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03-07-2007, 08:09 AM   #1
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P-TTL and Subject Blink

I'm new to DLSR photography. I have been using a point and shoot camera for several years and a Pentax P3 with Sunpak Auto 433D prior to that. I've noticed that with my new K100D and AF540FGZ set up, I folks tend to be blinking in flash shots when 540 is in P-TTL mode. I know that P-TTL does pre-flash to set flash power for proper exposure and this is likely the cause. I switched to "Auto" flash mode on the 540 and that seems to have fixed it.
Am I missing something, or is using the 540 (or any similar flash) in Auto mode rather than P-TTL mode a necessity when shooting people shots to avoid subject flash blink?
Thanks for any insights you can give,
SB

03-07-2007, 08:15 AM   #2
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Didn't you get the tape and toothpick accessory kit with the flash? On folks with young eyes you just tape those pesky eyelids to the forehead; on old droopy eyelids, prop them open with a couple of picks.

Get the flash out of their eyes; Google "Strobist".
03-07-2007, 08:31 AM   #3
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QuoteOriginally posted by atnbirdie Quote
I'm new to DLSR photography. I have been using a point and shoot camera for several years and a Pentax P3 with Sunpak Auto 433D prior to that. I've noticed that with my new K100D and AF540FGZ set up, I folks tend to be blinking in flash shots when 540 is in P-TTL mode. I know that P-TTL does pre-flash to set flash power for proper exposure and this is likely the cause. I switched to "Auto" flash mode on the 540 and that seems to have fixed it.
Am I missing something, or is using the 540 (or any similar flash) in Auto mode rather than P-TTL mode a necessity when shooting people shots to avoid subject flash blink?
Thanks for any insights you can give,
SB
How does this differ from red-eye reduction which is also a preflash of sorts?

Note that using auto mode makes use of the sensor on the flash body, like we all did 20 years ago before TTL flash, but has drawbacks as it does not know what you want to meter from.

If the preflash problem persists, perhaps (although this is a retrograde step) using an *istD?? camera (?? for specific model) and an AF500 FTZ flash which is true TTL metering would be better.
03-07-2007, 09:48 AM   #4
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QuoteOriginally posted by atnbirdie Quote
I'm new to DLSR photography. I have been using a point and shoot camera for several years and a Pentax P3 with Sunpak Auto 433D prior to that. I've noticed that with my new K100D and AF540FGZ set up, I folks tend to be blinking in flash shots when 540 is in P-TTL mode. I know that P-TTL does pre-flash to set flash power for proper exposure and this is likely the cause. I switched to "Auto" flash mode on the 540 and that seems to have fixed it.
Am I missing something, or is using the 540 (or any similar flash) in Auto mode rather than P-TTL mode a necessity when shooting people shots to avoid subject flash blink?
Thanks for any insights you can give,
SB
I noticed this when using a Nikon speedlight with a D50. They could be blinking because their eyes are adjusting to the bright pre-flash before the real flash goes off. Try using red-eye reduction and get them to blink and adjust as the red-eye strobe goes off. When the pre-flash fires, they are all set.

Hope that helps.

03-07-2007, 04:56 PM   #5
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Am I missing something, or is using the 540 (or any similar flash) in Auto mode rather than P-TTL mode a necessity when shooting people shots to avoid subject flash blink?


That's what I do -- but I've only run into a couple of people that are fast enough to blink consistently from the P-TTL preflash. After chimping a number of P-TTL shots, if the person's eyes are always closed or "lazy", I just switch to Auto mode on either the 540 or 360 and shoot them again. Not really a big deal.

Scott
03-12-2007, 06:32 AM   #6
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I think the big difference is the lag between pre-flash for P-TTL and that for red-eye reduction. The red eye pre-flash is very obviously separated from the main flash whereas that for P-TTL is indisinguishable to most folks. I've seen posts elsewhere that imply for the K100D the P-TTL preflash is probably a little over 100 ms. The red eye seems like it must be closer to 250 ms.
I'll try red eye mode w/P-TTL and see how that works for those folks who are sensitive to the 540's P-TTL preflash.
With respect to another camera, I didn't spend a chunk of money on one system only to have to buy another! :-) I'd rather make this one work as it should. What good is a flash that you can't use with people as subjects?
Thanks.
03-12-2007, 07:17 AM   #7
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Let us know you findings.
03-12-2007, 07:40 AM   #8
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Maybe I have bad luck, or maybe my expectations are off, but I still find TTL/P-TTL exposures on digital sensors to be a little inconsistent. I find that if I put the flash on manual and aim it at the ceiling I can wander around a room full of family and get better consistency. Not to mention softer light.

03-14-2007, 10:18 AM   #9
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I regularly cover weddings and do on-location portraiture using a combination of P-TTL, Auto and manual flash units. I honestly cannot say that I get more "blinkers" with P-TTL than Auto or manual. Some people just blink more than others.

I shot some portraits two weeks ago using off-camera manual flash units (no preflash) and the subject blinked in about 25 percent of the shots I took. I don't deny that preflash can potentially make subjects blink during the actual exposure, but I cannot honestly say that I have more problems with blinkers when I use P-TTL ... blinkers are just a fact of life.
03-14-2007, 12:20 PM   #10
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JJJ, I appreciate the input. One of the things I'll be doing in the fall is taking the photos for my niece's wedding. It's been many years since I've done a wedding, and I never did do that many so I want to ensure I work all the kinks out of my system, and know it well, before then. I'll use yours and other's responses to focus how I experiment with my system to determine how to get the best performance out of it. After all, I'm not one to pass up a chance to play with toys :-)
Thx
03-14-2007, 01:47 PM   #11
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QuoteOriginally posted by JJJPhoto Quote
I regularly cover weddings and do on-location portraiture using a combination of P-TTL, Auto and manual flash units. I honestly cannot say that I get more "blinkers" with P-TTL than Auto or manual. Some people just blink more than others.
Funny story but I was using the 540 on-location at the bar I work and take pictures for and found a group of people that wanted me to take a picture for their buddies 24th b-day and of course I grabbed my gear took 6 shots and to my amazement all but one person blinked in every single shot. I talked to the person who admitted that no one has ever gotten a picture of him where he didn't blink if the flash was used. The only remedy for this was to make him look almost 90 degrees to the camera and re-do all the shots which came out fine this time. I guess some people are just super sensitive so it's not always the settings/flash causing the problem but lacy people and their sensitive retinas lol

ps. yes I mean lacy not lazy
03-14-2007, 07:28 PM   #12
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Yes, some people are very sensitive to those pre-flashes, for red-eye reduction or for P-TTL. You have not much to do to avoid those lazy eyes, indeed, as those are physical reactions of human bodies :-)

To switch to Auto mode should be a good idea, provided that you must switch also to M mode. But for flash photography, M mode is what one should use to control fully the amount of ambient light to be exposed (so the Tv counts more here) as well as the DoF control and the flash range control are important (so an appropriate f-stop should be selected).

Also, I found that the Auto mode do produce more consistent and accurate results than the P-TTL too, under normal situations, say, a scene with objects which are close enough and with average reflectance of sujbect and background. For further read, you can see my detailed "lab" test in my K100D full review, below:-

RiceHigh's Pentax K100D Full Review


QuoteOriginally posted by atnbirdie Quote
I'm new to DLSR photography. I have been using a point and shoot camera for several years and a Pentax P3 with Sunpak Auto 433D prior to that. I've noticed that with my new K100D and AF540FGZ set up, I folks tend to be blinking in flash shots when 540 is in P-TTL mode. I know that P-TTL does pre-flash to set flash power for proper exposure and this is likely the cause. I switched to "Auto" flash mode on the 540 and that seems to have fixed it.
Am I missing something, or is using the 540 (or any similar flash) in Auto mode rather than P-TTL mode a necessity when shooting people shots to avoid subject flash blink?
Thanks for any insights you can give,
SB
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