The Bulb lens or technically known as the Aqua Spherical lens has not had much exposure. Much to do with this build has been pioneering and experimental. Being one of the four prototype directions, this exercise was meant to only use waste material to create a working Kamra. It has since been designated the name Kamra #3 Bulb.
Rating the lens, to engineering the design to fit, calculating the focal formula, it was a challenge from the start to make this Kamra work. Producing a visible focused image, sharp and bright enough to get an exposure with a sensitivity of ASA 3. Here are some of the documentation of the build.
 |
| Globe Bulb ±100mm Ø and the standard E24 Light Bulb |
A glass bowl with water as a lens is nothing new and has been experimented with from the 15th century. Even the Vikings used quartz crystal as well as optical devices. It was a light bulb moment when I figured the glass bulb would be a great solution as a lens, easily found and many options for sizes suddenly seemed so feasible. *note* leave casing on, break from the bottom and remove the insides from that opening. / Globe Bulb was a contribution of Justin Lim, who sourced it from a lamp designer up in Penang. Thanks dude.
 |
| Thomas Sutton Patent Spherical Aqua Lens drawing, Light bulb lens |
Thomas Sutton in 1895 submitted a design for a Spherical Aqua Lens, basically the world's first fisheye lense, I believe 30+ were only made. The Light bulb filled with water was an excellent substitute of that design too. *note* be mindful of weight/ volume, 1 millilitre = 1 gram.
 |
| measuring the bulb, making the holder |
Figuring out how to mount the lens was also challenging, here is a full aperture opening (size of the bulb), profile of the bulb cut in plywood. *note* glass bulbs are not symmetrical.
 |
| Bulb lens mounting |
This mounting wasn't suitable and was scrapped in the final build. It leaked light and needed another attachment for the aperture size too.
Running test on focal length, aperture steps
 |
| the focus train concept (left), the finalised design (right) |
With the limitation of resources and skillsets, simpler designs with found objects were explored, although producing very interesting build and promising results. A fair amount of calculations on the lense axis and focus length etc later, the focusing train with horizontal load rails and a simple screw tightener to secure the focus.
 |
| focus carriage |
The focus train carriage with the arsenal of screws meant to hold together the lengths of plywood. It looks complex but the function filled the requirement for design. *note* nead drill press for more accurate work and better craftsmanship.
 |
| prototype kamra #3 Bulb finished Dec 2014 |
The finalised prototype kamra #3 Bulb was finished on Dec 2014. The design was kep at a minimum, as more functions are added on if and when needed. The bulb lens was mounted on the exterior with just a light bulb E24 screw mounting. The Globe Bulb was used which had a focal length of about 100mm. It was further secured with blu tac at the sides.
 |
| light bulb lens mounted on exterior of kamra |
The kamra finally went through some testings for print in July 2015 which produced its first print hence ending the project with all prototypes producing prints. The kamra was further developed, and the lense was moved and mounted from the inside. The lense was rated at /ƒ4, but from test prints, it showed to be overexposed by at least 1-2 stops. I deduced that the bulb on the outside capture light sources and also reflected from all directions and produced a big amount of flare.
 |
| first print July 2015 |
The first print revealed a fair amount of flare, even reflected ones. The image circle was big atleast 4", but the sharp focus was only concentrated in a very small circle.
 |
| further test lighting and results |
More test were run at varying light intensity. The lens proved to be more accurately rated at /ƒ2. It has an ethereal feel to the image, but does not distort as an expected 100mm would.
The concept of this camera is undeniably fascinating. I would love to develop this into a workable mobile unit, at a bigger format, 5 x 7, with wheels!
