About Off Camera Flash - Manual Mode Questions

ChristopherCoy · Jun 18, 2020

I used to be pretty good with OCF, but only because of the TTL capabilities of my DSLR, and the Nikon Creative Lighting System. I've kept two Nikon SB-700's, and added some Godox radio receivers, a radio trigger, and a Godox TT685n speedlight. This three light setup works wonderfully on my D700 DSLR in TTL mode. However, NONE of these pieces of equipment are compatible with my F5, or F100, unless I'm in full manual mode. The trigger and receivers become "dumb", and the flashes don't even turn on unless they're in manual mode. This limits me to a 1/250th shutter speed, removes the auto FP functions, and tremendously confuses things for me.

When it comes to artificial lighting, I'm pretty confident with a light meter. I can pick my aperture and shutter speed and get the lighting to match. I suppose I could do the same with the light meter, radio trigger, and the speedlights. However it becomes very muddy, and overwhelming when I try to think about using manual flash WITHOUT a meter etc, especially when trying to figure out the power ratios.

Let me give you an example scenario:

"Golden hour ambient light, with a setting for a colorful sunset in the background. Subject is 10-15 feet from the lens, and fill light is needed to light the subject. Lets say we're somewhere around f5.6 and 1/100th, whatever gives us the shallowest DOF with the best sunset colors."

Questions:
Without a light meter, how do you find which power setting to put the flash on? 1/2 power? 1/8 power? And how do you ensure that the flash power wont blow out your subject when using bare flash (no modifiers)?

The SB-700 has a GN of 28/39 or 92/128 ft. Is this at full power? And if that is the case, if the subject was about 15 ft from the camera/flash, would I start around 1/8 power?

Thanks in advance!

voceumana · Jun 18, 2020

Flash meters make it so easy, that if you're thinking of much work using this approach, I'd recommend you get one.

But, the manual method is to divide the guide number by the distance and that gives you the f/ stop. Shutter speed doesn't matter, as long as it is the sync speed or slower (for any focal plane shutters). Guide numbers are at full power. Adjust power level so that you get the f/stop where you want it. This lets you balance the flash illumination with the ambient light background.

Chan Tran · Jun 18, 2020

Flash meter is the good choice but if you don't feel like buying one then.
Use the D700 and shoot with all the flashes in manual. Make adjustment until you like it then switch the camera to the F5. People say digital isn't the same as film but it's better than polaroid.

MattKing · Jun 18, 2020

ChristopherCoy said:
The SB-700 has a GN of 28/39 or 92/128 ft. Is this at full power?

There are too many numbers here!
Looking at Nikon's website I see:
Guide Number
28m/92ft. (at ISO 100, 35mm zoom head position, in FX format, standard illumination pattern, 20°C/68°F) to 39m/128ft. (at ISO 200, 35mm zoom head position, in FX format, standard illumination pattern, 20°C/68°F)
Which isn't great either - I think that they are just giving two guide numbers - one for ISO 100 and one for ISO 200.
It is, of course, important to note that the flash has a zoom function which will change its coverage, and therefore change its guide number, depending on the setting.
That will be for full power.
If you use, for example, 1/4 power, the ISO guide number will be 1\4 of the full power one.

ChristopherCoy · Jun 18, 2020

MattKing said:
There are too many numbers here!
Looking at Nikon's website I see:
Guide Number
28m/92ft. (at ISO 100, 35mm zoom head position, in FX format, standard illumination pattern, 20°C/68°F) to 39m/128ft. (at ISO 200, 35mm zoom head position, in FX format, standard illumination pattern, 20°C/68°F)
Which isn't great either - I think that they are just giving two guide numbers - one for ISO 100 and one for ISO 200.
It is, of course, important to note that the flash has a zoom function which will change its coverage, and therefore change its guide number, depending on the setting.
That will be for full power.
If you use, for example, 1/4 power, the ISO guide number will be 1\4 of the full power one.

Ok, so lets assume I'm using 200 film. In the 35mm position, the GN is 128ft. With my subject being 113 feet closer than the GN of 128ft, full power would certainly be quite a bit brighter and possibly blow out my subject. So should I start at 1/8 power if I didn't have my meter?

I came to that conclusion by starting with 128ft (full) ÷ 2 = 64ft (1/2) ÷ 2 = 32ft (1/4) ÷ 2 = 16ft. (1/8 power).

wiltw · Jun 18, 2020

Manual flash (studio strobes or portables) with a flashmeter is easy. Doing so with no meter is a real pain in the arse! But you can do lighting ratios with some very basic understanding:

You can ratio by flash power setting...e.g. Main flash set to 1/2 power and Fill flash set to 1/4 power, with both units set a same distance from subject...if the Fill illuminates the entire face visible to the lens, while the Main illuminates one side only, the Main contributes 4 units (2EV) of light, the Fill contributes 1 unit (1EV) of light, so where they overlap they combine to 5 units of light...a 5:1 subject illumination ratio, or a 2:1 light source intensity ratio.
You can ratio the flash by DISTANCE...simply think of distances as virtual f/stops. One flash at 4' will be one EV brighter than a second (equal intensity) flash at 5.6'
You can set ratio by combining the two above bullets, using both power and distance to determine subject illumination ratios.
3:1 subject illumination is 'low contrast' for portraiture, 5:1 is 'moderate contrast, 7:1 is 'high contrast'

So you can set RATIO without a meter, but you are unable to set Exposure without a meter unless you use time consuming method of trial and error, with a digital camera for immediate feedback... a method which is horrid if your subject is waiting for you to finish setup!!!

All of this is most useful when shooting indoors. It gets complicated by any effort to set your supplementary lighting in some proportion to ambient light (like setting sun). Then you truly are best served by the flashmeter which can factor in the combination of a slow shutter speed with flash when determining exposure.

Then there is the added complexity that published Guide Numbers for modern electronic flash vary by zoom flashhead, plus the fact that they are rather overstated by the manufacturer (vs. what you measure via flashmeter)...typically 1EV too powerful claim by the manufacturer.

MattKing · Jun 18, 2020

Sure - or even easier, use 15/128 ~ 16/128 = 1/8 power.
It might be wise though to experiment a bit.
Guide numbers are based on average conditions, and usually oriented toward interior photographs - which involve some reflection from surfaces like walls, ceilings and floors. A guide number that works inside, may not be right for outside.
In addition, guide numbers are based on fully illuminating a subject, without other light sources being available. For fill work, you usually want less than full illumination, and you need to take into account the affects of other available light.

ChristopherCoy · Jun 18, 2020

wiltw said:
So you can set RATIO without a meter, but you are unable to set Exposure without a meter unless you use time consuming method of trial and error, with a digital camera for immediate feedback... a method which is horrid if your subject is waiting for you to finish setup!!!

Ratios I understand, I've used both power and distance for ratios in the studio.

But what I was wanting to figure out is exactly what you touched on. How to get a starting ratio with no meter, and no digital means (or polaroid) to test before exposing a whole roll.

wiltw · Jun 18, 2020

ChristopherCoy said:
Ratios I understand, I've used both power and distance for ratios in the studio.

But what I was wanting to figure out is exactly what you touched on. How to get a starting ratio with no meter, and no digital means (or polaroid) to test before exposing a whole roll.

Hard to do but eased with immediacy of digital photo chimping review, impossible without meter (or Polaroid) when dealing with always-variable circumstance of shooting with ambient light.
Use of same light at same setting (and a fixed ouput of fixed zoom flashhead) will yield results of known experimentally proven GN (not merely manufacturer claimed GN)...you know what to expect because you know the output power! Throw a small look-up table in the bag when going outside a studio setting.

MattKing · Jun 18, 2020

ChristopherCoy said:
Ratios I understand, I've used both power and distance for ratios in the studio.

But what I was wanting to figure out is exactly what you touched on. How to get a starting ratio with no meter, and no digital means (or polaroid) to test before exposing a whole roll.

Guide numbers can do that, but you need to customize them to your needs. You need to do trials, and then apply the results to future work. All of which can be both interesting and sort of fun.
A flash meter or digital trials - or in the past, working with Polaroid materials - will allow you to shorten the trial period.

foc · Jun 18, 2020

In the example golden hour scenario, your sunset will be changing very quickly and so will your ambient lighting.
So you have to decide which will be your key light, the ambient light or your flash.
I would find it very hard to calculate lighting ratios in such a situation without a flash meter and an incident meter.
Guide numbers can only do so much, especially in a mixed lighting situation.

Chan Tran · Jun 18, 2020

I would do manual multiple flashes lighting in full manual. The flashes that you have all have adjustable manual power level. I just set them up and use the digital camera for test shots. It's real easy. No need for lighting ratio calculations anything. No need for GN. You see the effect fully with the digital camera. Then simply put the same lens on the film camera using exactly the same settings. The F5 and D700 have pretty much the same features so you can easily duplicate the shot on film. Just don't use TTL or any form of auto.

M Carter · Jun 18, 2020

I came up on Polaroid; I'm with the "proof with your DSLR" (or mirrorless) crowd. You'll often spot little reflections or issues that way, too. Even shooting 4x5, I just match the focal length to my Z6. got an extra pocket wizard so I don't have to mess with swapping transceivers around.

With a little work, you can even make camera profiles that roughly match your films and save them in the camera - that's some cool stuff!

eli griggs · Jun 18, 2020

If you do no want to meter, get good with Sunny 16 (11) in low to high light settings, and set your fill flash a stop or two, depending on the light, below or above, that number depending on what you want. with your sunny 16, settings.

Also keep your strobe light simple, two flashes at best, and have an assistant with the strobe or reflector or both.

IMO.

voceumana · Jun 18, 2020

Just get a flash meter. It is worth it. I got a Polaris flash meter quite a while ago--it was the cheapest I could find from a reputable meter manufacturer. It includes regular (ambient) incident and reflected metering, multiple flash "pops" mode (i.e., open shutter and fire flash multiple times; good for product photography and still life work), single flash pop mode, and will trigger the flash from a PC cord to meter. No longer made, but Sekonic's low end does the same thing.

eli griggs · Jun 18, 2020

You might also consider the older LunaPro F, I forget at the moment the U.K. name, and use that with a homemade flash trigger on each flash position.

The Luna Pro F is needle match and like I indicated, you can no directly trigger the flash unit by way of meter cord to flash, but it works very well, can fulfill multi-able roles, including darkroom enlarging meter, wide spot meter and it is one of the best low light ambient meters you could use.

IMO.

MattKing · Jun 18, 2020

eli griggs said:
LunaPro F, I forget at the moment the U.K. name

In almost all of the world, except the USA, that meter is badged as a Gossen Lunasix F.
As far as I'm concerned, this is a really great recommendation for a meter in general.
If you want something new and currently produced and small, I like the Gossen Digiflash - also a really great recommendation for a meter in general.
I have both!
As well as a couple of others.
Yes, I have a problem.

ChristopherCoy · Jun 19, 2020

I have a meter. I picked up a Sekonic L-408 I think. Haven’t used it yet though.

reddesert · Jun 20, 2020

If you look at the Strobist website, there is a mountain of information mostly geared toward using off-camera flash with manual setting of the lighting ratios.

It's generally aimed at digital, DSLR users, but all of the lighting techniques were developed during the film era and perfectly applicable to film shooting. You can use a meter and/or use a digital camera for proofing. A good place to start is here: https://strobist.blogspot.com/2006/03/lighting-101.html

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