Structure of TLR
(1)…Focusing Screen
You can see image that you are going to expose on film, and focus on subject through the focusing screen. When subject is in focus on the screen, it will be exposed on film in focus.
(2)…Mirror
Mirror is located at 45 degrees angle behind the view lens. This mirror transports the image from the view lens to the focusing screen. And when the image comes on the screen, it will be horizontally reversed. This is because it is to be reflected at the mirror to reach the focusing screen.
(3)…Film surface
Almost the same image that you see on the focusing screen will be exposed on the film surface. But because the image is through the taking lens (and not the view lens), parallax occurs fundamentally. Most TLRs introduced after 1950′s is equipped with parallax correction mechanism.
(4)…View Lens
The image on the focusing screen comes from the view lens, and this lens is needed when you focus subject.
(5)…Taking Lens
The image exposed on film comes from the taking lens. This lens is coupled with the view lens, so when you focus subject through the view lens, it will automatically focus on the subject.
TLR in America
Around 1840, Daguerreotype had started to be manufactured in New York. Then, as the large-size TLR camera appeared in Europe, it was exported to America little by little, and around 1900, manufacturing was started there, too.
Twin-Lens Graphics Special, released in 1901, looked like a TLR camera, but it was not exactly Reflex camera, for the focusing screen was put on the camera back. On Twin-Lens Graphics, location of the focusing screen was changed for the camera to be a TLR.
In addition, Twin-Lens Graphics was a forerunner to the Graflex SLR camera.
Cloud Camera..
Around 1880, a staff of the meteorological observatory near London came up with the idea to build the mirror inside the camera to take a picture of cloud. That was when the camera employed the mirror in it for the first time.
Well, it is certainly effective because you just see forward to catch cloud above in the focusing screen.
This camera, therefore, was called “Cloud Camera”.
On this camera, two lenses were coupled with gear in the middle which syncronized the lense’ movement with the other, and the image on the focsuing screen standed up thanks to the mirror (before that, the image was up side down). This have been thought the direct root of TLR camera now.
But, there were still problems. One of them was that the camera was big, and not practical for that reason. And also, it was not for close photography because of parallax.
via Structure or TLR « History and structure of SLR, TLR Camera.
Seagull 4A TLR Inside Tour
If you are tring to fix your seagull tlr, better to watch this video first. Very useful in TLR restoration and repair.
Inside tour of Seagul TLR. I believe most TLRs share the similar structure.
DIY Replacing Mirror in Old twin lens reflex cameras
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This time, replace the mirror surface (mirror surface reflection) is the name of the domestic machine Ricoh flex VII.
Twin-lens reflex, so it is most similar to the structure, time does not change the Minolta auto code in Rolleiflex. Mirror surfaces are then extracted in this way is usually degraded. Focus position is not changed even by changing the mirror surface of the structure because it is pressed against the stopper plate spring on the left. |
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To which the mirror surface is available, those sold for repair camera is generally very expensive.
Cut glass is in the hardware store. It is sufficient for the cheapest ones. |
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It is a simple glass cutting than I had expected. I think the bend while pulling on both sides put the scratches in the glass cut it hang. Can not peel off the protective sheet until the end of the blue.
Repair of dozens of twin-lens reflex is possible with a single mirror of ¥ 1,890. No doubt because it is so you do not put a face sheet of blue glass cutting shed. |
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You have put a protective sheet surface of the front side blue. I’ll leave this up to the mounting surface of the sheet, so very weak. |
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This is a Ricoh flex, it is exactly the same procedure in the Rolleiflex. |
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The mirror is fixed by simply pressing plate spring. Then, peel off the protective sheet of blue. |
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Shiny. Brightness of the finder was felt more than doubled to experience.
I want to try so very simple. Finder of the old twin-lens reflex is to regain the glow of the time. |
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This flex Aires automat (with Nikkor).
Hood focus of many twin-lens reflex depart with four screws. |
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Severe degradation of the mirror surface. Is how the mounting plate is pressed against the stopper in the spring as well. Even if there is no movement of the focus to be replaced. |
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We cut a new surface mirror. Since the tip of the cut glass is not stable at normal scale, I will use one that does not slip if there is a certain thickness.
Cutting units of 100-yen shops, this is also useful as a mouse pad actually. |
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Here but have to peel off the sheet, those who do not have good peel.
So I tried to put Fresnel incidentally here buying. |
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WARNING *** *** Let’s not act to earn margins, such as auction based on information that has been opened to the public on amateur camera repair workshop. |
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