Two Sigma EF500 DG Super's Wirelessly with DL

Hi All,

First time post for me, but let me start by thanking you all, i have
been reading the forums for a while now and they are a fantastic
resource for Pentax Users.

I have two questions the first is regarding the tittle, i picked up a
second EF500 DG Super yesterday and went home to play with the wireless
function. I am particularly interested in the function whereby the on
camera flash doesnt fire but the off camera does. I have read and
followed the manual and the on camera flash still fires and appears to
effect the photo regardless of settings in the manual (ie the master
having the "CL" setting or not.

Has anyone used this function succcessfully if so how, am i doing the
right thing?

Thanks in advance.

Welcome to a-board

Can't comment on the Sigmas, but with two Pentax AF360/AF540 this is the what you need to do:

1) set the flash on the camera to "Controller" (if it was "Master" then it would fire and contribute to the exposure)
2) set the remote flash to "Slave"

You will still get the tiniest effect from the controller. On my *ist-D you get a tiny dot of a catch light when doing portraiture in controller-only mode.

I'll have a look at the Sigma manual later and see how it compares...

Matt

Looking at the (fairly dreadful) manual on page 24, I would say that "When only-off camera flash is triggered" is the section you want.

So, it would like the flash on the camera should have "C1 CL" on the display, while the slave should have "C1 SL".

If this still doesn't work:
* Try swapping the flashes and see what happens
* Turn down the power of the on-camera flash by setting exposure compensation to -3 (page 21,22)

Hope that helps!
Matt

Hi Matt,

Appreciate the reply, i have in fact tried all that you mentioned besides the exposure comp. I would have thought that if you set such that the only off camera flash is triggered, then you would only see the effects of the off camera flash on the photo, this is the problem, no matter how i have the master set i can still see the on camera flash effect on the photo, it appears no different to if i have both firing.

I have tried switching flashes etc.

Is my line of thinking accurate?

Thanks again for the reply

Yes, your line of thinking is correct...

One more thing you can try:
* Turn off the slave flash and your exposure should be very, very underexposed in controller only mode (do it in a dark room)

Other things to check: try disabling sensitivity correction (Auto ISO) on the camera and see if that makes any difference.


I worry slightly about Sigma because I've heard they reverse engineer the body-flash and body-lens protocols, and I wonder if things have changed a little since the *ist-D days (which is when Sigma did the flash).
But let's eliminate all other possibilities first...

Matt

Hi Matt,

Just tried the on camera only in controller mode (as if it were set for off camera flashonly) in a dark room adn the exposure was pretty good. One thing i noticed is that on Tv Mode the aperture did not move from f2.8 no matter what the shutter speed is set to or the focus distance. I would have thought this would change?

And for more info i wasnt using auto ISO (dont think i ever have!).

Somethings not right?

Thanks for you help

Doesn't sound right to me...

I can check later with my *ist-D and *ist-DS with the Pentax guns, but I know for sure that if the *ist-D pop-up is used as controller-only in a dark room and the slave isn't on, the image is super dark.

As for Tv mode - I suspect that the displayed aperture will never change. It'll want to open up the aperture wide enough to let ambient light in. It may stop down the aperture when you fire the flash - so you'll have to check the info on the resultant images

Again, I can check that later.

Matt

Thanks Matt, if you wouldnt mind that would be good.

I was looking at the image info, and it also reflects that the aperture appears to never change.

Just tried it with the *ist-D and it worked exactly as I described. A controller with a slave off will produce a dark image.

Will try the *ist-DS later...

In Tv mode the aperture stays wide open - it's metering for ambient light. To be honest, you don't generally do that with flash as it's either P, A, or M mode.

Matt

The *ist-DS does exactly the same as the *ist-D (except maybe exposure is slightly better controlled).

So, either:
a) Sigmas don't work as they should on the newer bodies
b) You have a dud pair (which is highly unlikely)

Doesn't look good for you
Matt

Thaks Matt for clarifying that.

The only other thing i can think of is that i have just updated the firmware, that was before i got the second flash though so it may have nothing to do with it and yet it may have something to do with it. Do you happen to know if one can roll back the firmware to test my theory?

I must admit i did play around with them this afternoon outside and had a look at the shadows ont he photos and they were better than in a dark room. Im wondering if perhaps the dark room is causing the master to over compensate for the slave or perhaps it detects that no slave is present. When one looks at the sequence as outlined in the Pentax Manual here is what happens when a wireless master/slave is used:

1) On camera flash discharges a pre-flash
2) The external flash discharges a pre-flash to test lighting conditions
3) The on camera flash discharges another pre-flash transmitting the correct settings for exposure
4) the external flash discharges the main flash.

Given that the flashes use light signals to transmit, I wonder if there is a problem with the Sigma's and the camera over compensates when t does not detect the off camera pre-flash (to test light conditions) which then causes the on camera flash to fire a signal that is too strong, or perhaps the sigma is able to detect that there is no off camera flash and it automatically corrects for exposure?

incase you havent realised I really have no idea just thinking out loud?

Any thoughts?

Thanks again for your time appreciate the help

Well, there's no guarantee that the Sigmas use the same wireless signalling as the Pentax guns. Sigma may use any other method they like - because as far as I know the body doesn't have to know how the signalling takes place.

You may have something though about the body knowing whether the flash is going to fire and compensating... so have a go at this:

1) Set the camera to fully manual
2) Select 1/125s, and f8, ISO200
3) Check that the viewfinder says you will be drastically underexposed (at least 3 stops under would be a good test).
4) Just have one Sigma on the body, and try:
4a) Controller only mode (should be very dark)
4b) Master mode (should be correct with flash)

5) Now power up the slave and try:
5a) Controller only mode (should be correct with shadows from only the slave)
5b) Master mode (should be correct with dual shadows)

Try taking a shot of a simple object (a tin can for instance) on a white piece of paper. Position the slave to point directly from the right hand side and this should make it easier to see where the shadows are coming from.


Note: at least with the Pentax guns you can use P-TTL flash when the body is set to fully manual. I've had great results from doing this

Matt