Beginner Trouble with fill flash

[PeetyPeet]

Hi guys.

Recently got myself a Speedlight SB-700 and trying to teach myself some fill flash. Sometimes the EV value on the flash will automatically reduce itself to -3.0, regardless of my manual settings, under exposing the subject. The few times it's happened is when we're outside and the subject is in the shade with an overcast, but nonetheless, quite bright background. I've tried to recreate this at home by placing an object in front of a very bright light, however the flash fires at my chosen EV settings, lighting the object and over exposing the background if necessary.

Settings on flash are TTL-BL, auto-iso. Camera is Nikon D610, shooting in Aperture Priority.

Sorry for noob question, thanks for your help.

Peety

 

[Kodiak Qc]

•
I think your problem may come from the Auto ISO!
Since Auto ISO is applied to the scene readout of the meter without
considering the flash, every scene will have a different ISO making
the flash behaviour quite unpredictable for you.

Try this test:
— to save you flash power, set the ISO to 800 manual.
— Auto WB
— a mid tone subject occupying most of the centre screen once on
dark and then on light BG.
— on TTL, ƒ8, same crop for both.

Shoot RAW, do not process, publish as jpg and please post here.

 

[sk66]

There is no auto ISO setting for the flash that I am aware of. And the EV setting isn't "auto" either. However, on Nikon's a +/- EC setting is transmitted to the flash, unless the camera has the option to set camera EC to BG only (the D610 does).

Offhand I can't think of a plausible cause other than a loose/intermittent connection causing glitchy behavior.

 

[PeetyPeet]

Thanks guys. I think Kodiak QC was correct with the auto-iso. Perhaps I should change metering mode in certain situations, Unfortunately I haven't had time to try the test yet but I'm hoping yo get round to it soon.

 

[Phil V]

What Steven said, I can understand the flash under exposing because it doesn't have the power, or overexposing because of the camera metering in certain situations. But I'm fairly sure the flash settings shouldn't change like that, I don't shoot Nikon, but I can't think of any situation my Canon flash would dial in its own ec.

 

[russellsnr]

Hi, Are you useing the flash on or off camera? Like Phil above I have Canon so the workings of Nikon camera/flash I no nothing about but if you are useing on camera are you sure that it is the flash and not the camera that causing the problem as you can dial in flash comp via the camera, have you tried resetting any custom functions to zero on the flash and camera?
Russ

 

[snerkler]

I'm a bit confused by this tbh as I can't recall my SB700 reducing EV by itself regardless of shooting settings and ISO settings. Can you confirm what metering mode you were using and what scene you were shooting, whether the flash was on/off camera and whether you had any exp comp, or flash exp comp, either set on camera or the flash and I'll see if I can reproduce it. If you have flash exp comp set on camera is it set for flash only or the whole scene?

 

[realspeed]

you mention the subject being in the shade. I hope you lock off your camera exposure where the subject is and not from where the shot is taken to start with?. that may well make a difference before thinking about using a speedlight

 

[snerkler]

you mention the subject being in the shade. I hope you lock off your camera exposure where the subject is and not from where the shot is taken to start with?. that may well make a difference before thinking about using a speedlight

I don't understand this, why are they taking the shot elsewhere? But even if the flash TTL is exposing for the background it wouldn't change the exp comp, TTL just changes the flash output AFAIK.

 

[realspeed]

I don't understand this, why are they taking the shot elsewhere? But even if the flash TTL is exposing for the background it wouldn't change the exp comp, TTL just changes the flash output AFAIK.

Example subject under a shady tree and photographer in bright light some distance away is the answer. No good taking a picture like that, the camera exposure needs to be the same as where the subject ,ie person, is. Or alternatively use a light meter the same way.
Try it for yourself and see the result difference against just taking a photo without doing the light reading first.


Lock switch "L" on Nikon D800

 

[russellsnr]

View: https://www.youtube.com/watch?v=Y01cwu4RouI

 

[sk66]

Example subject under a shady tree and photographer in bright light some distance away is the answer. No good taking a picture like that, the camera exposure needs to be the same as where the subject ,ie person, is. Or alternatively use a light meter the same way.

Lock switch "L" on Nikon D800

The only way what you're saying makes *any* sense is if you are using a handheld incidence meter... In which case you need to have your camera in manual mode, the camera metering is irrelevant, and locking it is pointless.

BTW, the "L" doesn't lock the exposure/metering...

 

[snerkler]

Example subject under a shady tree and photographer in bright light some distance away is the answer. No good taking a picture like that, the camera exposure needs to be the same as where the subject ,ie person, is. Or alternatively use a light meter the same way.
Try it for yourself and see the result difference against just taking a photo without doing the light reading first.


Lock switch "L" on Nikon D800

Ahh, I see what you mean, I thought you meant focus decomposing from a light area to a dark area as you talk about locking exposure. But I assume you mean that you need to meter right for the subject? This is where TTL comes in though isn't it, the flash should properly expose for the subject regardless of the background?

 

[realspeed]

.

 

[realspeed]

My post was about not using flash as I said in my first post

 

[snerkler]

My poSt was about not using flash as I said in my first post

But the whole thread is about using fill flash and the OP's issue with the flash automatically reducing flash comp by 3ev???? The OP's trying to learn fill flash.

 

[Kodiak Qc]

The OP's trying to learn fill flash.

•
+1

 

[PeetyPeet]

Thanks for all your input everyone. In answer to some of the points/questions raised:

1. I don't think I have a faulty flash connection
2. Flash was attached to the camera
3. Metering mode was evaluative
4. Was I in the shade as well? Can't remember. I won't have locked my camera.
5. I'm really sorry, as a complete flash noob I have no idea whether I was using flash exp comp.
6. Scene was some friends in a shaded area on an overcast day. Behind them was a lake and overcast, but nonetheless quite bright, sky. I was stood perhaps a couple of meters back from the subjects. I will try to dig out the original photo and post in the next few days.

 

[Nawty]

Could it be that the flash is dialling down the power as the shutter speed increases beyond the normal sync speed?

 

[snerkler]

Thanks for all your input everyone. In answer to some of the points/questions raised:

1. I don't think I have a faulty flash connection
2. Flash was attached to the camera
3. Metering mode was evaluative
4. Was I in the shade as well? Can't remember. I won't have locked my camera.
5. I'm really sorry, as a complete flash noob I have no idea whether I was using flash exp comp.
6. Scene was some friends in a shaded area on an overcast day. Behind them was a lake and overcast, but nonetheless quite bright, sky. I was stood perhaps a couple of meters back from the subjects. I will try to dig out the original photo and post in the next few days.

This would be the first thing I would look at. The flash should only alter the flash power as it feels fit (such as 1/1, 1/16 etc) it shouldn't AFAIK alter the compensation (which is measured in EV). AFAIK the only time the flash will use +-EV is if the user has dialed in flash exp comp.

 

[snerkler]

Could it be that the flash is dialling down the power as the shutter speed increases beyond the normal sync speed?

If the flash dials down the power the I would have thought it would have altered the power output (such as 1/1, 1/16) and not changed the exp comp. AFAIK the only time the flash changes exp comp is if the user has dialed it in themselves, although as always I'm happy to be proven wrong. The flash has HSS though, assuming the OP has set the camera up for HSS?

OP what was the shutter speed of the shots that caused a problem? Were they over the sync speed of 1/250 (or 1/200 if you chose this)? If so have you set high speed sync (1/250 Auto SP or 1/200 auto SP in the custom setting menu (menu with pencil icon)?

 

[Phil V]

...Sometimes the EV value on the flash will automatically reduce itself to -3.0, regardless of my manual settings, under exposing the subject. ...

I (and others) assumed from the above that you knew your flash was dialled down 3 EV, which is why we suggested that if you hadn't done it, your camera / flash had adjusted itself and was therefore faulty

...
5. I'm really sorry, as a complete flash noob I have no idea whether I was using flash exp comp.
...

But now it seems you just mean that the subject is underexposed and that there was no FEC (flash exposure compensation) set.

It'd help to see the image, but my guess is that you have a scene that's quite bright overall, with your subjects in shade, and that you're trying to light the subjects to match the background. This is quite easy for fill flash as long as you're not making life too difficult for the flash. My guess is that the flash is too far away from the subjects, and that even at full power it has no way of competing with the bright sun, particularly if your shutter speed has gone above sync speed.

If this is the case, your options are:

• More flash power
• Move the flash nearer by shooting with a wider lens
• Move the flash nearer by using it off camera

 

[sk66]

I have never seen anything but a user input change the EV setting. The EV setting is only available in TTL, and in TTL the flash adjusts power output (actually, flash power is the only thing that can ever be adjusted at the flash)... The EV display is only there to remind you that you set the flash to adjust the power differently than it otherwise would.

The only other possibility besides a user adjustment/setting is a fault of some type... and the most probable/common is a weak/dirty/loose connection causing electrical glitches.

 

[sk66]

But now it seems you just mean that the subject is underexposed and that there was no FEC (flash exposure compensation) set.

I didn't get that from the reply...

But assuming she simply means the subject was underexposed then the issue was probably evaluative metering with a bright BG...

 

[Phil V]

I didn't get that from the reply...

But assuming she simply means the subject was underexposed then the issue was probably evaluative metering with a bright BG...

It took me a while to dig it out, the OP used the phrase 'the EV value on the flash will automatically reduce itself to -3.0', when from the following responses she doesn't fully understand the meaning of exp comp, I believe she meant 'The subject is underexposed by 3 EV' and even then I'm guessing it's not 3 stops, but 3 clicks on whatever processing software is being used.

As I said, we've taken a literal interpretation of the terminology, and it seems the OP was struggling to understand the situation and has used terms that make sense to them.

 

[snerkler]

I didn't get that from the reply...

But assuming she simply means the subject was underexposed then the issue was probably evaluative metering with a bright BG...

The OP stated in the first post that the flash was showing -3EV by itself, but then in post 18 says they don't know whether they've got exp comp set or not. My guess is that they've got -ve flash comp set via the camera, which is why they think that the flash is doing it by itself. Doesn't explain why it doesn't happen in other scenarios though

 

[PeetyPeet]

Oh dear, sorry everyone, I've caused some confusion due to my lack of experience using a flash and shocking grasp of terminology.

So when I've been using my flash I've always set exp comp (EV value) myself on the flash gun. I've never set it on the camera while using the flash gun. On this occasion though, regardless of what EV value I set (I tried several), the flash automatically took itself down to -3.0 when I took the shot, before returning to the value I'd set after the photo was taken.

The photo in question is below. Alas I seem to have deleted the original raw. This is a jpeg conversion. The background isn't as bright as I remember. Details from the file: f2.8, exp time: 1/2000 sec, ISO-250, exp bias - 0 step, focal length 38mm, max aperture: 3, Metering mode: pattern, flash mode; flash, compulsory, strobe return, aperture priority, auto white balance.

 

[Phil V]

I think it's down to the flash not being powerful enough. 1/2000 sec would reduce flash output by about 4 stops.

I haven't got all the data to do the maths, but that's my hunch.

 

[snerkler]

I think it's down to the flash not being powerful enough. 1/2000 sec would reduce flash output by about 4 stops.

I haven't got all the data to do the maths, but that's my hunch.

But that wouldn't explain why the exp comp changes on the flash. If it was just under powered then the image would be underexposed but it wouldn't change the exp comp to something the op hadn't set.

OP have you set your camera to high speed sync as per my post above as you would have to do this to use shutter of 1/2000 with flash. Not sure it would be this either though as I'd imagine it just wouldn't let you select the shutter speed rather than changing exp comp. Are you absolutely sure you've not accidentallychanged exp comp/flash comp in camera?

 

[snerkler]

Oh dear, sorry everyone, I've caused some confusion due to my lack of experience using a flash and shocking grasp of terminology.

So when I've been using my flash I've always set exp comp (EV value) myself on the flash gun. I've never set it on the camera while using the flash gun. On this occasion though, regardless of what EV value I set (I tried several), the flash automatically took itself down to -3.0 when I took the shot, before returning to the value I'd set after the photo was taken.

The photo in question is below. Alas I seem to have deleted the original raw. This is a jpeg conversion. The background isn't as bright as I remember. Details from the file: f2.8, exp time: 1/2000 sec, ISO-250, exp bias - 0 step, focal length 38mm, max aperture: 3, Metering mode: pattern, flash mode; flash, compulsory, strobe return, aperture priority, auto white balance.

View attachment 52773

Ok I've tried recreating this but can't do it, where are you seeing it reduce to -3ev, on the readout on the flash itself, or the light meter on the camera?

The only time I get 'similar' is if I had auto ISO set at 100 and for a scene the camera would normally meter at say 1/2000 f2.8 ISO 3200. If you turn the flash on the ISO drops to 400 which underexposes the whole scene and the light meter shows -3ev. But this is expected as the ISO has dropped 3 stops. AFAIK when using flash auto ISO will only go up 2 stops over the ISO you have set as the base.

 

[sk66]

I'm convinced it's metering related...
The camera was in matrix, and the flash uses a metering that is like smart matrix or CW... and neither is going to do well with a backlit, off-center, dark subject. So, whatever was set to auto (exposure, ISO, Flash(TTL), etc) is going to be set "wrong" unless you override it.

 

[Ulfric M Douglas]

On this occasion though, regardless of what EV value I set (I tried several), the flash automatically took itself down to -3.0 when I took the shot, before returning to the value I'd set after the photo was taken.

How do you know this? I'm not doubting you, I just can't picture where and when you see this happening if your eye is to your viewfinder during the time the flash is, as you say, setting itself -3 ev then going back to whatever you told it to be.

 

[snerkler]

I'm convinced it's metering related...
The camera was in matrix, and the flash uses a metering that is like smart matrix or CW... and neither is going to do well with a backlit, off-center, dark subject. So, whatever was set to auto (exposure, ISO, Flash(TTL), etc) is going to be set "wrong" unless you override it.

But as I've said before this would change the power and so underexpose the shot, but not reduce the EV/exp comp. Plus matrix will expose the scene, the flash should expose the subject (assuming the focus point is on them) and is 'metered' so to speak via TTL.

Happy to be corrected if I misunderstood how it works.

 

[Phil V]

But that wouldn't explain why the exp comp changes on the flash. If it was just under powered then the image would be underexposed but it wouldn't change the exp comp to something the op hadn't set.

OP have you set your camera to high speed sync as per my post above as you would have to do this to use shutter of 1/2000 with flash. Not sure it would be this either though as I'd imagine it just wouldn't let you select the shutter speed rather than changing exp comp. Are you absolutely sure you've not accidentallychanged exp comp/flash comp in camera?

My thought (and it's only a guess asi don't shoot Nikon) is that the flash is outputting full power then momentarily telling the OP that it's 3 EV underexposed.

 

[snerkler]

My thought (and it's only a guess asi don't shoot Nikon) is that the flash is outputting full power then momentarily telling the OP that it's 3 EV underexposed.

Interesting. I'll try and create a scenario where the flash doesn't have enough power and see what happens. I'd have thought at f2.8 and from that distance (assuming the image isn't cropped too much) that the flash is more than powerful enough though

 

[Phil V]

Interesting. I'll try and create a scenario where the flash doesn't have enough power and see what happens. I'd have thought at f2.8 and from that distance (assuming the image isn't cropped too much) that the flash is more than powerful enough though

You might be right, I was trying to work out how much power would be lost to HSS and the fact the zoom head would be on a wide setting which takes a flash well below its assumed power.

Edit: I've just looked, the GN at 35mm is down to 14.4m so at 2.8 and a loss of 4 stops for HSS, I calculate it at about 3 stops under. (back of fag packet figures)

The killer here was the high shutter speed, there's plenty of flash power if the OP had used ISO 100 and sync speed.

 

[snerkler]

You might be right, I was trying to work out how much power would be lost to HSS and the fact the zoom head would be on a wide setting which takes a flash well below its assumed power.

Edit: I've just looked, the GN at 35mm is down to 14.4m so at 2.8 and a loss of 4 stops for HSS, I calculate it at about 3 stops under. (back of fag packet figures)

The killer here was the high shutter speed, there's plenty of flash power if the OP had used ISO 100 and sync speed.

Possibly yeah. Unfortunately I don't have a fast short zoom to try this out, but I'll see what results I get using my 18-35mm f3.5-4.5 at 35mm at some point in the next few days. Looking at the OP's picture I would guess the couple are a lot closer than 14m though.

 

[Phil V]

Possibly yeah. Unfortunately I don't have a fast short zoom to try this out, but I'll see what results I get using my 18-35mm f3.5-4.5 at 35mm at some point in the next few days. Looking at the OP's picture I would guess the couple are a lot closer than 14m though.

I know that, the GN is 14.4m,
So that's 7m at f2
3.5 metres at f4

2.8 at about 2 metres gives us a couple of stops headroom, but then we have to deduct for the HSS.

 

[snerkler]

This is the chart from my SB700 manual. At f2.8 ISO 200 @35mm the flash distance is a max of 13m. If you reduce it 4 stops due to the HSS so look at f8 you still get a distance of 3.4m and I'd be surprised if that couple were much more than 3.4m away, not enough to account for 3 stop underexposure I wouldn't have thought...... by my calculations at least

 

[snerkler]

OK, so I've just done a test where I've deliberately taken a subject massively outside of the flash range and on the back of the flash unit itself it did flash up -3EV so it appears that @Phil V is right, so the problem that the OP had was that he was outside the flash range by at least 3 stops. I must admit, I thought they looked closer than this to me. To be 3 stops outside the flash range they'd have had to be 9.7m away.