Urgent help please

I'm due to do my first bodyscaping shoot tomorrow and I'm experiencing an odd problem. I'm a hobbyist and must confess I've not used off camera flash much before.

The issue I'm having is that I am getting alternating dark and bright shots without changing any settings. My setup as follows:

D7100 in commander mode with BIF set to -- in e3. Group A channel 1 Tried both 250th and 250th (auto) for flash synch speed.
SB-700 set to remote. Noting else adjusted.

Black backdrop
Nifty fifty
F16
ISO 200
Shutter 200th

Any help greatly appreciated. Save me from looking an ass.

Can you post examples with metadata?

Your camera communicates with the remote flash using pre-flashes from the built-in flash. If the remote flash is out of sight or just far away, it might not get enough light to transmit the signals. If it is just at the edge of its sensitivity, you will get random response: sometimes the flash fires, sometimes it does not.

The sensor that receives pre-flashes in SB-700 is on the right-hand side of the unit (when you look at the LCD screen), it is a tiny circular dark window. Make sure this sensor can see your pop-up flash directly.

Felisek said:

Your camera communicates with the remote flash using pre-flashes from the built-in flash. If the remote flash is out of sight or just far away, it might not get enough light to transmit the signals. If it is just at the edge of its sensitivity, you will get random response: sometimes the flash fires, sometimes it does not.

The sensor that receives pre-flashes in SB-700 is on the right-hand side of the unit (when you look at the LCD screen), it is a tiny circular dark window. Make sure this sensor can see your pop-up flash directly.

Click to expand...

I've tried different distances and I always have the sensor in clear view of the BIF. I'm very baffled and frustrated by this.

I would also like to add if this is for shooting people, then there is no need for a sync speed of .250, you would just want to keep settings at/around a matching shutter speed. Also it would be easier not using TTL for shooting the subjects, put the flash in manual mode, adjust for lighting (if you have a lightmeter/if not and you have a smartphone download one) and I would use warm color gels if possible to offset any light differences, as the flash is set for a more daylight temperature (5k) vs whatever the room lighting would be (usually 3k-4k).

Sorry if I am misreading for your "Bodyscaping" images, I am under the assumption that you would be shooting indoors and it would be people as the subjects.

Looking at the metadata I see massive differences in exposure time and bias. I'm shooting in M so I don't understand why this would change? Is this a feature of TTL?

I forgot to add....I know the flash is firing on both shots because I heard the recharge beeps.

1) (edit out, question already answered while I was typing)

2) Are you in manual or another mode on the camera (sounds like manual), and TTL or manual mode for the flash? Any off-camera flash usage, I'd recommend being in manual on both sides. That way, YOU always control the exposure. Does it make for minor adjustments along the way which would slow down the shoot a bit? Yes, until you train your eye to dial it in closer and closer, but that only comes with the experience of doing.

3) Are you bouncing the flash or just straight on with a diffuser of some sort? If bouncing, perhaps the surface is too far away, and a 1/200th shutter speed would help a bit?

I can't see the EXIF info on the photos, but if the exposure is changing that much, something is set to compensate somewhere. Auto ISO maybe?

Pretzel said:

1) Is the off-camera flash firing every time? That would be one obvious solution, as if it's not, it would indicate something blocking the signal.

2) Are you in manual or another mode on the camera (sounds like manual), and TTL or manual mode for the flash? Any off-camera flash usage, I'd recommend being in manual on both sides. That way, YOU always control the exposure. Does it make for minor adjustments along the way which would slow down the shoot a bit? Yes, until you train your eye to dial it in closer and closer, but that only comes with the experience of doing.

3) Are you bouncing the flash or just straight on with a diffuser of some sort? If bouncing, perhaps the surface is too far away, and a 1/200th shutter speed would help a bit?

Click to expand...

1. Yes
2. M on camera and Remote on SB-700....which is the corresponding mode that works with CLS (BIF as commander)
3. Straight plus diffuser

I'm not at the stage in my photographic journey yet where I am comfortable using manual on flash. I'll get there but for now there are more fundamental things for me to learn.

Manual flash is easier to deal with, IMO, than TTL. Shoot, view the shot, increase or lower the flash and shoot again. Once ya get a nice exposure, you're ready to shoot a few knowing the exposure is gonna be similar. Just my thoughts, take it for what it's worth. Constant light is even easier, because you can move around and meter to where you know you're getting the right light.

I don't recognize BIF, but I assume it must mean Builtin Internal Flash?

Manual means the camera? Or the flash?

Manual camera is fine, a TTL flash is still automatic.

But turn Auto ISO off for flash. Auto ISO is based on the ambient. A manual flash cannot respond to ISO changing. Camera manual mode will vary shutter speed with ISO. There was no clue offered what you might be doing in this regard?

If shooting too fast, not allowing full recycle, that will cause the flash power to vary poorly.

You probably do not want a fully exposed bright TTL picture for this. Try manual camera, and manual flash (adjust manual power as desired), and Auto ISO Off. In the Commander menu, you can set Group A to be either TTL or Manual flash at a specified power level. Adjust flash power level to give the desired result.

I'm not using auto ISO I'm manually setting because that is really a required feature of low-key work. I have noticed that I just took a pic at 200th shutter speed, but when I looked back it had changed to 1600th. Whats going on there? I'm definitely in M on camera.

Update: I've reset Custom Settings and it is now fine. In commander mode it now will not allow me to go above 250th shutter speed.

Thanks for all your input and for welcoming me to Nikonites. Bit sad that I have resolved the issue without actually finding the root cause.

It could have been Auto FP then (menu E1). Reset Custom resets it Off. Auto FP allows the TTL SB-700 to do HSS flash (shutter speed faster than maximum sync speed), which reduces its power capability to about 20% of speedlight power (which might be insufficient). In Auto FP mode, changing shutter to be above 1/250 second (anything faster) will cause that reduction.

But manual camera mode should not have allowed shutter speed to change from what you set it to be (unless Auto ISO was a factor).