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05-01-2015, 07:08 AM   #1

pentax k-x using ring flash on manual lens

I have a pentax k-x I bought a 50mm manual "A" lens and a ring flash for macro photography. I'm not sure what settings I should use. If I was just shooting manually I would use a F22 and 1/250 but when I use manual settings the flash won't fire. When I set it to auto pic it over exposes the photo. Do I need to adjust the flash modes in the camera itself?

05-01-2015, 07:24 AM   #2
Rimfiredude's Avatar

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At 1/250 you might be out of the flash sinc range. Try 1/60.
05-01-2015, 08:41 AM   #3
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As said, your shutter speed exceeds the X-sync. The maximum speed at which the flash will fire is 1/180s (with current Pentax dSLRs).
05-02-2015, 03:32 PM   #4
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Hi Wendy, what flash are you using? Is it a full manual flash or does it have an auto sensor or supports P-TTL metering? Is it a true flash or an LED ring light with flash mode.

If it is a full manual flash or one with auto sensor with manual mode can the output power be set - usually 1/4, 1/16 or 1/64 depending on the unit.

If it is a true flash set the camera to X-sync mode (will set the shutter to 1/180). Set the aperture on the lens to "A" - you can then adjust the f-stop from the eDial. Set the flash to 1/16 power and start at f/8 or f/11 and take a few shots at the closest focus distance. You can then judge from the images what f-stop to use or if you need to use a higher or lower power setting (if any). Take notes and do the same for various other focus distances. Eventually you can make a cheat sheet of the f-stop, power, and distances. Use a fixed ISO like 100 to start with. If you need to stop down more for increased DOF you can always up the ISO and f-stop accordingly.


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