A test of SMC Pentax-FA* 24mm f/2 AL versus Sony Distagon T* 24mm f/2 ZA SSM on Sony A7R II

I tested on Sony A7R II the only two autofocusing 24mm lenses with the speed of f/2 ever marketed: SMC Pentax-FA* 24mm f/2 AL [IF] and Sony Distagon T* 24mm f/2 ZA SSM, The entire test is available at my blog:
https://towarzystwonieustraszonychsoczewek.blogspot.com/2017/09/wspoczesne-obiek...
The test is in Polish but the captions under photos should be self-explanatory. Besides test photos taken with Sony A7R II, there are also a lot of photos in the gallery taken with a Pentax K-1. Below is the most part of the test summary in English, which can be found at the end of my blog entry:




Modern 24mm f/2 lenses - a happy medium or neither fish nor fowl

This is a test of the only two autofocusing 24mm f/2 lens models ever marketed: SMC Pentax-FA* 24mm f/2 AL [IF], manufactured from 1991 to 2004, and Sony Distagon T* 24mm f/2 ZA SSM, produced since 2010, via adapters on a Sony A7R II camera. Sony Distagon T* 24mm f/2 ZA SSM is a technically better lens: more solidly built, equipped with a silent AF motor with full-time manual override and some performance strengths over the Pentax. While in terms of vignetting and barrel distortion both lenses are well above average, with the Sony only slight edging the Pentax, then CA is visibly better corrected in the Distagon. Both lenses are resilient to flare and ghosting – a testament to the quality of both SMC and T* multicoating. Pentax also displays excellent contrast. Its weakest point is edge sharpness: fairly poor wide open and not really catching up with the centre – which is reasonable at f/2 and excellent already at f/2.8 – until about f/5.6. The Sony’s sharpness is much more uniform across the frame, and edges are good already at f/2. Sony has more neutral bokeh, but its technical perfection is only half of the story, and appears dull at times, while images taken with the Pentax have more character, most likely attributable to its imperfections, and some images taken with it look both warmer and more three-dimensional.

The Distagon can be thrown at any photographic task without hesitation, and it will always deliver technically sound pictures. In the case of the Pentax, one needs to know it flaws and use it skillfully. Near full aperture opening it will work well in reportage and portraits, where central sharpness matters most while fuzzy edges even help to focus attention on the main subject. In the range of f/5.6-f/11 the quality is excellent across the frame so the lens can be successfully used in architectural or landscape photography. The lens works very well on Pentax K-1, and it can join the trio of Limited primes. I can recommend it to K-1 users, but finding one is not easy.

On Sony A7R II the usefulness of the Pentax lens is restricted by sometimes poor quality of adapters – it took me a whole day to blacken mine inside as it was reflecting silver bayonet mount back to the sensor, ruining almost every shot. On the other hand the Distagon works perfectly via LA-EA3 on Sony A7R II.

Now back to the question asked in the title of the test: does a 24mm lens with the speed between lightweight and tiny f/2.8 optics and ultrafast f/1,4 ones make any sense? Definitely yes, if it is of Sony Distagon T* 24 mm f/2 ZA SSM quality. Its combination of price, built and image quality is attractive, while sensor stabilization built in such cameras as Sony a99 II or A7R II offsets the one-stop advantage of 24mm f/1.4 lenses made by Canon or Nikon.

Thanks for sharing your time and findings. If anyone wishes to read your blog page in English, here's a link to a Google translated version:
https://translate.google.com/translate?tl=en-us&u=https%3A%2F%2Ftowarzystwonieus...
The translation has some anomolies such as 'the K-1 user who eats self-focusing.' Tasty!

Well some Google translations are tasty - particularly is one uses some idiomatic expressions. My sentence is something like: "A Pentax K-1 user craving for autofocusing primes ..."
Thanks for giving me a good laugh.
Best
Jarek

Thanks for putting so much effort into this - I'm sure a few members on here will find it interesting and useful

Thanks a lot. My blog is non-commercial and I run it only to share my findings with others. I started it in June this year and initial tests were of Nikon and Canon lenses. But I have deep love for Pentax and used their gear for many years. I still keep my LX - one of the best-engineered, worst-marketed cameras ever.
Best

Yes thanks for this.

Thank you for sharing. A very interesting read. Love the blog, too. Pozdrawiam.

Thanks
Pozdrawiam