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FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 24 Feb 2018 (Saturday) 04:57
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FerozeK
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Feb 24, 2018 04:57 |  #1

I current use Elinchrom 500w lights as my main lights, and an old Falcon Eyes 150w as a background light with barndoors. Im not getting the effect I would like on the background for portraits. Im considering getting the Elinchrom dlite one with background reflector. I got a Elinchrom skyport plus with the ELC Pro kit.

1)Will the Skyport fire the ELC's and the Dlite together as opposed to me firing the falcon eyes as a slave currently?

2) Will the 100w's of the dlite be that much less noticeable power loss as opposed to 150W of the falcon eyes?

3) What is the normal power difference of the main to background light?

I'm normally using the setup for school photos, headshots.... mostly




  
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Wilt
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Post edited 9 months ago by Wilt. (2 edits in all)
     
Feb 24, 2018 11:18 |  #2

Ferozek wrote:
2) Will the 100w's of the dlite be that much less noticeable power loss as opposed to 150W of the falcon eyes?
3) What is the normal power difference of the main to background light?

A2) If 500w-s is the Main light, a delta from150w-s to 100w-s is miniscule! The change is not A vs. B (-33%), but the relative power of Main-vs-A and the relative power of Main-vs-B

0EV 500 w-s
-1EV 250 w-s
-2EV 125 w-s

...so 150 vs. 100 w-s power is roughly between 1/3 EV to 1/2 EV change in intensity compared to Main.

A3) There is no 'normal difference', there is only what you wish to achieve photographically.
If shooting B&W, it is important to get TONAL DIFFERENCE to 'separate' the main subject from the background so the subject does not disappear into the bacground. That is a reasonable principle to follow for color photos, too.
You also do not want to distract the viewer's attention from the sublect with either a too bright background, or with a cluttered background.


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FerozeK
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Feb 24, 2018 12:29 as a reply to  @ Wilt's post |  #3

Im trying to get a better separation from the background. Im limited with the space provide to do the shoots at the schools so cannot always get a lot of distance between the student and the background, thought a reflector would look better, or maybe a grid? I'll set up my gear and play with the ratios a but tomorrow. Thanks




  
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Wilt
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Feb 24, 2018 13:31 as a reply to  @ FerozeK's post |  #4

Keep in mind that distance = falloff of intensity !

If your source is not 'virtual point source', falloff of intensity is per 'Inverse Square'

    ...double the distance, 1/4 the intensity
  • If light to subject is 2', two feet back from subject (4') is -1EV, 3.6 feet back from subject (5.6') is -2EV
  • If light to subject is 5.6', 2.4 feet back from subject (8') is -1EV, 5.5' feet back from subject (11') is -2EV,


If your light-to-subject distance is >3 * largest dimension of modifier, the falloff of intensity is closer to 'Inverse Linear'

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FerozeK
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Feb 24, 2018 14:05 as a reply to  @ Wilt's post |  #5

If your light-to-subject distance is >3 * largest dimension of modifier, the falloff of intensity is closer to 'Inverse Linear'

My octa is 70cm/27.5", so are you saying I should keep the lights within 2m/6 feet of the subject and 1m/3 feet of the background?




  
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Wilt
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Post edited 9 months ago by Wilt. (3 edits in all)
     
Feb 24, 2018 14:15 |  #6

FerozeK wrote in post #18571290 (external link)
If your light-to-subject distance is >3 * largest dimension of modifier, the falloff of intensity is closer to 'Inverse Linear'

My octa is 70cm/27.5", so are you saying I should keep the lights within 2m/6 feet of the subject and 1m/3 feet of the background?


I am not recommending a distance where anything should be, per se.

I am merely identifying the fact that if your Octa is 28", as long as it is within 56" of the subject the light does not fall off in intensity as rapidly as the Inverse Square law would predict.

If your subject is 48" away, if your background is doubling the distance (at 96") will merely have the light fall off about -1EV
Inverse Square law would predict that with 48", if your background is doubling the distance (at 96") a virtual point light source would be -2EV in strength


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FerozeK
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Feb 24, 2018 14:23 as a reply to  @ Wilt's post |  #7

I think I'm with you so far.....

What ratios can I apply to work out the distance between the subject and the background if I maintain a distance of roughly 56" from the octa to the subject?

I dont need exact figures....just a rough idea




  
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Wilt
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Feb 24, 2018 15:14 |  #8

FerozeK wrote in post #18571309 (external link)
I think I'm with you so far.....

What ratios can I apply to work out the distance between the subject and the background if I maintain a distance of roughly 56" from the octa to the subject?

I dont need exact figures....just a rough idea

To achieve what end?


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FerozeK
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Feb 24, 2018 15:43 |  #9

Wilt wrote in post #18571352 (external link)
To achieve what end?

At the moment my photos lack a bit of contrast, the tips of the wisps of hair seem burnt out. It appears as the background is way too bright. What I would like to achieve is well exposed photo, with good contrast and hair detail on the outer fringes. The background can be a plain white or grey but I would really like to get that oval graduated halo behind the head with the least amount of photoshop, I would really like to get it right in camera and reduce the amount of time I spend correcting the contrast




  
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Left ­ Handed ­ Brisket
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Feb 24, 2018 16:07 |  #10

I think maybe you are trying too hard.

https://photography-on-the.net …showthread.php?​p=17245532

You could rig up a snoot, or maybe something like the above to help control the light. Since the background is flat, using a soft box isn't necessary. Hard (small source) or soft light (large diffused source) will look the same. The goal is simply to control the edges.

Can you link to a photo of your light? I could give a better idea of what would work if I could see what you are working with.


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FerozeK
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Feb 24, 2018 16:17 as a reply to  @ Left Handed Brisket's post |  #11

I feel if you paying me to do something I should put the maximum effort into it. Its not about the money, I just always try hard at everything

That is more or less what I'm trying to achieve

I'm using this currently http://www.benel.eu …studio-flash-ss-150d.html (external link)




  
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Wilt
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Post edited 9 months ago by Wilt. (3 edits in all)
     
Feb 24, 2018 16:22 |  #12


  1. Blown out hair wisps is not a background exposure thing, it is a hair lighting issue
  2. Hair which is 'lost in the background' is a relative lighting intensity thing, and I would suggest (as a start) simply lighting the b/g to a differential of 1EV compared to the hair color.



Let us assume 'blonde' is +1.5EV compared to 18% tonality, brunette is same as 18% tonality, 'raven' is -1EV compared to 18% tonality (and your exposure is set to capture 18% tonality at its inherent brightness)
Let us also assume that we let -1EV falloff illuminate the b/g, and the b/g is an 18% tonality b/g roll
  • blonde is at +1.5EV, b/g is at -1EV: should be no problem as there is 2.5EV of 'separation' in tones
  • brunette is at 0EV, b/g is at -1EV: should be no problem as there is 1EV of 'separation' in tones
  • raven is at -1EV. b/g is at -1EV: problem that hair disappears into background tonality. solution is to light hair brighter, OR light background brighter


Now let us instead assume that we separately light to illuminate the b/g at +1EV, and the b/g is an 18% tonality b/g roll
  • blonde is at +1.5EV, b/g is at +1EV: problem that hair disappears into background with a differential of only 0.5EV tonality. so I would try to reduce the b/g by -0.5EV or more, by moving the b/g away from its own light by doubling its distance (not being analytical in this distance, merely moving it so that it falls off enough...I would meter before and after to achieve at least 0.5EV reduction in intensity at the background)
  • brunette is at 0EV, b/g is at +1EV: should be no problem as there is 1EV of 'separation' in tones
  • raven is at -1EV. b/g is at +1EV: should be no problem as there is 2EV of 'separation' in tones

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FerozeK
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Feb 24, 2018 16:30 as a reply to  @ Wilt's post |  #13

Thank you so much. I need to go test this. 98% of my customer base has black hair, so I should be work out a setting much easier now




  
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Wilt
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Feb 24, 2018 16:36 |  #14

What I described in post 12 was merely to illustrate fundamental principles. If you use a hairlight on any of the three hair colors, you have to consider what happens in the highlights of the hair, both in terms of control of not blowing out hair, and in terms of tonal differences to the background and its lighting. More complexity, same principles.


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FerozeK
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Feb 24, 2018 16:47 as a reply to  @ Wilt's post |  #15

I mostly get what you saying, its just going to be easier for me to try it out than trying to envision it in my mind. I would really not want it to get more complex until I put in a bit more practice. You can watch a lot of vids, ask a lot of advice but I learn better when I actually do it




  
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