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11-04-2013, 11:44 AM   #1
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Problem with Auto Flash

I have a k-30. I mostly shoot outdoors and don't use the flash very much. When I do, it uses a slow shutter speed as if I weren't using the flash. I generally shoot in AUTO with a Pentax 18-55 lens. Last week I was at an important event where I really needed the flash to work. I was also having a hard time even getting it to fire. The green focus light at the bottom of the focusing screen would be on and everything would look ok but nothing would happen. My old ist*D used to do that all the time. I tried switching from AUTO to Night Scene Portrait. That didn't help. Is my camera defective or what is going on? I also would like to force it to flash in day light for fill flash and I haven't been able to get it to do that.

11-04-2013, 01:40 PM   #2
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Hi JMerrill,

I don't have a K30, and some aspects of flash use have been different on the entry level models than the bodies that I've shot, so any answers that I try to give might be incorrect. . .

That being said, I do know what causes the camera to go to a slow shutter speed -- Auto mode with Auto ISO -- For some time now, (I can't remember what model generation, Pentax has programmed in a type of automatic "dragging the shutter" metering for its P-TTL system. This technique tries to balance ambient light with flash use so you don't get that "ghostly white subject with a totally dark background" flash shots. Generally, what the camera tries to do is to set shutter speed, ISO, and aperture to give you a reasonably exposed shot (not including the flash) for the background, and then use P-TTL flash metered to the main subject as determined by the camera. P-TTL metering cuts off flash duration instead of varying the intensity of the flash.

Indoors, this usually forces ISO up, aperture to its widest, and shutter speed down -- the same metering as it would do for available light only. The answer is to take out most of the variables and let the P-TTL flash adjust itself with preflash metering. What I do is pick a fixed ISO, then go to M mode, set the shutter to 180 or slower, and pick the aperture you want to use. It pretty much doesn't matter what setting you use as the flash metering will take over. This way, the P-TTL system is limited to only metering for the scene with flash. You can drag the flash or not, but it's your choice.

An easy way to drag the flash is to use TAV which gives you auto ISO, but manual control over the shutter speed and aperture. With ISO floating, the camera will adjust the ISO to give you a reasonable exposure for ambient with your chosen shutter speed and aperture -- and you can use Ev compensation (not flash compensation) to get the right ambient exposure. The P-TTL metering will take care of the flash exposure by cutting off the duration of the flash to give you proper exposure of your main subject (you can use flash compensation to quickly adjust the flash contribution). Doing this, you must decide what your upper limit for ISO (based on IQ preferences) will be -- but you can let it go higher than you might normally shoot at for ambient light only because the added light from the flash will give you considerably lower noise at a given ISO than ambient light only would. You can also use M mode, set the aperture, shutter, and ISO to give you proper exposure for the ambient, then shoot with a P-TTL flash to give you a proper flash contribution.

For outdoor fill flash, there should be a reasonable explanation of how to do this with your camera in the Manual.

The reason that the flash doesn't fire sometimes is probably the setting in the flash menu to Auto Flash (A), This tells the camera to fire the flash only when you can't otherwise get a proper exposure within the metering system's limit, or if the programmed shutter speed falls below the "recommended" (@ 1/Focal Length) to properly expose the shot. Here you might try the flash "On" setting (lightning bolt). This will force the flash to fire whenever it's popped up.

I realize this is confusing stuff. If you just want an easy solution, then I'd suggest that you try the above, then when you find a reasonable combination of settings, save it as one of your User settings, then just use this for when you want to shoot with flash.

Scott
11-04-2013, 05:57 PM   #3
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Snostorm, you gave an accurate answer.
11-04-2013, 10:50 PM   #4
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Ok I'll do some experimenting.

If that is the way I'm always going to have to do it, I don't like it. I'll do some experimenting. Maybe I'm old school but I don't need a lot of the bells and whistles on this camera and they just make it more complicated. Then there are other features I wish it had but it doesn't.

Thanks for your help, Joel

11-04-2013, 11:16 PM   #5
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The easiest way to do flash is to get out of auto mode and use manual mode. I don't like the camera making all the decisions. As stated in the lengthy answer above, Pentax has programmed the camera to work for an ambient light shot with only flash for fill. As a result it will adjust shutter speed down to 1/FL, open aperture and bump ISO up (within your auto ISO range) to get a shot, then add about 1/2 stop of light for fill. The result is images with motion blurr, shallow DOF and a lot of noise.

Shot manual, set exposure manually for about -2 stops, with a respectable shutter speed, (usually I shoot at 1/180) and aperture and let the flash work.

Also allow for flash without focus confirmation.
11-05-2013, 01:12 AM   #6
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OK, Thanks, Joel
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