Which f-stop is the sharpest? GFX 50S Diffraction Test
How do you determine the sharpest f-stop for your camera and lens? Is diffraction more impactful in infrared light than visible light? In this video, I will test the sharpest f-stop on a Fujifilm GFX 50S full spectrum conversion at each aperture with multiple infrared filters, 550 nanometers, 590 nm, 720 nm, 830 nm, 850 nm, IR Chrome, and a hot mirror filter. I’ll share the results and my observations.
Fujifilm GFX 50S full spectrum conversion, GF 45 mm f/2.8 lens
|STC Optics UV/IR (hot mirror)||visible light||f/11|
|Kolari Vision IR Chrome||dual-bandpass||f/11|
|Kolari Vision 550||550 nm||f/8|
|STC Optics IRP 590||590 nm||f/8|
|STC Optics IRP 720||720 nm||f/8|
|Hoya R72||720 nm||f/5.6 & f/8|
|B+W 093||830 nm||f/5.6|
|STC Optics IRP 850||850 nm||f/5.6|
|Filter||Adjustment from sharpest visible light f-stop|
|Hot mirror, IR/UV cut, IR Chrome||Use sharpest visible light f-stop|
|550 to 720 nm||1-stop lower|
|800 nm and higher||2-stops lower|
- Lower f-stops: Sharpness is reduced with f-stops lower than the sharpest f-stop due to less depth of field. The loss of sharpness is minimal. Lower f-stops will not substantially impact sharpness. Use lower f-stops to reduce the depth of field.
- Higher f-stops: Sharpness is reduced with f-stops higher than the sharpest f-stop due to increased visible diffraction. The loss of sharpness is dramatic. Avoid these higher f-stops unless you are explicitly looking for a soft effect, want to create a starburst effect, or are willing to trade reduced sharpness for greater depth of field.
Previous Diffraction Article/Video on Fujifilm X-T20 (APS-C)
If you have comments, questions or feedback, use the comment section for this video.