Adding a backgorund light and metering

[TMR Design]

I currently have 2 AB B800's being used as key and fill lights. I want to learn about background and hair lighting. I'll be using my 580EX as the background light and also want to use gels to create colored backgrounds but now the question of how to meter and incorporate that light comes up.

Recently I have started to learn about setting ratios between key and fill and then how to meter the composite light. If I now add a background light is there a formula or partiucular setting I should be using or do I just play with it, make adjustments for effect or desired hairlighting and then take a composite of the whole scene? That doesn't sound right because the background light is behind that spot that the subject would be and where incident light was metered.
Can someone shed some light (eek, a horrible pun) on this subject?

[Benji]

(copy) "If I now add a background light is there a formula or particular setting I should be using or do I just play with it, make adjustments for effect or desired hairlighting..."

If you have a hand held meter simply meter both of them. Meter the background light at the same place that it shows on the image. I have placed a white dot on the image below on the spots on the background where you should meter the background light. Either spot will work. On the hair light, it should meter the same as what the fill light only meters. If you need a bit more for dark hair or a little less for blondes, adjust accordingly.

Benji

[TMR Design]

Thanks Benji but I'm a little unclear as to the position I take the meter reading from. The dots you are indicating are the areas that are lit by the background light but are you mtering at the same distance as the subject or are you stepping back and taking the reading against the background, as you would meter the subject's face?

Once I have reading on the bg light do I average it with the other composite reading? Can you further explain?

In the above picture, are you only using one main light at camera left. I ask because I see one large catch ight in her eyes and I would expect to see 2 if you were using a key and fill? If you're using 2 lights ow do you get just one catchlight?

[Benji]

(Copy) "The dots you are indicating are the areas that are lit by the background light but are you metering at the same distance as the subject or are you stepping back and taking the reading against the background, as you would meter the subject's face?" Place the meter directly against the background so the reading will be of the background light and any spill from the fill or main.

(Copy) "Once I have reading on the bg light do I average it with the other composite reading? Can you further explain?" For a brighter background color the reading should be about the same as the combined main and fill light reading. For a more subdued color back the power down.

(Copy) "In the above picture, are you only using one main light at camera left. I ask because I see one large catch ight in her eyes and I would expect to see 2 if you were using a key and fill? If you're using 2 lights or do you get just one catchlight?" I Photoshopped out the fill light catchlight and enhanced the main light catchlight.

Benji

[TMR Design]

Thank you. I'm just waiting on a lightstand and off camera shoe adapter for my 580EX and I'll let you know the results. This definitely helped.

[Wilt]

Robert,
In using gels on the background (either reflected or shoot thru), I would take a reading with a REFLECTED light meter (a reflected light spot meter would be best if the gelled light is localized and not across the full area of the background!) The brightness, relative to the brightness of the incident reading for the subject, will dictate how luminous the colored background will be. In fact, it would be a good idea to just shoot the background from -3EV to +3EV to see the results of different levels, before the real shoot.

[TMR Design]

Robert,
In using gels on the background (either reflected or shoot thru), I would take a reading with a REFLECTED light meter (a reflected light spot meter would be best if the gelled light is localized and not across the full area of the background!) The brightness, relative to the brightness of the incident reading for the subject, will dictate how luminous the colored background will be. In fact, it would be a good idea to just shoot the background from -3EV to +3EV to see the results of different levels, before the real shoot.

If I use the attachment for the L-358 to measure refected light I don't think that is for spot metering so can I still properly measure this way?

When you say "shoot the background from -3EV to +3EV to see the results...." are you referring to the overall exposure for the entire scene? I'm not sure I'm getting this.

[Wilt]

If I use the attachment for the L-358 to measure refected light I don't think that is for spot metering so can I still properly measure this way?

(I don't own a Sekonic, so I have to assume the attachment is a normal coverage reflected light attachment, and not a 5 or 10 degree spot attachment. Assuming it is the about 45 degree coverage...) If you stand too far back the meter sees the area where there is no/little gelled illumination, so you do not have a good idea of the brightness in the center of the illuminated zone. That is why a spot reading attachment is beneficial, to measure how bright the middle of the gel illuminated area is, for comparison to subject illumination.

When you say "shoot the background from -3EV to +3EV to see the results...." are you referring to the overall exposure for the entire scene? I'm not sure I'm getting this.

I would bet most of you have no clue as to the appearance of the backgroud illumination at different brightness levels. So this is merely a series to help you visualize the result before you have a model. You are shooting 7 exposures of the background only, at -3EV -2EV -1EV 0EV +1EV +2EV +3EV.

Hint: The outcome is from Black to White, with varying degrees of color saturation in between.

[TMR Design]

(I don't own a Sekonic, so I have to assume the attachment is a normal coverage reflected light attachment, and not a 5 or 10 degree spot attachment. Assuming it is the about 45 degree coverage...) If you stand too far back the meter sees the area where there is no/little gelled illumination, so you do not have a good idea of the brightness in the center of the illuminated zone. That is why a spot reading attachment is beneficial, to measure how bright the middle of the gel illuminated area is, for comparison to subject illumination.



I would bet most of you have no clue as to the appearance of the backgroud illumination at different brightness levels. So this is merely a series to help you visualize the result before you have a model. You are shooting 7 exposures of the background only, at -3EV -2EV -1EV 0EV +1EV +2EV +3EV.

Hint: The outcome is from Black to White, with varying degrees of color saturation in between.

Hmm ok let me ask specific questions so I can sort this out.
Regarding the metering of the background....you're saying that is done with spot metering, measuring reflected light, so that means that the meter is pointing at the background. When you say not to stand too far back you mean that I shouldn't have too much distance between the meter and the background. Is this correct?

So does the composite exposure for the subject stay intact and it's not affected by the relative exposure of the background?

Also, would this scenario be an example of why I might want to get a 1°, 5° or 10° spot metering attachment? If I do get this attachment what other applications would it be useful for? Which angle of spot metering would be the most useful if I was to get only one?

[Wilt]

Regarding the metering of the background....you're saying that is done with spot metering, measuring reflected light, so that means that the meter is pointing at the background. When you say not to stand too far back you mean that I shouldn't have too much distance between the meter and the background. Is this correct?

Right. Let me state differently...if the central 3' circle is illuminated brightly with colored light and outside the 3' circle remains dark, why would you want to include the dark area when reading the brightness of the center?!?!?! You wouldn't!


So does the composite exposure for the subject stay intact and it's not affected by the relative exposure of the background?
Right again! Outside the studio, the brightness or darkness of the room 20' in the background does not change the fundamental flash exposure of your subject standing 10' away either. The studio obeys the same laws of physics.



Also, would this scenario be an example of why I might want to get a 1°, 5° or 10° spot metering attachment? If I do get this attachment what other applications would it be useful for? Which angle of spot metering would be the most useful if I was to get only one?


For your purposes I would think a 5 degree is fine. (While I use a one degree in certain situations, understanding the use of that required more insight into metering reflectances of varying levels and interpreting multiple spots, not just one. For that backgroud metering, I put a 5 degree attachment on my flash meter.) You actually can screw up an exposure quite nicely with a poorly understood one degree reading! A 5 degree reading is merely 'reading a more targeted area' than Partial (or 10 degree) or Averaged (45 degree) metering area.

[TMR Design]

Now I understand. Thank you. :cool:

I just checked and the Sekonic spot attachment is around $125. Is there any practical way to meter the background, even if it gives me a rough starting point to make adjustments from, without adding this attachment right now?

[StealthLude]

Now I understand. Thank you. :cool:

I just checked and the Sekonic spot attachment is around $125. Is there any practical way to meter the background, even if it gives me a rough starting point to make adjustments from, without adding this attachment right now?


You dont need a spot meter to meter the bg light. Just use the incident metering (white 1/2 dome) on the L-358 and I hold the light to the backdrop.

I remember another post were we were talkin about ABs and Ratios and how to meter lights with more than one light. You can just add this into your workflow. Meter Main, Meter Fill, Meter BG light. (BG light isnt part of yor primary exposure on the person) so just set it to 1ev less than the total exposure. 1:2 ratio and or adjust accordingly. Thats how ive been doing it.

I dont shoot often, but if there is a better way, someone let me know :D

[Wilt]

You dont need a spot meter to meter the bg light. Just use the incident metering (white 1/2 dome) on the L-358 and I hold the light to the backdrop.

No, no, no, no, no! You are wanting to meter the brightness of the background, not how much light it hitting it, when you are metering a gelled light on the background! After all, a gelled light falling onto a dark gray background is not the same in result as the same gelled light on a white background.

PS By the way, did I say 'No'? ;)

[Wilt]

I just checked and the Sekonic spot attachment is around $125. Is there any practical way to meter the background, even if it gives me a rough starting point to make adjustments from, without adding this attachment right now?

If you walk up the background and measure as small of an area as you can...you can even simply put a telephoto lens on a camera and meter with that!

[StealthLude]

Wilt,

I must be missing something here. Ill be honest, im kinda new with studio lighting as ive only received my alien bees a week or so ago. Maybe you can clear the air for me here.

Ive learned the basics of two light metering here... TMRs post...
http://photography-on-the.net/forum/showthread.php?t=248729

When adding a bg light, id assume you just want to use an incident reading on the backdrop itself... I still want to understand the proper way to meter and set things up, but right now, i am taking the trial error approach thinking i know what im doing, and just adjusting output based on how it looks on my camera LCD.

how is the gelled light comming into play? I assume if you want the backdrop 1ev less than the main two lights, you just check that up with you meter, and you are done... Unless im wrong and please clarify.

[StealthLude]

If you walk up the background and measure as small of an area as you can...you can even simply put a telephoto lens on a camera and meter with that!


I dont see why that would work, since you are only metering the modeling light. I am trying to meter the strobe itself.

I am metering the left and right of the persons head,... and having my bg light strobe go off each time I do it. Im using a radio slave on the light meter to do this.

[Wilt]

I dont see why that would work, since you are only metering the modeling light. I am trying to meter the strobe itself.


Doh, of course you are right! too late in the day, I suppose!

[TMR Design]

Even though I don't have my 580EX wired in to use as a background light I could not resist trying some things I learned here last night so I took one of my B800's and moved it to the back and positioned the other B800 behind a diffuser panel, close to the subject (me) so there was nice, soft light with a soft shadow. I had about 8 feet between the background and subject and about 6 feet from subject to camera.

The B800 in the background was far too powerful, even stopped down all the way but it did let me test what I learned and essentially created 2 seperate exposures... one for the background and one for the subject without spill from either light affecting the metering of the other. I have to say, that's pretty cool. I had to play with the backgorund light a bit to 'tame' the light and I didn't have any snoots or anything to contain the light so it spread quite a bit on the background. I shot for a while, trying many different positions and taking notes along the way and despite the huge power output of the B800 I was still able to seperate it from the exposure of the subject and the pictures came out pretty good, with excellent looking histograms.

Thank god for my modded remote extension or I would be using self timer, manual focus and going nuts. I have to play photographer and subject.

[Benji]

(Copy) "You are wanting to meter the brightness of the background, not how much light it hitting it" Huh? I have been metering my backgrounds for the past 25 years using the KISS method, (Keep It Simple Stupid.) You place the dome of the meter against the background in an area that will show in the final image and take a meter reading. If that reading is more than the combined meter reading of the fill/main lights reading the background will be brighter. If it is less, it will be darker. Simple, quick, and easy. The sitter isn't interested in your multiple meter readings and you using all of your gadgets on her, she is interested in getting a beautiful image of her. I try and do all of this stuff BEFORE she gets there, so I can concentrate on the lighting and pose, not technical stuff. After you have done this several times (hopefully) you will remember that the blue gel on full power on the gray background is bright blue. It is a darker blue on 1/2 power and even darker on 1/4th power.

(Copy) "a gelled light falling onto a dark gray background is not the same in result as the same gelled light on a white background." Correct, the white will reflect the light back toward the subject and rim her hair. Sometimes this looks great. Most of the time it sux!

Benji

[Wilt]

The B800 in the background was far too powerful, even stopped down all the way but it did let me test what I learned and essentially created 2 seperate exposures... I had to play with the backgorund light a bit to 'tame' the light and I didn't have any snoots or anything to contain the light so it spread quite a bit on the background. I shot for a while, trying many different positions and taking notes along the way and despite the huge power output of the B800 I was still able to seperate it from the exposure of the subject and the pictures came out pretty good, with excellent looking histograms.

(Snip) for all the people who debate about whether there is such a thing as buying 'too much light', in trying to have a 'one size fits all' ...yet another example where too much power can be a handicap!

[TMR Design]

(Snip) for all the people who debate about whether there is such a thing as buying 'too much light', in trying to have a 'one size fits all' ...yet another example where too much power can be a handicap!

I'm glad I didn't get a third AB B800 for a background light. The 2 B800's for key and fill are great and give me all the light I need as well as letting me back it off or use modifiers to control it. For my purposes even the B400 might still be too much. I have a feeling that using the 580EX will give me the amount of light and the control I need for background lighting.
Since I haven't played with hairlights yet I don't know what's best.

I suppose heavy diffusion or a snoot of some kind might have worked on the B800 but even at minimum power output it kicks out a ton of light.

[StealthLude]

I'm glad I didn't get a third AB B800 for a background light. The 2 B800's for key and fill are great and give me all the light I need as well as letting me back it off or use modifiers to control it. For my purposes even the B400 might still be too much. I have a feeling that using the 580EX will give me the amount of light and the control I need for background lighting.
Since I haven't played with hairlights yet I don't know what's best.

I suppose heavy diffusion or a snoot of some kind might have worked on the B800 but even at minimum power output it kicks out a ton of light.


I still bought a 3rd light (AB400) to use an either my background light or hair light. The MAIN reason i didnt want to use my 580ex, is really only because if im shooting at an event, I need it on my camera for shooting, and the lack of light modifiers was a problem for me too.

By using grids , color gels, and if you needed to, ND filters , I think the AB400 was a wise purchase.

I also wanted a smaller unit, instead of a 3rd AB800, so if i even wanted to use a AB400 as my main light, for when i want to shoot wide open at f 1.4, 1.8, 2.8 kinda thing.

I dont think the AB800 is THAT powerful, I have found times where im shooting outdoors or in a VERY large room and leaves me wanting more out of a strobe unit. My 4th light, should I ever decide to but a 4th light might be an AB1600 for that just incase.

You can have as many lights as you want, assuming the photog has the skills need to CONTROL the light. I guess w/o control, more lights = more problems ?

[TMR Design]

I still bought a 3rd light (AB400) to use an either my background light or hair light. The MAIN reason i didnt want to use my 580ex, is really only because if im shooting at an event, I need it on my camera for shooting, and the lack of light modifiers was a problem for me too.

By using grids , color gels, and if you needed to, ND filters , I think the AB400 was a wise purchase.

I also wanted a smaller unit, instead of a 3rd AB800, so if i even wanted to use a AB400 as my main light, for when i want to shoot wide open at f 1.4, 1.8, 2.8 kinda thing.

I dont think the AB800 is THAT powerful, I have found times where im shooting outdoors or in a VERY large room and leaves me wanting more out of a strobe unit. My 4th light, should I ever decide to but a 4th light might be an AB1600 for that just incase.

You can have as many lights as you want, assuming the photog has the skills need to CONTROL the light. I guess w/o control, more lights = more problems ?

Hi StealthLude,

Based on what you're describing I could see why the B800 is not THAT powerful. As of right now all applications for me are in my home studio which is fairly limiting in size so when I turn the B800's up to around half power or more it is very powerful.
I would have to actually try a B400 to see if it would be good as a background light but I think as a means of getting things going and having the control I want the 580EX will be fine.
It's important to understand that I am not a pro, nor do I have clients. Everything I am doing is for me, my friends, some people that might pay for some things, but mostly my own personal use, enjoyment and self gratification.....that being said...my needs become a bit different from those that need portability or shoot outdoors, events, or ad work.

I suspect my entire approach would be different if photography was my profession and that is how I made my living.

[StealthLude]

Just for the record photography isn’t my day job either. I have a full time job as a salesman but I love photography. Its my hobby, I don’t have a client base and most of the shooting I do is also for myself.

I do however take on the occasional, “hey shoot this for me” or “ can you do our family portraits” And when I get those requests, I end up charging for the skills I have acquired in both photography and post processing/Photoshop. This is an expensive hobby, and im sure we all love to buy expensive gear, and its nice to make a few hundred on a weekend to pad that lens purchase or light purchase we just made.

I do however plan on using photography as my fall back career should anything happen to my day job. For that reason I dont feel guilty to spending what my budget can afford on photography gear.

[TMR Design]

When you were referring to the power level were you using the B800's on an outdoor shoot or was that in your home/studio? If in your studio, how big is your space?

[StealthLude]

When you were referring to the power level were you using the B800's on an outdoor shoot or was that in your home/studio? If in your studio, how big is your space?

Keep in mind I had these challenges when I only had one AB800 unit. And was a total noob at the time as well. Not much experience with both lighting and metering.

I was using the AB800 outside as a fill flash for one of my uncles anniversary parties.. It did the job, but I had to mix flash with ambient light into my exposure calcs. I can’t remember the details, but if I wanted to overcome the son all together it was very hard. I got really fussy after I set it all up since the lighting was uneven, and I was getting shadows. So I put the AB800 away and took out the 580ex and Two 420ex slaves and used those with brollys. It was a mix of ambient + flash still, but no shadows =)

For my, the AB800 takes care of 80-90% of all my needs. IMO its a great all around sized light.

When my brother had his high school prom going on, I took al of their pictures in the living room of the house, about 3-4 people with only ONE AB800 and a 60" brolly. At that point, I was trying to shoot around f/8 - f/11 but since it was a while ago, I cant remember the details. I had to out the light kinda far away to cover as much of the kids evenly as possible. I think I ended up shooting at f 5.6 or something like that.

Shots still came out good, but at that point I was done with having just one light. Which is why I sold my 420ex slaves and ordered 2 more AB lights.

[StealthLude]

Id say details of my space for the prom picts was about room thats 10 feet wide by 20-25 feet deep..... Just trying to give you a guess idea.


There wasnt anything wrong with just one light... I just didnt like how i had to position it all the time.. the shadows on the backdrop just didnt fly with me. So I wanted a background light, and a fill light.

[TMR Design]

Id say details of my space for the prom picts was about room thats 10 feet wide by 20-25 feet deep..... Just trying to give you a guess idea.


There wasnt anything wrong with just one light... I just didnt like how i had to position it all the time.. the shadows on the backdrop just didnt fly with me. So I wanted a background light, and a fill light.

I completely understand. The room I am using as my studio is about 10 ft x 14 ft and there is a hallway that, when I need to , I can move with the camera and back up another 8 feet, also allowing me to further distance the subject from the background.

I like how one large soft light looks on a subject but from what I've done so far it looks the best when the light and diffuser are close to the subject (one person, head and shoulder shots) so that is why I got a second light for fill. As you know, its a money pit and endless cycle because once I added the fill light I then became interested in background lighting so now a third light comes in to play. I would like to make a very large diffuser panel and try doing larger and full length shots with the one light. I'm not sure if there are technically correct angles to use but when I use the one light I move the light from its normal 45° angle off camera axis to about a 30° angle off camera axis and the lighting looks smoother and softer across the face.

[StealthLude]

Sonuds like I was doing the same thing when I had just one light. I was trying to keep the light as center as possible. If i was standing right in front of the subject, I usually had the light almost directly to my left or right. Id say about 15-20 degrees from center.

I have a habit of putting the light kinda far from the subject. I did take a studio class once and the instructor put the softbox so close to the model I was suprised. Guess I got a lot of things to try out.

[Benji]

My background light is a little inexpensive unit from Photographer's Warehouse. It has a gel holder and is quite small but is fairly powerful (150 Watt seconds I think.)

Benji

[TMR Design]

Benji,

Do you have a link? I always like to see these things.