Optical viewfinder for camera
Application of viewfinder
The optical viewfinder is a tool to composition and review images before shooting. It also helps the photographer to choose the focal length of the lens. Also, when the light is low, it is a great help to image composition.
The ALVANDI new optical viewfinder is redesigned. It has a 120° angle of view, with spirit level, that can be seen from the viewfinder. You can change a variety of masks based on lens and format. It has the ability to adjust the diopter. Read more
Viewfinder structure
An important part of this device is the optical system. This tool should be able to create an image of super wide-angle at least 140 degrees, directly (no reverse). For this purpose, I used WinLens 3D software for basic design. And according to the patents, and study them, I have created a sketch. This lens is comprised of three elements in the two groups. The front section containing two negative lens and a positive lens is included in the back section.
The next step was cutting and polishing glass lens according to the design. After a long time search, I found artisan it, I ordered for the production. Next step, collection lens is built based on the design, should be assembly inside a chamber. Thus, external body of viewfinder, also designed and were made.
The composition system
But, for composition in landscape,with a variety of formats and lenses, I made special frames (mask) for it, which will be installed in front in viewfinder. To make this part, I used from a glass transparent plastic (Plexiglas). By using machines, according to lenses angle of view, I've carved frame with very thin lines. In this regard, I have tried as far as possible do remove error parallex. Table below shows selected format, compared to the focal lens in optical viewfinder.
| focal lenght of large format lens | ||||||
| 210 | 150 | 90 | 75 | 65 | 47 | film format |
| ok | ok | ok | ok | ok | ok | 6x6 cm |
| ok | ok | ok | ok | ok | ok | 6x9 cm |
| ok | ok | ok | ok | ok | ok | 6x12 cm |
| ok | ok | ok | ok | ok | ok | 6x17 cm |
| ok | ok | ok | ok | ok | ok | 4x5 in |
Optical viewfinder by using standard flash mount, can be installed on a variety of cameras.
Technical Specification
Viewing Angle: 140°
Masks: 5 Piece, 6X6cm – 6X9cm – 6X12cm – 6X17cm – 4X5in
Material: Aluminum Alloy 7075
Coating: Anodizing
Internal Paint: Anti-reflective black
External color: Semi-gloss black coating
External dimensions: W:77, H:87, D:80 mm
Weight: 300gr
