This post will give you a basic understanding of what you need to do if you want to start experimenting with square bokeh. On the way, we’ll visit some basic photographic concepts like depth of field and looking for a different subject. 😁
To get square bokeh, you need a lens with a square aperture. The aperture is the opening in the part of the lens that people often mistakenly call the shutter. One way to try this is to get a set of filters — but I have a future post on how to make your own — so maybe wait!
The filters are going to restrict the incoming light a lot. If you can, with simple shapes, it is often more fun, interesting, and effective to look for lenses with unusual-shaped apertures.
How to get a vintage lens with a square aperture
Lenses with square apertures are unusual, but not really that expensive or hard to find. At least they don’t have to be. The Meopta Belar seems to sell for $40 as I write this, and you can find it cheaper if you know how to look — especially if you have some basic tools and are willing to watch a few YouTube videos and figure out how to clean a lens.
Not all Meopta Belar enlarger lenses have square apertures. Even if you find a 50mm f4.5 like mine, I am not sure if it will have a square aperture. You have to find out about the specific lens you are looking at. Just looking on eBay it appears that many of them have more than four aperture blades.
Notes about lens maintenance (cleaning, lubrication, and adjustment)
- Some vintage photographic equipment can be seized and impossible to open.
- This problem is especially common where steel and aluminum parts, are pressed or screwed together.
- Avoid lenses that appear to have excessive corrosion.
- The Meopta Belar I used is pretty simple, but even it has a surprising number of parts that you need to remember how to put together again correctly.
- Do not disassemble anything that you don’t have to disassemble!
- Try to work on the lens in a dust-free environment.
- Peroxide seems to take off fungus without hurting the coatings, though the fungus itself may have hurt the coatings.
This post isn’t about vintage lens cleaning, lubrication and adjustment though, and you can probably buy one that’s CLAed if you really want to.
How to mount an enlarger lens for and start experimenting with square bokeh
Enlarger lenses are designed for printing photographs from film to paper. That means they are not made to mount on a camera. They typically screw into a flat metal plate that attaches to the enlarger. That plate then moves up and down to focus. That means there is no focus ring on an enlarger lens.
On a camera, you will need a way to move the lens otherwise you won’t be able to focus. You can buy a helicoid, a variable length extension tube that extends and retracts when you turn a ring. Think of it as a focus ring for lenses that don’t have one.
It is not likely though, that your helicoid will have the threads you need for the enlarger lens you get. Just make sure that the lens mount threads are a smaller diameter than the helicoid’s. And then get an adaptor.
In the case of my particular Meopta Belar 4.5/50 and helicoid, I needed to adapt from 23.5mm with a thread pitch of 0.5mm (23.5×0.5) to m42, which is 42mm and 1mm thread pitch.
There are myriad adapters, so you can probably find one for the lens you are going to use. Just check before you order the lens because some are easier to find than others. Also some are only available from China which often means a couple weeks of waiting.
How to use a lens with a square aperture to create different square bokeh effects
This post is more about finding creative ways to add image-making capability. The Meopta Belars with square apertures are a fun and inexpensive way to do get some really unusual bokeh results.
Create interesting bokeh effects with a square aperture is just like creating interesting bokeh effects of other shapes. As a photographer, you alter bokeh by manipulating three interrelated factors: Aperture, Distances, and Background Contrast.
How background contrast affects bokeh
We’ll start with the last one, because it’s easiest to explain. If you have a background with very similar values and very similar colors there will be less difference between a bokeh square and its edges. More contrast in the background makes the bokeh textures show up more and makes bokeh squares and diamonds stand out.
Using lighting to create more pronounced bokeh shapes
One way to achieve pronounced bokeh shapes is with lighting. Typical images made with a Helios 40-2 or 44-2. These lenses have spherical distortion also called “swirl bokeh.” It is common to see these lenses used for portraits taken in front of backlit trees. And there’s a good reason for that.
Sunlight between the leaves makes a high contrast pattern of specular highlights. These are perfect for creating variation in the blur that will reveal shapes and patterns in it. It’s the easiest way to see what the lens is doing.
Another common subject is Christmas lights or night-time street photography. Again you have bright and dark and a mixture of colors. This is a good way to see what your lens is doing.
Though subtle effects can be interesting too.
How aperture affects square bokeh
You will usually want the widest aperture possible (lowest f-number) to blur our more of the background. The wider the aperture, the shallower your depth of field. Depth of field is just what is in focus. Think of it as a distance range that is in focus. Where it starts and ends depends on focus and aperture.
If you are trying to make bokeh patterns like bokeh squares (or bokeh boxes) it may work to stop down. This is reducing the size of the aperture and it reduces the size of bokeh shapes.
Smaller shapes give you bokeh more like squares, diamonds, or square bubbles (maybe we should call those bokeh boxes). Larger shapes give you more overlap. This can resemble plaid or become almost a texture like linen, as mentioned above.
Stopping down also gives you more depth of field so a deeper range of things in the image will be in focus. When you are trying to manipulate blur, this can be a problem.
Apertures that give different bokeh shapes depending on settings
Apertures can change shape depending on their setting. Some go from round to triangular to heart-shaped. The Meopta Belar that I have, goes from round to square with curved corners to square.
With the aperture wide open, at least on the Meopta Belar the aperture is round, so you will get more typical bokeh results wide open. This isn’t necessarily a bad thing. Just note that in order to get squares, you have to stop down at least one stop.
Because enlarger lenses don’t tend to be especially fast, and you need to stop down to get squares, it can be challenging to get good blur for bokeh effects.
Which brings us naturally to the next factor: distances.
How to use distances to get different square bokeh effects
Distance affects focusing. The closer your lens is focused, the less depth of field you have. At the furthest extreme, if you focus on a subject too far away, your lens is focused at infinity. Your the depth of field goes from wherever it starts all the way to horizon or even the stars. You have no background blur.
At the other extreme, if you are focused on something very close, your depth of field even at f11 can be very thin. This produces a lot of blur.
So try to find ways to move your camera closer to the subject to get more blur.
As long as you are focused closer than infinity, you will get more blur in things farther from your depth of field — either closer to or farther from your camera. Sometimes foreground blur can be very interesting. So a more-distant background and a closer foreground will be more blurred.
This affects bokeh shapes in the same way that aperture does. More blur gives you more of a texture, and less gives you more individual shapes. So a closer background will give you more individual bokeh diamonds and bokeh boxes and a more distant one will give you more linen texture. Somewhere in the mid-range you get the plaid-like overlapping squares.
Square bokeh lenses are about fun and experimentation
I think sometimes photography gets too serious and too technical. Experimentation with your particular gear is worth more than armchair photography. If nothing else, experimentation gets you making actual images!
One reason I like the my Ektoplasmars, Meopta Belar, and even my nifty 50 (old Nikkor f1.4 AI), is that they show how you can take something that is old, possibly worn, low-tech and use it to create unique evocative images.
And all of this is a lot of fun!
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P.S. — You will sometimes hear that lenses with square apertures have “only two” aperture blades. That may be true of some, but mine clearly has four.
P.P.S. — Once you understand making bokeh shapes, you also understand avoiding distracting, unpleasant, busy bokeh with lenses that have it. Open the aperture, move closer to the subject, or move so that objects behind the subject are farther away.