Canon EF 400mm F5.6L 佳能456

The Canon EF 400mm f/5.6L USM is a classic telephoto prime lens introduced in 1993, long regarded as a favorite among wildlife and aviation photographers. Recently, I purchased a used one and use it on my R5 with 1.4x and 2.0x teleconverter, IBIS on mirrorless body makes it perform even better.

佳能 EF 400mm f/5.6L USM 是一支经典的远摄定焦镜头，自1993年发布以来，受野生动物与航空摄影师喜爱。我最近购入了一只的镜头，搭配我的R5使用，同时也配了1.4x和2.0x两个增距镜，新无反自带防抖，让这个无防抖镜头实用性更高了。

Part of Canon’s professional L-series, it features a robust white metal body, weighing only about 1.25 kg, can easily hold and shoot by hand for a considerable while.

镜头有佳能红圈头的全金属结构与白色涂层，重1.25公斤，能手持拍摄很长一段时间。

It has excellent optical sharpness, good enough under F5.6, even better than most newer zoom telephoto lenses. It’s autofocus is driven by a ring-type USM motor, good enough but obviously slower than some modern L lenses (e.g. my RF 70-200 L), even for flying birds, it has acceptable success chance. One problem is that its closest focus distance is 3.5M, which means you cannot focus on little birds near you.

光圈全开F5.6锐度就很好，对比大部分近些年发售的超长变焦镜头都不虚。用旧的USM马达对焦，够用但和新的红圈如RF70-200比，明显要慢，拍飞鸟成功率也还可以接受。最大的问题是最近对焦距离3.5M，没法拍身边的小鸟。

There are a few sample images, mostly birds, and also some other topic.

有几张样片，打鸟为主，还有一些其他题材的。

One more thing, I think its image quality is still very well with a 1.4x teleconverter and acceptable with a 2.0x. With teleconverter, its F will be F8 under 1.4x and F11 under 2.0x, I experienced no autofocus issue with my R5 body during daytime.

最后测一下增距镜，1.4x下画质衰减很小，2.0x下也算可用, 1.4x和2.0x下光圈分别8和11，我在R5上用，白天没有遇到任何对焦问题。