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12-10-2011, 12:44 PM   #1
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Reliability of wireless P-TTL

Since it is getting too cold to be outside much, one of my winter projects is to learn to use my flash. I am using a Metz 48 AF-1 as my starter flash.

Learning how to use the flash today, I wanted to try the wireless option. I set the camera for wireless, and set it as controller as I want the Metz flash to do all the work. I set the flash on a table pointing at the side of a teddy bear as my subject. I learned through reading here that the sensor to receive the signal on the Metz flash is next to the battery door, so I made sure that sensor was pointing toward the camera.

Without moving anything, I got the Metz flash to work properly in wireless mode like this 50% of the time. By having the Metz flash pointing directly at the side of the teddy bear, I could easily tell when it worked properly as I had the left side of the bear bright while I had a heavy shadow on the right side. Only half the time did it work like this - the other 50% of the time the light on the teddy bear was even and underexposed.

So is this the unreliability of wireless P-TTL I have been reading about? This all really doesn't matter much as I am planning on ordering a set of wireless triggers and learning how to control the flash manually - I can see now that doing it manually will allow much more creativity.


Last edited by stormtech; 06-25-2012 at 07:16 PM.
12-10-2011, 02:49 PM   #2
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Manual flash and wireless triggers are the way to go, but there may be occasions when you don't have time to make the proper calculations, and so pTTL can mean the difference between getting the shot or missing it. I believe that in "controller mode" the output of the pop-up flash is simply reduced to minimum power, but it still has to fire during the exposure in order to tell the slave flash when to fire. In certain situations the weak control flash may be indistinguishable to the Metz from the normal ambient light. Try your experiment again in either a darker room, or set the pop-up to "master" rather than "controller", but dial in -2 or -3 on the power. If that works, but the flash seems underexposed, try increasing the power on the Metz by the amount you reduced the pop-up, (so -2 on camera, +2 on the slave) Let us know what you find.
12-10-2011, 03:42 PM   #3
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Were you using the built-in flash as the trigger? I've managed to use it outside within say 20 feet depending on the angles of the flash and camera.

Using flash based wireless, a better option would probably be to use a more powerful flash (higher guide number) connected to the camera that can act as the trigger. The negative is more light coming from the camera. Not all flash can do that.

RF wireless is the way to go. It's too bad no one offers P-TTL through RF (yet). Hopefully as Pentax/Ricoh become more popular, better options for us will show up.
12-10-2011, 04:13 PM   #4
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maxfield_photo - Now that it is dark out, with the same setup with the room mostly dark, the external flash fired every time successfully 10 times in a row. In the room where I am working, I have a large glass door (8' x 8') so as you say I was getting a lot of ambient light from that. Now I understand that the pop-up clash in controller mode puts out a small signal that can be overrun by ambient light.

sjwaldron - your idea of using a bigger flash as the controller fits in with what maxfield_photo says and my findings after my experiment in the dark.

Well, this was my goal for the day - I learned something! As I said above, I do plan on purchasing wireless radio triggers, but wanted to see how the wireless aspect works.

I now can change my thoughts from "unreliable" to just "finicky" I guess - now I know the limits of using the wireless P-TTL.

Thanks!

12-11-2011, 10:54 PM   #5
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If you take a look at the bear's pupils, you will notice easily when the metz fired...and not. The optical sensors on any of the flashes / strobes seems to be unreliable at best, downright frustrating sometime. Plus, some others will get triggered by P-TTL preflash, some wont. As you have gathered, i think wireless radio triggers are the way to go.
12-11-2011, 11:08 PM   #6
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And of course you can maximise the efficiency of the wireless setup by ensuring a direct line of sight between the control light and slave flash. An external flash unit with swivel acting as the controller is clearly very versatile in this setting - the only limitation with this setup is distance, and I've been successful with triggering a slave about 10m away.
12-12-2011, 05:46 AM   #7
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QuoteOriginally posted by stormtech Quote
Without moving anything, I got the Metz flash to work properly in wireless mode like this 50% of the time. By having the Metz flash pointing directly at the side of the teddy bear, I could easily tell when it worked properly as I had the left side of the bear bright while I had a heavy shadow on the right side. Only half the time did it work like this - the other 50% of the time the light on the teddy bear was even and underexposed.
This may be obvious, but: what type of batteries were you using in the flash, and how fresh were they? Did you wait for the flash to be ready between each shot?
12-15-2011, 08:51 AM   #8
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QuoteOriginally posted by mattdm Quote
This may be obvious, but: what type of batteries were you using in the flash, and how fresh were they? Did you wait for the flash to be ready between each shot?
That is what I was thinking. Most of the time when I have had problems like this, my flash had just blown its guts out and needed a few seconds, there was a setting on the flash that preventing wireless from working or the off-camera flash was in a dark corner where the light from the control did not reach. If the settings and location are the same, and the flash doesn't work, it is usually the batteries or the refresh cycle. I find wireless P-TTL to be quite reliable in general.

01-06-2012, 07:57 AM   #9
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I'm going to modify my last post with respect to the K5. I find the K5 to have the least reliable wireless flash of any Pentax camera I've used, including film models with wireless TTL. For no apparent reason, the AF540FGZ will stop firing in response to the onboard flash of the K5 no matter how fresh the batteries. The accuracy is also erratic--perfect on one shot and way under or over on another. I love the K5 for work without a flash, but the K20d blows it away for wireless P-TTL.
01-23-2012, 10:49 AM   #10
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QuoteOriginally posted by GeneV Quote
I'm going to modify my last post with respect to the K5. I find the K5 to have the least reliable wireless flash of any Pentax camera I've used, including film models with wireless TTL. For no apparent reason, the AF540FGZ will stop firing in response to the onboard flash of the K5 no matter how fresh the batteries. The accuracy is also erratic--perfect on one shot and way under or over on another. I love the K5 for work without a flash, but the K20d blows it away for wireless P-TTL.
Found this thread and have been noticing the same thing (with a Metz 58). I, like the OP, am trying to learn more about flash photography and have been playing around indoors with mine and the wireless modes. My photos either come out a little overexposed (by 1/3 of a stop) or completely underexposed (flash isn't firing).

On a side note, I've noticed that a firmware update for the K5 and Metz flashes may allow me to go manual mode with the flash and give a bit more reliability. I'm going to check that out tonight.
01-24-2012, 09:15 PM   #11
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QuoteOriginally posted by emalvick Quote
Found this thread and have been noticing the same thing (with a Metz 58). I, like the OP, am trying to learn more about flash photography and have been playing around indoors with mine and the wireless modes. My photos either come out a little overexposed (by 1/3 of a stop) or completely underexposed (flash isn't firing).

On a side note, I've noticed that a firmware update for the K5 and Metz flashes may allow me to go manual mode with the flash and give a bit more reliability. I'm going to check that out tonight.
Those are pretty much my experience. I have the latest firmware on the K5, but there does seem to be something different about the way the K5 works with wireless TTL. The K10/20/x were far more reliable, and often actually worked better in wireless mode than on the top of the camera.
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