Ephotozine Review: Z 100-400/4.5-5.6 S VR

Started Jan 25, 2022 | Discussions thread
Leonard Shepherd Forum Pro • Posts: 24,292
Re: Ephotozine Beware - Poor testing protocols…

anotherMike wrote:

It's another flat chart testing site, who is *not* reporting MTF information in the way a proper MTF optical bench test would, so I lump most of these into the same category of flat test chart sites that are minimally useful in the real world.

Perhaps adding a bit more detail an optical bench test MTF is primarily a measure of contrast - often based on infinity focus.

MTF 50 is primarily a measure of resolution at a 50% contrast of a test chart filling the frame.

Both provide information - though in different ways.

Back to ephotozine - they use a test chart consisting of several sections which seems much larger than a common around 3 foot resolution test chart. I have not been able to establish where they place "edge". This might partly explain why their results can be different to some others.

A large MTF target makes alignment of very wide angle lenses easier - offset with focus distance issue with longer lenses.

The bigger problem is, as I've typed endlessly about, that an MTF50 scoring from a test chart in NO way fully categorizes a lenses resolution performance nor it's image quality - it is but a small singular data point that sadly far too many forum readers use as some absolute proof of quality in an attempt to prove or defend their lens opinion. Useful, yes, but as an absolute indicator of resolution and/or image quality, not at all.

+1

Moral of story: look at consensus of opinions, including the chart tests, look at subjective reviews, think about differences in distance performance vs close performance and obsess less about MTF50 scores.

Nearly +1.

Many S lenses (and several Sony lenses) have twin focus motors to try to better equalise performance at different focus distances.

-- hide signature --

Leonard Shepherd
In lots of ways good photography is much more about how equipment is used rather than anything else.

 Leonard Shepherd's gear list:Leonard Shepherd's gear list
Nikon Z9 Nikon AF-S Micro-Nikkor 60mm F2.8G ED Nikon AF-S Nikkor 300mm f/2.8G ED-IF VR Nikon AF Micro-Nikkor 200mm f/4D ED-IF Nikon AF-S Teleconverter TC-17E II +22 more
Post (hide subjects) Posted by
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow