一般而言,单反相机是不可更改画面比例的。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/00e93901213fb80e6b32352a3bd12f2eb838946f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
当用取景器取景时,取景器的视界比例即是 3:2 的,且取景器长宽比无法更改。为避免不必要的麻烦,故成片也是 3:2。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/9825bc315c6034a87026ec7cc613495408237602?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
当用屏幕取景时,实际上是相机对画面进行了裁切,所以可以调整画面比例。因为不是使用取景器,而是使用屏幕。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/e824b899a9014c08deed7c58077b02087af4f47d?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
屏幕所见即所得,避免了某些麻烦,故支持屏幕取景修改照片比例。而实际上也是相机系统拍摄后得到一张 3:2 的图片,然后自动裁剪而得。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/503d269759ee3d6d90abd0364e166d224e4adeda?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
针对取景器取景拍得的照片,建议可以后期裁切。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/9e3df8dcd100baa1980b10464a10b912c8fc2e23?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
不论是后期裁切,还是屏幕实时取景由相机裁切,都是在原 3:2 图片基础上删减了部分像素,使像素的利用率降低。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/b21bb051f8198618ab26b87947ed2e738ad4e6ee?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)