The Atmospheric Dispersion Corrector Professional from Gutekunst Optiksysteme
The Atmospheric Dispersion Corrector (ADC) corrects the effects on the telescope image caused by the atmospheric dispersion to maintain the full optical performance of the telescope. This holds true for photographic applications and especially for visual observing.
Why is correction of atmospheric dispersion important?
Atmospheric refraction describes the deviation of a lightray from a straight line as it passes through the atmosphere. Refraction depends on the wavelength of light: blue light is more affected than red one. As a consequence the blue part of an image is shifted to a higher position than the red one and a star appears as a tiny trail perpendicular to the horizon.
The greater the distance to the zenith is the larger the displacement is. Depending on the distance to the zenith the spread between blue and red starlight grows and exceeds 1 arcsec for zenith distances over 55° (35° above horizon). For comparison the resolution of an 8" telescope is about 0.5". For zenith distances greater 30° no diffration limited image can be achieved anymore, for a 24" telescopes this is already the case for 15°.
Features of the Gutekunst Optiksysteme ADC
- the only corrector on the market which ensures diffraction limited images by maintaining the optical performance of the telescope.
- complete restoration of the contrast
- easy adjustment optimization of the dispersion correction because only one adjustment screw is need for adjustment (dispersion elements are automatically synchronized)
- the object absolutely keeps its position during the adjustment
- the 28mm aperture of the ADC compact is absolutely sufficient for visual observations with 1.25" eyepieces and with observations with binocular viewer.
Functional principle
The ADC has two pairs of prisms. Each prism pair is configured as a plan parallel plate with a crown glass and a flint glass. The glasses are selected to have identical refraction indices but different dispersions. The identical refraction index guarantees that the image doesn't move when the prisms are turned. When the prism pairs are turned by the same angle but in reverse directions the effect of compensation can be varied. In case the two prism have the same orientation the compensation effect is maximal. The compensation becomes zero in case the orientation of the prisms is exactly opposite (180°).
Simple correctors using two single prisms which have to be turned contra directionally to achieve the appropriate correction suffer from the following disadvantages:
-The single prism system will shift considerable the image during the adjustment process for eliminating the atmospheric dispersion
-Further on, the single prism system introduces an asymmetry into the optical system which results in a reduced optical performance.
Systems Performance of the ADC System for different Classes of Telescopes
200mm (8") Telescope
Refractor: APM-LZOS180, APM-LZOS 200, APM LZOS 254, TEC APO 180 FL, TEC APO 200 ED
Reflecting Telescopes: Takahashi Mewlon 210 and 250, Meade LX 200 10", Celsestron 8 SE, EdgeHD 800 and EdgeHD 925
300mm (12") Telescope
Refractor: APM-LZOS280, APM-LOZOS 304, APM-LZOS 330 and APM-LZOS 365
Reflecting Telescopes: Meade LX 200 12" and 14", Takahashi Mewlon 300, Celestron EdgeHD 1400
above 400mm (16")
Mead LX 200 16", Alluna RC 16" System, Alluna RC 18" System, Alluna RC 20" System, Alluna RC 24" System, Argus Optics 24" Cassegrain, Planewave 17" CDK, 20" and 24" CDK
Delivery Contents of ADC-Compact unit
- ADC Compact unit with 48mm dove tail interfaces
- T2-Interface eye piece side: M42x0.75 female thread –
- 48mm dove tail connection to the ADC unit
- T2-Interface telescope side: M42x0.75 male thread –
- 48mm dove tail connection to the ADC unit
- Optical inspection record
Remark
In case of using a binocular viewer a barlow lens system should be used for telescopes with an aperture ratio less than 12.
Products specifications
| Prism angle | 2° 24' |
| Optical accuracy | 1/30 lambda rms |
| Weight | 440 g |
| mechanical path | 47 mm |
| Connection to telescope | dove tail 48 mm |
| Connection to telescope | T2 internal thread |
| Optical Length | 45 mm |
| Connection to eyepiece | dove tail 48 mm |
| Connection to eyepiece | T2 external thread |
