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Forum: Pentax K-3 & K-3 II
01-04-2019, 08:55 AM
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If the flash is providing the majority of the light that won't matter. A camera at 1/180 and a flashgun will freeze action just as if you had used 1/2000 in ambient light.
Experiment with HSS by all means but you lose a lot of power in doing so which may mean your bounce distance is too far. And HSS can lead to more motion blur as you are now dealing with a light that is more akin to continuous light rather than single flash burst.
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Forum: Pentax K-3 & K-3 II
01-04-2019, 12:38 AM
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A picture with flash is basically two exposures in one.
First is ambient light. This is controlled directly by the camera's three settings shutter speed/aperture/ISO. Test this first with the flash turned off.
The second exposure is the flash. In P-TTL mode the flash fires a pre-flash, reads the exposure and calculates a power level for the actual flash. This happens so quickly you wont even notice it.
As Clackers mentioned, the shutter speed is pretty much irrelevant as far as flash exposure is concerned because the flash duration is so quick so it is aperture and ISO that only determine how much power the flash needs. One thing about shutter speed however is your camera wont let you shoot above the sync speed which will be 1/180 on your K3 I believe. So 1/180 or slower will work fine. (There is a mode called HSS which does allow faster shutter speeds but I won't go into that here.)
If you are getting inconsistent results in manual mode on camera and P-TTL on the flash that can be because you are bouncing the flash. The light has a lot further to travel and it may be depending on your aperture/ISO, that the flash cannot produce enough light. When the flash head is in its normal straight ahead position, it will display a range in meters or feet. That is a minimum/maximum range that you can shoot with the flash pointed direct. As you change the aperture/ISO that range will increase/decrease. Bounced flash drops off in intensity much quicker and it may be that your bounced flash distance is not enough to light your subject even at full power. You can test this by changing the flash to full manual flash output an look at the results. Also make sure your camera is set to matrix metering, not spot.
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