At the moment it is still a big mystery to me how to set up the flash and in what direction to flash. I keep getting mixed results with the same settings. Too bright, too dark, not sharp, focus in the wrong spot. Going to be a very long time to get the hang of it.
that might be due to the effective aperture.
the effective aperture depends on the magnification. the formula is: effective aperture=f-number*(magnification+1).
some examples to clarify this:
you are shooting at f/8 and the magnification is 1:2 (x0.5). 8x(0.5+1)=12, the effective aperture is f/12.
now f/8 and you get closer to the subject, shooting at 1:1 (x1). 8*(1+1)=16, the effective aperture is f/16, you have lost almost 1 full stop of light compared to the previous example.
now f/8 and shooting even closer, at 2:1 (x2) the maximum magnification of the Laowa 100mm. 8*(2+1)=24, the effective aperture is now f/24, you have lost more than 1 full stop of light.
that could be a reason for you getting mixed results, unless you were getting those mixed results even working at the same distance. if you get different exposures using the same ISO, shutter speed, aperture and distance to subject, then the options are: something is faulty or there are changes in the ambient light, the one you may not be paying attention to because you are using a flash and forgot about it.
the effective aperture also affects at which point you begin to see diffraction softness. there's a rule of thumb that suggests not to work with an effective aperture bigger (in f-number) than f/20 if you want to get maximum sharpness. the first to examples aren't diffraction limited, as the effective apertures (f/12 and f/16) are smaller than f/20. the third example would be diffraction limited, as it is bigger (f/24) than f/20, and softness would begin to be visible.
