巴德 Baader MPCC 慧差改正镜 适合牛顿式天文望远镜深空摄影 目视修正边缘的慧差。前面是标准的2寸接口，后部是M42X0.75螺纹，搭配各种配件多是非常方便。摄影接环和目视接环另外购买 Baader Multi-Purpose Coma Corrector
The Baader Multi Purpose Coma Corrector | The Baader Multi-Purpose Coma Corrector can be used with all Newtonians with a focal ratio between f/4 and f/6. Beyond f/6 you will not need a coma corrector anyway because the Newtonian coma is very little in such telescopes.
A coma corrector works by reducing the design inherent coma of Newtonian telescopes (see left image below). It does not change the focal length.
The telescope connection is 2", so the corrector fits directly into the focuser's 2" clamp. On the other side a T2 (M42x0.75) thread is used to connect a camera. T-rings are available for most common SLR and Digital SLR cameras. Mechanical length is only 3mm. |
| | M 81 / 82 without Coma Corrector
take a look at the magnified stars in the corners of the image. These large "blobs" are typical for fast focal ratio Newtonians.
The useful field is limited to the central regions. | North America Nebula with Coma Corrector
The stars are much smaller and clearer in the edges of this image. More stars are visible because their light is concentrated on a smaller area of the chip / film.
The useful field is much larger. |
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