F-stops in the studio

Janice

Janice

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Sorry to sound like even more of a twit than usual....... but when discussing studio lighting... they say for instance that you take a reading from the subject's face and it is F14. Then you set up the light which goes onto the white background at 1-2 stops more ie, F11 or F9.

How do you set a light at an F-stop? Do some expensive ones have them on or something? Mine just has full power and a sliding knob down to about 1/4 power.

Or do they mean that I keep the camera on the same settings as i had from the subjects face and flash the background with that light, and if it isnt F11 then make the flash brighter till it is. (in the absence of a light meter that is!)

But if I am using manual on the camera then it will just stay at F14 where I set it wont it?

Sorry! :shrug:
 
Janice, that is the question that I have been asking for a while now. My studio lights just have qtr, half and full. I have been tweaking the background in PS to get the bright white effect. It would be good to get some response to your query from the pros here. Gillian
 
Then you set up the light which goes onto the white background at 1-2 stops more
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That's all there is to it. Just set ther power on that flash so it's 2 or 4 times as bright (one or two stops).

If you were buzzing around the scene with a flash meter, you would be looking for something like f5.6 for your subject and f8 or f11 for the background.

Photography is still full of things that are very simple but always written to sound clever. :cuckoo:
 
dazzajl said:
That's all there is to it. Just set ther power on that flash so it's 2 or 4 times as bright (one or two stops).

If you were buzzing around the scene with a flash meter, you would be looking for something like f5.6 for your subject and f8 or f11 for the background.
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Dazzajl, I hear what you say but how do I set the lights to be 1-2 stops (2 - 4 times as bright)? Are the lights adjustments 1/4, 1/2 & Full representative of stops? Now I am confused... Sorry Janice to hijack your thread, I will shut up and wait for your penny to drop as mine is wedged between the eyes. :help:
 
So is mine! :)

you arent hijacking.... you are saving me asking so many questions!
We can share the stupidity between the 2 of us and we wont sound so silly!!

I think they mean that you power the light brighter and use a light meter on the bg at the moment the flash goes off and it should show 2 stops brighter than the subject.
Its a bit difficult with the camera as that uses reflective metering... and incident is best, where you put the meter against the white backdrop and meter actually what light reaches it.
 
I will shut up and wait for your penny to drop as mine is wedged between the eyes.
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No no, keep asking until someone explains it properly. That's the whole point of a forum surely.

The power settings on the flash heads do indeed increase and decrease the brightness by stops. 1/4 up to 1/2 is onw stop brighter, 1/2 to full is a stop further.

Distance from the flash to the surface it's lighting also changes the brightness too. Double the distance and you 1/4 the brightness. So if the subject and background lights are the same brightness you can still have a 2 stop difference by moving the subjects lights twice as far from the subject as the background light is from the background.

Hope that makes a little sense.
 
Keltic Ice Man said:
so if you have 2 lights - would 1 be on the background and one on the subject? The one on the background perhaps on full power, and the one on the subject half power?

Sorry trying to learn quickly on this subject
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Well thats what I do, yes .... but struggling to get the powers right. the bg one doesnt seem to make it bright white enough.
 
You can move the lighting nearer/further to and from the subject/background
until you get the correct setting.
 
Yes but you cant move the bg one farther away or it is then in front of the subject! Unless of course you have a huge studio! :)
 
If you can't move the BG one further away can't you just turn the power down a bit?
 
The power is fully down most of the time anyway!
Also to remember that further away means harsher light too... although less bright it is harsher.

Closer = more diffused.
 
Janice said:
The power is fully down most of the time anyway!
Also to remember that further away means harsher light too... although less bright it is harsher.

Closer = more diffused.
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By harsher you mean stronger shadows I guess. When you move a light away you are making the light source smaller so it casts a harder shadow. With the light closer the direct light comes from the width of the lamp and therefore makes softer shadows.

Some diffusing film in front of the main lights would dim them and diffuse the light. I have some lee filter opal frost (think that is what it was called - it is whitish opal polycarbonate 0.5mm thick) film on 4 foot wide rolls if you want to try some Janice. I might be heading your way in the next week or so too.
 
Try using some white cloth to diffuse the light.
This will also help reduce the output.
 
Thanks for your ideas everyone. At the moment, my problem is getting the light onto the white background to be bright enough to make it really white.

The other studio flash which goes onto the subject is set to flash away from the subject and bounce into a white brolly and reflect back so that doesnt seem to be too much of a problem at the moment.

TBH although a conservatory seems an ideal place.... there is probably actually too much light everywhere bouncing about, polycarbonate roof, glass on 2.5 sides. Just get it all sorted then the sun comes out! :D :lol:
 
Janice said:
TBH although a conservatory seems an ideal place.... there is probably actually too much light everywhere bouncing about, polycarbonate roof, glass on 2.5 sides. Just get it all sorted then the sun comes out! :D :lol:
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Your 'studio' sounds the same as mine - a conservatory! know what you mean about the Sun coming out. :thumbsdown: Mine is worse, as I pull the Terracotta coloured blinds down to stop the beaking neighbours and Sun and end up with very warm skintones. :bang: :bang: :bang: :lol:
 
The other studio flash which goes onto the subject is set to flash away from the subject and bounce into a white brolly
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Is it set to the minimum outout though? If it can still be turned down a bit then the bg light can stay as it is. All you need is difference in brightness, you can adjust the aperture to make sure the subject is still where you want it.

This is where lower power lights do start to limit you though. If you can ony get the bg lit to require f5.6 for example, then you need to get the light on the subject down to f2.8ish to be sure of a pure white bg with no detail. Now for one you may not have an f2.8 lens and even if you do, more than one person in shot and the DoF could become a real problem.

Of course you can always ramp up the ISO and deal with the problems you get there in processing later.
 
What we get told to do in college is to set the lights up with modeling light and adjust the lights to suit what we want i.e central frontal lighting, side lighting? once that is done we then take readings from the light, in the studio shutter speed does not matter that is set to something fast 1/250th. We take our readings with a light metter in flash mode, you don't get a shutter speed just an f-number whatever f-number your get you set that on your camera e.g f16 on the flash meter, f16 on your camera.

If your using two lights you take each reading on each light and set the lights up how you want to use them. If you wanted a background or hair light you would take the reading in the same way and set the power till the reading on your flash meter was the same as 1 or 2 stops under your main light e.g main light F16 set our background light to F11 or F8 and your camera is set to the same as your main light (F16).

I've done my best to explain this I hope that it helps :)

Ally
 
Janice said:
Thanks for your ideas everyone. At the moment, my problem is getting the light onto the white background to be bright enough to make it really white.

The other studio flash which goes onto the subject is set to flash away from the subject and bounce into a white brolly and reflect back so that doesnt seem to be too much of a problem at the moment.

TBH although a conservatory seems an ideal place.... there is probably actually too much light everywhere bouncing about, polycarbonate roof, glass on 2.5 sides. Just get it all sorted then the sun comes out! :D :lol:
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What heads are you using?
 
A 150w head with a brolly and a sigma 500 dg super wirelessly onto the background.

I cant get to grips with all this. :( Im wondering how continuous lighting would suit me.
Heat wont be a problem as I have 3 outside doors in the conservatory.
White balance can be changed in RAW later.

Is it easier??
 
Janice said:
A 150w head with a brolly and a sigma 500 dg super wirelessly onto the background.

I cant get to grips with all this. :( Im wondering how continuous lighting would suit me.
Heat wont be a problem as I have 3 outside doors in the conservatory.
White balance can be changed in RAW later.

Is it easier??
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Sounds like you just dont have the power needed to light up the background,I don't know a lot about those continuous lightins sets as I have never used them,are you doing full lengh or head and shoulder shots?It might be worth looking at a bigger flash head?
 
It's mostly kids diving about on a white sheet!

I just dont know where to use the studio flash and where to use the wireless sigma. there is such a combination of choices that I am lost.

i could use the studio flash on the background and the sigma on the camera bouncing off the ceiling.
| could use the studio flash bouncing in brolly on the subjects and wireless sigma on background


My head is spinning! :'( :shrug:
 
Janice said:
It's mostly kids diving about on a white sheet!

I just dont know where to use the studio flash and where to use the wireless sigma. there is such a combination of choices that I am lost.

i could use the studio flash on the background and the sigma on the camera bouncing off the ceiling.
| could use the studio flash bouncing in brolly on the subjects and wireless sigma on background


My head is spinning! :'( :shrug:
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I would try the studio flash on the background.:)
 
Ally said:
What we get told to do in college is to set the lights up with modeling light and adjust the lights to suit what we want i.e central frontal lighting, side lighting? once that is done we then take readings from the light, in the studio shutter speed does not matter that is set to something fast 1/250th. We take our readings with a light metter in flash mode, you don't get a shutter speed just an f-number whatever f-number your get you set that on your camera e.g f16 on the flash meter, f16 on your camera.

If your using two lights you take each reading on each light and set the lights up how you want to use them. If you wanted a background or hair light you would take the reading in the same way and set the power till the reading on your flash meter was the same as 1 or 2 stops under your main light e.g main light F16 set our background light to F11 or F8 and your camera is set to the same as your main light (F16).

I've done my best to explain this I hope that it helps :)

Ally
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Thank you Ally, Ive only just read this. It is much clearer now... I will have a practise tomorrow.
Its little things like the front light spilling behind the subject and onto the background which you have already metered before on its own....that will now change wont it.... if the front light is on it too?
 
Janice said:
Thank you Ally, Ive only just read this. It is much clearer now... I will have a practise tomorrow.
Its little things like the front light spilling behind the subject and onto the background which you have already metered before on its own....that will now change wont it.... if the front light is on it too?
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if your using central frontal lighting light will spill on to the background, but if you use central side lighting it will not spill on to your background and you can then use a hair light or background light. HTH ally :)
 
Janice - have you read this month's Digital SLR Photography? If not, pages 76-81 are all about the different studio setup. It gives examples of settings that worked and those that didn't. Also, how to capture perfect Whites with the background. If you are unable to get a copy of the mag, pm me and I will photocopy and pop in the post to you. :)
 
Ah thanks Gilly. I will have a look and see if I can find it. Sounds like just what we need, you and I.!!:thumbs:
 
Janice said:
Ah thanks Gilly. I will have a look and see if I can find it. Sounds like just what we need, you and I.!!:thumbs:
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Phew! flipping eck, Janice I'm exhausted, what with this thread and the metering one you have going I having trouble keeping up. I had a similar problem with the Canon ST-E2 wireless trigger. It had a pre flash sensor that triggered my Portaflash heads to fire nanoseconds before the shutter went off. This ended up with me having black images. Result was I sold the ST-E2 and bought a mini-magic radio trigger and haven't looked back.

Going back to this thread. I am going to practice in my glass house over the weekend and try and adopt the advice from our very patient peeps on this site. If you are thick, then I must be 'set'. :cuckoo:

When this is over, we must post our efforts - Yeah, right! :thumbs:
 
We will! All I want is a good portrait shot with a nice white bg with hardly anything needing to be done to the white bg in photoshop!
Although you might hve to give me a while as I think my sync lead is knackered!
The 180W light doesnt work with the sync lead, but does with the infra red light on the top, and with the button to flash.
So, new lead.... then away we go!! :D
 
Janice said:
We will! All I want is a good portrait shot with a nice white bg with hardly anything needing to be done to the white bg in photoshop!
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Here! Here :bang: :bang: :bang:
 
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