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09-01-2009, 09:29 PM   #1
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P-TTL Auto with popup flash?

In the manual it says the on-board flash supports P-TTL Auto - how do I get this working? I only see Auto flash in Auto mode, and I would definitely not prefer to use this.

Its my understanding that P-TTL Auto will either do a preflash to determine correct compensation or actively read the compensation and cut off the flash before it overexposes the subject. If not, how does Pentax do it and how well does it work? How does it meter in its different exposure modes? The manual was not fully informative.

I've read a bunch of tutorials on flash and can't wait to buy a good one - but for now I'm just working with the on-board flash and using some kind of home-made bounce card or diffuser. I've found that tissue paper is a pretty crappy diffuser and also eats tons of the flash power, but saw some interesting things that use mirrors to bounce to the wall or ceiling.

However, this is all pointless if I can't get flash to correctly expose the subject (while I will control the amount of ambient light that comes in with the shutter?).


Last edited by Eruditass; 09-01-2009 at 09:48 PM.
09-02-2009, 03:51 AM   #2
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I have a k2000, and I have been playing with a variety of flash units and the onboard flash.

When using just the pop-up flash, there will not be any P-TTL preflash. When you us the built-in flash in conjuction with another PTTL flash wirelessly- that's when the built-in flash can be set to work with the PTTL.

The on-board flash of the K2000 is pretty darn wimpy. As far as PTTL flashes- I've been using the AF360FGZ, and the size is just right with the k2000 (for me). I use one of these to bounce the flash in portrait mode. I really like it.

I also have spent some time working with a AF280T (older Pentax flash with tilt AND swivel) on the K2000. The compact size of the AF280T is really nice with the K2000. I can't imagine any flash larger than the AF360FGZ with such a small camera. In both auto and manual mode, the AF280T works very well with the K2000 - no P-TTL- didn't miss it either. I was sorely tempted to keep both flashes, but I really don't need two. I listed it on "that" auction site. It was realy a tough choice between the two. For someone looking to try their hand at a hot shoe flash on a buidget, an AF280T is a great option IMHO.

Anyhow, that is my experience with the k2000 and the on-board flash and a couple of different dedicated flash units. The deidcated flashes are soooo much better than the built-in flash. When you get one, you will really like it.
09-02-2009, 06:36 AM   #3
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QuoteOriginally posted by Sew-Classic Quote
When using just the pop-up flash, there will not be any P-TTL preflash. .
This is incorrect. Unless you are using a lens which does not transmit the f-stop to the body (in that case the pop-up flash will fire at full power), the pop-up flash will ALWAYS be using P-TTL. There is no way to override this and use manual flash (except in the case I mentioned above which gets you 1/1), and you can't use AUTO flash because there is no AUTO sensor on the body
09-02-2009, 06:48 AM   #4
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QuoteOriginally posted by egordon99 Quote
This is incorrect. Unless you are using a lens which does not transmit the f-stop to the body (in that case the pop-up flash will fire at full power), the pop-up flash will ALWAYS be using P-TTL. There is no way to override this and use manual flash (except in the case I mentioned above which gets you 1/1), and you can't use AUTO flash because there is no AUTO sensor on the body
Yep...seeing spots now, there is a pttl pre-flash with the popup. I guess I never watched it before.

I have some manual focus lenses, but not manual aperture lenses. But I would expect the flash compensation to still work allowing some adjustment of onboard flash power....?

I still highly reccomend a dedicated flash - much better than the pop-up IMHO.

09-02-2009, 06:57 AM   #5
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so it always fires a pre-flash? is there no manual setting?

why do my shots with a (bad) diffuser come out much darker? shouldn't it compensate or did it reach max discharge
09-02-2009, 07:00 AM   #6
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QuoteOriginally posted by Sew-Classic Quote
Yep...seeing spots now, there is a pttl pre-flash with the popup. I guess I never watched it before.

I have some manual focus lenses, but not manual aperture lenses. But I would expect the flash compensation to still work allowing some adjustment of onboard flash power....?

I still highly reccomend a dedicated flash - much better than the pop-up IMHO.

As long as the body gets the f-stop from the lens (ie the lens has an "A" setting), your pop-up flash will use P-TTL (and as such you can use flash exposure compensation)

If you use a fully manual lens (M or K series, no "A" setting on body), the pop-up flash will ALWAYS and ONLY fire at full power. You would then need to control the flash exposure by adjusting the ISO and f-stop.
09-02-2009, 07:02 AM   #7
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And yes, an external flash is MUCH better than the pop-up

I started with the Sigma EF-500 Super, than upgraded to the Pentax 540, and since I've "changed teams", I picked up the Canon 580EXII and 430EXII.

I should note that Canon has FINALLY caught up with Pentax with letting the pop-up flash control off-camera speedlights (with the new 7D)
09-02-2009, 07:08 AM   #8
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QuoteOriginally posted by Eruditass Quote
so it always fires a pre-flash? is there no manual setting?

why do my shots with a (bad) diffuser come out much darker? shouldn't it compensate or did it reach max discharge
The on board flash is not very powerful, so it might reach full power and not have enough to light the subject properly.

Also, if there is something (anything) highly reflective in your picture, like chrome, stainless steel or a mirror, those thing will reflect a lot of the light that comes from the pre-flash and cause the camera to under expose. Take a picture with the flash, then the same picture, but add a small mirror to the scene, and look at the difference. I always try to avoid those situations whenever possible.

09-02-2009, 07:21 AM   #9
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QuoteOriginally posted by Eruditass Quote
so it always fires a pre-flash? is there no manual setting?

why do my shots with a (bad) diffuser come out much darker? shouldn't it compensate or did it reach max discharge
You would think the PTTL would compensate for the diffuser, but I also noticed that it didn't. That's why I was under the impression that the PTTL wasn't utilized with just the onboard flash. However, I checked, and I did see it pre-flash- dunno- maybe it just puts on a good show.... If it comes out too dark, try some + flash compensation manually.

Honestly, I messed with diffusers and adjusting the onboard flash, etc... on both the K2000 and my 'old' Panasonic fz28 PnS camera. Some of the used, hot shoe flashes aren't much more money than some of the diffusers that are sold for the pop-up flash. No, you won't have PTTL for some of the less expensive units, but you can get an 'auto' mode and a manual mode.

Since the k2000 is a small body, I took the size of the flash into consideration as well when I made my choices.

Do some searching on the board before you buy. From what I understand some (not al) of the voltages for certain, older, non-Pentax units aren't safe to use with your DSLR.

If you really want to get into using some effective flash, you are going to want a dedicated, hot shoe unit.
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