In some recent photographs shot with my Nikon 50mm F1.4 AI-s lens, I starting seeing some softness. By softness, I mean not just at the edges of the picture, but all over. This doesn’t seem to show up in photos where I use a higher F-stop number, just at F1.4 or F2. I like to shoot B&W film in low light by pushing it to 1600. A lot of my photos are either taken indoors by ambient light, or by the light from city streets at night. That being the case, many of my photos are shot at wide open aperture.
I mostly use a Nikon FM camera because it has a good focusing screen that makes proper focus easier to judge in near darkness. This camera also has red diodes on the right hand side of the viewfinder to indicate exposure metering, making it super easy to meter in low light.
As for my choice of lenses, I like the look of photos shot with a 50mm lense and that particular length is one the cheapest ways to get a fast lense. A used 50mm f1.4 AI-s is often for sale used on ebay and the 50mm F1.8D (nifty fifty) is only a little over $100 brand new. At those prices, either of these lenses are a real solid performance value.
What was confusing and troubling me was the idea that the new cheap plastic lenses still sold by Nikon was sharper than the old all metal lense from the late 70s and early 80s
Now back to the softness issue I was talking about before I wondered off track a bit. I did some testing and what I determined was two things were creating this softness issue. First up in recent photos I had been using my old Nikkormat EL instead of my Nikon FM. After testing them side by side, I determined my Nikkormat is harder to focus in low light. The screen is bright enough but the center area you use to judge proper focus is a little harder to use. It is as if the Nikon FM center area lets me line the split image up much more precisely than most other cameras I own. That identified the first issue of softness, me not focusing dead on.
Now for the second issue. I had a filter on the front of the 50mm f1.4 AI-s that came with it when I got it used. The filter looks clean and OK, but taking it off makes for a sharper photo. So with these two issues identified, I set about shooting some photos in a controlled environment to verify I was understanding these issues properly and not just imagining it all.
I set up a small still life scene indoors and put the Nikon FM on a tripod to eliminate camera movement. Next I lit the scene with a lamp to make the exposure constant. I also used a cable release to prevent jarring the camera when firing the shutter. I used Ilford HP5 400 pushed to 1600 in Rodinal just as if I was photographing at night in a bar, restaurant or on a city street.
This what the still still life scene looked as shot by my digital camera to test the exposure.
The point of focus in all these pictures will be on the TX letters on the Tri-x film box.
Now to the film pictures.
This first picture was shot on the Nikon 50mm f1.4 AI-s @ f1.4.
This next picture is same angle but shot with the 50mm f1.8D @ f1.8.
Keep in mind the point of focus is the on the TX letters on the Tri-x film box. By my eyes the 50mm 1.8D might be a touch sharper but it is close. Even when I blow these pictures up to much larger size, the results are the same.
Now let’s compare these lenses at f2.
First up we have the 50 f1.4 AI-s @f2.
The next picture is the 50mm f1.8D @f2.
In these pictures the results are so close I can’t tell them apart even when blown up to a huge size on my computer. At f2 I think these lenses offer equal results, or at least appear that way to my old eyes.
I was mostly interested in comparing results at the widest aperture and i was curious to see if I gained anything by stopping down to f2. I think both lenses gained a bit of sharpness and a bit of depth of field by being stopped down to f2. Out of curiosity I decided to step them both a bit more and compare results at f8.
This next picture is the 50mm f1.4 AI-s @f8.
The next picture is the 50mm f1.8D @f8.
I think I see a little more sharpness on the Tri-x box ( the point of focus) and also lot more depth of field at f8. In the type of low light photography I typically do, F8 is seldom used.
I am sure you noticed the grain these pictures. Ilford HP5 is an excellent film and if shot box speed and developed in a more modern developer, the grain would be a fraction of what you see here. Since I was using a tripod and shooting still life, I really did not need to push the film. I choose to push it because I wanted to see how these photos would look using my normal low light shooting and developing techniques. My normal processing is a 1:100 Rodinal semi stand for 90 minutes to push either HP5 or Tri-x to 1600. I stuck with that here just for consistency.
After all the testing, developing, and staring at these photos I have drawn a few conclusions.
First, be very wary of any glass or filter you put in front of the lense. While it is nice to have some protection for the lense, it might create softer pictures unless it a very good filter.
Second, when shooting an older film camera in low light, if possible pick one you can focus easily. Regardless of what camera you use, practice focusing it before shooting some important event. The faster you can focus and set the proper exposure the fewer great photographs you will miss. I have been doing for over 40 years and I still find myself being too slow sometimes. Usually that is caused by me picking up a camera I haven’t used lately and not taking time to practice and get up to speed before hand. No matter what you are trying to photograph, being very familiar with the camera is very important.
Third, with the resurgence of film and old film cameras, prices are going up. If this continues it won’t be long until an older used 50mm f1.4 AI-s lense could cost a lot more than a brand new Nikon “Nifty Fifty” f1.8D. Older cameras and lenses from Nikon continue to go up on ebay. I have seen considerable price increases in just last year. This test showed me that the older all metal AI-s lense offers few advantages to me over the current 50mm f1.8 D. Sure the new one is plastic and doesn’t look as cool, but you can by one brand new and the price is cheap.
One good reason to would buy an older lense is if you need to use an older camera that requires the pre-AI rabbit ear lenses. I have some Nikon cameras that require the older lenses and that is why I have the 50mm f1.4 AI-s. It has the rabbit ears for pre-AI cameras as well as the “cut out” that allows it to work with later AI film cameras.
just for reference the “AI” does not mean artificial intelligence or something like that. AI stands for Auto Indexing. That means the AI lenses could be installed on AI cameras and you did not have to line the indexing pin up with the rabbit ear slot on the lense and then twist it back and forth to index the lense to the camera. In the old days this twisting back and forth was called the “Nikon two step.”
If you want to read more about Nikon AI-s lenses I have a few links to share:
The Mir website has great info on Nikon Lenses Mir website click here
Ken Rockwell page on 50mm f1.4 AI and AI-s Ken Rockwell lense page
Thanks for stopping by,