One reason for some external flash problems

[Pat Glenn]

This is a long and boring topic, unless you've had the problem.

I have discovered one reason for the intermittent no-flash or low-flash problems I have had. In my case, the problem is fairly simple. I'm using a Sto-Fen diffuser and a Metz flash.

The reason the Metz is a problem is that both the Auto and TTL flash programs use information from the flash sensor as well as the camera sensor to determine when to squelch. This would be O.K., but...I'm using a Sto-Fen flash diffuser. I was certain the problem wasn't random, although it seemed to be. What is happening is that the Sto-Fen, when the flash is in direct flash mode (facing forward), spreads the light in such a broad pattern that it reaches the sensor on the flash before it reaches the subject. This causes the flash to either squelch early or lessen the flash power, I'm not sure which. My best guess is that it squelches early.

If the flash is in bounce position or rotated horizontally, flash is normal and exposures are as expected. If the flash is in manual mode, naturally it flashes regardless of position, because the sensor is taken out of play.

I am of the opinion that Metz is aware of the problem because they recessed the sensor, but apparently not enough. I also noticed that they have stopped selling the Sto-Fen as an accessory.

I was able to verify my suspicions by simply blocking the light coming down from the flash by holding a piece of cardboard under the head or removing the Sto-Fen. With the cardboard in place, and the Sto-Fen attached, the flash fired every time. Remove the cardboard and the problem returned. Remove the Sto-Fen and the problem disappeared, replace it and it returned.

Block the sensor with my finger, the problem disappeared, remove my finger and it returned.

I suspect that this is the reason some of us get intermittent flash on occasion, usually in less than optimum light conditions. If the ambient light is bright enough, the extra light from the flash doesn't have as much of an effect. In lower light conditions, usually normal room light, the flash sensor sometimes reads the light from the flash before it reads the light returning from the subject and shuts down too soon. This can happen even without a diffuser in place, on occasion, and depends on the flash design. I don't think the problem is unique to the Metz 40MZ 3i, but since those of us who have complained about it haven't said what flash we're using, I don't know what other flashes may have the problem.

I don't know how to tell you to test your flash. I just had an "ah ha" experience when my flash didn't fire properly. It was flashing, but just a "small" flash, and something "clicked" for me.

If you're having an intermittent flash problem, drop a line to say what flash you're using. There may be a commonality that we've missed.

Pat Glenn

 

[Bryan Biggers]

It sounds like the problem would be confined to just certain flashes. I sounds like that Metz flash has no real "TTL" mode but is always in some sort of program mode where the sensor on the flash is always used and that it decides not to fire some times because it sees too much light. Are you sure that there is no real TTL mode on that flash so that the camera can squelch it? Even my super cheapo Sunpak has a real TTL mode (as well as program modes where it would act like the Metz). I think that the Sunpak will always fire a little bit in program mode, it is probably not as good at squelching at a nice flash.

It does bring up, maybe people are trying to use other flashes in program mode, either by mistake, or because they don't have the Nikon hot shoe pinout. That could cause those flashes to not fire if they think that there is already enough light.

Bryan

 

[Pat Glenn]

So far as I know, the Metz is a "TTL" flash and on the Metz web site they say that TTL with the 990 is supported. (For $400.00+ it OUGHT to be)!

Obviously, the on-flash sensor is "getting into the act" as well, though, because every possible setting except manual causes the problem unless I block the light getting to the sensor directly from the flash head. As far as I can tell, this is the first time anyone has come up with a way to replicate and solve the problem.

I'm satisfied that I've solved MY problem, but that's why I wonder what flashes others with the problem are using. The Sto-Fen and its light spread is definitely a big part of the problem, but there still may be other factors.

Pat

It sounds like the problem would be confined to just certain
flashes. I sounds like that Metz flash has no real "TTL" mode but
is always in some sort of program mode where the sensor on the
flash is always used and that it decides not to fire some times
because it sees too much light. Are you sure that there is no real
TTL mode on that flash so that the camera can squelch it? Even my
super cheapo Sunpak has a real TTL mode (as well as program modes
where it would act like the Metz). I think that the Sunpak will
always fire a little bit in program mode, it is probably not as
good at squelching at a nice flash.

It does bring up, maybe people are trying to use other flashes in
program mode, either by mistake, or because they don't have the
Nikon hot shoe pinout. That could cause those flashes to not fire
if they think that there is already enough light.

Bryan

 

[Roger Circle]

I'm satisfied that I've solved MY problem, but that's why I wonder
what flashes others with the problem are using. The Sto-Fen and
its light spread is definitely a big part of the problem, but there
still may be other factors.

I'm using the Sto-Fen Omni Bounce on a Sunpak 266D connected to my CP950. I really like it. The Omni Bounce instructions state, "Never use the Omni in the normal straight ahead position... as it will fool the auto sensor of your strobe unit. For optimum results tilt the head to the 45 or 60 degree position."

The straight ahead position fools the sensor on the camera too... sort of a double whammy.

I, too, have experienced underexposed results when accidently aiming the flash straight ahead with the Omni attached. I've never had problems with my flash is tilted at 45 degrees or straight up, and the resulting pics are quite nice.

--Roger

 

[Pat Glenn]

Actually, the instructions say " Never use the Omni in the normal straight ahead position EXCEPT FOR TTL UNITS, as it will, etc." Apparently the "except" is wrong since I was having the problem in TTL mode as well. At least I now know that I was right about the cause of the problem. I was only using straight ahead when I was trying to get more "reach" than bounce would give me while trying to have a softer, diffused light. In general, I hate direct flash, which is why the problem was interrmittent and apparently random. Thanks for verifying my "discovery." I did RTFM, but assumed the exception applied. At least I got it figured out before I drop kicked the camera. (Barely). This also explains why I didn't have the problem in straight ahead position with aux lenses. The camera TTL sensor was partially blocked, so it wasn't receiving too much light too soon.

I KNEW there had to be an answer, but until everything came together at one time, I couldn't figure out what it was. With all the different possible combinations, it's not surprising that it seemed random.

You're right, when everything is working as it should, pictures taken with the Sto-Fen and my Metz are quite nice.

Pat

I'm satisfied that I've solved MY problem, but that's why I wonder
what flashes others with the problem are using. The Sto-Fen and
its light spread is definitely a big part of the problem, but there
still may be other factors.

I'm using the Sto-Fen Omni Bounce on a Sunpak 266D connected to my
CP950. I really like it. The Omni Bounce instructions state, "Never
use the Omni in the normal straight ahead position... as it will
fool the auto sensor of your strobe unit. For optimum results tilt
the head to the 45 or 60 degree position."

The straight ahead position fools the sensor on the camera too...
sort of a double whammy.

I, too, have experienced underexposed results when accidently
aiming the flash straight ahead with the Omni attached. I've never
had problems with my flash is tilted at 45 degrees or straight up,
and the resulting pics are quite nice.

--Roger

 

[Reno29810]

I KNEW there had to be an answer, but until everything came
together at one time, I couldn't figure out what it was. With all
the different possible combinations, it's not surprising that it
seemed random.

You're right, when everything is working as it should, pictures
taken with the Sto-Fen and my Metz are quite nice.

Pat

I'm satisfied that I've solved MY problem, but that's why I wonder
what flashes others with the problem are using. The Sto-Fen and
its light spread is definitely a big part of the problem, but there
still may be other factors.

I'm using the Sto-Fen Omni Bounce on a Sunpak 266D connected to my
CP950. I really like it. The Omni Bounce instructions state, "Never
use the Omni in the normal straight ahead position... as it will
fool the auto sensor of your strobe unit. For optimum results tilt
the head to the 45 or 60 degree position."

The straight ahead position fools the sensor on the camera too...
sort of a double whammy.

I, too, have experienced underexposed results when accidently
aiming the flash straight ahead with the Omni attached. I've never
had problems with my flash is tilted at 45 degrees or straight up,
and the resulting pics are quite nice.

--Roger

I have had the same thing happen with my SB-22s and only when using the Lumiquest ultrasoft. It also is a bounce with diffuser over the front.

This happens rarely but when it has I have been in M-mode with the internal flash off and the flash in TTL mode and the room has been pretty dark. Reno

 

[Pat Glenn]

It's starting to look like we're on to something here. I suspect the same thing that was happening to me is happening to you. I'll have to try it with the Lumiquest. (Which I own, but have never actually used. In another group I'm in that sort of thing is called Rules of Acquisition). Are you using the Pocket Bouncer or the 80-20?

Pat

I have had the same thing happen with my SB-22s and only when using
the Lumiquest ultrasoft. It also is a bounce with diffuser over the
front.
This happens rarely but when it has I have been in M-mode with the
internal flash off and the flash in TTL mode and the room has been
pretty dark. Reno

 

[ian]

Actually, the instructions say " Never use the Omni in the normal
straight ahead position EXCEPT FOR TTL UNITS, as it will, etc."

Except, that we all know the cp950/990 are not true TTL.
When they say "never straight ahead except for TTL" they're
thinking of a true Through The Lense sensor in an SLR
where the flash sensor reads the light that has entered
through the lens and reflected off the film itself insde
the camera, and the front end of the lens is well ahead
of the flash and the diffuser.

On the CP9XX the TTL sensor is just a photo eye on the
front of the camera next to the lens. If the diffuser sticks
out in front of the body of the camera, then you'll get light
reflected from the flash diffuser directly into the TTL sensor of
the camera and it will squelch early.

My theory on why covering the flash sensor even in TTL mode
(make sure you've really put the flash in TTL mode and not Auto)
is that when you put a finger over the sensor you may
also be shading the camera's TTL sensor below the flash
with your hand, so it doesn't get flash light bounced directly
into it any more.

BTW, you can fix your flash's own sensor by extending it
with a small plastic tube (pen body cut up) or even a
small piece of cardboard stuck on. If you were using the
pen body you'd simply cut off about 3/8 of an inch, but
make the cut diagonally and put the longest side on top
so that it shades the sensor from above, but doesn't have anything
sticking out on the bottom to catch light and bounce it down
the short tube. With the cardboard you could just make a little
flap that sticks straight out from the body of the flash above
the sensor to shade it from the diffuser.

ian

 

[Reno29810]

Pat

I have had the same thing happen with my SB-22s and only when using
the Lumiquest ultrasoft. It also is a bounce with diffuser over the
front.

I'm using the Promax ultrasoft it's shaped like the 80-20 without the cutouts and has a plastic curtain that makes it similar to a soft box using a bounce.

This happens rarely but when it has I have been in M-mode with the
internal flash off and the flash in TTL mode and the room has been
pretty dark. Reno

 

[Pat Glenn]

I don't have the Ultrasoft, but I do have an 80-20 with a white insert and a "diffuser", which I'm sure is similar. I'll give it a try.

Pat

Pat

I have had the same thing happen with my SB-22s and only when using
the Lumiquest ultrasoft. It also is a bounce with diffuser over the
front.

I'm using the Promax ultrasoft it's shaped like the 80-20 without
the cutouts and has a plastic curtain that makes it similar to a
soft box using a bounce.

This happens rarely but when it has I have been in M-mode with the
internal flash off and the flash in TTL mode and the room has been
pretty dark. Reno

 

[Pat Glenn]

In order:

1. True, but I was new to the camera when I bought the Sto-Fen, and I didn't know what I know now. I sort of forgot about it even after I DID know, and didn't think about the relevance.

2. Yeah, I know. I figured that out for myself.

3. I know the difference between TTL and Auto. Auto has an A and TTL has a TTL showing in the display. Other than that, you're probably right.

4. The fix is even easier for me: Follow the instructions for the Sto-Fen, and remember that the 990 is NTTL (Next to the lens or Not TTL). If I MUST use direct flash, remove the Sto-Fen.

The cool thing about this, though, is that we may finally be close to understanding why some people have an intermittent problem and others don't. Given the number of variables, and the way everything had to come together, it's no wonder we've never been able to replicate the problem or figure out exactly what was causing it. I'm willing to bet that anyone who's having the problem can, with this hint, figure out what in their flash setup or camera handling is causing the flash to spill over into the sensor, whether on the flash or on the camera, and eliminate it.

Someone just wrote in another thread that the reflection from the edge of his hand was causing the internal flash to underexpose. I guess it was time for this problem to be solved.

Pat

Except, that we all know the cp950/990 are not true TTL.
When they say "never straight ahead except for TTL" they're
thinking of a true Through The Lense sensor in an SLR
where the flash sensor reads the light that has entered
through the lens and reflected off the film itself insde
the camera, and the front end of the lens is well ahead
of the flash and the diffuser.

On the CP9XX the TTL sensor is just a photo eye on the
front of the camera next to the lens. If the diffuser sticks
out in front of the body of the camera, then you'll get light
reflected from the flash diffuser directly into the TTL sensor of
the camera and it will squelch early.

My theory on why covering the flash sensor even in TTL mode
(make sure you've really put the flash in TTL mode and not Auto)
is that when you put a finger over the sensor you may
also be shading the camera's TTL sensor below the flash
with your hand, so it doesn't get flash light bounced directly
into it any more.

BTW, you can fix your flash's own sensor by extending it
with a small plastic tube (pen body cut up) or even a
small piece of cardboard stuck on. If you were using the
pen body you'd simply cut off about 3/8 of an inch, but
make the cut diagonally and put the longest side on top
so that it shades the sensor from above, but doesn't have anything
sticking out on the bottom to catch light and bounce it down
the short tube. With the cardboard you could just make a little
flap that sticks straight out from the body of the flash above
the sensor to shade it from the diffuser.

ian

 

[Pat Glenn]

Reno:

I couldn't replicate the problem with my setup, but that doesn't mean you're not right. There might just be enough difference in our setups to keep it from happening for me. What are you using for a flash bracket? And where is your flash in relation to the camera sensor?

Pat

Pat

This happens rarely but when it has I have been in M-mode with the
internal flash off and the flash in TTL mode and the room has been
pretty dark. Reno

 

[ian]

Someone just wrote in another thread that the reflection from the
edge of his hand was causing the internal flash to underexpose. I
guess it was time for this problem to be solved.

That is a very common problem, and if someone had said
they were having that problem they'd get 20 people
telling them what was wrong right away.

It's that noone ever mentioned that they had some big
monster contraption hanging off the front of the flash
or it would have been sorted out long ago.

ian

 

[Pat Glenn]

I hardly think the Sto-Fen Omni Bounce qualifies as a "big monster contraption". It fits snugly over the flash head, and extends a little less than 3/4 inch to the front. http://www.stofen.com

As was discussed earlier, the clue was in the Sto-Fen instructions, I just didn't think it applied to my situation.

By the bye, in all the threads I've read here about underexposed flash pics, I am pretty sure that's the first time "reflection from the users hand" has been mentioned. Finger over the sensor, sure, and several other things, but this was a new one. (At least for me).

Someone just wrote in another thread that the reflection from the
edge of his hand was causing the internal flash to underexpose. I
guess it was time for this problem to be solved.

That is a very common problem, and if someone had said
they were having that problem they'd get 20 people
telling them what was wrong right away.

It's that noone ever mentioned that they had some big
monster contraption hanging off the front of the flash
or it would have been sorted out long ago.

ian

 

[Andy M]

I am the guy Pat was referring to regarding underexposure via the palm of the hand.

I did undertake a quick search of the archives to make sure I wasn't wasting anyone's time before posting my observations. I agree with Pat in that I did find threads covering finger over the sensor etc., but nothing on this. Though you may prove me wrong with a detailed search.

I have recently purchased a second-hand SB22 and I am thinking of getting a diffuser. I will certainly bear the findings of this thread in mind. Looking at the 990 the flash sensor appears to be recessed a reasonable way into the body, yet it still seems to be capable of sensing light over a wide angle.

Andy

Someone just wrote in another thread that the reflection from the
edge of his hand was causing the internal flash to underexpose. I
guess it was time for this problem to be solved.

That is a very common problem, and if someone had said
they were having that problem they'd get 20 people
telling them what was wrong right away.

It's that noone ever mentioned that they had some big
monster contraption hanging off the front of the flash
or it would have been sorted out long ago.

ian

 

[Reno29810]

This is a long and boring topic, unless you've had the problem.

I have discovered one reason for the intermittent no-flash or
low-flash problems I have had. In my case, the problem is fairly
simple. I'm using a Sto-Fen diffuser and a Metz flash.

The reason the Metz is a problem is that both the Auto and TTL
flash programs use information from the flash sensor as well as the
camera sensor to determine when to squelch. This would be O.K.,
but...I'm using a Sto-Fen flash diffuser. I was certain the problem
wasn't random, although it seemed to be. What is happening is that
the Sto-Fen, when the flash is in direct flash mode (facing
forward), spreads the light in such a broad pattern that it reaches
the sensor on the flash before it reaches the subject. This causes
the flash to either squelch early or lessen the flash power, I'm
not sure which. My best guess is that it squelches early.

If the flash is in bounce position or rotated horizontally, flash
is normal and exposures are as expected. If the flash is in manual
mode, naturally it flashes regardless of position, because the
sensor is taken out of play.

I am of the opinion that Metz is aware of the problem because they
recessed the sensor, but apparently not enough. I also noticed
that they have stopped selling the Sto-Fen as an accessory.

I was able to verify my suspicions by simply blocking the light
coming down from the flash by holding a piece of cardboard under
the head or removing the Sto-Fen. With the cardboard in place, and
the Sto-Fen attached, the flash fired every time. Remove the
cardboard and the problem returned. Remove the Sto-Fen and the
problem disappeared, replace it and it returned.

Block the sensor with my finger, the problem disappeared, remove my
finger and it returned.

I suspect that this is the reason some of us get intermittent flash
on occasion, usually in less than optimum light conditions. If the
ambient light is bright enough, the extra light from the flash
doesn't have as much of an effect. In lower light conditions,
usually normal room light, the flash sensor sometimes reads the
light from the flash before it reads the light returning from the
subject and shuts down too soon. This can happen even without a
diffuser in place, on occasion, and depends on the flash design. I
don't think the problem is unique to the Metz 40MZ 3i, but since
those of us who have complained about it haven't said what flash
we're using, I don't know what other flashes may have the problem.

I don't know how to tell you to test your flash. I just had an "ah
ha" experience when my flash didn't fire properly. It was flashing,
but just a "small" flash, and something "clicked" for me.

If you're having an intermittent flash problem, drop a line to say
what flash you're using. There may be a commonality that we've
missed.

Pat Glenn

Spent the day using my SB-22s and Lumiquest Ultrasoft shooting portraits inside and could not replicate the problem (go fiqure) I have noticed that the Lumiquest setup on my camera and bracket over hang the front of the lens and sensor. I'm using a modified "L" bracket "bent" which puts the flash above and a little to the left of the lens.

After about 40 shots with no problem I'm confused. I can see how some of the diffused light could trigger the sensor but don't understand why it's so infrequent( I'm glad it is) Reno

 

[Pat Glenn]

As near as I can tell, the amount of ambient light is one of the variables. The less there is, the more likely you are to have the problem. It's still somewhat wierd, but I think we're closer to a solution than we've ever been.

Incidentally, I confirmed the "edge of the hand" problem with the internal flash. It's almost like doing a magic trick. http://www.dpreview.com/forums/read.asp?forum=1007&message=747871 (Evil magic, indeed).

Pat

Spent the day using my SB-22s and Lumiquest Ultrasoft shooting
portraits inside and could not replicate the problem (go fiqure) I
have noticed that the Lumiquest setup on my camera and bracket over
hang the front of the lens and sensor. I'm using a modified "L"
bracket "bent" which puts the flash above and a little to the left
of the lens.
After about 40 shots with no problem I'm confused. I can see how
some of the diffused light could trigger the sensor but don't
understand why it's so infrequent( I'm glad it is) Reno

 

[ian]

Oh well. You're right. The problem used to turn up on the forum
every month or so when the cp950 was new, and less so
with the cp990. I did a search now and because of the 50
results limit (didn't used to do that) the older posts are not visible
in the search results using searches like "flash too dark".
That or the search criteria have to be so specific you'd have to know
the answer to the question before searching for it.

ian

I have recently purchased a second-hand SB22 and I am thinking of
getting a diffuser. I will certainly bear the findings of this
thread in mind. Looking at the 990 the flash sensor appears to be
recessed a reasonable way into the body, yet it still seems to be
capable of sensing light over a wide angle.

Andy

Someone just wrote in another thread that the reflection from the
edge of his hand was causing the internal flash to underexpose. I
guess it was time for this problem to be solved.

That is a very common problem, and if someone had said
they were having that problem they'd get 20 people
telling them what was wrong right away.

It's that noone ever mentioned that they had some big
monster contraption hanging off the front of the flash
or it would have been sorted out long ago.

ian