20mm f2.8 AI-S, my first super-wide angle manual lens

[Roland Vink]

I had an AI-S 20/2.8 and AI 20/3.5 at the same time many years ago. In a brief head-to-head comparison, I found the 20/3.5 needed to be closed down about one stop compared to the 20/2.8 to match the sharpness. However I preferred the 20/3.5 due to the smaller size and standard 52mm filter size - the 62mm filter of the 20/2.8 didn't match any other lens so wasn't a good fit in my kit.

On a side note, I was looking at some shots I took with my 24/2.8 (AI converted K lens which uses the older 9/7 optical design). Pictures taken with my D600, fast shutter speed and lowish ISO are not really crisp, even at f/11. There are no noticeable side-to-side differences which might indicate mis-alignment.  Maybe this lens is just not good enough for 24MP images, which is disappointing.

[Zang]

I had an AI-S 20/2.8 and AI 20/3.5 at the same time many years ago. In a brief head-to-head comparison, I found the 20/3.5 needed to be closed down about one stop compared to the 20/2.8 to match the sharpness. However I preferred the 20/3.5 due to the smaller size and standard 52mm filter size - the 62mm filter of the 20/2.8 didn't match any other lens so wasn't a good fit in my kit.

On a side note, I was looking at some shots I took with my 24/2.8 (AI converted K lens which uses the older 9/7 optical design). Pictures taken with my D600, fast shutter speed and lowish ISO are not really crisp, even at f/11. There are no noticeable side-to-side differences which might indicate mis-alignment.  Maybe this lens is just not good enough for 24MP images, which is disappointing.

I never pixel-peeped before, but after you shared your experience with Nikon 24mm, I decided to test it at f2.8. 24mm's extreme corner taken near MFD looks worse than that from 20mm! I know testing at MFD is not fair, but with my limited mini home studio lighting, that is the only setup that I can use in dim lighting situation.

[Zang]

If you do not shoot brick walls, you will like its small size. It can pass for a standard lens and help you shoot interesting street views (I know, that's unethical but some rare people deserve that).

I always found its wavy distortion difficult to handle.

The 20/3.5 AI is definitely the better alternative (and even smaller) but that is no reason to throw away the 20/2.8.

I made no side-by-side comparison with the Viltrox 20/2.8 for Z mount, but the latter does not feel superior (even though its wavy distortion is less conspicuous). The old 20/3.5 UD better but needs to be stopped down.

Hi Akira,

I heard from a lot of people about the 20/3.5 being better than the 20/2.8, but I also hear voices telling they perform similarly or even with the 20/2.8 being better in several areas. I have impression that I am lucky enough to get a good sample of the 2.8

Cheers!

[Zang]

I have the  20/3.5 -very small- in very good condition that’s OK in the digital age, but I have a lot of time with no use.
24-70/4 is too good with Z8 to pass.
But 20/2.8 is a nice choice to have

I am sure the modern lenses are much better and lenses from previous era suffer from a lot of shortcomings. I have no idea why I can't stop collecting the later

[Birna Rørslett]

The modern lenses *are* better -- in many aspects. However, the point to pay attention to is how they work as a translator of your visual expressions ....

The vintage Nikkor 20mm f/3.5 UD is a good example to the above. It is one of the nicest lenses imaginable for IR shooting. The modern equivalents exhibit nasty IR hot spots, so their superior optics really aren't very helpful.

[Birna Rørslett]

I never pixel-peeped before, but after you shared your experience with Nikon 24mm, I decided to test it at f2.8. 24mm's extreme corner taken near MFD looks worse than that from 20mm! I know testing at MFD is not fair, but with my limited mini home studio lighting, that is the only setup that I can use in dim lighting situation.

Again, the 24 Nikkors have CRC. My sample of 24/2.8 got gradually worse until I adjusted the CRC, then it started to behave properly. Image quality of my 24/2  suddenly was horrible and really needed a CRC shake-up.

For close-distance testing, don't use flat subjects to evaluate corner performance unless you specifically refocus for the corners. Focusing on the centre of the frame may leave corners mushy. Most lenses are not designed to be true flat-field performers.

[Zang]

Again, the 24 Nikkors have CRC. My sample of 24/2.8 got gradually worse until I adjusted the CRC, then it started to behave properly. Image quality of my 24/2  suddenly was horrible and really needed a CRC shake-up.

For close-distance testing, don't use flat subjects to evaluate corner performance unless you specifically refocus for the corners. Focusing on the centre of the frame may leave corners mushy. Most lenses are not designed to be true flat-field performers.

I am aware of the spherical aberration, so I adjusted the focus individually for each test shot. The 24/2.8 lens I tested is in near new condition. I also have another 24/2.8 lens that appears to be unused, so I might test that one later as well.

That said, I mentioned before, testing wide angle lenses wide open in the corners, at their MFD is inherently unfair. I am confident that stepping back a few meters would improve corner performance. Additionally, the picture quality degradation is only noticeable from 25% of image diagonal.

Below is a real life test shot taken at f2.8. As you can see, the photo is more than just usable.

[Zang]

And this is 100% crop from the previous picture:

[Zang]

A couple of test shots this morning at f2.8 and f5.6.

[John Geerts]

I love my sample

In this topic several examples can be found

https://nikongear.net/revival/index.php?topic=9764.msg165516#msg165516

[Zang]

Thanks John. I have heard more positive opinions about the lens in this group than outside of it, so I am happy I own the lens

I love your picture too. How did you focus yourself and do you remember the aperture setting?

[John Geerts]

That shot was with the Z7 at f/8  and using the focus zoom on the Z7

[Zang]

That's what I guessed - this lens performs well from f5.6 onwards.

I was joking about "focusing yourself", but that part could be confusing. You weren't the guy with the boat, were you? As for the selfie I took in my basement (shared in the previous post), I had to focus then camera on myself and that is not easy with a manual lens.

[Airy]

Exactly, corners are bearable at f/4 and fully acceptable from f/5.6. The other real issue with this lens is, apart from the wavy distortion, the sensitivity to flare (unlike the 20/3.5 AI). Otherwise it is a joy to use because of its ideal size. Manual focussing (on a matte screen) is difficult in dark places, but with the Z cameras that's no longer an issue.

[Akira]

A couple of test shots this morning at f2.8 and f5.6.

Looks like a very good sample.  Or you have assembled the parts successfully!