Sigma Telemac 2X
Teleconverter • Film era • Discontinued
no photo
- Announced:
- · No data
- Production status:
- ● Discontinued
- Country of design:
- · Japan
- Original name:
- · SIGMA TELEMAC TELECONVERTER 2X MAGNIFICATION RATIO 1:1/2
Specification
| Optical design: | |
Magnification factor: | 2x |
| 35mm full frame | |
| Canon FD | |
| Canon FL | |
| Exakta | |
| Konica AR | |
| Leica R | |
| M42 | |
| Minolta SR | |
| Nikon F | |
| 4 elements - 4 groups | |
| Physical characteristics: | |
| 130g (mount not specified) | |
| ⌀60×32mm (mount not specified) | |
| - | |
| - |
Source of data
- Manufacturer's technical data.
Manufacturer description
Because of its patented design the Sigma 2X rear lens converter, Telemac, is instantly convertible, changing from a rear lens converter to an extension tube. In both applications automatic diaphragm operation and meter coupling are fully retained. You will find the 2X Telemac to be the ideal companion for your Sigma MACRO lens.
Unscrewing the lens group will enable you to remove the lens group from your 2X Telemac, transforming it to an automatic extension tube with meter coupling.
For best results when using your Telemac as a 2X converter, use it in combination with a high quality lens, such as a Sigma MACRO or Telephoto lens. For maximum definition, stop the lens down to F8 or more, and for handheld shooting, be sure to use a shutter speed which most closely matches the combined focal length.
For example, a 135mm + 2X Telemac combination equals 270mm, therefore use a shutter speed of at least 1/250 second. For slower shutter speeds, mount the camera on a sturdy tripod.
If your camera's micro-prism blackens out, focus on the mat section of your ground glass. At times mirror cut off is visible, that is in cameras with a short mirror the upper portion of the ground glass will grow dark; however as this does not affect the picture being taken in any way, there is no need for concern.
When using the Telemac as an automatic extension tube it will necessary to increase the exposure. Of course, for cameras with built in meters no exposure computation if required. However when using a hand meter please use the following formula.
EF = IF x (F + EX) / F
EF: The effective F number
IF: Indicated F number
EX: The extension of the tube which is 25
F: Focal length of lens
Example: If you have your 50mm lens mounted on the extension tube and set the lens diaphragm to F8, what is the effective F stop, or its true value?
EF = 8 x (50 + 25) / 50 = 12
That is, the effective F stop is approximately F11, so use a shutter speed one stop slower than that indicated by the hand meter.