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Focus Shift Assessment (Bottle with Lettering)
This page assesses shows how the focus shift of the Hasselblad XCD 90mm f/3.2 is relevant, particularly for a curved surface such as an eye—by using a curved surface to show that f/8 can be worse than f/3.2 due to the focus shift.
See Detecting and Mitigating Focus Shift.
Lens Solution bottle
Whether or not the focus shift will wreck the final image depends entirely on the initial focus. If the lens front-focuses slightly as it often might, then stopping down will shift focus just about the right amount for a crisp image! If the focus starts out as shown, the leading edge loses focus—even at f/8 as seen here.
There is no margin for error with a 90mm lens. The Hasselblad 90/3.2 clearly is a very able performer when focused for peak performance as can be seen in peak focus areas. The nagging doubt when using it will always be whether the focus might be off just enough to wreck that crispy-sharp effect that one was after.
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- Aperture series from wide open through stopped down, showing the full range of lens performance and bokeh.
- Optical quality analysis of field curvature, focus shift, sharpness, flare, distortion, and performance in the field.
