Flash Sync Question

I thought I understood how flashes and how sync worked, but this problem got me. My goal is to photograph another flash (B) firing. B has a built-in slave. A is my built-in pop-up flash in the camera,which is set to1st-curtain sync. I can see with my eyes that A and B are firing, but the picture, regardless of being shot at 1/60s or 1/4s, shows only evidence of A having fired. I seem to be unable to catch B firing. Any ideas?

The B flash duration is too short?

RalphLambrecht said:

A is my built-in pop-up flash in the camera

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Can you confirm that A does NOT emit a pre-flash intended for red-eye reduction or metering purposes? It's possible that a pre-flash would trigger slave B before the actual exposure in A occurs.
What kind of camera is A?

koraks said:

Can you confirm that A does NOT emit a pre-flash intended for red-eye reduction or metering purposes? It's possible that a pre-flash would trigger slave B before the actual exposure in A occurs.
What kind of camera is A?

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I cannot confirm or deny but that isquite possible;I need to check the handbook of the Nikon D800 to verify.

OK, I suspect this is indeed the problem. Be sure to disable red eye reduction. Then take a measurement manually using the FV Lock button; I expect this will emit a measurement preflash and trigger your slave flash. Just wait for the slave to recharge, then fire off the main exposure.

It may also be possible to configure the D800's flash in manual mode so it doesn't try to do TTL in the first place. Refer to the manual for information on this; I'm not sure if the camera offers this feature.

None of my Nikon DSLR's has built in flash but my Coolpix always emit preflash with its built in flash even when I turn it off. I agree with Koraks that the problem is with preflash. You have to set the flash mode to Manual. The camera defaults to one of 2 i-TTL modes which emit preflash.

Chan Tran said:

None of my Nikon DSLR's has built in flash but my Coolpix always emit preflash with its built in flash even when I turn it off. I agree with Koraks that the problem is with preflash.

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I believe so too. I will redo the test if I can figure out how to turn the pre-flash off. I, however, need to take this picture for a club assignment, and I like the challenge.

RalphLambrecht said:

I believe so too. I will redo the test if I can figure out how to turn the pre-flash off. I, however, need to take this picture for a club assignment, and I like the challenge.

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I read the manual you have to have the flash in manual mode not iTTL.

Does the club assignment require that you use the built in flash? If not it's simple to use a flash that is not TTL compatible on the hot shoe as flash A and thus you don't have preflash.

Set the camera to bulb and hold another flash (or another camera with built-in flash) above your camera. Open the shutter, fire that flash, which will trigger the other flash, then close the shutter.

Chan Tran said:

Does the club assignment require that you use the built in flash? If not it's simple to use a flash that is not TTL compatible on the hot shoe as flash A and thus you don't have preflash.

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Your proposal is intriguing. No, the club assignment simply states to photograph a firing flash. Anyway, I didn't find a way to turn a red-eye(pre-flash) on or off, but I found a setting to switch from TTL (which it was set to) to M for manual.Tat,seems to me, is equal to your proposal I will try that next.

RalphLambrecht said:

Your proposal is intriguing. No, the club assignment simply states to photograph a firing flash. Anyway, I didn't find a way to turn a red-eye(pre-flash) on or off, but I found a setting to switch from TTL (which it was set to) to M for manual.Tat,seems to me, is equal to your proposal I will try that next.

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Now, I found how to turn the preflash off. But Itried the pop-up flash in manual mode, and that worked just fine. I got the image I needed. Thank you all for helping me and spending your time on this. I like this camera a lot but it is too complex to remember all the options.

RalphLambrecht said:

No, the club assignment simply states to photograph a firing flash.

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Use a mirror and just the D800. Done.

koraks said:

Use a mirror and just the D800. Done.

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of course.Why didn't I think of that?

Yes I did this with the mirror

that's exactly the picture I should have taken! Bravo

koraks said:

Use a mirror and just the D800. Done.

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For people who like to play around and experiment...

If you try to photograph yourself in mirror, using the camera flash for illumination, the reflected flash will glare brightly. But if you wanna bring it under control you can use a pair of polarizing filters.

One polarizing filter goes on the lens. The other covers the flash (you can get a large flexible sheet of polarizing material; use a scissors to cut out a small piece to cover the flash... just tape it on).

Now... in order to squelch the reflected flash the two polarizers must have the "planes of polarization" properly aligned - that is, rotate one of the filters to block polarized light from the other. The way you can do this, with an SLR type camera, is to look through the eyepiece to see yourself in the mirror. Since the polarizing filter taped to the flash is fixed you have to make adjustments the camera lens filter. So, rotate that filter until the reflected image of the flash head goes dark. (If you can't see this happening you need a little more ambient light.) Once the polarizers are aligned use a small piece of tape to prevent further (accidental) rotation. At this point you can photograph yourself in the mirror, with on-camera flash, and the glare of the reflected flash is greatly diminished. Even though the reflected flash is bright enough to illuminate your own self.

A possibile use of this setup is when photographing some sort of indoor event. If there are large windows in the background, perhaps glass-framed artwork on the walls, etc., (AND you are using on-camera flash) you would normally try to avoid direct reflections of your camera flash. But using the pair of polarizing filters as described it's not a significant problem. As a note, if you have other photographer friends trying to photograph the same event they will most likely be astounded that you are not having the reflected glare problems that they get; they'll have no idea how you are getting away with it.

RalphLambrecht said:

I like this camera a lot but it is too complex to remember all the options.

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I know this is not what you asked, but... I used to occasionally deal with this sort of thing at the outfit where I worked. Couple thousand full-time portrait studios with many relatively "untrained" photographers. ("Camera operators" is probably a better way to put it.) They were mostly good at working with their subjects, and not so much with the technical details of the camera equipment.

There was a large staff of in-house tech support people to assist the studio people. When studio has a problem they call in; tech support ideally solves camera problems in one to two minutes. But... tech support also has a number of relatively untrained staff. So... how to deal with this?

I was, at that time, one of the main people doing preliminary evaluations for cameras to potentially be used in the studio chain. So, tech support has to be able to support anything we want to trial in any studios. So the problem is, how can we make this work? (Fwiw we generally used mid-grade pro type cameras of the day).

A method I came up with was this: these cameras generally had, on the display screen, one information menu that displayed icons for nearly all of the major settings. Perhaps 15 or so icons. So I made a one or two page document for these. First I photographed this info screen in the preferred configuration. This is the first item in my document. I numbered every item, in sequence (each number has arrow pointing to the icon). Next, the document lists every item, what it is, with a short description of how to set it. I included snapshots of the camera menu where these get set, etc., so tech support can confirm that the studio is doing it correctly.

This pretty much solved our tech support problems for the camera in question. Studio calls in, tech support answers. If tech support thinks a likely camera problem they pull up the document for the specific camera in question. They guide the studio to the info menu and have the studio describe each icon, one by one. Since tech support is looking at an image of said info screen, they can easily recognize if the studio is describing the correct icon. If something is wrong, say icon #12, for example, they go down their document to #12, which will describe a menu sequence to fix the setting. Note that there are typically several ways to change some given setting; the document would typically give a straightforward menu-based method of getting there.

This sort of document is something I would recommend to anyone doing professional work with any relatively new (to them) digital camera. It used to take me, as I recall, about a day or two to make one of these docs. But this includes making it "readable" with correct grammar, etc. For hobbyists, mainly playing around, it's not usually a big deal to take the time to wade through the camera manual. But imagine shooting a wedding, or whatever, and one of your big thumbs accidentally rolls a control dial, etc., without your noticing it.

Sorry to answer the wrong question, but I think this is something a lot of people could benefit from.

FWIW I'm not familiar with pro grade cameras of the last 10 years or so. So I'm presuming that they still have similar info menus. But perhaps not? I dunno.

Nikon iTTL system (which DOES emit preflash) uses radio signal to synchronize the slave flashes. Are you using Nikon iTTL flash?

ic-racer said:

Nikon iTTL system (which DOES emit preflash) uses radio signal to synchronize the slave flashes. Are you using Nikon iTTL flash?

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I think only the SB-5000 is capable of radio. Others like SB-800, 900, 910 are optical.

Chan Tran said:

I think only the SB-5000 is capable of radio. Others like SB-800, 900, 910 are optical.

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Ok, I see, coded bursts of flashes.

Mr Bill said:

For people who like to play around and experiment...

If you try to photograph yourself in mirror, using the camera flash for illumination, the reflected flash will glare brightly. But if you wanna bring it under control you can use a pair of polarizing filters.

One polarizing filter goes on the lens. The other covers the flash (you can get a large flexible sheet of polarizing material; use a scissors to cut out a small piece to cover the flash... just tape it on).

Now... in order to squelch the reflected flash the two polarizers must have the "planes of polarization" properly aligned - that is, rotate one of the filters to block polarized light from the other. The way you can do this, with an SLR type camera, is to look through the eyepiece to see yourself in the mirror. Since the polarizing filter taped to the flash is fixed you have to make adjustments the camera lens filter. So, rotate that filter until the reflected image of the flash head goes dark. (If you can't see this happening you need a little more ambient light.) Once the polarizers are aligned use a small piece of tape to prevent further (accidental) rotation. At this point you can photograph yourself in the mirror, with on-camera flash, and the glare of the reflected flash is greatly diminished. Even though the reflected flash is bright enough to illuminate your own self.

A possibile use of this setup is when photographing some sort of indoor event. If there are large windows in the background, perhaps glass-framed artwork on the walls, etc., (AND you are using on-camera flash) you would normally try to avoid direct reflections of your camera flash. But using the pair of polarizing filters as described it's not a significant problem. As a note, if you have other photographer friends trying to photograph the same event they will most likely be astounded that you are not having the reflected glare problems that they get; they'll have no idea how you are getting away with it.

Click to expand...

Sounds like a fun exercise, I'll have to try it!

I've found polarised lighting useful on other occasions but have just used an LCD screen for those

Mr Bill said:

For people who like to play around and experiment...

If you try to photograph yourself in mirror, using the camera flash for illumination, the reflected flash will glare brightly. But if you wanna bring it under control you can use a pair of polarizing filters.

One polarizing filter goes on the lens. The other covers the flash (you can get a large flexible sheet of polarizing material; use a scissors to cut out a small piece to cover the flash... just tape it on).

Now... in order to squelch the reflected flash the two polarizers must have the "planes of polarization" properly aligned - that is, rotate one of the filters to block polarized light from the other. The way you can do this, with an SLR type camera, is to look through the eyepiece to see yourself in the mirror. Since the polarizing filter taped to the flash is fixed you have to make adjustments the camera lens filter. So, rotate that filter until the reflected image of the flash head goes dark. (If you can't see this happening you need a little more ambient light.) Once the polarizers are aligned use a small piece of tape to prevent further (accidental) rotation. At this point you can photograph yourself in the mirror, with on-camera flash, and the glare of the reflected flash is greatly diminished. Even though the reflected flash is bright enough to illuminate your own self.

A possibile use of this setup is when photographing some sort of indoor event. If there are large windows in the background, perhaps glass-framed artwork on the walls, etc., (AND you are using on-camera flash) you would normally try to avoid direct reflections of your camera flash. But using the pair of polarizing filters as described it's not a significant problem. As a note, if you have other photographer friends trying to photograph the same event they will most likely be astounded that you are not having the reflected glare problems that they get; they'll have no idea how you are getting away with it.

Click to expand...

I don't think I need any polarizer using the mirror. There is no different with shooting directly.

Chan Tran said:

I don't think I need any polarizer using the mirror. There is no different with shooting directly.

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No difference? Are you sure? Are you trying to say that two (linear) polarizers cannot be rotated in such a manner as to block the light?

What I'm describing is a similar scenario, except that a mirror is placed between the two polarizers. The mirror will preserve the polarization characteristics of the light, allowing the camera lens polarizer to block such light. However, polarized light that does NOT pass through the camera lens filter is NOT blocked, and thus able to illuminate the self-portrait subject. Now, said subject most likely does not preserve the polarization of the light (unless the subject is a specular reflector) and thus is seen by the camera as a normal subject.

The end result is a seemingly mostly normal self-portrait in a mirror, but with the mirror view of the flash unit nearly extinguished (within the limits of the actual polarizing filters used). Except that the flash illumination is reduced by more than a couple of f-stops (once by the polarization of light from the flash, once by the camera lens polarizer, and further reduced by the increase in distance due to the mirror).

Mr Bill said:

No difference? Are you sure? Are you trying to say that two (linear) polarizers cannot be rotated in such a manner as to block the light?

What I'm describing is a similar scenario, except that a mirror is placed between the two polarizers. The mirror will preserve the polarization characteristics of the light, allowing the camera lens polarizer to block such light. However, polarized light that does NOT pass through the camera lens filter is NOT blocked, and thus able to illuminate the self-portrait subject. Now, said subject most likely does not preserve the polarization of the light (unless the subject is a specular reflector) and thus is seen by the camera as a normal subject.

The end result is a seemingly mostly normal self-portrait in a mirror, but with the mirror view of the flash unit nearly extinguished (within the limits of the actual polarizing filters used). Except that the flash illumination is reduced by more than a couple of f-stops (once by the polarization of light from the flash, once by the camera lens polarizer, and further reduced by the increase in distance due to the mirror).

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I don't need any polarizer. I have a normal portrait using the mirror without using polarizer.