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05-06-2011, 12:14 PM   #1
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Vivitar TTL

Hi all!
I Recently purchased the vivitar DF-383-PEN for my K-X, and was told it interfaced perfectly with the camera.
I however since read that the pentax flashes use P-TTL which gives a more accurate exposure. I like the flash for the money but was dissapointed about this issue.
I don't see any "pre-flash" (not using red-eye) and I'm assuming that this pre-flash is needed to adjust the exposure more accurately.
Any of you know if it is or not and if yes, how do I get it into P-TTL mode?
Thanks! Jake

05-06-2011, 02:06 PM   #2
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Location: Alameda, CA
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Disclaimer: I've never used or seen the particular flash myself.

Did you find anything wrong with the flash in use?

My feeling is that the flash does support p-TTL. Many people, for whatever reason, use TTL and p-TTL interchangeably, while the terms refer two totally different animals. Pentax (and other camera makers) don't make things any easier. They use similar names (TTL, i-TTL, p-TTL, e-TTL, ...) for different technologies.

If a flash does not support p-TTL, when attached to a K-x, will fire at full power. This often results in overexposed photos. Do you observe the same symptom here?

To verify if the flash is in p-TTL mode, set the camera in 2 second delay. If the flash does support p-TTL, you will see this sequence:

1. The pre-flash strobe.
2. Mirror raising.
3. 2 sec delay
4. The main strobe while the shutter opening.
05-06-2011, 03:51 PM   #3
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QuoteOriginally posted by FrumPilot Quote
Hi all!
I Recently purchased the vivitar DF-383-PEN for my K-X, and was told it interfaced perfectly with the camera.
I however since read that the pentax flashes use P-TTL which gives a more accurate exposure. I like the flash for the money but was dissapointed about this issue.
I don't see any "pre-flash" (not using red-eye) and I'm assuming that this pre-flash is needed to adjust the exposure more accurately.
Any of you know if it is or not and if yes, how do I get it into P-TTL mode?
Thanks! Jake
I think it has PTTL, I don't usually see the preflash with my Metz either - its a very short weak pulse. Use it and see if it otherwise works ok, is my suggestion.
05-06-2011, 03:59 PM   #4
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flash works ok

The flash does work in all modes and does not overexpose. It doesn't automatically sync at a faster shutter speed as my me superprogram did. I have to manually set the shutter speed. Must be a menu for that (still learning). As far as ttl it is for sure.
I was jsut sying I didn't think it's P-TTL.
SOldBear;
To verify if the flash is in p-TTL mode, set the camera in 2 second delay. If the flash does support p-TTL, you will see this sequence:

1. The pre-flash strobe.
2. Mirror raising.
3. 2 sec delay
4. The main strobe while the shutter opening.

Sorry I'm not familiar with how to do your experiment
You don't mean setting the timer do you?
Anyway thank you all for your input!
Jake

05-06-2011, 04:32 PM   #5
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QuoteOriginally posted by FrumPilot Quote
The flash does work in all modes and does not overexpose. It doesn't automatically sync at a faster shutter speed as my me superprogram did.
If you use the camera in Av or P mode, the shutter speed is set depending on the focal length of the lens. The camera is trying to get some ambient light in the exposure. This is not a drawback. If you want to set the shutter speed, do what you're doing: use manual or X mode.

QuoteOriginally posted by FrumPilot Quote
To verify if the flash is in p-TTL mode, set the camera in 2 second delay. ...

You don't mean setting the timer do you?
Yes, I DO mean the 2 second delay of the timer.

Here are some more details:

- The purpose of the 2 second delay time is to minimize the vibration caused by the mirror. The camera waits 2 seconds after the mirror is lifted then opens the shutter.

- In general, the light metering has to be done when the mirror is in the "down" (normal) position (the light sensor is behind the focusing screen, receiving the light reflected up by the mirror).

- In p-TTL, the pre-flash strobe is for light metering. Thus this strobe has to happen before the mirror is lifted.
05-07-2011, 07:59 PM   #6
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SOldBear
Thankds to your suggestions I've answered my question.

I set the timer and it indeed flashed before the mirror went up and again to take the picture. Interestingly, If I set the timer for a 2 sec. delay, then the flash went off immediately. Not so when it was set for 12 sec. It was hard to determine if the flash went off twice, but I believe it did so close to each other, it was hard to determine. (in 12 sec mode apparently the mirror doesn't go up right away).
So I guess this flash works with the P-ttl mode.
Thanks so much!
Jake
05-07-2011, 09:59 PM   #7
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Location: Alameda, CA
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So now you feel better about your flash

QuoteOriginally posted by FrumPilot Quote
SOldBearIf I set the timer for a 2 sec. delay, then the flash went off immediately. Not so when it was set for 12 sec. It was hard to determine if the flash went off twice, but I believe it did so close to each other, it was hard to determine. (in 12 sec mode apparently the mirror doesn't go up right away).
The two strobes are about 1/50 sec. apart. Most people can't tell that there are actually 2 strobes. Note that cinema frames are about 1/30 sec. apart, but we can't tell that they are separate frames.

The 2 sec delay and the 12 sec delay serve two different purposes. The main purpose of the 2 sec delay is to minimize vibration caused by the action of the mirror. So the sequence is (1) the mirror lifting up, (2) 2 sec for the vibration to die down, and (3) the actual exposure. Since the metering has to be done when the mirror is down, the pre-flash strobe has to happen before the mirror going up.

The main purpose of the 12 sec delay is to let the photographer to be included in the photo. In general, the metering should be done as close as possible to the time of actual exposure. In this case, the sequence is (1) 12 sec delay (2) the mirror lifting up, and (3) the actual exposure. The metering (and thus the pre-flash strobe) is done just before the mirror going up, after the 12 sec delay.
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