In this article, I would like to look at how the contenders handle a large number of bright highlights that are out of focus (oof highlights), I call them Bokeh Balls.
A future article will focus on the actual rendering of out of focus areas in the background, the bokeh. See my Nikkor comparison for an example.
What is Bokeh?
Boke is japanese: ボケ
Originally, among other meanings, boke is an insult and means stupid, clueless or unaware, but it’s also the name of the japanese quince, a fruit. Lastly, boke also means “blurry” or “deliberately out of focus”.
It has been taken over into the English language with an -h added to the end, to help with the pronunciation: Bokeh.
In photography, anything that is not in focus, is bokeh (blurry). (See the Wikipedia article for a more precise definition.)
On a side note: people who believe that only bright balls of light in the background of an image should be called bokeh are utterly boke (clueless).
How to get Bokeh?
How do you get stuff to be out of focus in a photograph?
Looking at images like this, many wonder how the blurry background was achieved.
What you can tell from looking at the image and the information provided:
The subject was really close (the image is not cropped), the aperture was all the way open and the camera has a pretty large sensor.
Without further ado, I can tell you that Bokeh is directly influenced by the following parameters:
- Subject distance (the closer the subject is to the camera, the blurrier the background)
- Aperture size (the larger the aperture, the shallower the depth of field and the blurrier the background)
- Sensor size (the larger the sensor, the shallower the depth of field)
What are Bokeh Balls?
Bokeh Balls occur when a small point source of light is in the out of focus area of a lens. The more out of focus this point source of light is, the larger the ball will be in the image.
Usually, you can see this with street lights, candles on a christmas tree, shop decoration, etc. Some people really like to play with this effect as a background for portraits and such.
The effect can also be observed in images with lots of leaves in the background of your subject, which was the case in this picture of a squirrel in Bristol. If you look at the upper right half of the image, you notice a lot of circles of different colour and brightness. These are the result of reflections on leaves, sunlight breaking through and even differences in colours of said leaves.
Additionally, these balls take on the shape of the aperture and are influenced by internal vignetting of the lens.
This leads to two things:
- Upon stopping down the aperture, the Bokeh balls usually lose their round shape (unless the aperture blades are rounded)
- With the light source further away from the image centre, internal vignetting will lead to a cats eye (or lemon) shape instead of round Bokeh Balls (This effect is more pronounced at large apertures).
How did I test?
As usual, I used a black background cloth to maximize the contrast. As a “subject” I used the 50mm lens collection placed on my table.
To create the “interesting” part, I hung a long chain with >300 lights in front of my background (10 bucks at the super market).
The lenses on my table were less than 1 metre away from the camera, the background approximately 3 metres, which makes for a nice size of Bokeh Balls.
First, let’s look at all the contenders shot wide open, where every lens presents a round aperture opening and the Bokeh balls are not influenced by the shape of the aperture blades.
It becomes quickly obvious that the bokeh balls are largest in the case of the Nikkor 50mm f/1.2 Ai-S, because this lens has the largest aperture opening (approx. 42mm) followed by the Rikenon 55mm f/1.4 with a 39mm aperture. The 50/1.4 lenses follow with approx. 36mm diameter, then comes the Helios with 29mm ahead of the 50/1.8 lenses with 28mm and the Tessar with an underwhelming 18mm opening.
The second thing that seems to be the case is the fact that some lenses render the edges of the bokeh balls smooth, while other produce strong bright edges with high contrast overlaps.
The Rikenon, Fujinon (non-EBC) and also the Takumar are noticeably smoother in the center of the image compared to all the rest.
Looking at the image borders, the Fujinon looks the most pleasing to me, where the EBC-Fujinon delivers sharp edges and harsh differences in brightness between the different balls. The Olympus is a complete mess, whereas the Tessar at least keeps the “rendering” the same throughout the frame.
The Helios shows some tendency to non-uniformly shaped cats eyes. They are the cause for the famous swirly bokeh you can obtain with the Helios.
Stopping down by 1 stop
Let’s look at the situation once all lenses have been stopped down by 1 stop.
The Yongnuo keeps a fairly round shape because the 7 aperture blades are slightly rounded, but the edges are still very harsh. The Nikkors both show their aperture shapes with both seeming quite harsh.
The Takumar looks good so far, especially comparing it to the Planar T* where the aperture takes on a weird saw blade shape. The non-EBC Fujinon still has the lead with the smoothes bokeh balls and the EBC-Fujinon falls far behind.
The Olympus is still a mess, but the Rikenon looks great, despite its 6-bladed aperture.
The Pancolar and the Color-Ultron are close but the Pancolar looks slightly better in my opinion.
The Tessar shows its ugly pentagonal face, whereas the Helios shines with smooth bokeh balls.
Let’s compare the lenses at specific aperture values now, because sometimes the situation calls for a certain depth of field and won’t allow you to simply shoot wide open.
At f/1.4 the Fujinon (non-EBC) is my clear favorite, followed by the Rikenon. I’m really curious to see how the lenses handle real life bokeh.
Also, notice how the Nikkor 50/1.2 already shows the shape of its aperture at f/1.4. Let’s be glad that it has 9 aperture blades, so the effect isn’t that bad.
At f/2, the field of contenders grows significantly larger and some lenses now have a clear advantage due to their aperture being wide open.
The Yongnuo, thanks to the rounded blades, still shows perfectly round bokeh balls, which is a clear advantage.
Shape-Wise, the 8- and 9-bladed 50/1.4 lenses have a clear advantage here, but the Rikenon and the Fujinon (both 6 blades only) still present the smoother bokeh balls.
I couldn’t set the Color-Ultron to f/2 and forgot to take a picture at f/2 with the Pancolar, but the Yongnuo was set to f/2 for this comparison.
The Helios is the winner at f/2 if you ask me, but I still really love the Fujinon bokeh balls.
At f/2.8, all lenses have been stopped down at least once, except for the Tessar.
Compare the Nikkor 50/1.4 to the Yongnuo and you see what a massive difference rounded aperture blades can make.
The Pancolar now clearly beats the Color-Ultron, due to the better aperture design (8 vs 6 blades) and the balls overall look less distracting.
At f/2.8 I clearly prefer the Helios, but now the Rikenon took second place in front of the Pancolar and the Fujinon (non-EBC).
and at f/4
Many lenses now present harsh bokeh balls with clearly outlined aperture shapes.
The Helios leads the field, followed by the Pancolar and the Rikenon, where the aperture shape becomes obvious now.
At f/1.4 I love the looks of the Fujinon 50mm f/1.4 and the Rikenon 55mm f/1.4, but upon stopping down to f/2 – or generally using a lens at around f/2 – the Helios takes over the field with smooth, round bokeh balls. The Fujinon still looks quite good with most of the other fast fifties falling behind, either because of ugly aperture shapes or because of harsh edged balls.
Upon further stopping down, the Pancolar becomes interesting too, with the Rikenon catching up again, but the Helios stays king.
I’m really looking forward to seeing how the lenses will handle a real life situation with busy background to render.
Knowing from experience, the Helios will hardly be the king of smooth bokeh once the swirl sets in.