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p.1 #8 · p.1 #8 · LensRentals: MTF Tests for Batis 18mm and 135mm f/2.8 Lenses | |
philip_pj wrote:
'the 25 is at f2 and the 18 at f2.8. At the long end it is 1.8 for the 85 and 2.8 for the 135.'
A major flaw that seriously devalues the results, maybe there is a reason (not enough time?). Playing fields cannot have a ten degree slope, and we disregard tail wind sprint times for good reason. Once past the narrow case of 'best wide open' trophy winner (surprise, surprise: it went to the slower lens), what else can be imputed?
Lloyd Chambers has published 'all aperture' Zeiss lens MTF in the past, but he now hides it behind his pay wall. What buyers need to know is how each lens changes its (MTF-indicated) characteristics with each advancing aperture on stop down. I don't much care how fast my car goes at redline RPM - in first gear.
FWIW, here are Lloyd's series for the 25mm and 85mm Batises, so you can (kind of) compare these with Zeiss data sheets for the other two at two (WO and best overall) published apertures at least, or buy into LC. Every picture tells a story, but you need the full story.
https://diglloyd.com/blog/2015/20150429_0952-ZeissBatis-25f2-MTF.html
https://diglloyd.com/blog/2015/20150429_1044-ZeissBatis-85f1_8-MTF.html...Show more →
Yes I wish Zeiss published the full aperture series of MTF results.
Anyhow one can see that the difference between f2 and f2.8 is pretty dramatic on the 25mm.
The MTF 40 at centre for instance goes up almost 20% from just over 50% to just under 70%.
Which makes for most, but not quite all as @Fred Miranda has pointed out, the difference with the phenomenal 18.
Zeiss own data show that the 18 is centrally about 10% (MTF 40 again) ahead of the 25 both at f2.8, and it stays that way as you stop then both down; the truly remarkable thing about the 18 which we can't tell from a one aperture test is that according to Zeiss data (and my copy is similar) it is basically unchanged as you stop down. It's pretty much diffraction limited from wide open. For an 18mm??
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