• BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

    Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

A7RIV needs high-end glass (1 Viewer)

marcsantacurz

Well-known member
Lloyd Chambers has a post today about finding lenses that are up to the 61MP challenge of the A7RIV.

I've noticed something similar with the d850, to a lesser extent. I cannot use my old 800mm f/5.6 AI-s with it. Results just look poor. It needs a lower resolution camera. The d500 and Olympus E-M5m2 both have smaller pixel pitch, but they only use the center of the lens so their IQ is decent on the lens.

To quote a few things:

Today in going over the files I was shocked at how disappointing most of them were—yikes, this is going to require careful selection and usage to really use the Sony A7R IV to its best. The gains for 60MP are real, but you’d better have the best lenses and perfect shot discipline and be aware of focus errors, focus shift and field curvature and lens asymmetry, with most of the lenses showing symmetry issues of varying degrees (and I’m beginning to question Sigma’s quality control, looks like the claims are bogus as to MTF testing).​

Here’s a headache: stopping down is not much of a solution for focus shift and field curvature and lens asymmetry because f/4 is the last aperture (for a high-grade lens) that avoids diffraction effects! Using f/5.6 shows subtle micro contrast losses with the best lenses, and f/8 visibly degraded. It’s exactly analogous to f/8 vs f/5.6 on the Sony A7R III—f/8 is the new f/11, so to speak.​
 

Spiekeries

Well-known member
That is why Sony recommend their own glass. Not as a selling point but because they know the Sony 600 prime and 200-600 is made with the A7R4 in mind. They where tested together in the development of both.
 

Users who are viewing this thread

Top