I heard that spending time along the Cote d'Azur can be good for one's art. While I make no claims to be an artist, spending time in the sun along the Mediterranean Sea inspired me to more deeply consider optics as applied to photography. For many years I have looked at one dimension of commercially available optics. Now I wanted to start looking at other aspects of optical performance. For this series I look at under, neutral, and over corrected spherical aberration in out of focus rendition on subject matter behind the point of focus.
Setup -
If you click on the following image you can inspect it at 100 percent.
Comments -
NOTE: I feel the Lens Turbo II focal reducer adds a bit of under-corrected spherical aberration.
The Nikon Nikkor 55mm f/3.5 pre-Ai shows very very slight over corrected spherical aberrations. In normal photography I would expect, based on these comparisons, that there will be a smooth out of focus field rendition.
The Nikon Nikkor 55mm f/2.8 Ai shows quite neutral spherical aberration corrections with just a hint of under-corrected behavior in the center of the out of focus disk. In normal photography I would expect, based on these comparisons, that there will be an extremely smooth out of focus field rendition.
There is something interesting about the Micro-Nikkor 55mm macro lenses. They are pretty neutral in their renderings. These are the first (though not the only) lenses I encountered that exhibit this kind of behavior. In practical use I loved the f/3.5 version in this regard for many of the images I made along the Cote d'Azur this winter. Now, after these comparisons, I have mounted the f/2.8 version on a camera and have already found it's out of focus rendering to be as beautiful as I expected/hoped it would be.
Resources -
For further information on how the topic of out of focus rendition, optical properties, and Nikon lens design history, please refer to the following -
A PhD thesis on the impact of "soft focus" lenses on the history of photography - http://research-repository.st-andrews.ac.uk/handle/10023/505
An excellent starting point for understanding out of focus rendition (I might not completely agree with his interpretations/observations, but his foundation of understanding is quite good) - http://jtra.cz/stuff/essays/bokeh/
Nikon lens design histories - https://imaging.nikon.com/history/story/
Point light source discussions - https://www.dpreview.com/forums/thread/4031515
Zeiss comments on optical design - https://lenspire.zeiss.com/photo/en/article/how-does-zeiss-define-bokeh-an-interview-with-dr-stefan-ballmann
Metabones Focal Reducer whitepaper - https://www.metabones.com/assets/a/stories/Speed%20Booster%20White%20Paper.pdf
Setup -
- Sony NEX5T, ISO 100, 2 second timer, -1 EV
- Big Beefy Manfrotto tripod
- Nikon lenses using with a Lens Turbo II focal reducer -
- Nikon Micro-Nikkor 55mm f/2.8 Ai
- Nikon Micro-Nikkor 55mm f/3.5 pre-Ai
- NOTE1: Lenses were shot at their widest apertures only
- NOTE2: Out of focus samples are from points _behind_ the point of focus to compare background out of focus rendition
- RawTherapee to convert RAW files into black and white and to set the black levels
If you click on the following image you can inspect it at 100 percent.
Comments -
NOTE: I feel the Lens Turbo II focal reducer adds a bit of under-corrected spherical aberration.
The Nikon Nikkor 55mm f/3.5 pre-Ai shows very very slight over corrected spherical aberrations. In normal photography I would expect, based on these comparisons, that there will be a smooth out of focus field rendition.
The Nikon Nikkor 55mm f/2.8 Ai shows quite neutral spherical aberration corrections with just a hint of under-corrected behavior in the center of the out of focus disk. In normal photography I would expect, based on these comparisons, that there will be an extremely smooth out of focus field rendition.
There is something interesting about the Micro-Nikkor 55mm macro lenses. They are pretty neutral in their renderings. These are the first (though not the only) lenses I encountered that exhibit this kind of behavior. In practical use I loved the f/3.5 version in this regard for many of the images I made along the Cote d'Azur this winter. Now, after these comparisons, I have mounted the f/2.8 version on a camera and have already found it's out of focus rendering to be as beautiful as I expected/hoped it would be.
Resources -
For further information on how the topic of out of focus rendition, optical properties, and Nikon lens design history, please refer to the following -
A PhD thesis on the impact of "soft focus" lenses on the history of photography - http://research-repository.st-andrews.ac.uk/handle/10023/505
An excellent starting point for understanding out of focus rendition (I might not completely agree with his interpretations/observations, but his foundation of understanding is quite good) - http://jtra.cz/stuff/essays/bokeh/
Nikon lens design histories - https://imaging.nikon.com/history/story/
Point light source discussions - https://www.dpreview.com/forums/thread/4031515
Zeiss comments on optical design - https://lenspire.zeiss.com/photo/en/article/how-does-zeiss-define-bokeh-an-interview-with-dr-stefan-ballmann
Metabones Focal Reducer whitepaper - https://www.metabones.com/assets/a/stories/Speed%20Booster%20White%20Paper.pdf
2 comments:
"I have mounted the f/2.8 version on a camera and have already found it's out of focus rendering to be as beautiful as I expected/hoped it would be."
Yes, I use this lens around 85% of the time. Sharp and wonderful blur rendition.
See http://www.kennethleegallery.com/images/micronikkor55/18.jpg
Ken, I have marveled at some of your images and how smooth they are in their out of focus rendition. The f/3.5 Micro Nikkor 55mm impresses me. The f/2.8 blows my mind.
Post a Comment