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Hasselblad MTF Charts: Calculated, Not Measured, Distortion Correction not Accounted-For

Hasselblad XCD 25mm f/2.5 V

re: fantasy MTF

I posed two questions to my Hasselblad press contact 2024-05-09.

Hasselblad response, 2024-05-13

Thanks again for your questions. Below are our answers. 

  1. DIGLLOYD: does Hasselblad calculate or measure for MTF?  No statement is made, I presume it is calculated from a model.

The published data are calculated in the datasheet- attached to this email.

  1. DIGLLOYD: do the  MTF charts take into account distortion correction that is mandatory in Phocus.

Our calculations are conducted without factoring in distortion correction, which typically has a negligible effect on MTF. While distortion correction in Phocus is available, it's not mandatory.

Additionally, the published curves do not incorporate the Phocus correction for lateral color. However, it's worth noting that this correction usually yields a positive impact on MTF.

Thank you, Hasselblad Press

Calculated not measured

AFAIK, the only company that actually measures MTF for publication is Zeiss. The Zeiss K8 MTF tester was demonstrated to me in Oberkochen by the late Hubert Nasse, who coined the term fantasy MTF to describe the shenanigans (my word) used by companies to make performance claims.

Hasselblad seems to have high levels of quality control, but when selling $$$$$ lenses whose performance claims are not actually verified by testing real lenses... that leaves me disappointed.

Computer models for behavior (virtually any kind) range from wish-goals to little more than propaganda, as recent years demonstrate. We would like to hope that the lenses we buy deliver tp the MTF chart claims, but my experience over 15 years of testing hundreds of lenses from virtually every vendor tell me otherwise. They rarely describe real lens performance. The most recent example I can point to here is my quest to find a Fujifilm GF 20-35mm f/4 as good as the one I first tested.

That different samples of the same lens can perform quite different makes a mockery of MTF charts of any kind, unless the vendor explicitly guarantees at least as good a performance as the published charts. The Zeiss Otus lenses were held to that standard. Some were better, but none were worse, or at least that was what I was told.

CLICK TO VIEW: Hasselblad Wides

Toggle to compare f/2.5 to f/5.6. See detailed commentary in my review.

Hasselblad XCD 25mm f/2.5 V: calculated (not measured) MTF including diffraction MTF

Distortion Correction

I am glad to hear that Hasselblad Phocus does not mandate the correction.

I take huge issue with the claim above that distortion correction “typically has a negligible effect on MTF”. This is emphatically false, as I have shown with every vendor’s lenses repeatedly in numerous articles with A/B comparisons. Namely the areas in which maximum stretching is required are guaranteed to lose resolving power, by simple math if nothing else. And this is readily visible in a loss of brilliance and detai.

Lateral color

I agree that correcting lateral chromatic aberration improves MTF when the model of it maps exactly to the lens actual behavior for the specific lens in use. However, I regularly see cases where a lens is 'off' in which case the correction can improve things on one side of the frame while creating LaCA on the other side, and thereby reduce MTF. A lens whose LaCA is nil is always a superior choice, because real lenses always deviate significantly from computer model designs.

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