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03-22-2010, 06:22 PM   #1
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cannot adjust shutter speed in manual on K-x..

hello dear pentax users! Im complete amature , preparing for my first shoot with my new K-x. i cant figure out why the shutter speed cannot be faster than 180 in manual mode , unless i hide the flash???? i have a feeling that its gotta be something simple im missing , and the answer will make me feel like an idiot

03-22-2010, 06:30 PM   #2
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I've been told that 180 is the auto setting once the flash is up... but let the experts divulge the truth!
03-22-2010, 06:31 PM   #3
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QuoteOriginally posted by ARSLONGA VITABREV Quote
hello dear pentax users! Im complete amature , preparing for my first shoot with my new K-x. i cant figure out why the shutter speed cannot be faster than 180 in manual mode , unless i hide the flash???? i have a feeling that its gotta be something simple im missing , and the answer will make me feel like an idiot
No need to feel like an idiot.. The shutter speed sync is maxed out at 1/180 second on ALL Pentax DSLRs. If you want to go faster, you'll need an external flash (AF360 or AF540 or other) that supports High Speed Sync (HSS).

Beyond that, welcome and enjoy the camera.

03-22-2010, 10:00 PM   #4
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See Focal-plane shutter - Wikipedia, the free encyclopedia

Basically a sensor/film is exposed by moving a window over it. The size of the window depends on the selected shutter speed. At high shutterspeeds, the size of the window is smaller than the size of the sensor/film.

A flash will fire at the moment that the 'first' edge of the window reaches the end of the sensor.

If you (could) use a shutter speed faster than 1/180 (the so called X-sync speed) and the flash fires, only the part of the sensor/film that is exposed at that stage will get the flash light. This will give you a picture that is dark at one side and correctly exposed at the other side.

At the X-sync speed, the window is equal in size to the sensor/fim; at even slower speeds the window is bigger than the size of the sensor/film. So when the 'first' edge of the window reaches the end of the sensor/film, the sensor/film is fully exposed to light and when the flash fires the whole sensor gets the light.

X-sync speeds used to be 1/30sec, got to 1/60sec and 1/90sec, got to 1/125sec and on your camera it's now 1/180sec. I think there are cameras with higher X-sync speeds (Nikon/Canon?).

Hope this helps in understanding why you can not go faster than 1/180sec (without using tricks).

03-22-2010, 10:22 PM   #5
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All cameras have a maximum shutter speed that can be used with flash - it's called the sync speed. 1/180" is pretty typical. Unless you have a special reason to need a faster shutter speed when using flash, though, there's no reason to be concerned - it's not something most people would ever need to do.
03-22-2010, 11:03 PM   #6
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QuoteOriginally posted by JeffJS Quote
No need to feel like an idiot.. The shutter speed sync is maxed out at 1/180 second on ALL Pentax DSLRs. If you want to go faster, you'll need an external flash (AF360 or AF540 or other) that supports High Speed Sync (HSS).

Beyond that, welcome and enjoy the camera.

thank ya'll so much! but now more questions... am i right to believe that i can use only dedicated big name flashes in order to shoot at hi speeds? or there is a way to shoot at 1/6000 with something like vivitar 285 hv?
03-22-2010, 11:06 PM   #7
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QuoteOriginally posted by ARSLONGA VITABREV Quote
ank ya'll so much! but now more questions... am i right to believe that i can use only dedicated big name flashes in order to shoot at hi speeds? or there is a way to shoot at 1/6000 with something like vivitar 285 hv?
and what would be the most affordable HSS flash for my K-x baby?
03-23-2010, 06:03 AM   #8
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If you're new to DSLR and have a KX, for what you're trying to do, I would STRONGLY suggest you get familiar with that camera's high ISO capabilities first.

Set it for Expanded Sensitivity to give you the full range.

But what exactly are you trying to do? Hardly anyone ever needs faster than the camera's sync speed.

03-23-2010, 12:24 PM   #9
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QuoteOriginally posted by Ira Quote
But what exactly are you trying to do? Hardly anyone ever needs faster than the camera's sync speed.
And the people who do need higher speeds are almost always people are already very familiar with the idea of a max sync speed and wouldn't have needed to ask in the first place. So I can't figure out if the OP is just erroneously assuming he needs a higher shutter speed for ordinary flash shots (not realizing, perhaps, that flash duration is so short that shutter speed doesn't normally matter much), or if he has perhaps read about some specialty technique that does require higher speeds and wishes to try this out.
03-23-2010, 04:14 PM   #10
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i'm really excited about shootin small objects, insects, water drops and etc. alot of them moves very fast.. and i just wanna use whole nine yard of my cameras capebilities . i'm just dying to know how those drops of summer rain, falling of a century old roof could look like if shot wit plenty of light, and high speed. i tried to do it without a flash(camera doesn't allow other way) and results were not that good, and i was hoping HSS flash coul help .
03-24-2010, 01:28 AM   #11
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QuoteOriginally posted by ARSLONGA VITABREV Quote
i'm really excited about shootin small objects, insects, water drops and etc. alot of them moves very fast.. and i just wanna use whole nine yard of my cameras capebilities . i'm just dying to know how those drops of summer rain, falling of a century old roof could look like if shot wit plenty of light, and high speed. i tried to do it without a flash(camera doesn't allow other way) and results were not that good, and i was hoping HSS flash coul help .
How shutter speed and aperture affect your image when using flash photography is slightly different than using just ambient light.

When using a flash, your shutter speed will only have an effect on the ambient light in the image and not the motion of your subject. This is because the burst of light that is your flash only happens for roughly (for arguments sake) 1/1000th of a second. So only 1/1000th of a second of your subject will appear on your image. This is because after the 1/1000th of a second burst of flash your subject is unlit and darker than the already exposed area from the flash.

For example: I set my camera for a 30 second exposure on a tripod. I hit the shutter and proceed to walk in front of my camera, pose and pop a flash on myself, then walk back behind the camera and wait for the rest of the exposure. The resulting image will be pitch black except for me posing when the flash went off. No other motion will have shown up.

The sync speed (1/180th) only indicates the fastest shutter speed that 1/1000th can occur between to leading and trailing curtains of the shutter in the camera.

In summation, when using a flash:
Shutter speed: Controls the amount of ambient (natural) light in the scene.
Aperture: Controls the intensity of the light emitted from the flash.
Using a flash will "freeze" the motion of your subject.
03-24-2010, 11:57 AM   #12
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thanks everyone ! just to make it clear : i was not intending to shoot my self in the mirror with an HSS flash)) i wanted a fast flash , for fast moving objects. and by now i've found the answer to my original qwestion, there are no HSS flashes much under 200$((( unless there is some kind of trick to make a good manual flash work as HSS?
03-24-2010, 01:16 PM   #13
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QuoteOriginally posted by ARSLONGA VITABREV Quote
thanks everyone ! just to make it clear : i was not intending to shoot my self in the mirror with an HSS flash)) i wanted a fast flash , for fast moving objects. and by now i've found the answer to my original qwestion, there are no HSS flashes much under 200$((( unless there is some kind of trick to make a good manual flash work as HSS?
Please see my post. I think you are misunderstanding the purpose of a HSS flash. You should be set with what you have.
03-24-2010, 03:38 PM   #14
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QuoteOriginally posted by ARSLONGA VITABREV Quote
i'm really excited about shootin small objects, insects, water drops and etc. alot of them moves very fast
Yes, but not faster than the duration of the flash unit on your camera. it's duration is so short that, as I siad it before, it usually doens't matter how fast you shutter speed is. If the picture is only illuminated by the flash for 1/1000 a second, then it doesn't matter if your shutter speed is 1/1000, 1/500, 1/100, or 1/50 - you'll get pretty much the exact same image. OK, when the shutter speed gets slow enough, more the ambient light can illuminate your background, but that won't generally affect your ability to stop motion.

I suggest you read up on flash photography and how it works. While there *are* very special purposes and techniques that involve HSS, it's *not* something you need just to freeze ordinary motion like you are describing. the fact that the flash itself is firing for only about 1/1000" is enough.

QuoteQuote:
i tried to do it without a flash(camera doesn't allow other way) and results were not that good
Yes, of course - because without flash, shutter speed *does* matter, a lot. But try the flash you've got with the shutter speed set to 1/180" and you'll see that it really does freeze motion that you otherwise couldn't freeze at that shutter speed.
03-25-2010, 10:32 PM   #15
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thanks noahpurdy , and thanks Marc! i was reading your posts at work form a blackeberry, and i didn't get quite right. and today i recieved my vivitar 285, and thats all i needed, just a strong flash. i digged deeper on Hss photography and now i am realy interested in it, but thats a next level.... i'm just starting to realise how much i was underestimating photography , and what an amazing world i've opened the door to by getting a DSLR.. thanks again, i'll be back soon with more silly questions))
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