I thought I wrote an article about the Pentax AF-280T flash unit describing what settings work best with the flash. I spend a few minutes searching through the site with no luck. I was making a large number of video overviews today and did one on the AF-280T. I guess that I mentioned an article that only existed in my mind! I’ll fix that post haste…done (see below).
Put the camera in Sv, Tv or P mode and the flash in red/green auto mode.
Sv mode settings and overview:
– Put the camera in Sv mode and modify the ISO to change depth of field. ISO 80 on the K-5 will force the camera to use the largest aperture it can when the flash is powered. I’ve used Sv with my Pentax AF-280T flash with good results. This is the simplest mode to use with the flash as all you will need to control is the ISO setting. It is also the mode I get the best results in without much effort on my part.
– Matrix metering is fine.
– Set the ISO yourself.
– Allow the camera and flash to control aperture and shutter speed.
– Optionally change exposure compensation for artistic effect.
Tv mode settings and overview:
– In Tv mode, use the ISO and/or exposure compensation to control artistic aspects. For example, increasing the ISO will force the camera to select a smaller aperture. Changing the shutter speed (from seconds to 1/180th of a second) will change the aperture as well. Using auto ISO will be difficult for the camera to understand, so at times you will need to lock exposure to avoid letting the camera select an unnecessarily high ISO setting.
– Let the camera control aperture .
– Optionally let the camera control ISO or control it yourself.
– Optionally use spot metering with AE-L (exposure lock) or matrix weighted metering.
– Change the shutter speed for your desired look. Try long exposures for artist effect.
– Optionally change exposure compensation for artistic effect.
Program mode settings and overview:
– Program mode can work alright with this flash, but the other two modes are probably better to use. For Program, the camera doesn’t seem to figure out settings too well when matrix or center weight metering are being used. Using spot metering and exposure lock will allow you to get the best results.
– The camera will control ISO, aperture, and shutter speed.
– It is necessary in my opinion to use spot metering with AE-L (exposure lock) to avoid unnecessarily high ISO and aperture settings being used by the camera.
– You can try changing the program-line setting, but I’m not sure they actually do anything with this setup.
– Optionally change exposure compensation for artistic effect.
Using spot metering with AE-L is pretty easy. Find the brightest object in your scene and put it in the center of the frame. Once the camera has metered and the settings change, press the AE-L button to lock that exposure. You can then recompose the image with your correct metering value.
Modifying the exposure compensation in any of the modes will further allow you to control aperture size and the cost of overall exposure correctness. This can be compensated for in a few ways. First would be attaching a neutral density (ND) filter of your choosing to the lens. That will allow you to use the maximum aperture of your lens yet still have proper exposure to achieve the most background blur due to small depth of field. The second option would be putting some type of diffuser or light limiter to the flash itself. That way your auto-focus sensor won’t have trouble from an add-on that limits light like a ND filter does.