GFX 100 vs a7RIV landscape IQ Locked

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Erik Kaffehr
Erik Kaffehr Veteran Member • Posts: 3,585
Re: GFX 100 vs a7RIV landscape IQ

Hiphopapotamus wrote:

So you don't agree with the science of MTF charts and you prefer to come to your own conclusions that support your own views. This is human fallibility in action. In technical terms its called...


I do agree with MTF charts that are correctly handled. A website called 'Photodo' did tests at the Hasselblad factory, using their MTF testing bed:

Mamiya N 150mm f/4.5 L for Mamiya 7

Hasselblad Sonnar 150/4 CF

The Mamiya is a bit sharper at the center.

I also did a very simple calculation on MTF from Velvia:

But that analysis does not involve the MTF of the enlarger or of the scanner used.

Now, some guys stated that Phase One's IQ180 (an 80 MP 54x41 mm CCD back) performed comparably to 8"x10" film. Tim Parkin, who shoots large format didn't agree, so he investigated. Here are some samples from his testing.

Mamiya T-Max 100 compared, drum scanned to Phase One IQ 180

Mamiya 7, T-Max 4800 PPI Epson V750, not very close.

4"x5" on Provia scanned at 4000 PPI yields more detail than the IQ180.

The IQ180 tested here is an old back. How does it compare to the GFX100?

It seems that GFX 100 (blue curve) is a bit better than the IQ1380MP

Comparing the IQ 180 with the A7rIV the IQ 180 (red curve) is a bit better.

So, I would say that the IQ 180 results are a bit below what can be expected from the GFX 100.

Confirmation bias

Well, I think I looked at the facts.

If you're prepared to actually look at the history books, Mamiya got to where it was by copying and then exacting Schneider and Zeiss optical designs. Their rangefinders were copies of military-grade European rangefinders...

They not only made copies but they improved upon them which is why the Mamiya 7 is still regarded as one of the best rangefinders ever made.

Most Mamiya lenses are actually excellent, rather than good... And I have it on the authority of the types of people I actually know who are trained to rebuild the things and have been working on the tools for more than 50 years now.

Nothing that contradicts that. But lens design has developed a bit since 1990...

Best regards


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Erik Kaffehr
Magic uses to disappear in controlled experiments…

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