[Twarp]

I'm a litle confused since I have my AF-360FGZ flash connected to my K-x.
With the camera set to P (or Scene) and the flash in P-TTL mode and selector switch on the green symbol, I would expect the shutter to default to its 1/180 flash sync speed and automate everything else. At least, this is what happens in TTL-mode on the Super A with AF280T: flash symbol next to 1/125 speed, aperture/flash on the fly.
The K-x however, sets the speed to 1/20 next to the flash symbol when ready. The resulting pics show a 1/20th speed indeed. Even when I use the E-key (scrollwheel) in Tv-mode to adjust speed, I can't crank it up to faster than 1/30 with the flash activated.

Now this is not what I intend with this setting, I want to freeze subjects in the first place and have the flash supply me with some proper light. 1/20th is way too slow.
Is this a camera setting, a flash setting, a faulty setup, human error, or what am I missing? I truly hope I'm the error and there's no hardware problem...

[olenl]

Why don't you just use M mode? You select everything and the flash fires as much as needed to make it work.

I think the automatic selection uses 1/focal length for some reason, although I never get sharp images at this setting - maybe my SR is faulty or something.

[Twarp]

Do you mean A-mode? In M-mode the flash is constant and for every shot you have to adjust speed and/or aperture following a table or something.
In A-mode you set a fixed speed and aperture and a sensor on the flash decides whether sufficient light has been thrown and terminates the flash. In my experience this is a rather fool proof way of shooting.

But I want the P-TTL process to do just that through measuring by the K-x instead of the flash. And because it is invented as a dummy proof mode, nearly everything should be automated with some sound settings to begin with in its programming. A speed of 1/20 does not fit in this picture I think...

I had the DA 35/2.4 AL fitted so it is not 1/focal length then.

[olenl]

M is a camera mode, flash is set to P-TTL (that's on my Metz 58af-1, I dont' know how is it called on Pentax flash) and it's definitely NOT constant. The same goes for built-in flash (I think it is always in PTTL mode).

Does 360FGZ not allow to use PTTL when camera is in M mode?

[twitch]

Put camera in m mode, camera needs to be told what to do with flash, let flash provide correct exposure.

[Twarp]

Ok, I confused manual flash mode with M mode on the camera. The latter I only use with M-series lenses (the "M's" are just a coincidence...). I'll try it at once when I get home.

[usrbrv8]

Twarp,
I have tried to us A or Tv mode with my flash also and I could never get consistent results, some shots would have too much ambient and some not enough. So I switched to shooting in M mode and it has made things actually much easier.

With the DA 35mm 2.4 I would start with these setting, assuming you are shooting indoors under tungsten lights.

Apateur - f4 to f5.6, lower if you need more subject isolation
ISO - 200 or 400, you shouldn't need to go higher unless your subject is very far from the flash or it is really dark
Shutter Speed - Variable, I would start at 1/30 and work up from there until you get an ambient balance that you are happy with. The flash should be stopping the motion if the subject looks blurry it is because your shutter was open too long and there was too much ambient exposing your subject after the flash fired.

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Last edited by usrbrv8; 02-15-2012 at 08:32 AM.

[godavari]

This might be of help. Digital SLR and P-TTL flash guide

[Twarp]

The tips are great! It all seems to work.
In Tv-mode the shutter speed can be adjusted up to 1/180, only the aperture is at the widest setting. In M-mode the same applies for the shutter speed but you can choose any aperture you need for the situation. Just ignore the alarming sight of a lightmeter that flashes that it is more than 3 stops off. The flash takes care of that. See pic. Also switched on the Catch-in-focus feature and suddenly I'm faster than the cat :-)

For now I printed the manual given above for some bedtime reading.

[maxfield_photo]

pTTL will try to balanace the flash 50/50 with the ambient light in P mode, try again in a brighter room and see if you can't get the shutter speed up. The flash is really what does the freezing, but with a 50/50 balance you'll see some blur in dim conditions. Manual mode is your friend, don't be afraid of it. You could also try -1 EV on the camera, and +1 EV on the flash.

[Anvh]

You could also try -1 EV on the camera, and +1 EV on the flash.

Does it work like that?
I always assumed the camera EV is for global eposure with the flash included.
So if you use -1ev on the camera that means the whole exposure will be -1.
And if you use +1 on the flash that means the flash will take over +1 ev in the total exposure.
It sounds very complicated now trying to explain.

-1 camera = -1 total exposure
+1 flash = 0 total exposure, -1 ambient light +1flash light
-1 camera & +1 flash = -1 total exposure, with that the blance would be -1 ambient light +1 flash light.

I can be very wrong though...

[maxfield_photo]

The camera's EV comp affects the flash, so dialing in a -1 on the camera will result in a photo that is 1 stop underexposed (assuming exposure was correct at 0). Since the camera will try to balance flash and ambient light, it will lower the flash power by half a stop and the ambient exposure by half a stop in order to maintain that balance. Setting the flash EV comp to +1 counteracts the camera's EV comp so the picture will be correctly exposed, but now the balance is more like 65% flash and 35% ambient. This should help to minimize the blur caused by the slow shutter speed.

[Anvh]

The camera's EV comp affects the flash, so dialing in a -1 on the camera will result in a photo that is 1 stop underexposed (assuming exposure was correct at 0). Since the camera will try to balance flash and ambient light, it will lower the flash power by half a stop and the ambient exposure by half a stop in order to maintain that balance. Setting the flash EV comp to +1 counteracts the camera's EV comp so the picture will be correctly exposed, but now the balance is more like 65% flash and 35% ambient. This should help to minimize the blur caused by the slow shutter speed.

But i doubt you actually counteract the -1 EV with the +1 flash EV.
Like you said the camera EV influence exposure and the Flash EV the balance.
If so then diaing in -1EV on the camera will always result in a underexpose photo no matter how you set the flash EV.

[mattdm]

But i doubt you actually counteract the -1 EV with the +1 flash EV.
Like you said the camera EV influence exposure and the Flash EV the balance.
If so then diaing in -1EV on the camera will always result in a underexpose photo no matter how you set the flash EV.

There's several ways it could work and still be logical consistent. One way would be what I think you're describing: that the master EV control affects the overall exposure, while the flash EV affects the ratio. But it happens that it works the way maxfield_photo describes instead: the two EV settings basically operate separately but cumulatively.

[Lowell Goudge]

You have now discovered why people hate computers, here is the deal. The camera will try to figure out what you intend based on all the settings. In various flash mode the camera attempts the following
first and foremost it will assume you want fill flash and will let as much light in as possible to attempt to get exposure without flash first, and then add in flash. As a result,
- if you have auto ISO this will be set as high as possible given what other constraints you have set
-shutter speed will go as slow as possible for hand hold rule of thumb 1/35mm equivalent focal length for hand hold ability
- lens will try to open up as much as possible
The only way to deal with the flash and remain sane, in my opinion is to go to manual mode and manually set the aperture and shutter for the base light exposure you want and then add flash