24-70 f4 is or 24-105 f4 II dilemma

Started Feb 21, 2018 | Discussions thread
OP maboleth Contributing Member • Posts: 692
Re: 24-70 f4 is or 24-105 f4 II dilemma

Steve Balcombe wrote:

maboleth wrote:

Steve Balcombe wrote:

Alexsfo wrote:

I think 24-70 F4 lens is underrated and somewhat misunderstood. Early copies suffered from RSA and focus shift which I have none of with 2017 lens and 5div.

This is not correct. Residual Spherical Aberration, which results in focus shift, is a consequence of the optical design and is *not* limited to early copies.

However the issue only manifests itself at close focusing distances - that may be why you haven't seen it.

Can you please explain to me what focus shift does practically? I read something about it, but not sure I understood correctly why it happens.

It's when you focus correctly with the lens wide open, but then when you stop down to take the shot it causes the focal plane to move back slightly. This is nothing to do with focusing accuracy - the camera can be correctly focused using manual focus and even Live View, and would take a perfectly sharp shot wide open, but the act of stopping down causes the plane of sharpest focus to shift.

In theory you should be able to focus stopped down by holding the depth of field preview button and focusing manually in Live View, but to be honest I've never tried it. In any case I have my DoF preview button reassigned to something more useful!

Thanks a lot Steve. Depending on the severity, it could potentially be an issue for me, as I do more closer scenes than infinity shots or landscapes.

This got me thinking about this lens again... I was almost decided to buy it. :-/

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