bizarre aperture question

RubyT · 05-24-2015, 04:32 PM

Hi.

I don't use flash much, but it was necessary today. I had used the mounted flash for a few pictures (TAv), and that went fine. Then later I was taking a couple that needed fill flash, and I just used the on-camera flash. For some reason (still TAv) it kept opening the aperture by a stop or more after each picture. I figured I must have hit something, but I have no idea what. All the settings seemed normal. I took the battery out for over a minute, but it continued to do this so long as I used the flash, causing massive overexposure if I didn't reset the aperture after each shot. I did not have the shutter speed too high for the flash.

Does anyone know what setting I inadvertently hit to cause this?

Last edited by RubyT; 05-24-2015 at 05:04 PM.

**mattt** · 05-24-2015, 05:10 PM

I have best luck with flash shooting w fixed ISO. TAv uses auto ISO to adjust exposure. Best to shoot manual, let the auto flash go from there.

RubyT · 05-25-2015, 03:19 AM

I might try that next time, although it was a sunny day, so I was just using fill because I had their backs to the sun and the ISO stayed at 100. I set the aperture at f/11, and took a few shots, and checked and it was at f/1.8. At first I thought I'd somehow spun the dial, so I reset it, but it kept happening. It would open a stop or two every time I took a shot. It did this with two different lenses. I've never had anything like that happen before.

**mattt** · 05-25-2015, 04:39 AM

The other piece you may be missing is the shutter sync speed is max 1/180.. Although you may dial in something faster, the popup flash does not support HSS so it will default to its fastest value.

05-24-2015, 04:32 PM	#1
RubyT Pentaxian Join Date: Sep 2008 Location: TN Photos: Gallery Posts: 621	bizarre aperture question Hi. I don't use flash much, but it was necessary today. I had used the mounted flash for a few pictures (TAv), and that went fine. Then later I was taking a couple that needed fill flash, and I just used the on-camera flash. For some reason (still TAv) it kept opening the aperture by a stop or more after each picture. I figured I must have hit something, but I have no idea what. All the settings seemed normal. I took the battery out for over a minute, but it continued to do this so long as I used the flash, causing massive overexposure if I didn't reset the aperture after each shot. I did not have the shutter speed too high for the flash. Does anyone know what setting I inadvertently hit to cause this? Last edited by RubyT; 05-24-2015 at 05:04 PM.

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05-24-2015, 05:10 PM	#2
mattt Site Supporter Join Date: Feb 2011 Location: Niagara Photos: Gallery \| Albums Posts: 3,907	I have best luck with flash shooting w fixed ISO. TAv uses auto ISO to adjust exposure. Best to shoot manual, let the auto flash go from there.

05-25-2015, 03:19 AM	#3
RubyT Pentaxian Join Date: Sep 2008 Location: TN Photos: Gallery Posts: 621 Original Poster	I might try that next time, although it was a sunny day, so I was just using fill because I had their backs to the sun and the ISO stayed at 100. I set the aperture at f/11, and took a few shots, and checked and it was at f/1.8. At first I thought I'd somehow spun the dial, so I reset it, but it kept happening. It would open a stop or two every time I took a shot. It did this with two different lenses. I've never had anything like that happen before.

05-25-2015, 04:39 AM	#4
mattt Site Supporter Join Date: Feb 2011 Location: Niagara Photos: Gallery \| Albums Posts: 3,907	The other piece you may be missing is the shutter sync speed is max 1/180.. Although you may dial in something faster, the popup flash does not support HSS so it will default to its fastest value.