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12-31-2011, 05:37 PM   #1
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K-x and flash sync....dumb question?

Maybe it's just me, but in a low light situation with my K-x if I pop up the flash or connect a flash to the hot shoe the camera exposes as if no flash. In other words, I thought popping up the flash would cause the body to switch to 1/180th automagically? Most times I'm shooting in manual mode, but sometimes auto/program comes in handy and I could swear my old K100d would automatically adjust to having the flash in use. I've tried checking the fine pdf manual but don't seem to be seeing this ....can someone [gently] steer me in the right direction? Thanks!

12-31-2011, 05:49 PM   #2
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Is it switching to something slower than 1/180?
12-31-2011, 06:11 PM   #3
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No, it won't flip to X-sync speed automatically in Av mode as the camera will also be trying to expose for the background.
So in those situations, you'd go to M or Tv mode and set your 1/180 speed as desired.
Av mode will continue to try to balance ambient and flash lighting in the exposures.
12-31-2011, 06:49 PM   #4
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Yes, the exposure is usually less than 1/180th/sec. Say I'm in AUTO PICT mode sitting here at my laptop under ambient room lighting. ISO set to 800:

The camera selects 0.6s/f5.6

Pop up the built in flash and

The camera selects 1/25ths/f7.1

This is in AUTO PICT not Av mode.

12-31-2011, 07:31 PM   #5
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As Ash mentioned, the camera is trying to balance ambient light and flash. Did you try taking a picture like that? How did the exposure look?

Having a maximum flash sync speed of 1/180 doesn't necessarily mean that all flash shots will be or even should be shot at 1/180. If you just absolutely want to use 1/180 then you can go into one of the modes that allows you to set your shutter speed and the camera should then adjust flash output and/or aperture for you (except in M mode, of course). On camera models that have an X mode, that can be used to quickly set the shutter to the maximum sync speed.
12-31-2011, 08:14 PM   #6
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Mine will adjust DOWN to 1/180 second, but will stay where I have it if I have it set slower when using flash.
12-31-2011, 10:15 PM   #7
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QuoteOriginally posted by Mike Cash Quote
the camera is trying to balance ambient light and flash.
In AV mode K-x ignores the flash completely (it will maintain its initial metering, as if there is no flash), as mentioned above by Ash, your only option is Tv if you want some control/Auto (you already know M works) but all other auto program will keep up with flash as I remember.
01-01-2012, 02:48 AM   #8
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I've just tested this on a K100D (I don't own a K-x). In auto-pict the camera takes its own decisions. It judges the scene and thinks 'hey, this looks like whatever' and next sets aperture and shutter speed based on what it thinks matches the scene. It does NOT use 1/180s by default.

You should be able to see which 'mode' (e.g. portrait) the camera actually uses. On the K100D there's an icon that changes in the viewfinder that indicates the 'mode'; the K-x might have an indication on the rear LCD.

On a side note:
In Av mode, the camera sets a shutter speed (in my experience) for flash that is partially based on the focal length used. In a dark scene, the K100D in combination with DA55-300 uses roughly 1/FL (1/60 @55mm, 1/125 @ 100mm, 1/180s @ 150mm). In a brighter scene the same combo uses 1/180s regardless of focal length, possibly attempting 'fill-in flash'.

K5 with FA31Ltd or DFA100WR is more conservative and uses 1 / (2 * FL) in a dark scene; not tested in a bright scene.

01-12-2012, 08:09 PM   #9
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That's all just I guess a little weird...I've been using a digital camera for years but never really noticed this until recently....I always assumed that if the camera was in auto mode with the flash turned on that the body would adjust the flash for the best posssible shot up to the guide distance based on a relatively fast sync type shutter speed, and anything beyond would just fall off to black. Maybe I'm just mis-recalling the behavior of my P&S cameras which, when the flash is turned on, do this. Seems odd that turning on the built in flash just makes it automatically into a fill flash.....so in pitch black the body will normally choose, what, up to a minute exposure with a brief flash? What's the point of the built in flash if they camera won't automatically sync to it? Still scratching my head....
01-12-2012, 08:42 PM   #10
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If the camera adjusts to under 1/180 then it is adjusting to sync speed. You just have a misunderstanding of what sync speed means.

So long as the entire surface of the film/sensor is exposed during the flash then the shutter and flash are in sync. If part of the film/sensor is obscured by the shutter blade/curtain during the flash then they are not in sync.

The maximum sync for us is 1/180, but any speed slower than that is also in sync.
01-13-2012, 04:07 PM   #11
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Gotcha...nomenclature....besides my incorrect usage is just my thinking that with the flash the camera would select a non---long-time-exposure shutter speed and just give me mostly what the flash lights and not the ambient lighting....am I making sense?
01-13-2012, 04:13 PM   #12
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Yes, you make sense. As mentioned in some other posts, behavior seems to depend on what mode the camera is in.

I've always been more comfortable just going to either M or X mode so I am never left in doubt what the shutter speed is going to decide to do from one shot to the next.
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