It includes, but is not limited to, out-of-focus highlights. Very sharp wide open, in fact too sharp I would think for portrait work, but while the Asahi doesn't have the rep the shorter Nikkor does, it seems to be reasonably well known. These characteristics will, in general, do one of three things: complement the image, be a non-factor in the image, or distract from the subject. Phil liked the effect enough that he had framed the picture. In the past, aspheric optics had to be hand-ground.
Technically, isn't it all just using the selective focus technique? Whether or not that success was realized wasn't known until after a trip to the darkroom. He had tested many lenses for magazines. The same goes the other way around so pick what works for you. Now it all seems to be poo-poo. A lens can often produce a sharper image in some regions than others.
I know a portraitist who uses a Tessar-type large format lens, a Goertz. It would be beneficial to many of us to know which ones to look for without having to buy a lot of lenses we don't need. In-focus rays go where they're supposed to go, obviously. It's very sharp even wide open. But you can readily see how there's another dimension to examine: what does the nature of that OoF area do for the photograph, and for the person making it? By using barcodes as small as 3 mm with a small lens over them, if the barcode is viewed out of focus through an ordinary camera focused at infinity, the resulting image is large enough to scan the information in the barcode. The direct definition of Bokeh is often not certain, as not much in Japan is, but it simply refers to the amount of background blur used to give the image definition.
Because of the variation of the angles of light as you move from the center of the image to the edges, the shape of the bokeh changes. The older I've gotten, the more important perpendicularity becomes. A similar sounding term was used in the Los Angeles area cira 1970. This is a separate issue from the just being out of focus. Additionally, specular reflections can indeed create out-of-focus highlights in an image.
Some people like that kind of thing, some people don't. Computer simulation has its limits when it comes to optical design. A bit like the gardeners' definition of a 'weed' - a plant in the wrong place. There's a lot of individual taste involved. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit for additional information. A complement to the photograph 4. Depending on how a lens is corrected for , the disc may be uniformly illuminated, brighter near the edge, or brighter near the center.
Leica M 35mm lenses for instance are quite good, and some of them have a bokeh signature that leans towards the look of medium format. A photo may be with or without out of focus areas but not bokeh. In the three images you present, the second and third have a bokeh that I don't consider to be very pretty. Note how the dark edges of the stranded rope line on a boat and the dark edges of the winch bracket mount etc are seemingly outlined with sort of flare. This makes it much easier to have a shallow depth of field in images. The photographer uses selective focus.
Not that people don't address the details of good or bad bokeh in technical ways - the elements of a lens that produce the things you might like or dislike for example or the specific elements of displeasing blur. It's probably no coincidence that my more expensive lenses tend to produce a less harsh, less crunchy-looking blur. It makes the in-focus objects stand out more. So I worked on getting what I wanted. You don't want good bokeh so people will be drawn to the background, you want it so the background just gives the illusion of being in the distance. This gives the lens the characteristic pentagonal highlights.
You can even create your own shape of bokeh by placing a certain shape over the front of your lens. I refer you to an excellent article by one of our own, Dr. Harold's article is online; I think you can find it at The Luminous Landscape. You cannot slice a sphere and create an aspherical lens. However, the effect is also used as a cool trick to play with brightness and lights. Call it what you may, it has become like this discussion, quite unruley. And I'm sure that at some point, someone realized that with certain subjects, it it creates a pleasing picture by using a shallow depth of field and a soft background.
His column, 37th Frame, explains his facination with out of focus areas in a picture. Photographers sometimes deliberately use a shallow focus technique to create images with prominent out-of-focus regions. But your example of why one would want harsher bokeh is excellent. I was only responding to the claim which I likely incorrectly inferred that the only want to get a smooth bokeh is to shoot medium format. A Google search just now yielded 2,790,000 hits. They came up with the terminology to better discuss what they were seeing. Interesting part starts at 1:11.
The Japanese term boke is also used in the sense of a mental haze or senility. When a point of light is at the focal plane middle illustration , it is reproduced as a point of light at the image plane. I think it was a legitimate question. It can be re-purposed for defocus control. So they started overcorrecting for spherical aberration.