回帖：这个帖子走到了这里，其实我也很累，回复别人的回复是很累的一件事，在我这段时间跟大家交流上我感觉，各位对主平面似乎没怎么思考过，但其实个人认为这是一个很严重的问题，指导性的东西一旦出错，根基就不稳。在日本，计算主平面对于变焦系统的学习是相当重要的，美能达，尼康，佳能……各大光学公司的光学设计人员都是要求对主平面有一定认知的。高斯公式建立在主平面基础之上，你用高斯公式却不计算主平面，其中的问题可想而知。我最后举一例子，一个四主群的变焦镜头，一三群固定不动，二群移动变焦，四群补偿，起聚集作用。下面这组数据是1至3群在变焦过程中的主平面位置，前主平面是以L1R1为基准，后主平面是以3群最后一块镜片R2面为基准，单位是mm，如下

1至3群后主平面1至3群前主平面
-492.260 220.8067919
-536.013 241.198356
-589.135 265.9121471
-655.003 296.5062035
-738.844 335.3905538
-849.199 386.5018623
-1001.031 456.7397623
-1223.182 559.4007168
-1579.298 723.8282558
-2243.030 1030.081803
-3916.514 1801.870179
-16236.722 7482.171829
7379.169 -3405.308987
2975.171 -1374.645671
1850.679 -855.9434792
1336.289 -618.5144786
1041.380 -482.2691261
850.143 -393.8150364
716.057 -331.7041159
616.813 -285.6508203
540.374 -250.1063037
479.676 -221.8132033
430.298 -198.7334131
389.334 -179.5263905
354.792 -163.2742119
325.265 -149.3271665
299.725 -137.2124354
277.411 -126.5777015
257.741 -117.1550368
240.265 -108.7370409
224.631 -101.1606416
210.557 -94.29583221
197.816 -88.0376756
186.222 -82.30052082
175.624 -77.01374854
165.894 -72.11859431
156.926 -67.56574369
148.629 -63.31348885
140.929 -59.32629942
133.758 -55.57370284
127.062 -52.02939858
120.791 -48.67055111
114.902 -45.47722091
109.359 -42.4319028
104.129 -39.5191488
99.183 -36.72525774
94.495 -34.03801828
90.044 -31.44649469
85.808 -28.94084734
81.770 -26.51218128
77.913 -24.1524179
74.222 -21.8541855
70.685 -19.61072549
67.288 -17.41581155
64.021 -15.26367955
60.874 -13.14896651
57.837 -11.06665707
54.903 -9.012036259
52.062 -6.980647575
49.309 -4.968255501
46.635 -2.970811734
44.036 -0.984424523
41.504 0.994669434
39.034 2.970130976
36.622 4.945542762
34.262 6.924432216
31.950 8.91029344
29.681 10.90660842
27.451 12.91686777
25.255 14.94459133
23.091 16.9933488
20.953 19.06678074
18.839 21.16862019
16.744 23.30271507
14.666 25.47305182
12.599 27.68378046
10.542 29.93924143
8.489 32.2439946
6.438 34.60285088
4.385 37.02090677
2.326 39.50358268
0.256 42.05666523
-1.827 44.68635463
-3.929 47.39931775
-6.053 50.2027479
-8.204 53.10443257
-10.388 56.11283043
-12.610 59.23715921
-14.874 62.48749656
-17.189 65.87489612
-19.559 69.41152179
-21.992 73.11080364
-24.496 76.9876198
-27.079 81.05850956
-29.752 85.34192426
-32.525 89.8585241
-35.409 94.63153101
-38.418 99.68715053
-41.567 105.0550789
-44.872 110.7691164
-48.353 116.8679139
-52.032 123.3958872
-55.935 130.4043463
-60.090 137.9528988
-64.533 146.1112114
-69.302 154.9612375
-74.447 164.6000641
-80.024 175.1435886
-86.101 186.7313193
-92.760 199.5327262
-100.105 213.7557565
-108.261 229.6584273
-117.385 247.5648792
-127.680 267.8880267
-139.407 291.1622037
-152.908 318.0913576
-168.647 349.6221746
-187.258 387.0586076
-209.643 432.2479994
-237.121 487.8970953
-271.709 558.1376136
-316.641 649.6061526
-377.467 773.6816161
-464.562 951.6424869
-599.838 1228.425073
-838.946 1718.159777
-1376.869 2820.715188
-3713.479 7612.04972
5564.002 -11414.89854
1609.233 -3305.008862
946.634 -1946.724626
673.327 -1386.792855
524.028 -1081.169703

可以发现主平面的位置变化时极大的，若你不去计算主平面，在求解4群的位置时问题就很大了，物距为无穷远当然影响