Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-10-2007, 10:46 AM   #1
Veteran Member




Join Date: Dec 2006
Location: Dallas, Texas
Photos: Gallery
Posts: 2,482
540FGZ wireless operation

All summer long, I've been playing (and occasionally working, although mostly playing) with the 540 FGZ off-camera. But last night I just figured out something rather important -- and it leads me to wonder what else I have missed so far.

What I figured out last night for the first time is that the 540 won't fire, in wireless mode, unless it's set to the same channel as the camera (in my case, a K10D). I guess I never realized this before because the flash and the camera have stayed on channel 1 since forever. I have read this part of the manual several times, but honestly, the 540 operating manual is a sorry piece of work and I have found it good mainly for hints rather than instructions.

In the light (no pun intended) of this discovery, I'm reevaluating the rest of what I thought I knew about this subject.

First, it makes me wonder about something that I was told here in another thread. In that other thread, I was asking why you'd bother to connect the off-camera flash (say, one mounted on a bracket) with cables when you could save $100 and use the wireless connection. The answer I got -- well, the answer I thought I got -- was that, if you're using the camera's wireless mode to trigger the camera, the flash might get triggered when somebody else (Uncle Larry, with his Rebel XT) snaps a flash shot. This got me thinking that it was the camera's preflash that triggered the off-camera 540. I now believe that this is not the case. I must have misunderstood what I was told (not for the first time). If I set up my K10D and the off-camera flash for wireless operation, I am not able to trigger the 540 simply by popping the flash on another camera. Right?

Now, I do understand that, if I'm taking wedding formals in wireless mode using channel 2 and Uncle Bob (the smart one in the family) also has a K10D and his camera is also set to wireless flash mode AND to channel 2 (the channel I'm now using), I expect that his camera will trigger my off-camera 540. But that seems like a real long shot. Or are these channels universal, non-brand specific standards? In other words, does Uncle Larry's Rebel XT have the same 4 channels and do they work the same way? Is this something I really have to worry about?

I've tried once again to puzzle out the apparently pertinent sections of the operating manual for the 540, and it says there that the pre-flashes are used to exchange information between the camera and the flash. But my impression now is that the final off-camera flash -- the one that illuminates the subject for the photo -- is not triggered by a pre-flash, but rather, is triggered by some other sort of signal of coming from the camera. Right?

And if that's right, then what sort of signal is it? "Channel" makes me think radio, but I have done some experiments that suggest that it's not a radio signal. If I turn the 540 around so that it's facing completely the opposite direction of the camera, the wireless trigger does not work. This makes me think that the trigger signal is not a radio signal but something that requires line-of-sight. Right? What is it? Infrared? Are there infrared channels?

Finally, I'm back to wondering: why should I bother with cables?

Thanks,

Will

10-10-2007, 10:54 AM   #2
Veteran Member
mysterick's Avatar

Join Date: Oct 2006
Location: 44266
Photos: Gallery | Albums
Posts: 567
Now I can't wait to see the responses that follow. Like your style, Will.
10-10-2007, 10:58 AM   #3
and
Veteran Member




Join Date: Mar 2007
Photos: Gallery
Posts: 2,476
Its not really channel per se, from the 360 you have 2 channels. one for triggering the flash via the optical slave, ie no p-ttl, just normal slave triggering and it will fire on any flash it detects. the other channel is for the pentax wireless protocol, which as far as I know uses a series of preflashes to communicate and then trigger. it does not use infrared afaik, because then you wouldnt have to use the popup flash to trigger it.

so the channels are more like modes, pentax wireless mode and normal slave mode.

why cables:
cables lets you do HSS mode. built in flash plus 540 does not let you use HSS.
10-10-2007, 11:00 AM   #4
and
Veteran Member




Join Date: Mar 2007
Photos: Gallery
Posts: 2,476
OH, and no, there is no radio!
I believe one of the reasons why no camera maker is offering built in radio is to avoid having to have different versions of the camera in different countries due to frequency differences, like pocket wizards are available in different versions for US and Europe etc. Also if you put a radio in the camera then you have to go through more government approvals.

10-10-2007, 11:04 AM   #5
Veteran Member




Join Date: Dec 2006
Location: Dallas, Texas
Photos: Gallery
Posts: 2,482
Original Poster
QuoteOriginally posted by and Quote
Its not really channel per se, from the 360 you have 2 channels. one for triggering the flash via the optical slave, ie no p-ttl, just normal slave triggering and it will fire on any flash it detects. the other channel is for the pentax wireless protocol, which as far as I know uses a series of preflashes to communicate and then trigger. it does not use infrared afaik, because then you wouldnt have to use the popup flash to trigger it.
Don't you're talking about the same thing I'm talking about.

On the 540FGZ, there are two slave modes: SL1 and SL2. I don't understand exactly what these do, but they are not relevant (I think) to my question. I'm talking about the four channels used for wireless mode. Completely different thing.


QuoteQuote:
why cables:
cables lets you do HSS mode. built in flash plus 540 does not let you use HSS.
OK, that's helpful. Think I've seen that in the operating manual and didn't remember it. Thanks.

Will
10-10-2007, 11:08 AM   #6
and
Veteran Member




Join Date: Mar 2007
Photos: Gallery
Posts: 2,476
Oh I see, perhaps the 540 is different from the 360 in this case, I will have to look into that. Altho I do remmeber setting two channels, 1 being optical slave and 2 being the pentax wireless system.

Oh, and I think you might be able to get wireless HSS if you are triggering the 540 with another 540 or 360 but the jury is still out on that one. with the built in flash you cannot, though.
10-10-2007, 11:24 AM   #7
and
Veteran Member




Join Date: Mar 2007
Photos: Gallery
Posts: 2,476
Ok, just took out my 360. Indeed it has 4 channels and these work as channels, meaning that the camera and flash(es) need to be on the same one for everything to work.

That being said, I beleive there is no radio and no infrared being used, just preflashes. And the channels exist to prevent k10d owners from triggering each others flashes.

Cameras from other makes should not trigger the flash, although you cannot be guaranteed when its using light to communicate. They should be able to confuse the flash, however.

If the flash is set to optical slave mode then it will of course be triggered by any other user.

In short I would not rely on the pentax wirelss system if I was a wedding photorapher. I would not settle for anything less than pocket wizards. Altho if I was not willing to do manual flash and if I wanted to have the flash in my hand or in a bracket anyway then no reason not to use the cable.

which leads us to another advantage of the cable: it will not get triggered by any other flash, pentax or not.

10-10-2007, 11:41 AM   #8
Veteran Member




Join Date: Dec 2006
Location: Dallas, Texas
Photos: Gallery
Posts: 2,482
Original Poster
QuoteOriginally posted by and Quote
Ok, just took out my 360. Indeed it has 4 channels and these work as channels, meaning that the camera and flash(es) need to be on the same one for everything to work.
Now you're with me. This is where I started. ;-)


QuoteQuote:
That being said, I beleive there is no radio and no infrared being used, just preflashes.
Can you elaborate on that? I don't see what "channels" have to do with pre-flashes. I will admit openly to what I think is already perfectly obvious, namely, I'm not a physicist or a communications engineer. But didn't realize that flashes (light bursts) could be transmitted via CHANNELS.


QuoteQuote:
which leads us to another advantage of the cable: it will not get triggered by any other flash, pentax or not.
Should have been clearer. I take this advantage for granted. My question was designed to suggest that, as far as I can tell at the moment, the odds of the flash getting triggered by another camera seem to be very small. So I'm asking, am I right in calculating the odds? If I'm not, then what exactly has to happen for another camera to trigger MY flash? I can't make it happen here with any of the camera's I've got, and I'm trying. And if I'm right and the odds of somebody else triggering my flash are very small, then what other advantages does the cable connection have besides reducing the chance of accidental flash from small to zero?

Will
10-10-2007, 12:15 PM   #9
Veteran Member




Join Date: Jun 2007
Location: California
Posts: 426
Channels in a more traditional sense are different frequencies (different wavelengths, etc). So light can actually be on different channels, red light is different from blue light, etc... however that's not how our flashes distingish channels.

Our flashes create different channels by using different patterns of pre-flashes. So a flash on channel one will have a different preflash sequence than a flash on channel 4.
-----------
The other advantage are in situations where your flash unit and camera are unable to communicate. Maybe the scene is too bright, physical objects blocking light transmission, etc.

Wireless does what it's supposed to most of the time, that's why it's becoming more popular to have this feature. The convenience it's given me far outweigh the shots that I've missed or have been unable to take because those situations are so rare.
10-10-2007, 12:23 PM   #10
Veteran Member




Join Date: Dec 2006
Location: Dallas, Texas
Photos: Gallery
Posts: 2,482
Original Poster
QuoteOriginally posted by AVANT Quote
Channels in a more traditional sense are different frequencies (different wavelengths, etc). So light can actually be on different channels, red light is different from blue light, etc... however that's not how our flashes distingish channels.

Our flashes create different channels by using different patterns of pre-flashes. So a flash on channel one will have a different preflash sequence than a flash on channel 4.
Interesting. So it's not what I think of as "channels" at all -- they're just using the word "channel" a bit loosely to refer to different ways of patterning the pre-flashes? Am I understanding you correctly?

And if I am understanding you correctly, what does this say about the odds of unwanted interference from other camera's? Seems to me that, at a minimum, the other camera would also have to be using an off-camera flash in wireless mode, which isn't likely. And are these "channels" (patterns) specific to Pentax's flashes, or do they work with all brands of cameras and flashes?


QuoteQuote:
The other advantage are in situations where your flash unit and camera are unable to communicate. Maybe the scene is too bright, physical objects blocking light transmission, etc.
Ah, yes, excellent. Forgot about that, too. Will add that to the list of the advantages of cables.


QuoteQuote:
Wireless does what it's supposed to most of the time, that's why it's becoming more popular to have this feature. The convenience it's given me far outweigh the shots that I've missed or have been unable to take because those situations are so rare.
Yeah, exactly what I'm thinking....

Will
10-10-2007, 12:39 PM   #11
Veteran Member




Join Date: Jun 2007
Location: California
Posts: 426
QuoteOriginally posted by WMBP Quote
Interesting. So it's not what I think of as "channels" at all -- they're just using the word "channel" a bit loosely to refer to different ways of patterning the pre-flashes? Am I understanding you correctly?
Yes

QuoteOriginally posted by WMBP Quote
And if I am understanding you correctly, what does this say about the odds of unwanted interference from other camera's? Seems to me that, at a minimum, the other camera would also have to be using an off-camera flash in wireless mode, which isn't likely. And are these "channels" (patterns) specific to Pentax's flashes, or do they work with all brands of cameras and flashes?
As far as I know, there are no standards for pre-flashing, so chances are that those "channels" are proprietary. I wouldn't rule out the possibility that other wireless flash systems can trigger your flash, but the chances are minimal as well. And even if they do, that's when you're supposed to change to a different channel
10-10-2007, 01:03 PM   #12
Veteran Member




Join Date: Dec 2006
Location: Dallas, Texas
Photos: Gallery
Posts: 2,482
Original Poster
QuoteOriginally posted by AVANT Quote
As far as I know, there are no standards for pre-flashing, so chances are that those "channels" are proprietary. I wouldn't rule out the possibility that other wireless flash systems can trigger your flash, but the chances are minimal as well. And even if they do, that's when you're supposed to change to a different channel
Thanks, AVANT. For what it's worth -- and as you probably know -- changing channels with the Pentax system involves turning the camera off, taking the strobe off the bracket, changing the channel on the strobe, putting the strobe on the camera, turning on the camera and holding down the shutter button halfway to register the new channel, shutting things down, removing the strobe from the camera and putting it back on the bracket. Sigh. And you're doing this with a family holding a pose in front of you, just because somebody else accidentally triggered your strobe. I think it would be easier to ask the onlookers to hold off shooting for a minute or two.

But I'm convinced now this is not something I have to lose sleep about.

I just found a nice little summary of the various technological options involved in wireless flash, on Adorama's web site; click here. After reading this article, I see that there actually ARE or at least used to be flash systems that were triggered simply by some other flash, any flash. Fortunately, the Pentax 540/K10D system is not subject to that problem, because it uses the "channels".

I think that answers all my questions pretty well.

To summarize the reasons for using cables:
  1. Eliminates any risk of accidental firing of the flash. I don't consider this worth much since the risk looks like it's close to zero anyway.
  2. Off-camera flash connected via cables can do high-speed sync. Not a big deal. I do use high-speed sync outdoors occasionally, but not often, and when I'm outdoors, I don't usually have the flash off the camera anyway.
  3. Cables allow remote triggering when wireless won't work because there's no directly line-of-sight between off-camera flash and camera, or when the camera's pre-flashes aren't picked up by the off-camera strobe either because it's too bright or because the distance between the flash and the camera is too great. But here again, this doesn't strike me as a big deal for me personally and the kinds of shots I'm taking.
So, wireless is looking better and better. If the camera and flash are on a bracket, well, I bought the cables so I might as well use 'em. But I will now feel more willing to take the flash off the bracket, ask somebody to hold if five feet to my left, and count on wireless to make the connection. Which will be very useful.

Thanks both to Andreas and AVANT for your helpful responses.

Will
10-10-2007, 01:41 PM   #13
New Member




Join Date: Sep 2006
Location: Brussels / Belgium
Posts: 19
QuoteOriginally posted by and Quote
Oh I see, perhaps the 540 is different from the 360 in this case, I will have to look into that. Altho I do remmeber setting two channels, 1 being optical slave and 2 being the pentax wireless system.

Oh, and I think you might be able to get wireless HSS if you are triggering the 540 with another 540 or 360 but the jury is still out on that one. with the built in flash you cannot, though.
SL1 is the "real" wireless mode. Uses the pre-flashes to communicate.

In SL2 mode the flash fires when it detects another flash firing. The manual p. 51 says "do not use red-eye reduction ...". It even could fire whith the blinking of starting TL tubes. Works nicely.
10-10-2007, 01:54 PM   #14
Veteran Member




Join Date: Dec 2006
Location: Dallas, Texas
Photos: Gallery
Posts: 2,482
Original Poster
QuoteOriginally posted by polvda Quote
SL1 is the "real" wireless mode. Uses the pre-flashes to communicate.

In SL2 mode the flash fires when it detects another flash firing. The manual p. 51 says "do not use red-eye reduction ...". It even could fire whith the blinking of starting TL tubes. Works nicely.
EXCELLENT. Just tested this and you're right. With the 540 in SL2 mode, I can trigger it wirelessly using my *ist DS. Thank you for this explanation.


I've also noted now I made a mistake in my list of advantages of cable over wireless triggering. I just took a photo using high-speed sync, my K10D and the off-camera 540 (held in my left hand). The triggering flash was not another 540 or a 360 -- it was just the K10D's built-in flash.

So, revised summary of the advantages of cabled connection to the remote flash unit:
  1. Eliminates any risk of accidental firing of the flash.
  2. Cables allow remote triggering when wireless won't work because there's no directly line-of-sight between off-camera flash and camera, or when the camera's pre-flashes aren't picked up by the off-camera strobe either because it's too bright or because the distance between the flash and the camera is too great.
Makes wireless look even better, and it was looking good already.

Thanks again to everybody. Very helpful thread!

Will
10-10-2007, 02:43 PM   #15
Veteran Member




Join Date: Jun 2007
Location: California
Posts: 426
QuoteOriginally posted by WMBP Quote
Thanks, AVANT. For what it's worth -- and as you probably know -- changing channels with the Pentax system involves turning the camera off, taking the strobe off the bracket, changing the channel on the strobe, putting the strobe on the camera, turning on the camera and holding down the shutter button halfway to register the new channel, shutting things down, removing the strobe from the camera and putting it back on the bracket. Sigh. And you're doing this with a family holding a pose in front of you, just because somebody else accidentally triggered your strobe. I think it would be easier to ask the onlookers to hold off shooting for a minute or two.
I pretty sure you can change channels without turning the camera off. Specify new channel on the flash, plug it into the camera, half shutter, remove flash again. Changing channels does take a little bit of time, but should be a very rare thing.

But yes, if you can tell onlookers to stop, advising them to hold off shooting would work. However, you would probably notice your flash triggering by other flashes long before the posed family shots (if you're talking about weddings).

QuoteOriginally posted by WMBP Quote
I've also noted now I made a mistake in my list of advantages of cable over wireless triggering. I just took a photo using high-speed sync, my K10D and the off-camera 540 (held in my left hand). The triggering flash was not another 540 or a 360 -- it was just the K10D's built-in flash.
What was the shutter speed of your test shot?

Our K10D is not supposed to support HSS wireless flashing (Notice you only have a Wireless Flash mode, not a Wireless HSS mode in the camera). There has been one ist that supports wireless HSS iirc, but I don't remember which model.

Your onboard can still trigger the external unit with it set to HSS, I just don't believe you actually get HSS out of it. I'll test this out when I get a chance.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, channel, channels, flash, k10d, mode, off-camera, radio, trigger, tripod, uncle
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Troubles with wireless trigger on 540FGZ mparzuchowski Pentax Camera and Field Accessories 4 05-20-2009 10:16 PM
questions about 540FGZ as wireless slave WMBP Pentax Camera and Field Accessories 2 03-11-2009 10:36 AM
How do i associate 540FGZ to K100D via infra-red wireless? MRBHV Pentax Camera and Field Accessories 10 01-13-2009 01:33 PM
AF540FGZ Wireless Operation. NLAlston Flashes, Lighting, and Studio 4 12-04-2007 04:53 PM
Dual 540fgz - *NON*wireless ttl EdZarts Pentax Camera and Field Accessories 5 04-16-2007 09:48 AM



All times are GMT -7. The time now is 03:00 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top