it can’t match the image quality of the D FA★ 50mm.

Rokinon and Samyang offer 50mm lenses for the Pentax K-mount, but those lenses lack autofocus. Their image quality isn’t fantastic, but their lenses are great for their price.

At $399, you could buy both the Samyang and Rokinon 50mm f/1.4 lenses and still have money left over. Not just pennies, but hundreds of dollars!

Price

With the Pentax’s great image quality and premium build-quality comes a premium price.

With a USA list price of $1,199.95 as I’m writing this, the Pentax 50mm weighs as much as 6 nifty fifty’s, but costs as much as 10 of them! But it does currently sell for under $900 on Amazon.

By no means would this lens ever be considered budget-friendly unless your kit consists of a full set of Zeiss Otus primes!

Image Quality

Clearly the most important part of a lens review is the part where we break down the image quality.

Now, in my experience, the lens is superb and is my sharpest lens, especially stopped down.

I also own the Sigma 35mm f.1.4 Art for Pentax and there is little competition for the 50mm as the Pentax is sharper at all apertures and focuses much faster and more accurately.

In my personal testing, from a “lab” type setting to real-world shooting, the 50mm is superbly sharp at f/1.4 and seems to be sharpest between f/2.4 and f/11.

The lens has next to no distortion and the corners, when stopped down, look fine for shooting many different genres.

Stars at Wide Open – Coma

However, night photography is a particularly demanding genre, especially when it comes to lens performance and while great elsewhere, the Pentax D FA★ 50mm f/1.4 does have some issues.

There is no putting this lightly; this lens produces what are essentially unusable night images at f/1.4.

A crop of the corner of an image taken with the Pentax D FA* 50mm at f/1.4
A crop of the corner of an image taken with the Pentax D FA★ 50mm at f/1.4

As the image above shows, the coma distortion in the corners of the lens is horrible.

A 100% crop just off-center in an image shot with the D FA* at f/1.4.
A 100% crop just off-center in an image shot with the Pentax D FA★ 50mm at f/1.4.

The coma distortion is also not limited to the corners as even just outside the center of the frame, stars have triangular shapes.

A crop of the corner of an image shot with the Sigma 35mm f/1.4 Art at f/1.4
A crop of the corner of an image shot with the Sigma 35mm f/1.4 Art at f/1.4

For comparison’s sake, the above image is a 2:1 crop of a corner from the Sigma 35mm f/1.4 Art. The shape of the distortion is very similar, but the Sigma has less chromatic aberration.

Stopped Down – f/2.0

Despite the horrible performance at f/1.4, the lens does improve astronomically (no pun intended) when stopped down, however, it must be stopped down quite a bit.

A crop of the corner of an image taken with the Pentax D FA* 50mm at f/2.0
A crop of the corner of an image taken with the Pentax D FA★ 50mm at f/2.0

At f/2.0, the lens has not improved much in the extreme corners as the image above shows. There is still very heavy coma distortion, but the chromatic aberration has been slightly reduced.

Where the lens has improved considerably is in the center and off-center.

A 100% crop just off-center in an image shot with the Pentax D FA* 50mm at f/2.0.
A 100% crop just off-center in an image shot with the Pentax D FA★ 50mm at f/2.0.

As the screenshot above shows, the image quality is now very usable farther out from the center.

The coma is now restricted to the extreme corners and edges of the frame and planets, like the one in the frame, now have a very crisp sun star-forming around them.

At f/2.0, while not perfect, the image quality has been entirely usable, especially for Milky Way panoramas where image overlap would get rid of most of the edges and corners.

Stopped Down – f/2.8

When the lens is stopped down to f/2.8, a common aperture for many pro zoom lenses, the coma distortion is reduced dramatically.

A crop of the corner of an image taken with the Pentax D FA* 50mm at f/2.8.
A crop of the corner of an image taken with the Pentax D FA★ 50mm at f/2.8.

The image above is a 2:1 crop of the very extreme corner of the lens and only a small handful of the brightest stars are still distorted.

A 100% crop of the center of an image shot with the Pentax D FA* 50mm at f/2.8.
A 100% crop of the center of an image shot with the Pentax D FA★ 50mm at f/2.8.

This 1:1 crop of the center of the frame shows that the lens is as sharp as it would ever need to be at f/2.8.

For Pentax K-1 owners, the lens performance at f/2.8 is superb! And when used with the Astrotracer function, it is very easy to take very sharp and detailed images of the night sky.

Comparison with Pentax 24-70mm f/2.8

A 100% crop of the center of an image shot with the Pentax D FA 24-70mm f/2.8 at 50mm and f/2.8.
A 100% crop of the center of an image shot with the Pentax D FA 24-70mm f/2.8 at 50mm and f/2.8.

For reference, the above image is a 1:1 crop of an image shot with the Pentax 24-70 mm f/2.8 at 50mm and f/2.8.

It isn’t a day and night difference, but the Pentax 50mm prime is sharper.

(If you can’t decide between the two, check out my article on primes vs. zooms for night photography.)

Stopped Down – f/4.0

For test purposes, I stopped the 50mm all the way down to f/4.0.

A 100% crop of the center of an image shot with the Pentax D FA* 50mm at f/4.0.
A 100% crop of the center of an image shot with the Pentax D FA★ 50mm at f/4.0.

As the 1:1 crop above shows, there was next to no change in image quality between f/2.8 and f/4.0.

The corners of the frame remain unchanged as well, meaning that the only difference between f/2.8 and f/4.0 is the exposure duration.

At f/4.0, to get a proper exposure, I was pushing the limits of the Pentax Astrotracer function exposing for 80 seconds, which takes up more time and increases the chances of star trailing with no extra reward.

Vignette

As to be expected, the Pentax 50mm f/1.4 also has a very heavy vignette at wider apertures.

A full frame shot with the D FA* at f/1.4.
A full-frame shot with the Pentax D FA★ 50mm at f/1.4.

At f/1.4, the lens has a considerable vignette around the frame leaving only the center of the image exposed properly, as shown above.

A full frame shot with the D FA* at f/2.0.
A full-frame shot with the Pentax D FA★ 50mm at f/2.0.

Stop down to f/2.0 and the vignette greatly improves. Though still noticeable, it isn’t bad enough that it will be unmanageable and you won’t have to do any extreme corrections to brighten the corners and add noise.

A full frame shot with the Pentax D FA* 50mm at f/2.8.
A full-frame shot with the Pentax D FA★ 50mm at f/2.8.

For night photography, f/2.8 seems to be the sweet spot of this lens. Stopped down to f/2.8, the vignette is almost completely gone with the corners being only slightly darker.

The vignette is easily correctable and only minor adjustments are needed to make the exposure even across the frame.

It is worth noting that the vignette improves slightly more at f/4.0, but not enough to justify the risk of start trails.

Image Quality Summary

Throughout my real-world testing, as I have mentioned previously, the lens performs best at f/2.8 with a relatively even exposure across the frame and little to no coma in the corners.

At f/2.0, single exposures might be difficult if you’re a pixel peeper.

If you like to stitch panoramas, however, f/2.0 will allow you to shoot at a lower ISO and the lens performance at the edges can easily be overcome by overlapping shots more.

A silhouette shot at 15mm in front of a panorama shot with the D FA* 50mm f/1.4 at f/2.0.
A silhouette shot at 15mm in front of a panorama shot with the D FA★ 50mm f/1.4 at f/2.0.
A 3-part stacked panorama shot with Astrotracer and the D FA* 50mm f/1.4 at f/2.0.
A 3-part stacked panorama shot with Astrotracer and the D FA★ 50mm f/1.4 at f/2.0.

Overall, the lens is very sharp and performs well, but at the widest aperture, I have to admit, it is essentially unusable for night photography.

Pentax 50mm f/1.4 – Final Thoughts

Is it worth it?

Yes and no.

If you’re looking for a fast 50mm prime only for night photography, the answer is no. There are better options. As mentioned before, the lens is very expensive.

However, if you need a prime that can be easily used across several genres, then it is the best prime in the Pentax lineup.

Rokinon and Samyang make 50mm f/1.4 primes that are 1/3 the price of the Pentax and they perform well, especially stopped down. For the price, they are completely worth the comparatively small investment.

The Rokinon and Samyang are fully manual lenses with manual aperture rings and focus rings. The Pentax 50mm does not have a manual aperture ring and its autofocus is very accurate and quiet making it ideal for portraits, events, and photojournalism, amongst others.

If you’re looking for a quality, fast prime that can be used across all genres including night photography, the Pentax D FA 50mm f/1.4 is, without a doubt, the best option for Pentax users.

12 COMMENTS

      • Haha good luck with that Jeff! I never even knew there was a 30 art for the K-Mount! I might have to join you on that one. I’m using the Rokinon 24mm. Great lens, but it might be a bit wide for the Astrotracer. I get trails at 40 secs or so.

    • Yes, as you can imagine, I was a little bummed about the results from a lens I paid $1000 for, but it is still very usable and a lot sharper than my 24-70 @ 50mm. But I use it for several other genres so I can justify the cost, I suppose.

      • Well, I really appreciate you diving in Aaron and giving us Pentaxians some insight! I get excited whenever I see a new post here — always some valuable info. Sorry you’re bummed about the 50mm, but glad you’re still getting some solid usage from it. I know you use the 35mm Art quite a bit as well. Would you say that’s still your favorite with the Astrotracer overall? I wonder how it would compare with the 30mm Art. Thanks again for your invaluable page!

        • Bryan, I’m torn between the Sigma 35mm and the trusty Pentax 15-30mm for night photography overall, but paired with Astrotracer, the Sigma 35mm Art is fantastic! Unfortunately Sigma has dropped K-mount support so the lens may become difficult to find new, but I’d highly recommend it!

          • I appreciate the tips Aaron! Now I’m split between getting the Sigma 35 or a move shoot move tracker for my Samyang 24 🙂 I do love what you’ve been able to get from the astotracer at 35! Hmmm decisions. Thanks again for your help.

  1. Have you thought to compare this lens with a vintage Pentax 50mm, for example the SMC Pentax-A 50mm f/1.4? With a median price on eBay of about $100, it would be an interesting shoot-out.

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