Nikon SB 7 Flash - How to

Hi guys,

 

I wanted to know if anyone has had experience with the SB 7 (or similar flash) It's my first time using a flash on my Nikon f2 and struggling to really understand the basics of it.

 

I've had read the manual, and whilst i understand there are 2 automatic modes & 1 manual, i can't seem to wrap my head around it. For instance, I understand that if I select one of the auto modes, and set my setting's according to the ASA dial then my exposure should be correct - but how can this be when the flash doesn't know how much ambient in the room and therefore to correctly expose?

 

If I set to the blue setting, let say in this example 100 ASA and at F8 - does this mean the flash will cover from 0.6 - 3M?

If the red setting (ASA 100 at F4) does this cover everything from 7 - 20M?

 

In what instance would I use manual?

 

I'm assuming I'm missing some basic photography principles here, but any resources that someone could point me too would be super helpful.

 

Thanks again,

but how can this be when the flash doesn't know how much ambient in the room

From a distant past memory, most of these 'basic' auto flash guns have a small light sensor just above the Hot Shoe (just to the right of N in Nikon) mount pointing towards the target.

 

The flash fires at pretty much full wack, but when the sensor sees 'enough' light returned to satisfy the settings you've, err, set, it dumps the rest of the charge to a buffer.

Edited June 9, 2020 by mike_halliwell

Some explanation in this link

FlashZebra.com: Flash Exposure Control Methods

Until the invention of the Thyristor circuit, flashes fired either at full-power or some fraction thereof by setting a dial (1/2, 1/4/, etc.). The Thyristor circuit used a sensor on the flash, and took into account the total light being received at it (reflected and ambient), and near-instantaneously cut the power to the flash, saving energy in the capacitor as an added benefit (reduced recycle times). While this was a great breakthrough, it wasn't without its faults. When scenes/people were strongly backlit, the circuit didn't know the additional back light was just that, and you could get badly underexposed subjects. In fact, you still can.

Until the invention of the Thyristor circuit, flashes fired either at full-power or some fraction thereof by setting a dial (1/2, 1/4/, etc.). The Thyristor circuit used a sensor on the flash, and took into account the total light being received at it (reflected and ambient), and near-instantaneously cut the power to the flash, saving energy in the capacitor as an added benefit (reduced recycle times). While this was a great breakthrough, it wasn't without its faults. When scenes/people were strongly backlit, the circuit didn't know the additional back light was just that, and you could get badly underexposed subjects. In fact, you still can.

Except for studio flashes portable camera mounted flashes do not have manual partial power until thryristor is used.

Hi all,

 

Thanks for the help. I've attached below a shot of the ASA dial.

 

Now from what I've gathered, if flick to the blue setting, with ASA at 100 and aperture set to F8, the flash would trigger up to 3 M,

 

if set to red, and the camera was set to F4, the flash would cover a distance of 7M onwards - Is this correct?

 

What i cant understand then, is that if there is a light sensor and the flash is adjusting to that in these 2 auto settings - how can these fixed formulas be correct (as it wouldn't know how much ambient light is also around)

 

If you go to Butkus.org, you can get the Flash Manual

The sensor on the flashgun only measures the flash power being reflected back from the subject. It is not sensitive to ambient light, so if you want to balance flash with ambient, you have to set the camera shutter speed accordingly. The F2 flash sync speed being 1/80 if I remember correctly, you have to set the speed to 1/80 or slower, which often makes it difficult to balance flash and ambient.

The sensor on the flashgun only measures the flash power being reflected back from the subject. It is not sensitive to ambient light

That's not quite true John. Light is just light, and the flash sensor has no way of knowing if the light it's reading has come from the flash, the sun, or a tungsten light bulb.

 

Auto Aperture mode starts integrating the light hitting the flash sensor as soon as the flash is triggered. Once the circuitry decides that enough light has reflected back from the subject - from any source - the flash is cut off or dumped.

 

Overexposure will result if the shutter speed is long enough (by continuing the exposure after the flash is over) or the ambient light is bright enough to compete with the flash exposure. Very rarely will you get underexposure with AA mode.

 

Since the flash sensor is effectively just a selective-area reflective light meter, it has the same limitations and needs the same care in use.

 

And IME, i-TTL isn't fool proof either.

Edited June 9, 2020 by rodeo_joe|1

Hi all,

 

Thanks for the help. I've attached below a shot of the ASA dial.

 

Now from what I've gathered, if flick to the blue setting, with ASA at 100 and aperture set to F8, the flash would trigger up to 3 M,

 

if set to red, and the camera was set to F4, the flash would cover a distance of 7M onwards - Is this correct?

 

What i cant understand then, is that if there is a light sensor and the flash is adjusting to that in these 2 auto settings - how can these fixed formulas be correct (as it wouldn't know how much ambient light is also around)

 

 

When in the blue setting it's good for up to 3m. When in the red setting it's goof for up to almost 7m (in fact around 6 as it's exactly doubled the blue setting) (not from 7m onward.)

Except for studio flashes portable camera mounted flashes do not have manual partial power until thryristor is used.

 

Thanks for the catch.

 

If you consider the Graflex flashes (IV), they used a selector switch on the power pack to change the flash output, as did the Norman 200B, and Lumedyne. While not very portable by today's standards, they all have adjustable light output based in the power packs. I used to lug a Graflex IV around for weddings in the 1970's.

The Vivitar 283 has the variable power adapter as an option.

The Nikon SB-29 has manually adjustable output power. I've used it for fill-flash.

 

The Vivitar 283 and other flashes had more F-Stops available for auto operation, you select the one that is close to ambient light. Meter as typical, set the F-Stop of the lens and then use a setting on the flash to mix ambient+flash. If Ambient light is 1/80th and F8, select F11 or F16 on the flash for shadow fill. At least that's how I did this 40 years ago.Typically you had to shoot slow film, like Panatomic-X or Kodachrome 25.

 

The SB-7e that I have is thyristor, as is the older SB-2. Somewhere in the basement, lurks an SB-2.

If Ambient light is 1/80th and F8, select F11 or F16 on the flash for shadow fill.

That's completely the wrong way round.

 

In order to look natural, the fill should be weaker than the ambient light - unless the ambient light is backlighting. Therefore you need to set the auto flash to a wider aperture than you're using on the camera - usually by one or two stops. In the example of a lens aperture of f/8, as above, you would set the flash auto-aperture to f/5.6 or f/4. Setting the flash aperture to f/11 or f/16 would cause the flash to overexpose, and that's the very opposite of what you want fill-flash to do.

 

Alternatively, you can set the ISO on the flash to twice or four times the camera ISO (or any setting in between) while keeping the aperture to f/8. Either method works to give a weaker fill than full-on flash.

 

BTW. Most Nikon flashes that have Auto Aperture mode also allow for intermediate ISO settings, coupled to the flash output. This gives finer control than the coarse one or two stop intervals that you can get from the likes of a cheap Vivitar. Nikon's SB-24 through to SB-28 all have this feature.

Edited June 12, 2020 by rodeo_joe|1

Here's a quick improvised still life from my spice rack, to show how well Nikon's AA flash mode works:

Flash was an SB-24 speedlight mounted in the camera hotshoe. I used AA mode set at f/8 and 100 ISO. Flash was tilted and swivelled to bounce from white wall/ceiling above and behind camera, while the sensor remained pointing forward. Camera was a D7200 set to manual mode - shutter speed 1/250th; aperture f/8; 100 ISO; White Balance set manually to 5000k to compensate for bounce 'yellowing'.

 

So the whole setup was pretty straightforward and worked as specified, with no compensation needed - apart from the white balance tweak.

 

You can see that the exposure is very accurate, and that even a few specular reflections are accommodated.

Edited June 12, 2020 by rodeo_joe|1