Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flash)

Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flash)

Hi

I have a Nikon D3100. I am going to use an external flash (Yongnuo YN468-ii). I have also bought a Yongnuo wireless i-ttl flash trigger transceiver (YN-622N). I have yet to unbox the wireless transceiver or external flash.

My plan is to use the external flash wirelessly (any advice on which camera and flash settings to use would be great too).

My question is this: The D3100 has a built in AF assist lamp (white light I think). I assume the external flash has an AF assist lamp too (& I assume it must be infrared). Can the 2 AF assist lamps be used together at the same time? Do they simply increase illumination to help the auto focus system or is there some kind of critical distance being measured by the beams themselves and thus they will interfere with each others measurement (ie do the beams measure distance by calculating how long it takes the beam to reflect back off the subject back to the source)?

Any advice on the subject would be great as it something I know nothing about. Thanks

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

paul_b said:

My question is this: The D3100 has a built in AF assist lamp (white light I think). I assume the external flash has an AF assist lamp too (& I assume it must be infrared). Can the 2 AF assist lamps be used together at the same time?

Click to expand...

The AF assist lights do not measure distance. They are just a light to illuminate what the camera focus sensor is trying to see. It cannot otherwise focus in the dark.

Just saying, off camera lights in the house are probably in a halfway reasonably lighted room, and no focus assist is normally needed at all.
Only needed if in a rather dark place. Only needed if the camera is not able to focus. That seems fairly rare, at least if at home. The assist might be needed in a dark club or outside at night, etc.


Off-camera use still requires the speedlight AF assist light to really aim at the exact point where focus actually is. It is useless if it does not aim at the focus point for the camera to see. This aim is not normally the case for off camera lights. AF Assist is triggered only if in AF-S mode, and if with only one single focus point selected. That one focus point has to see it.

The Nikon SC-29 hot shoe extension cable provides yet another AF assist light at the camera hot shoe socket, which will aim at the central focus point.

Speaking of Nikon flash units: Speedlight AF light requires CLS communication (to know about shutter half press), so AF assist does not work if not attached to camera shoe (it would work in a hot shoe extension cord, but needs to be attached, and aimed at focus point).

If the speedlight is attached to camera, its AF assist is used, and the camera white AF assist is not used (remains dark, even if on in the menu).

The Nikon flash red AF assist light looks dim, but it is primarily infrared (nearly invisible to humans), and Nikon specs its range at 33 feet (vs 9 feet for white camera light). I was playing last night, and mine worked and focused fine at 40 feet in a pitch black room. Would not focus there with the camera white light, although it was much more visible to my eyes.

Yongnuo: Less sure? I have a YN565EX and its AF assist blinks incessantly every second in any off camera slave mode. Not a plus, I cover it with a piece of tape.

It would be in Manual flash mode for a radio trigger, and it would never blink then (no CLS communication), but it would work if instead on a hot shoe extension cable (but which must still be aimed at the focus point). However, my Yongnuo Assist beam pattern is very wide, where the Nikon beam is very narrow, just where it needs to be.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Thanks for the reply Wayne. I'm going to re-read it a few times to learn it.

The reason I bought a wireless TTL transceiver was to attempt to try and eliminate the issue of the speed light acting just like a manual flash when off camera. Would you recommend keeping both AF assist lamps on together then?

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

paul_b said:

Thanks for the reply Wayne. I'm going to re-read it a few times to learn it.

The reason I bought a wireless TTL transceiver was to attempt to try and eliminate the issue of the speed light acting just like a manual flash when off camera. Would you recommend keeping both AF assist lamps on together then?

Click to expand...

Sorry, I realize now that I missed a point. You said TTL transceiver, 622. I am not familiar with it, but if it does TTL, then it sees CLS communication, and the remote AF assist should work normally, same as on a hot shoe extension cable (it has to be aimed right to help though).

My GUESS is that the system has to treat the radio TTL flash system as a hot shoe flash, and that the camera white light will stay dark if it senses a hot shoe flash. Just try it to see, I guess.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Wayne.

Apologies for asking my query on this forum before using my equipment for the first time. I got ahead of myself. I've just been having a play about with them, and you are right. The camera's on board built in AF lamp becomes disabled as soon as i use the external speed light (either on top of the camera, or off camera wirelessly). The speed light's or wireless transceiver's Af lamp takes over instead (depending on which i use).

One thing i don't quite understand though, is that if i put my speed light on top of my camera (speed light in TTL mode) & leave it's power setting on default, my images are well overexposed (even at iso 100). I have to reduce the flash power on the flash all the way down to -3 before the images look ok. I thought TTL's job was to do that automatically. P.s I've tried it with the camera on automatic shooting mode too to make sure it wasn't my settings that were at fault.

In the camera's settings, I've tried looking for any settings i can change for the external flash, but all it has is a setting for 'built in flash' (but is greyed out). I've also got a Nikon SB-400, and when that's attached you can change it's settings in the camera between 'manual' and 'ttl'.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

This is because the 468II is not a TTL flash. It will only work in manual mode and will need manual adjustments. For your wireless receivers to work properly, you will need a TTL compatible flash.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

(Will do with the profile).

Wayne, on my YN468-II box it says TTL. I can also change it between manual and TTL on the flash itself too.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

paul_b said:

One thing i don't quite understand though, is that if i put my speed light on top of my camera (speed light in TTL mode) & leave it's power setting on default, my images are well overexposed (even at iso 100). I have to reduce the flash power on the flash all the way down to -3 before the images look ok. I thought TTL's job was to do that automatically. P.s I've tried it with the camera on automatic shooting mode too to make sure it wasn't my settings that were at fault.

In the camera's settings, I've tried looking for any settings i can change for the external flash, but all it has is a setting for 'built in flash' (but is greyed out). I've also got a Nikon SB-400, and when that's attached you can change it's settings in the camera between 'manual' and 'ttl'.

Click to expand...

I can believe the YN468 II does TTL. Its manual and specs say it does. Some of the Yongnuo 4xx models did not.

The camera menu for flash (that selects Manual or TTL flash mode) is for the cameras built-in flash. This menu is also used for the SB-400 (and 300 and 500) that have no menu themselves, so the camera sees it and this menu then applies to it. But just those. Other flashes have their own menus.
So for other flashes, this camera menu has no meaning or effect. If the internal flash door is shut, and the SB-400 is not attached, this camera menu simply does nothing, it is ignored.

The camera does meter the exposure for the hot shoe TTL flash. The +/- buttons on the flash are flash compensation buttons. They cause the regular TTL flash power level to be adjusted that way. The camera also has both Flash Compensation and Exposure Compensation (this last one affects both ambient exposure and flash exposure, the first one only affects flash exposure). All of these three add to a final flash compensation (the flash, and FC and EC, they all add).

If you have to add -3 EV more, the first thing to do is to make sure what the other two say now. Possibly one of them is not at zero?

The way my Nikons work, if any of the three of are not zero, then the top LCD (by shutter button) will show a +/- icon symbol. If that symbol does not show, then all sources of compensation are zero. You can of course also check them individually.

Check those first, and then if still an issue, let's dig deeper.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Sorry.
Have you looked into your flash compensation?

Also take a look at this thread maybe it may help you with your issue.
http://nikonites.com/flashes/15247-yn-468-ii-overexposes-when-using-ittl.html#axzz3IWGdov00

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Both flash and exposure compensation are at zero

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

OK, then what type of picture is it? Indoors I assume, not in exceptionally bright light. Just a regular picture of something in room? No special case, like an open dark background, or of anything especially dark? (meaning a dark color, like black).

What is your camera metering mode? Matrix, Center, Spot?

What is your camera mode? A, S, P, M, Auto?

Tell us more about what you're doing?


The camera meters the flashes preflash, and controls the show. It just programs the TTL flash power level to do its bidding. The flash just flashes, so to speak.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

skene said:

Sorry.
Have you looked into your flash compensation?

Also take a look at this thread maybe it may help you with your issue.
http://nikonites.com/flashes/15247-yn-468-ii-overexposes-when-using-ittl.html#axzz3IWGdov00

Click to expand...

Interesting read. Will try some of the suggestions once my camera has charged. Beginning to wish I had bought a Nikon flash now, they're just so blinking expensive though.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Will report back once camera charged.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

OK as suggested by the topic shared by skene, I tried the flash with and without the wireless transceiver between it and the cameras hotshoe. Without the transceiver the pictures are badly overexposed, and surprise surprise with the transceiver between them the images are perfect. Sounds like a faulty flash or its connectors. Its only taken a month to get here from China! Not sure how to send it back. It was bought through amazon.

Ps Wayne. Yes pictures indoors, direct flash test (not bounced). Moderate light in a small room (40w bulb). Camera focused on a face. Matrix metering. Aperture mode (but same happens in P mode too). Iso 100

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

That is a puzzler. Something new to me, don't think it is supposed to work that way.

It seems to be rare issue, in that there is very little mention of it on the many 468 Amazon customer reports.
One of them did mention it, and said theirs works OK at distances under ten feet, but overexposes if farther. That's hard to understand how.
You say it works OK if on the transceiver. I suppose that could be some sort of flash foot pin alignment? Make sure it is fully seated deeply in the shoe.
The other thread says OK if Center Metering instead of Matrix. That would be a camera problem instead, which makes no sense to me.
I'm guessing the right description is more random and variable...

The normal TTL complaint (any brand/model) is a little bit of underexposure. TTL BL does promote that, and a little necessary +EV compensation is common and routine, and no big deal. But +3 overexposure? I don't know how that could happen? Making things up without any clue, but maybe a preflash problem? Maybe a preflash timing delay that makes the camera miss most of it? No idea...

I'd feel much better by exchanging it for something else. Amazon is good about returns in 30 days, and is good about forcing vendors to do right, but China probably complicates that, both delivery time and returns? I would inquire of Amazon about that. Amazon does want us happy. Exchanging it from a US vendor at Amazon should have been no problem. You might ask Yongnuo about it too, but I hear shipping costs both ways to exchange it from China is prohibitively expensive.

See if works well off camera as a slave. It might make a good second flash that way? Two remote flashes in umbrellas is a very good thing.

I get the idea that most of the 468 II work well. Most Yongnuo reports of any model are delighted. My YN565EX works very well (there is a little thing or two, but the performance is wonderful, and the price was about unbelievable).

I'm just talking when I should shut up. Sorry, I wish I could help, but I don't have a clue.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Thanks for the advice. Its appreciated.

I like the sound of 2 flashes inside umbrellas but unfortunently most of my images are of my little girl who never sits still, lol. It would be a pain to keep repositioning them all the time. I actually have 2 umbrellas with proper lamps, but as just mentioned they were impractical to use for my needs. Maybe if they made smaller more portable ones it may stand a chance of working for me. Do they make smaller more portable ones?

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Up near 30 inches seems to be the usual small umbrella size, but the stands make them be pretty much fixed. And I don't know the age, but it seems not to take but a few years for little girls to like the camera, and become cooperative. I think we need all of it, walk around bounce for much of it, and the umbrellas for a few special times when more care is taken.

Sorry I don't know what to make of your problem, but hope you get a solution working soon.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Thanks Wayne for all the advice.

I'm now toying with the idea of using a dome diffuser on top of a wireless 'off camera' speedlight. Something like this one: Fotodiox Flash Diffuser Dome - Large On Camera Flash: Amazon.co.uk: Camera & Photo

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

I know that dome is not expensive, so it won't cause missed meals. And any experience we get is a good thing. And I ought to know to keep my mouth shut, no one asked. And this not addressed specifically to you Paul, but written in general on the forum for anyone interested.

But I'm not a fan of such diffusers. I'd suggest regular bounce would be better lighting.

Because, these little domes are still tiny, and they cannot increase the size of the light. All diffusion can do is to only simply scatter the light, output at all different angles. But from a tiny source, all it can do is scatter it outward, away from the subject, to entirely miss the subject. That seems wrong. We like to pretend it bounces off all the room walls and comes back to the subject, and maybe somewhat does if in a small room, but otherwise, giving thought to the inverse square law (reflections compared to the direct path) mostly makes it be wishful thinking.

In contrast, a large light (an umbrella, or a softbox... anything like 3 or 4 foot size, assuming appropriately close to subject) is large enough to scatter it inward, toward the subject from its wider edges. For example, from a 36 inch light (umbrella), there is some light from 18 inches to the subjects left, and some from 18 inches to their right, and top and bottom, and all paths in between - light from all angles - to the subject. If close (3 or 4 feet), the subject sees light from a wide source. All these different light paths and angles fill the shadows from all the other light paths, making very soft light. This does assume a light distance comparable to the size of the light, a 3 foot light can't do this if at 12 feet. But by the same argument, the little two inch flash head can do as much if at a distance of only 2 inches. And a little light maybe only one foot size can be tremendous for macro work at six inches.

So diffusion is good, but it needs to be from a large source. Light quality is primarily about light size, and the little domes don't have any size.

Beginners may not have learned to actually look at their pictures yet to evaluate the light, to see if the light is actually doing what they imagined it should do. We should be able to see whatever we think we are doing, but we first have to learn to look, and see. It is a classic situation, this is never the first thing beginners pick up. They are not yet aware what they are looking at. The domes can have one effect though, of causing the flash to have to use a higher power level to compensate. This power can give the speedlight flash a slightly warmer red cast, which sometimes we in fact tend to like. Which sometimes we confuse with better lighting. We need to learn to see the color, and the light, its shadows, etc. It's not hard, we just have to realize what we are looking for.

Bounce is quite good because it is LARGE bright spot on the white ceiling above, which is very much like a very large umbrella up there. Very soft light. The downside is that light from above is not really the best choice, so we do want it in front of the subject too (flash aimed straight up on camera does that). It is more power used that way too. But is natural light from up there, and clearly much better than other hot shoe choices. We can add a SMALL bounce card on the hot shoe flash, maybe 1.5x1 inches, to direct a little direct forward spill for fill. This can cause highlights in the eyes (desirable, looks "alive" in there), and slightly fill some of the shadows, eye sockets for example. But just a small bounce card, because such a bounce card that is too large just becomes direct forward flash again. Easy to overdo. We can see this if we think to look.

Umbrellas are good because we can aim them, and set them close to subject. They are fixed, but close makes them appear even larger, wider angles, as seen by the subject... which is softer. At least bounce is walk around, not fixed.

If interested, there are a couple of pages at Four Flash Photography Basics we must know - Soft Light intended to show this point.

Re: Can 2 AF assist lamps be used at the same time? (on camera & off camera ext' flas

Fantastic advice. Thanks for taking the time to share it.

I have tried bounce flash with my Nikon SB-400, but didn't like the uneven fall of light lighting up the top of the subject or protrusions, and then those pesky shadows underneath. For me it didn't look natural. The SB-400 doesn't have a white card (one of the benefits of buying a new speed light (once I get a refund from Amazon via China, lol)).