Difference between revisions of "Great Wall DF"
(added more information.) |
|||
| Line 19: | Line 19: | ||
The '''Great Wall DF''' cameras are a Chinese series of medium format [[SLR]]s made by [[Great Wall|Beijing Camera Factory]]. | The '''Great Wall DF''' cameras are a Chinese series of medium format [[SLR]]s made by [[Great Wall|Beijing Camera Factory]]. | ||
| + | |||
| + | The model "DF-2" is the most common type, of the perhaps 5 variations made. | ||
| + | |||
| + | The camera was made in the 1970s-80s. Its design was largely derived from the German "Pilot" camera made by KW. | ||
| + | |||
| + | The lens is a 90mm front-cell focusing Tessar type. Unlike most Chinese "basic" cameras which use a Cooke Triplet type, the Great Wall has a true Tessar formula lens. The front cell focusing barrel focuses from 1 metre. The lens mount is removable, and uses the standard Leica 39mm screw thread. No other lenses were known to have been made for this camera, and because of the shutter design, it was perhaps also impossible to design others which would fit and work satisfactorily. The removable lens option is probably to allow the photographer to use the lens on an enlarger to make prints from the Great Wall negatives. | ||
| + | |||
| + | The Great Wall shutter is of the guillotine/sector shutter type- neither focal plane nor leaf. The same type of shutter found and used in the original Pilot and the German-made "Exa" (scaled down Exakta) 35mm SLR. The viewing mirror is part of the shutter. In viewing/focusing position, it blocks the lens path and prevents exposure. When the shutter is tripped, the mirror swings up, unblocking the light path from the lens. Then follow another sector in the form of a curve shield to curtail the exposure, once the ordained timing is done. The second shutter sector moves up from 1/30 to 1/200 second after the mirror swings upwards, depending on the shutter speed selected. The shutter, for some reason, causes some vignetting at the upper or lower parts of the frame. This is the reason why a square (barely 6X6cm) mask is provided to mask off the fuzzy frame edges. | ||
| + | |||
| + | The shutter is also notorious for not opening during exposure on occasion, particularly at the 1/200 sec setting. | ||
| + | |||
| + | The film is advanced by knob, and positioned by observing the frame numbers on the film paper backing through a red (sometimes green) frame window at the back. There are two windows, one for square 6X6 (12 exposures) and another for rectangular 6X4,5 (for 16 exposures), for this purpose. Both windows are shielded by metal blind lids. When the lids are drawn, both windows open, so it is necessary to remember what format (12 or 16 exposures) is being used, otherwise framing errors will occur. The mask for 6X4,5 exposures is often missing since these were not attached to the camera itself. Masks for 35mm, 127 and 828 roll films were supposed to be available. Making a home-made mask for 6X4,5 can be an easy task. | ||
| + | |||
| + | |||
===Links=== | ===Links=== | ||
Revision as of 10:26, 15 September 2010
|
| Great Wall DF-2, by Hartacnut |
|
| DF-2 finder screen, by studio CvH |
|
| Great Wall DF-2, by Boxy Brown's Bling |
The Great Wall DF cameras are a Chinese series of medium format SLRs made by Beijing Camera Factory.
The model "DF-2" is the most common type, of the perhaps 5 variations made.
The camera was made in the 1970s-80s. Its design was largely derived from the German "Pilot" camera made by KW.
The lens is a 90mm front-cell focusing Tessar type. Unlike most Chinese "basic" cameras which use a Cooke Triplet type, the Great Wall has a true Tessar formula lens. The front cell focusing barrel focuses from 1 metre. The lens mount is removable, and uses the standard Leica 39mm screw thread. No other lenses were known to have been made for this camera, and because of the shutter design, it was perhaps also impossible to design others which would fit and work satisfactorily. The removable lens option is probably to allow the photographer to use the lens on an enlarger to make prints from the Great Wall negatives.
The Great Wall shutter is of the guillotine/sector shutter type- neither focal plane nor leaf. The same type of shutter found and used in the original Pilot and the German-made "Exa" (scaled down Exakta) 35mm SLR. The viewing mirror is part of the shutter. In viewing/focusing position, it blocks the lens path and prevents exposure. When the shutter is tripped, the mirror swings up, unblocking the light path from the lens. Then follow another sector in the form of a curve shield to curtail the exposure, once the ordained timing is done. The second shutter sector moves up from 1/30 to 1/200 second after the mirror swings upwards, depending on the shutter speed selected. The shutter, for some reason, causes some vignetting at the upper or lower parts of the frame. This is the reason why a square (barely 6X6cm) mask is provided to mask off the fuzzy frame edges.
The shutter is also notorious for not opening during exposure on occasion, particularly at the 1/200 sec setting.
The film is advanced by knob, and positioned by observing the frame numbers on the film paper backing through a red (sometimes green) frame window at the back. There are two windows, one for square 6X6 (12 exposures) and another for rectangular 6X4,5 (for 16 exposures), for this purpose. Both windows are shielded by metal blind lids. When the lids are drawn, both windows open, so it is necessary to remember what format (12 or 16 exposures) is being used, otherwise framing errors will occur. The mask for 6X4,5 exposures is often missing since these were not attached to the camera itself. Masks for 35mm, 127 and 828 roll films were supposed to be available. Making a home-made mask for 6X4,5 can be an easy task.
Links
- DF-3 at heayes.com [1]
- Great Wall on forum Holga [2]
