Flashsync speed on the K-X, stuck at 1/25!

melander · 12-26-2009, 04:06 AM

I have a problem with my flash sync speed on the Pentax K-X. It wont go below 1/25 if I dont put the camera on Tv mode and dial in 1/180. And I get correct exposure when I do this too, but im stuck at fully open lens then. I have never had this problem on my K20D (same flash).
I use the 540FZG.

Anyone know where it fails me?

bnorikane · 12-26-2009, 09:36 AM

Originally posted by melander

I have a problem with my flash sync speed on the Pentax K-X. It wont go below 1/25 if I dont put the camera on Tv mode and dial in 1/180. And I get correct exposure when I do this too, but im stuck at fully open lens then. I have never had this problem on my K20D (same flash).
I use the 540FZG.

Anyone know where it fails me?

In P mode, using a P-TTL flash, the Kx tries to set exposure based on available light. Forum members have informed me that Pentax has done this with flash for years. This balances flash with available light and exposes foreground and background objects more closely to the subject.

In typical flash conditions, this often means wide open and very slow shutter. The kx will use shutters down to the handheld blur limit with SR. This will change with FL. In P with flash up, at 18mm, my Kx often uses 1/15s at f/3.5. At 250mm, it often uses 1/125s at f/6.3.

Oddly enough, the P mode flash shutter speed can be slower than P mode with flash off for exactly the same scene.

If you want flash at faster shutter and stopped down, I read on the forum to use M mode. As long as you are within flash range, the camera will adjust the flash power to get the correct exposure.

To reduce motion blur, I use 1/160s and f/8. You need to carefully adjust the ISO, so you have enough flash range. The camera won't tell you when you are out of flash range. Using the internal flash, I bump the ISO up to 1600 which gives me a GN of 48 and a 6m maximum range.

12-26-2009, 04:06 AM	#1
melander Veteran Member Join Date: Jul 2008 Location: Sweden, Umea Posts: 876	Flashsync speed on the K-X, stuck at 1/25! I have a problem with my flash sync speed on the Pentax K-X. It wont go below 1/25 if I dont put the camera on Tv mode and dial in 1/180. And I get correct exposure when I do this too, but im stuck at fully open lens then. I have never had this problem on my K20D (same flash). I use the 540FZG. Anyone know where it fails me?

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12-26-2009, 09:36 AM	#2
bnorikane Forum Member Join Date: Oct 2009 Location: Colorado Photos: Albums Posts: 91	Originally posted by melander I have a problem with my flash sync speed on the Pentax K-X. It wont go below 1/25 if I dont put the camera on Tv mode and dial in 1/180. And I get correct exposure when I do this too, but im stuck at fully open lens then. I have never had this problem on my K20D (same flash). I use the 540FZG. Anyone know where it fails me? In P mode, using a P-TTL flash, the Kx tries to set exposure based on available light. Forum members have informed me that Pentax has done this with flash for years. This balances flash with available light and exposes foreground and background objects more closely to the subject. In typical flash conditions, this often means wide open and very slow shutter. The kx will use shutters down to the handheld blur limit with SR. This will change with FL. In P with flash up, at 18mm, my Kx often uses 1/15s at f/3.5. At 250mm, it often uses 1/125s at f/6.3. Oddly enough, the P mode flash shutter speed can be slower than P mode with flash off for exactly the same scene. If you want flash at faster shutter and stopped down, I read on the forum to use M mode. As long as you are within flash range, the camera will adjust the flash power to get the correct exposure. To reduce motion blur, I use 1/160s and f/8. You need to carefully adjust the ISO, so you have enough flash range. The camera won't tell you when you are out of flash range. Using the internal flash, I bump the ISO up to 1600 which gives me a GN of 48 and a 6m maximum range.