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
![ALVANDI optical viewfinder with spirit level and mask ALVANDI optical viewfinder with spirit level](../images/products/viewfinder-spirit-level.jpg)
![optical viewfinder and 4x5 in mask optical viewfinder and 4x5in mask](../images/viewfinder/viewfinder-front-view.jpg)
![optical viewfinder optical viewfinder back view](../images/viewfinder/viewfinder-back-view.jpg)
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.
![Optical viewfinder lenses 2 group-3 element section view Optical viewfinder lenses 2 group-3 element - section view](../images/viewfinder/viewfinder-lens.jpg)
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.
![Optical viewfinder with 4x5 in mask section view Optical viewfinder with 4x5 in mask - section view](../images/viewfinder/viewfinder.jpg)
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 - masks Optical viewfinder masks](../images/viewfinder/viewfinder-masks.jpg)
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