[Timd]

Wait for your son to fall asleep! (sorry, not helpful). How about a fast lens, high ISO, no flash? Failing that, you need to anticipate and trigger 0.5s beforehand. Sorry, no silver bullet here.

[asp1880]

What exactly were you using before with the Sony system? I don't think I've ever heard anyone raving about how amazing the Sony flash system is before.

The Sony cameras have "ADI" flash, inherited from the Minolta cameras. It regulates flash output from the focus system distance info. So it only gets it right with on-camera, direct flash and with the right kind of AF lens, but it works without preflash. Sonys also have p-ttl as an option.

Regards,
--Anders.

[Pheo]

Turn off pttl and go manual?

Never had this problem too much though.

[philbaum]

For my strobist work, i eventually bought a Yongnuo 460II and a 560 which only have manual controls. I find them easier to use in low light than my Metz 48, becasue the LEDs they have on the back are always visible outdoors in the night - the metz illuminated dial is a lot harder to read - at least mine was. i think i paid $40 for the 460 and about $65 for the 560. I used Cactus 5 radio triggers. You can also use your metz 50 in manual mode.

You put your camera in manual mode and then adjust settings till you get a minus 1 to -3 stops of light. The manual setting on the K5 will show exactly where you are in the exposure settings. Then trial adjust the fractional power settings and you're off to the races. No preflash to shut eyes or delay things, just instant light. And its also less irritating to the subject since you can really dial down the power. The 560 can be dialed down to 1/128th, the 460 down to 1/64th. This is way more control than any of the old pentax flashes on ebay which only had a few settings.

Strobist stuff with manual flashes is fun!




Example of 1/128: (not photoshopped) (plus if you put your kids in a kitchen cab. like me - they won't move so fast

---

Last edited by philbaum; 10-18-2012 at 12:36 PM.

[flyer]

it takes around 0.5 sec while actual picture is taken

There must be something wrong with your set-up. The pre-flash is so close to the picture taking flash that you don't even see it.

[SOldBear]

I have 2 copies of Pentax 540, but I don't use them in p-TTL for group photos. Some (sensitive) people blink at the preflash strobe, thus their eyes close during actual exposure. My son is one of them.

You can use the Pentax 540 in A or M mode.

But the p-TTL delay is NOT 0.5 sec. In my un-scientific estimate, it's in the neighborhood of 0.02 - 0.03 sec. Most people can't tell that there are actually two strobes. If your son moves considerably between the two strobes, you should consider training him for Olympics.

[ashurbanipal]

Now with P-TTL the issue is the pre-flash - I take focus of my boy, push the button and .... it takes around 0.5 sec while actual picture is taken and by that time he has moved and not in the same focus point anymore

The only time I've ever noticed a delay from the preflash is when I accidentally changed the flash setting on my camera to red-eye reduction. Freaked me out until I figured out what was causing it! I use a K-x, though, so not sure if this is possibly the cause of your issue or not.

[philbaum]

The only time I've ever noticed a delay from the preflash is when I accidentally changed the flash setting on my camera to red-eye reduction. Freaked me out until I figured out what was causing it! I use a K-x, though, so not sure if this is possibly the cause of your issue or not.

I think you're absolutely right. I just tried it with my Metz 48 on camera. Setting the camera flash mode to red-eye on my K5 makes for a very significant delay, easily could be 0.5 sec. Then when i removed red-eye, the shutter delay much reduced - seemed quite snappy and this is in pttl. When i experienced the same problem 1 to 2 years ago, i'm pretty sure i was in red-eye mode as well.

I think the red eye mode deliberately slows the shutter down to allow the eye's iris to close down and reduce the chance of reflection from the retina. I suspect most cameras will then have this delay in red eye, but haven't tested it.

[top-quark]

Don't use shutter priority mode - it appears to be bugged with K-5 and HSS. Use manual instead (best mode w. flash).

HSS is also bugged in that loss of light due to lower flash output is not automatically catered for - you need to bump up your ISO to do this. Something like ISO 800 @ 1/500, ISO 1600 @ 1/1000.

The P-TTL metering flash will not be something that you'll notice - it all happens very quickly. What you are almost certainly seeing is red-eye reduction in action. Don't use red-eye reduction, bounce your flash instead, or even better, use a Sto-fen or the like.

As others have pointed out, when using flash, all the light on your main subject will come from the flash and you control exposure of your main subject with aperture / flash exposure compensation. Because of quadratic fall off, flash does not expose the background overmuch. So you use shutter speed to control exposure of that. Flash freezes motion just fine - don't sweat too much about using an ultra-short shutter speed.

Shameless self-plug: mini guide to P-TTL:
https://www.pentaxforums.com/forums/pentax-k-5/191116-some-insight-into-flash...ml#post2020805

[superdavis]

Many thanks to all respondents! I think I have learned a lot during this post.

I agree with people suggesting going into manual or A mode. Some learning curve and should be there.

About P-TTL delay - of course 0.5 sec was rough estimate, but what I wanted to point out is that - it is noticable. Never checked this in connection with Red Eye reduction, but I guess my camera falsh mode is in there. So might be the case.

And yes, Sony had ADI and pre-flash option as selection, so at least I could choose. But I hope that with Pentax it is simply learning curve topic, so I have to admit AF540 powerfull and complicated flash that needs e bit of time to understand.

[top-quark]

Av will force your shutter speed to be 1/2f to a minimum of 1/180. Can't use HSS w. Av either. Just so you know.

[Jonathan Mac]

Switch from PTTL to manual to eliminate the pre-flash. Use as low an ISO as you can and shoot RAW, so that exposure can be adjusted afterwards. Take as many shots as you can to increase your chances of being in focus.

[top-quark]

Switch from PTTL to manual to eliminate the pre-flash. Use as low an ISO as you can and shoot RAW, so that exposure can be adjusted afterwards. Take as many shots as you can to increase your chances of being in focus.

This does not strike me as friendly advice: the whole point of TTL flash is that you don't have to worry about the flash output as well as everything else. You want to take pictures, not dick around with output levels until the exposure looks right.

For OP, however, you do want to shoot with your mode dial set to M. It may seem counter-intuitive but it is set-and-forget. What you are saying, in effect, is "here is the shot that I'd like to take" and then it's down to P-TTL to make that shot possible. Suggested settings: F5.6, ISO 100, shutter speed: whatever, FEC: to taste.

Two flashes is a red-herring. All modern TTL flash systems work more-or-less the same. It goes like this:

1. Tiny little flash to see how reflective everything is
2. Calculate required output to expose the subject nicely
3. FLASH!

This all happens in a split-second. YOU WILL NOT NOTICE IT (unless you've set something exotic like rear-curtain sync). Quick side note: if you've got some kind of strobist setup going on with off-camera flashes triggered by your on-camera flash, they will notice the pre-flash; you can configure them to ignore it. The "flash!...FLASH!" you're seeing is red-eye reduction. Turn it off and point the flash head at the ceiling instead.

The other thing that you need to know about P-TTL (don't know about other TTL systems) is that uses an algorithm to calculate output that attempts to get as-close-as to correct exposure with in-camera settings and then adds flash on top. Basically, it boils down to this:

• If the camera is in control of shutter speed (Av, Sv) you get min(1/2f, 1/180). P-TTL flash predates IBIS so you get a "sensible" shutter speed.
• If the camera is in control of aperture (Tv, Sv) you're likely to get aperture set to wide open
• If the camera is NOT in control of either shutter speed or aperture but IS on control of ISO (TAv mode will make this so), ISO will go right to the limit.

I hope that this makes clear why "M" is the correct setting for flash photography: it is the only one that puts you in control.

[StephenHampshire]

Doesn't the af540 have an "Auto" mode which uses the on flash sensor? (the old fashioned thyristor mode) This cuts off the flash once the "correct" amount of light is received by the flash - doesn't bother with a pre-flash or trying any fancy calculations to work out the lighting, it is a straight aperture/iso relationship. I use a Metz 48 which doesn't have this option, but also a number of old film era flashes such as the Vivitar 285, using the "A" or auto-thyristor setting. Works well for bounce too, and you can use "dumb" optical; triggers for remote flashes as there is no pre-flash to fool them.

[Allison]

There is some great stuff on this thread!!

So yes, I would get out of the HSS mode because you don't need it indoors for shooting your child. I hear you on your concerns about the A mode - it can be really frustrating. I find the combo of PTTL, the K-5 and bouncing really frustrating myself, so I often go into full manual. The flash speed will freeze your son, so you can adjust exposure with either aperture or shutter speed. Manual will eliminate the pre-flash. I know manual is not as convenient as pttl, but until a new flash system comes out that improves, it is a good work around. Plus, once you get used to it, you can be surprisingly quick.