这次又找到一位打过交道的本地同好,以下是他的意见:
"Just wanted to share some experiences on the performace of multi vs few element eyepieces. As you may have noticed, I'm all for fewer elements these days. Recently when Mr Harlequin came over for a quick saturn ob session, I got to try his 4mm UO ortho and compared it to the 4mm radian. With 4/2 elements/groups vs 7/5 in the radian, I was expecting the 4mm UO to trounce the radian and it came close to it. The image of saturn was noticeably brighter than in the radian, through sharpness was still close. Furthermore, the UO gave a cleaner image as compared to the radian's slight brown tinge, and was possibly slightly more contrasty. It resembled a more magnified view of the 5mm LE (5/3), bright and clean. Overall, the view through the radian looked as if you were looking through sunglasses (with brown tinge and dimmer image, analogy much exaggerated of course). I should also add that the UO was not perfectly sharp in the last 10-20% of the much smaller 40+ deg field whereas the radian was sharp up to 99% of the 60 deg field. The UO at 3mm eye relief was quite a pain to use as compared to the best-in-class 20mm in the radian. "
大意是:和4毫米焦距的Or目镜比较, Or目镜成像更加明亮,干净,锐度基本一样. 4毫米的Radian目镜好比透过太阳镜看(夸张了), 成像暗,略带棕褐色. Ra目镜一直到边缘都是清楚的, Or目镜边缘10~20%就不行了, 当然出眼点就更不行. 最后啥也没说, 只说让我自己抉择, 他的Ra 4最后也出了, 后来还发生连锁反应, 本地的Ra目镜通过Astromart出得光光的.
其实我也不戴眼镜看, 但我的镜子用无倍率的Telrad装置寻星,找目标时必须得戴眼镜(不然没法看 ), 后来眼镜也经常懒得摘了.
小蔡, 看来还是片数少的好,你的是六片, 短焦的Ra都7片了,还有啥好选择没? 实在不行只能把钱省下来上电跟了. |