Nikkor 28mm f/2.8 Ai-s vs Pentax K 28mm f/3.5

[caspert79]

Camera used: Sony A7rii (42,4 mp) on a tripod with self timer.
Note: the Nikkor is the famous 8-element Ai-s version; the Pentax is the rather rare 8-element K-series version.

First an overview of the close focus pictures taken (about 30cm). I did an exposure correction in RAW to make the pictures more comparible.


The differences are not too obvious yet, let's look at the 100% center crops.



The Nikkor is actually quite soft @f/2.8. The Pentax shows more detail up until f/5.6. At f/8 the pictures are quite comparable. I cannot 100% guarantee that the focus of the Nikkor was spot on; a small deviation may result in a different image, but I don't think this cannot account fully for the difference found between the two lenses.

Now the infinity focus pictures:

From a distance, the images from both lenses look pretty similar.

Now, 100% center crops:


The Nikkor shows a pretty solid performance already at f/2.8. When stopped down, the Pentax is a little bit sharper than the Nikkor.

Now look at the corners:



Here is where the Pentax clearly beats the Nikkor. Less purple fringing and more sharpness.

Conclusion:
The legendary Nikkor 28mm f/2.8 Ai-s is known to be a pretty awesome performer, but the K-series Pentax 28mm f/3.5 seems to be even better. A little more sharpness, a little more detail, and significantly better corner performance. Which makes it a great lens for high resolution full frame camera's. The Nikkor is a great lens as well, and has 20cm minimum focus, which allows for great artistic compositions.

[Oldhand]

Thank you Casper for this comparison.
Both are great lenses, but the Pentax is just wonderful.
Fabulous landscape lens.
Tom

[caspert79]

[lumens pixel]

Very interesting, have you corrected for field curvature, if any, when coming to the corners?

[caspert79]

[visualopsins]

I think he asks if focus/dof is placed identical. Corners can be oof if not included in dof due to field curvature.

Thanks very much for the comparison! I will attribute the difference to lens coatings, more transmission less noise on PK.

[cbass]

I have been looking at the Nikon 28mm f/2.8 AIS lens and I don't understand the great reputation it has from the research I have done. The lens is well praised and almost never criticized. However, I have looked at flickr albums and often see soft corners and nothing special about the rendering. It's possible that pictures are making it into those albums that are not from the 28mm f/2.8 AIS lens but the AI version or even the E-series. However, you also see plenty people saying they must of had a bad copy because it had soft corners.

Does anyone own this lens that can provide some perspective on what it does special other than it's close focus ability?

I have heard it's very sharp but again I haven't seen impressively sharp sample photos. That doesn't mean they were soft but nothing that stood out.

[caspert79]

[Alsatian2017]

[papasito]

I have an Ais 28/2,8.

I agree with IT's not a special lens.

The Hollywood is a very good 28 mm lens but it's a lot of bucks.

[caspert79]

[papasito]

[hasenbein]

The Pentax is a great lens and much fun to use.

Got mine for 100 euros, it looks and works like new.

Unfortunately I now use it rarely because my Tamron 17-28 is simply more versatile.

And there is one thing I don't like so much in the Pentax: The images are TOO contrasty. Problematic to work with in postprocessing.

[D1N0]

The SMC K 28mm 1:3.5 has become pretty hard to find. Currently can't find any on eBay. Not even from Japan.

[Oldhand]

[D1N0]