Problems with AF assist on Flash

JohnKSA · 03-11-2010, 10:45 PM

Hi,
I asked this question obliquely previously but received no replies. I have a K20 and a Pentax AF-360-FGZ flash. According to the flash instructions, to enable AF assist on the flash, I should set it to PB mode and it should work but I get nothing- the flash doesn't even fire. Does anyone have any tips for me?

Thanks,
John K

**Just1MoreDave** · 03-11-2010, 11:06 PM

I think you mean SB mode, at least that's what it's called on the AF540FGZ. In that mode, the only thing that the flash does is poduce an invisible focus-assist beam, and no flash at all. The focus-assist beam comes on in the other flash modes too.

I tested this years ago with a much different flash/camera combo, and it had to be pretty dark for the beam to do anything.

**Ash** · 03-12-2010, 12:07 AM

Firstly, ensure the flash hotshoe adaptor is fitted snug into the camera's hotshoe.
Then switch the camera on, then the flash.
Point and shoot in P-TTL mode and see if the flash fires.
If so, it's working fine.

But you have an incorrect assumption about the SB mode - it utilises a VISIBLE red beam to assist the camera to focus in LOW LIGHT situations (only). It does not permit the flash to fire.
If you want the flash to fire, then set the flash to any of the other modes, and you'll find the red spotbeam will be engaged ONLY WHEN THE CAMERA DEEMS IT IS NECESSARY (i.e. in low light situations) and then when the shutter is released, the flash will fire.

Hope this helps.

03-11-2010, 10:45 PM	#1
JohnKSA Inactive Account Join Date: Nov 2009 Location: Pietersburg, South Africa Posts: 26	Problems with AF assist on Flash Hi, I asked this question obliquely previously but received no replies. I have a K20 and a Pentax AF-360-FGZ flash. According to the flash instructions, to enable AF assist on the flash, I should set it to PB mode and it should work but I get nothing- the flash doesn't even fire. Does anyone have any tips for me? Thanks, John K

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03-11-2010, 11:06 PM	#2
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	I think you mean SB mode, at least that's what it's called on the AF540FGZ. In that mode, the only thing that the flash does is poduce an invisible focus-assist beam, and no flash at all. The focus-assist beam comes on in the other flash modes too. I tested this years ago with a much different flash/camera combo, and it had to be pretty dark for the beam to do anything.

03-12-2010, 12:07 AM	#3
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Firstly, ensure the flash hotshoe adaptor is fitted snug into the camera's hotshoe. Then switch the camera on, then the flash. Point and shoot in P-TTL mode and see if the flash fires. If so, it's working fine. But you have an incorrect assumption about the SB mode - it utilises a VISIBLE red beam to assist the camera to focus in LOW LIGHT situations (only). It does not permit the flash to fire. If you want the flash to fire, then set the flash to any of the other modes, and you'll find the red spotbeam will be engaged ONLY WHEN THE CAMERA DEEMS IT IS NECESSARY (i.e. in low light situations) and then when the shutter is released, the flash will fire. Hope this helps.