Newbie with flash (Nikon)

With lockdown I got to think of things and try things out to educate myself. I haven't used flash often but I have read stuff about it and then I left my flash for months before even taking it out. I've started playing with my softbox and then I tried bounce flash today.

 

Question: sometimes we are told to underexpose the ambient light by a bit and then fire the flash. I've been able to do this in M exposure mode and then manual flash output. When I want a bit of automation, I set my camera to A (aperture priority) with a -1 EV exposure compensation and then I turn my flash on either manual flash output or TTL flash, my camera's shutter speed changes. Why is this and when people want to underexpose the ambient light by a bit and then fire the flash what do they do?

 

 

Cheers.

 

Edit. Part of the issue might had been my flash shutter speed in the settings. I dropped that right back. I have a 1/30 speed in aperture priority mode it stays at 1/30 with manual flash power output. Once I switch my speedlight to TTL flash my shutter speed changes to 1/60. Why is this?

Edited July 13, 2020 by RaymondC

Once I switch my speedlight to TTL flash my shutter speed changes to 1/60. Why is this?

1/60th is the default synch speed for flash. The camera detects that you have a flash inserted and turned on, and sets the shutter speed to 1/60th automatically - no matter if the camera's shutter is capable of a higher synch speed.

 

You can alter the flash speed lower in menu option e2, but not higher (stoopid, Nikon, jest stoopid!). If you want/need a higher synch speed you have to use S or M mode to manually override the default flash speed.

RaymondC,

I would recommend going completely manual with the flash and the camera. You will have better control that way.

Good online reading on the subject can be had at Strobist. David Hobby who runs the site emphasizes manual control and low cost solutions.

A good read that might help you is Outdoor Flash Photography by John Gerlach. As Rodeo said your cameras will control and limit sync speed if left to its own devices. Manual will allow you to over ride the speed. I think 250th is the normal upper limit on some Nikon gear depending on the body. Good hunting.

It seems like manual is more predictable. I usually do use manual flash now anyway and in the past. I've just thought of more automation because I recalled one time I was at a large dinner party the camera would often underexpose the ambient light, also if the ISO is set to auto there is an upper limit maybe ISO 400 so I could not get more ambient light for the hall or dinner room hall. I usually shoot in manual anyway with landscapes on a tripod.

 

Testing with a dark corner of the sofa ie to represent low light.

Today, I set the e3 setting to 1 second for the min flash speed. I also set the auto ISO minimum shutter speed to way down.

 

So with aperture priority:

No flash - 1/20, F2.8, 400 Auto ISO

TTL flash - 1/40, F2.8 400 Auto ISO (quicker shutter speed)

 

Shutter priority:

No flash - 1/15 F3.2 400 Auto ISO

TTL flash - 1/15 F4.5 400 Auto ISO (aperture closed more down)

 

Manual camera:

No flash 1/20 F2.8, ISO 400 (not auto ISO)

TTL flash 1/40 F2.8 ISO 400 (not auto ISO). (quicker shutter speed).

 

 

TTL flash sounds like it cares about the main subject and less about the ambient light so the ambient may get underexposed.

TTL flash sounds like it cares about the main subject and less about the ambient light so the ambient may get underexposed.

Well, yeah. That's what it's designed to do.

 

Nikon's i-TTL defaults to "TTL-BL" - Balanced Lighting - when the camera metering is in matrix mode. It's supposed to treat the flash more like a fill light than as an overpowering key light. But if you switch the camera metering mode to CW or spot, then "BL" goes away and the flash is treated as the main source of light.

 

Personally, I'm not too keen on 'dragging' the shutter to boost the ambient exposure. Orange backgrounds from tungsten lighting always look a bit odd to me, and a CC flash filter loses you a lot of light. I'd rather bounce the flash from such a position that it gives good coverage over the whole room, or as much of the room as possible.

 

Also, the ambient lighting isn't of any use at many events - dim disco lighting or table candles, etc. You'd need about one million ISO and f/0.5 to make any use of it!

I recommend using manual (ambient) exposure mode for flash pics and then you can use TTL or manual on the flash, depending on what you want to do. On indoor location., I typically use TTL on the on-camera flash or key light if I use remote flash(es), but all other flash groups and the ambient exposure are on manual. If there is window light, then I use that together with flash without filter. If there is no window light but some artificial lights, then I gel my flashes typically with 3/4 CTO to bring the flash light closer to ambient but still maintain a bit of warmth in the ambient lights, and set the white balance to 3700K or thereabouts. Sometimes I do test shots to determine the correct filtering, but this seems to be OK as a starting point where I have used filters. For full flash lighting with no ambient (this situation is what I have in the studio but not often elsewhere) I again don't use filters and set all lights to manual. The reason for using TTL for key light when using flash and ambient together is so that the subjects can move relative to the photographer and relative to the key light, and the system adjusts automatically. The reason I don't have the other flash groups on TTL or ambient exposure on automatic is that with multiple autoexposed lights become too unweildy and difficult to control. One automatic light source (either ambient, in case I don't use flash at all or one flash group) I can manage.

 

As for why underexpose the ambient light, it's because the flash adds a lot of light to the main subject typically, and a little light to the background, and so you want the ambient to be slightly underexposed so that the flash light can be added without overexposing the scene, and also so that the flash can highlight the main subject. I do this using a test exposure with flashes or the flash trigger off, and evaluate it using the LCD before doing the actual pics. I am sure that in automatic exposure combined with TTL flash, the camera attempts a sensible result but I prefer not to use it that way.

 

I have also sometimes tried to provide an all-flash exposure to a location and while this can result in a clean-looking image the issue is that you need to use a lot of light to overwhelm the ambient, and stop down the lens, and such an amount of flash light starts to startle the subjects more than I like, so the kids start to squint their eyes and wince of pain. Another reason for avoiding this type of lighting is that existing light sources look dead in the pictures, and the ambient mood is lost.

RaymonsC, just remember that TTL varies the light output depending on where the camera is pointed. All it does is control power output and there is no way of being certain what that output may be or that it is repeatable. Don’t believe for a second that the flash in TTL will some how magically differentially light the subject or change the quality of the light. To do that you have to modify the shape of the light and filter it. Of course that is sometimes difficult or impossible . That said you can get better consistency in manual mode because you do not have to worry that moving the camera will change the flash output. In full manual if your bouncing light you can take advantage of the full power of your flash that you can’t get to in TTL. One last advantage to manual is that you don’t have to purchase new flash guns because your not chasing the latest and greatest flash TTL system. Last thing, don’t mount the flash on the camera hot shoe. You can buy reliable manual radio triggers for the same price or less than a quality Nikon sync cord.

BLUF: Full manual flash allows more control. More control is better.

Good hunting.

If you are using iTTL then you can affect the ambient light by changing the shutter speed, but I would not use aperture priority to do this..

Give Auto Aperture mode on the flash a try too. IMO it works well, and far more consistently than i-TTL.

 

It's my go-to mode if I need any flash automation. Also, it doesn't waste flash power or delay the shutter by popping off a pre-flash either.

Raymond, here is my usual practice with Nikon iTTL flash on latest Nikon DSLRs. Please double check all that I say as there may be some differences due to the specific camera used and flash used.

 

For me: Aperture Priority

Flash: Turn off TTL BL and set TTL. I do this on the flash. This way the computers in the camera and the flash are not directly linked to "balance" things.

Flash Sync: I use rear curtain synch most of the time when I want a good mix of ambient and flash light. Once rear curtain is set, the shutter speed works like non flash shutter speeds. There is no default to 1/60. (This may vary with camera.)

Exposure Compensation: For Nikon, flash and camera exposure compensation are additive. You set each separately. I now set both on the camera. You may be able to set flash exp comp on the flash. The choice is yours.

Fill flash: Ambient light is main light. No Ex comp set on camera. Flash exp comp set to a -1.7 or -2.0 or -3.0. This way you get a little bit of extra light on the subject.

Controlling background light: To darken a distracting background, set flash exp comp to o a +2.0. Set camera exp comp to a -2.0. Take the picture. Check to see if main subject is lit properly and background goes dark. Adjust as needed. Since they are additive, the + and - cancel each other out.

There are other ways to do the same thing. Experiment and decide which works best for you.