关于平场镜的像面距离

QHY8，SBIG83000，SBIG11K，这些冷冻CCD的靶面距离最前面的平面的距离一样吗？和单反加转接环的情况一样吗？
或者说，平场镜的截距是否是和冷冻CCD配合的，而单反是否情况不同？

回复 2# zbydd


    刚看了130s卖AT平场镜引用的网页http://www.astronomics.com/main/product.asp/catalog_name/Astronomics/category_name/Home/product_id/AT2FF
57mm +/- 4mm，单反加T环可以在范围内，

With CCD and DSI-type cameras, some experimentation with spacers will be necessary to achieve optimum performance, as these typically have much shorter camera front plate to sensor spacing than DSLR cameras.

对一些CCD，有必要加间隔圈，因为前面的距离比数码单反相机短得多。

你说的这种情况一般是在使用单反镜头时候才会出现，天文望远镜一般不考虑靶面到接环的间距。

就是不同品牌单反的法兰距也不同吧！

回复 5# shangql


    没错，这在原文也提到了“dependent on the thickness of the T-ring”


A Canon EOS DSLR/T-ring combination typically has a T-ring front flange to camera sensor spacing of approximately 55.5mm, although this number is dependent on the thickness of the T-ring you use and cannot be guaranteed. (Without T-ring, the distance from the front flange of the camera body to the sensor is approximately 44mm by itself.)  A Minolta/Sony DSLR and T-ring combo typically has an approximately 54mm T-ring front flange to sensor spacing. The exact number is again dependent on the thickness of your T-ring. (The camera front flange to sensor distance by itself is approximately 43.5mm.)  
A Nikon DSLR and T-ring combo typically has a total spacing of approximately 56mm. This number is again dependent on the T-ring thickness. (The camera front flange to sensor spacing is typically 46.5mm by itself.)

在QHY的中文网站看到些数据：
（和单反CCD到定位面的距离比较）