EF 400mm f/5.6L USM image quality

IBIS has very little effect at 400mm due to the fact that the sensor can not be moved far enough!

At 400mm it is almost unnoticeable.

Regardless the EF 400mm f/5.6 is a really nice lens.

I just got one last month.

Will T wrote:

IBIS has very little effect at 400mm due to the fact that the sensor can not be moved far enough!

At 400mm it is almost unnoticeable.

Regardless the EF 400mm f/5.6 is a really nice lens.

I just got one last month.

You have now got me really thinking about why I need to dial in the focal length on my A7R4, the ibis of which really works dramatically well on this lens.  It needs to, with that resolution!

I tried various length settings and interestingly found that a 500 setting is best for some reason. I gotta do some reading now you've said that!

e.g. I assumed the setting was not required to assist the amplitude compensation, but rather the " frequency" of the shake of a tube that long.

Octopuss wrote:

I've just had an idea. Considering the lens is still in production since 1993 (according to Wikipedia), do you think the newer (like from the past ten years or something) ones could possibly have better image quality due to better manufacturing process or something?

It is a noble idea and has merit yet the tradeoff or opportunity cost for a 400 prime and the invisible increase in resolution is too high.

Yes the 100 - 400 II would spend most time at 400 mm but the ability to reframe without moving or making sound , particularly with wildlife is there if you need it.

One can fine many bench test sites online - generally the 400 prime is slightly less sharp than the 100 - 400 II on center and slightly sharper off center.

Be reminded that these are all an n = 1 set and all production runs have variances.

400 prime

https://www.opticallimits.com/canon_eos_ff/612-canon400f56ff?start=1

EF 100 - 400 @ 400

https://www.opticallimits.com/canon_eos_ff/896-canon100400f4556is2?start=1