Metering ambient and flash advice needed

markbau · Aug 9, 2019

I mainly shoot outdoors so a portrait I am going to take soon is a bit of a new experience. It will be indoors during the day, the area, although it has ambient light, is quite dark, behind the subject will be a picture window. I will have a Elinchrome D-Lite RX4 using a softbox that of course has the ability to be changed in flash intensity. I have a leaf shutter lens so no sync problems. The meter I have is a Sekonic Flashmate L-308S and will be using HP5 rated at ISO 200.

If I get an ambient/incident reading I'm guessing it will be around 60th f4. If I were to set the flash for its smallest output (dont know what a flash reading would be) how do I combine the ambient and flash readings?

I've googled and youtubed this but mainly get situations were they are outside and are basically just doing fill flash. I'd like to keep the view outside as well exposed. Do I start by metering the view outside so I don't overexpose it and work back from there?

Thanks for any tips/instructions. Although I'm an experienced photographer, this type of work is just not something I know much about.

Chan Tran · Aug 9, 2019

Meter the view outside and set the camera to expose correctly for that view. Meter the flash and adjust its output until the meter gives you the same aperture.

markbau · Aug 9, 2019

Chan Tran said:
Meter the view outside and set the camera to expose correctly for that view. Meter the flash and adjust its output until the meter gives you the same aperture.

Beautiful, simple and makes perfect sense! I can't wait to try it on a dry run tomorrow!

odell1618photography · Aug 9, 2019

markbau said:
I mainly shoot outdoors so a portrait I am going to take soon is a bit of a new experience. It will be indoors during the day, the area, although it has ambient light, is quite dark, behind the subject will be a picture window. I will have a Elinchrome D-Lite RX4 using a softbox that of course has the ability to be changed in flash intensity. I have a leaf shutter lens so no sync problems. The meter I have is a Sekonic Flashmate L-308S and will be using HP5 rated at ISO 200.

If I get an ambient/incident reading I'm guessing it will be around 60th f4. If I were to set the flash for its smallest output (dont know what a flash reading would be) how do I combine the ambient and flash readings?

I've googled and youtubed this but mainly get situations were they are outside and are basically just doing fill flash. I'd like to keep the view outside as well exposed. Do I start by metering the view outside so I don't overexpose it and work back from there?

Thanks for any tips/instructions. Although I'm an experienced photographer, this type of work is just not something I know much about.

Typically you would use your aperture to control your background or ambient, adjusting your flash output to your given flash sync speed, generally around up to 1/250 for most curtain shutters.
Being that you have a leaf shutter that does give you more options.

RalphLambrecht · Aug 9, 2019

markbau said:
I mainly shoot outdoors so a portrait I am going to take soon is a bit of a new experience. It will be indoors during the day, the area, although it has ambient light, is quite dark, behind the subject will be a picture window. I will have a Elinchrome D-Lite RX4 using a softbox that of course has the ability to be changed in flash intensity. I have a leaf shutter lens so no sync problems. The meter I have is a Sekonic Flashmate L-308S and will be using HP5 rated at ISO 200.

If I get an ambient/incident reading I'm guessing it will be around 60th f4. If I were to set the flash for its smallest output (dont know what a flash reading would be) how do I combine the ambient and flash readings?

I've googled and youtubed this but mainly get situations were they are outside and are basically just doing fill flash. I'd like to keep the view outside as well exposed. Do I start by metering the view outside so I don't overexpose it and work back from there?

Thanks for any tips/instructions. Although I'm an experienced photographer, this type of work is just not something I know much about.

use the shutter speed to control ambient and the aperture to control the flash at that shutter speed.

StepheKoontz · Aug 9, 2019

odell1618photography said:
Typically you would use your aperture to control your background or ambient, adjusting your flash output to your given flash sync speed, generally around up to 1/250 for most curtain shutters.
Being that you have a leaf shutter that does give you more options.

You have that backwards, you use the shutter speed to control the ambient. The flash doesn't care what the shutter speed is as long as it's within the sync range of the shutter.

MattKing · Aug 9, 2019

Chan Tran said:
Meter the view outside and set the camera to expose correctly for that view. Meter the flash and adjust its output until the meter gives you the same aperture.

This is correct, but you need to make sure that when you meter the flash, the ambient light is the same as in your earlier measurements, because the ambient and flash light are cumulative.

RalphLambrecht · Aug 10, 2019

MattKing said:
This is correct, but you need to make sure that when you meter the flash, the ambient light is the same as in your earlier measurements, because the ambient and flash light are cumulative.

true for fill flash.

odell1618photography · Aug 10, 2019

At 4:30 he discusses his choice of aperture to control ambient. I’ll post a few photos later today of using aperture to control ambient. I like using aperture to control ambient, primarily after I have metered my flash exposure, I can decide to make the background darker by increasing my f stop or brighten my background by opening up an f stop with out having to re meter and adjust flash / shutter speed.

wiltw · Aug 10, 2019

Let's assume the outside scene is a Sunny 16 exposure...ISO 100, 1/100 f/16 (and you confirmed this using your incident meter taken outside, or with your meter in reflected light mode pointed out the window at the outdoors):

If you want the background to not be so bright, so that the viewer's attention is more on the indoor portrait subject, set 1/1200 rather than 1/100 and the b/g is underexposed -1EV from 'normal'
Then meter your flash, let's assume you get (any shutter speed) f/11 flash exposure (the indirect window light does NOT fall on the subject face with the window behind them, so there is zero contribution of subject exposure from window light!). Problem here, since you have 1/200 f/16 due to Sunny 16; so
...change to 1/400 f/11 for the window scene exposure. And all is well and good, with a properly exposed subject and a -1EV outside window exposure.

There is no 'combining' of exposure readings, as you have essentially TWO SCENES in a single frame, and the shutter+f/stop controls one of the scenes, while the flash power+ f/stop controls the other scened.

wiltw · Aug 10, 2019

Now let's assume the same outside scene is a Sunny 16 exposure...ISO 100, 1/100 f/16 (and you confirmed this using your incident meter taken outside, or with your meter in reflected light mode pointed out the window at the outdoors), and there is another window to the side of the subject, with indirect light coming in and falling on the subject:

If you want the background to not be so bright, so that the viewer's attention is more on the indoor portrait subject, set 1/1200 rather than 1/100 and the b/g is underexposed -1EV from 'normal'
Then meter your flash+ambient (shutter speed set on meter at 1/200), let's assume you get (any shutter speed) f/11 + 0.5EV flash exposure (the indirect window light does fall on the subject face with the window behind them, so there is contribution of subject exposure from window light plus flash!). Slight problem here, since you have 1/200 f/16 due to Sunny 16; so
...change to 1/250 f/11 +0.5EV for the window scene exposure to be somewhat dimmer than the portrait subject, and re-meter again for the subject (it might not make much difference at all, but at least you know the effect of the exposure on your subject). And all is well and good, with a properly exposed subject and a -1EV outside window exposure.

There is 'combining' of exposure reading from flash+window ambient as read by the flashmeter. And, you have essentially TWO SCENES in a single frame, and the shutter+f/stop controls the outside scene, while the flash power+ f/stop controls the other scened.[/QUOTE]

StepheKoontz · Aug 10, 2019

odell1618photography said:
At 4:30 he discusses his choice of aperture to control ambient. I’ll post a few photos later today of using aperture to control ambient. I like using aperture to control ambient, primarily after I have metered my flash exposure, I can decide to make the background darker by increasing my f stop or brighten my background by opening up an f stop with out having to re meter and adjust flash / shutter speed.

Changing the aperture will change the flash exposure, changing the shutter speed does not affect the flash exposure. I don't want to argue here but you seriously have this backwards. Once you set the flash exposure for the chosen aperture, changing the shutter speed controls how much ambient is recorded without affecting the flash exposure. I'm not sure if that video is talking about a modern DSLR using TTL flash in manual mode? That is a whole different animal and doesn't apply to old school film or using manual strobes.

odell1618photography · Aug 10, 2019

With speed lights and variable output flash heads like markbau has we can meter for flash and adjust flash output to our chosen aperture and shutter speed. If my meter reading for ambient (background sky) is 1/250 at f11 I can set my flash output to give me 1/250 at f11.

If I would like my background to be one stop darker, I can adjust my flash output to give proper exposure of 1/250 at f16.

The variable that can be adjusted is flash output. Flash does not affect background (outdoors). Inside in a small space with low ceilings it can or will based on flash output, modifiers, etc.

Yes, aperture does affect flash exposure, if you adjust aperture you need to adjust flash output accordingly. Outside I use Nikon speedlights in manual mode with a Magmod Magbox and my Mamiya RB 67ProSD, with wireless triggers. Once I know where ambient is I meter for aperture and shutter speed, adjusting flash output accordingly. If I decide to change aperture from f16 to f8 I can adjust my flash output down one stop, over exposing ambient (background) one stop without having to meter again as long as my subject to flash distance hasn’t changed.

odell1618photography · Aug 10, 2019

I handhold my Mamiya most of the time, so I typically use higher shutter speeds and prefer to adjust aperture than shutter speed. When I use my Nikon 35 mm gear I just prefer the higher max sync speed of 1/250.

John Koehrer · Aug 10, 2019

RE: #11.
Two scenes. There are only two scenes if two individual readings are taken. Flash meters don't combine ambient AND
flash with one reading.

odell1618photography · Aug 10, 2019

John Koehrer said:
RE: #11.
Two scenes. There are only two scenes if two individual readings are taken. Flash meters don't combine ambient AND
flash with one reading.

A good point.

AgX · Aug 10, 2019

odell1618photography said:
At 4:30 he discusses his choice of aperture to control ambient. I’ll post a few photos later today of using aperture to control ambient. I like using aperture to control ambient, primarily after I have metered my flash exposure, I can decide to make the background darker by increasing my f stop or brighten my background by opening up an f stop with out having to re meter and adjust flash / shutter speed.

I am puzzled.

The more easy way would be to control ambient lighting by the shutter speed.
(As long as ones camera still give one enough choices for sync-ed shutter speed that would meet the movements in the very situation.)

odell1618photography · Aug 10, 2019

StepheKoontz said:
Changing the aperture will change the flash exposure, changing the shutter speed does not affect the flash exposure. I don't want to argue here but you seriously have this backwards. Once you set the flash exposure for the chosen aperture, changing the shutter speed controls how much ambient is recorded without affecting the flash exposure. I'm not sure if that video is talking about a modern DSLR using TTL flash in manual mode? That is a whole different animal and doesn't apply to old school film or using manual strobes.

To StepheKoontz point - https://strobist.blogspot.com/2006/03/lighting-101-balancing-flash-and.html?m=1
This is a great source for background information and techniques to become familiar with. Once you have understood the basics you can better make decisions and creative choices from there.

StepheKoontz · Aug 10, 2019

odell1618photography said:
With speed lights and variable output flash heads like markbau has we can meter for flash and adjust flash output to our chosen aperture and shutter speed. If my meter reading for ambient (background sky) is 1/250 at f11 I can set my flash output to give me 1/250 at f11.

If I would like my background to be one stop darker, I can adjust my flash output to give proper exposure of 1/250 at f16.

The variable that can be adjusted is flash output. Flash does not affect background (outdoors). Inside in a small space with low ceilings it can or will based on flash output, modifiers, etc.

Yes, aperture does affect flash exposure, if you adjust aperture you need to adjust flash output accordingly. Outside I use Nikon speedlights in manual mode with a Magmod Magbox and my Mamiya RB 67ProSD, with wireless triggers. Once I know where ambient is I meter for aperture and shutter speed, adjusting flash output accordingly. If I decide to change aperture from f16 to f8 I can adjust my flash output down one stop, over exposing ambient (background) one stop without having to meter again as long as my subject to flash distance hasn’t changed.

Why wouldn't you just change the shutter speed, rather than changing the f stop and flash power (which forces you to change the flash setting and affects DOF) to adjust the ambient balance? I have never heard of anyone doing it that way. The shutter speed IS the variable that can be changed independently of everything else that will vary the balance of flash to ambient. If ambient is f8 at 1/60 you set the flash one time for f8 and then can just change to 1/30 or 1/125 to change the recorded ambient without affected the flash exposure. It's the whole reason people use leaf shutter lenses... Like what is the point of not just changing the shutter speed?

StepheKoontz · Aug 10, 2019

odell1618photography said:
To StepheKoontz point - https://strobist.blogspot.com/2006/03/lighting-101-balancing-flash-and.html?m=1
This is a great source for background information and techniques to become familiar with. Once you have understood the basics you can better make decisions and creative choices from there.

Did you even read what you posted? "The ambient exposure is controlled by the f/stop and the shutter speed. The flash, being instantaneous, is controlled by the aperture."

Look, I've been doing event photography for 30 years, I totally understand how to simply adjust for ambient. Please don't post condescending "Once you have understood the basics..." insults on this forum. What you have posted here is the most complex way of adjusting ambient/flash balance I have ever heard of.

odell1618photography · Aug 10, 2019

AgX said:
I am puzzled.

The more easy way would be to control ambient lighting by the shutter speed.
(As long as ones camera still give one enough choices for sync-ed shutter speed that would meet the movements in the very situation.)

For his particular situation he may have decided that he needed to work with a given shutter speed and vary aperture. The one thing that digital photographers are doing that film photographers aren’t is checking exposure on the back of the camera. It’s possible that he’s adjusting ISO and or shutter speed.

StepheKoontz said:
Did you even read what you posted? "The ambient exposure is controlled by the f/stop and the shutter speed. The flash, being instantaneous, is controlled by the aperture."

Look, I've been doing event photography for 30 years, I totally understand how to simply adjust for ambient. Please don't post condescending "Once you have understood the basics..." insults on this forum. What you have posted here is the most complex way of adjusting ambient/flash balance I have ever heard of.

My apologies, I had meant that link for markbau in support of your original point to shutter speed for him to refer to.

Chan Tran · Aug 10, 2019

John Koehrer said:
RE: #11.
Two scenes. There are only two scenes if two individual readings are taken. Flash meters don't combine ambient AND
flash with one reading.

Most modern flash meters do combine both ambient and flash reading in one reading. Some even display the percentage of flash to ambient light contribution.

odell1618photography · Aug 10, 2019

StepheKoontz said:
Why wouldn't you just change the shutter speed, rather than changing the f stop and flash power (which forces you to change the flash setting and affects DOF) to adjust the ambient balance? I have never heard of anyone doing it that way. The shutter speed IS the variable that can be changed independently of everything else that will vary the balance of flash to ambient. If ambient is f8 at 1/60 you set the flash one time for f8 and then can just change to 1/30 or 1/125 to change the recorded ambient without affected the flash exposure. It's the whole reason people use leaf shutter lenses... Like what is the point of not just changing the shutter speed?

I do not disagree, I typically use a shutter speed of either 1/125 or 1/250. I choose to control background by aperture and adjust flash output. It’s not wrong.

odell1618photography · Aug 10, 2019

StepheKoontz ,
Are you and I good? I didn’t mean that you should read that link, sorry for coming across condescendingly. I was just trying to give markbau another resource for information for him to consider.

StepheKoontz · Aug 10, 2019

odell1618photography said:
The one thing that digital photographers are doing that film photographers aren’t is checking exposure on the back of the camera. It’s possible that he’s adjusting ISO and or shutter speed.

"I have a leaf shutter lens so no sync problems. The meter I have is a Sekonic Flashmate L-308S and will be using HP5 rated at ISO 200."

And again, what you are doing will work, but it's a really hard way of doing it when there is a much more simple way. It's especially hard if you have multiple manual flash heads setup, have already balanced them between each other and just want a bit more ambient. It's like trying to drive a stick shift car using your left foot for the brake and the clutch. If we are talking using a digital camera using something like nikon's iTTL system, that's a whole different discussion, but we aren't.

Metering ambient and flash advice needed

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