HSS is a flash feature, but is dependent on the P-TTL feature of the body. The body must be in a mode that supports P-TTL and there are limitations. I don't own either of your flashes, but on my Sigma EF-610 DG Super, HSS is enabled on the flash and the body must be in a mode that allows setting of the shutter speed. Behavior is as follows:
Edit:I did some more experimentation with HSS on the Sigma EF-610 DG Super and need to revise this list
- P mode (hyper-program) -- aperture defaults to maximum for lens. Range is limited based on that aperture and displayed as a scale on the flash LCD.
- Tv mode -- same as above
- Av mode --
- M mode -- Both aperture and shutter speed may be set, but flash range may be limited by selected aperture. On my flash there is a distance scale indicating max range for the selected aperture.
- TAv mode -- gross overexposure with my flash
- Bounce flash with HSS is unpredictable with my flash
New list- The Sigma documentation defers to the camera manual for supported modes
- The K-3 manual indicates any mode that allows setting of the shutter speed (Tv is specifically suggested)
- All modes:
- The combination of ISO above about 200 and dim light is problematic for the Sigma HSS implementation resulting in potential overexposure
- Range is limited based on the taking aperture and ISO with the supported range being shown on the flash LCD display
- Exposure using bounce flash and HSS is unpredictable (see preceding point regarding range)
- P mode (hyper-program) -- Yes, per program line. Note that this is a deviation from the Pentax AF540FGZ implementation where the documentation indicates a mode other than Programmed AE.
- Sv mode -- No, shutter always at 1/180s
- Tv mode -- Yes, aperture will follow program line with risk for decreased range (see above)
- Av mode -- Yes, per program line. Note risk for decreased range (see above)
- TAv mode -- Yes. Significant risk for overexposure per note above due to higher ISO (see above).
- M mode -- Yes
- X mode -- No, shutter always at 1/180s
I hope this helps. For what its worth, I am pretty sure my K10D was the same way.
Steve