Paris

The lighting ratio is approximately 1 to 8 in this image, based upon a highlight reading of 243 on the highlight side of her face and a 128 reading on the shadow side (assuming one stop has a numeric value of 32.) A 1 to 8 ratio is rather steep but if lit properly one can "get away with it."







Enjoy!

Benji

Ben Jones said:

The lighting ratio is approximately 1 to 8 in this image, based upon a highlight reading of 243 on the highlight side of her face and a 128 reading on the shadow side (assuming one stop has a numeric value of 32.) A 1 to 8 ratio is rather steep but if lit properly one can "get away with it."

Click to expand...

Hi Benji,

Firstly, I like the portrait but I won't give any C&C on that. What I would like to ask is the following:

Could you please explain how you have come to the conclusion of lighting ratio of 1 to 8? Did you measure the light in the studio with a meter or did you do the math using the numbers your read in photoshop? If the latter, then did you take it into account that those values are gamma curve corrected? In other words, they need to be translated to a linear scale first. As such, one cannot say that a numeric value of 32 is approximately 1 stop. The distribution is not linear. Just wondering...


Cheers,

Hi, Benji,

Ben Jones said:

The lighting ratio is approximately 1 to 8 in this image, based upon a highlight reading of 243 on the highlight side of her face and a 128 reading on the shadow side (assuming one stop has a numeric value of 32.) A 1 to 8 ratio is rather steep but if lit properly one can "get away with it."

Click to expand...

For what it's worth, assuming by the numbers you quote you mean, for example, an RGB of about 243,243,243 in a "highlight" and 128,128,128 in a shadow, and assuming the sRGB color space, then the luminance ratio between the two is about 4:1 (or about 2 stops).

There is no meaning to the notion that "one stop has the numeric value of 32". That suggests that the numbers we see are on a logarithmic scale of luminance, which is not so. (It is actually very near a power function.)

I'd be glad to explain the actual mathematical relationship if you would like.

Doug_Kerr said:

Hi, Benji,



For what it's worth, assuming by the numbers you quote you mean, for example, an RGB of about 243,243,243 in a "highlight" and 128,128,128 in a shadow, and assuming the sRGB color space, then the luminance ratio between the two is about 4:1 (or about 2 stops).

There is no meaning to the notion that "one stop has the numeric value of 32". That suggests that the numbers we see are on a logarithmic scale of luminance, which is not so. (It is actually very near a power function.)

I'd be glad to explain the actual mathematical relationship if you would like.

Click to expand...

Doug,

This is a good opportunity for a clear tutorial on the math of ratios derived from incident or reflective measurements or else sampling points in photoshop. I was actually drafting a long message to you about this math but then I saw that Cem and you were direct and quicker to the draw than I was!

Thanks,

Asher

Hi Ben,

I'd like to comment your picture, first because you seem to appreciate frank speaking, and second because i think we have very different philosophies of photography

So, frankly speaking, i don't really see the interest in your picture. Ok, light is well managed and colors are warm. But, what do you mean with that ? I see a centered girl with a blured background and a halo of vignetting around her, but i don't FEEL any emotion. Common girl with a standard smile, maked-up and well haired. Her pose is quite unatural, due to his straight back. What is the sense, why this ? For me, it is essentially decorative. Good for a wearing catalogue for instance.

Yes, i am frank, but you seem to search that

Regards,

Cedric.

Cedric MASSOULIER said:

Hi Ben,

I'd like to comment your picture, first because you seem to appreciate frank speaking, and second because i think we have very different philosophies of photography

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Cedric,

Your point is excellent and there's a world between observing and making something up that does not exist in life., the fantasy for the girl, the photographer or the woman who reads the magazine.

Ben,

I find the idea of taking this girls picture on this older wooden swivel chair contrast between the older age and departed laughter of people long gone and the immediacy of the young fertile woman.

However, this has two many parts to it. Where should one look? There are limbs everywhere! I don't mind the dark background but I do find the idea n the picture difficult to get because of emphasis in detail that is not needed or distracting.

Asher

Hi Ben,

Thanks for allowing me to present an alternate delivery of your picture. These are just fast edits to give the general idea of removing distraction and enhancing interest.

I hope my changes might fit in with your ideas for this picture. However, you didn't state your purpose for the picture, so I just am working on what's there so my direction could be off mark.




I have brought back the vertical element on the right and the base of the char to provide balance and interest respectively. notice that the left arm is not seen and the right floor is much less important. The hair is better shown as weil as the right shoulder and her waist and the character of the old style chair.

So if I liked this approach, I'd light t that way and then reshoot.

Asher

I am basing my mathematical computation of 32 per stop based on the following: The dynamic range of my DSLR is 8 stops. Dynamic range is the difference in light intensity between the brightest and darkest areas that contain useful detail. We know that anything above 255 is pure white, and anything from 0 to 32 is pure black, so lets divide 255 by 8 and we get 32.

Actually, the sensor is capable of recording more than eight stops, but the CRT cannot show them nor can they be recorded onto photographic paper. So the supposed four stops that are able to be recorded by the sensor are a moot point.

Lighting ratios have been argued for about 100 years or so. Some say a fill light renders a 1 to 1 ratio, then when you add a second light at the exact same power but only on one side of the face we now have a 2 to 1 ratio, 1 from the fill and 1 from the main equals 2. Others say that no it is still a 1 to 1 ratio because both lights are at the exact same power level.

Actually my image appears to be about a 4 or 5 to 1 ratio but to be perfectly honest, my clients don't care, all they want is a nice portrait of themselves or their child.

Benji

Asher,

Your work of removing her left arm has also removed the pyramidal composition of the image. If we are going to remove her arm, I would crop it as shown below.

Benji

Ben Jones said:

Asher,

Your work of removing her left arm has also removed the pyramidal composition of the image. If we are going to remove her arm, I would crop it as shown below.

Click to expand...

Benji



The lighting is also better. The main issue in the beginning is the choice of pose as it's awkward. The may different directions that the arms and legs point to takes one's attention away from her face. Also if the hair and face are both dark, then the picture might be interpreted to be about the limbs, so for example one might have thought of a title, "Arms and Legs" and perhaps, then, with that fame of reference it's no longer awkward. Sometimes, when I pose subjects I suddenly decide to back off and allow them to get comfortable as the pose has become a twisted conflicting and unbalanced mess.

There are some people who, no matter how the move, are always perfect for photography. This is not one of those lucky circumstances. So it's not necessarily the fault of the photographer!

Asher

Hi, Benji,

Ben Jones said:

Asher,

Your work of removing her left arm has also removed the pyramidal composition of the image. If we are going to remove her arm, I would crop it as shown below.

Benji

Click to expand...

That's very nice!

Best regards,

Doug

Thanks Doug.

Too bad she was in short sleeves instead of long sleeves. Had she been wearing long sleeves our eyes would be immediately drawn to her face and they would stay there. As it is all that bare skin on her arm draws our eyes away from her face.

Ben

I like the portrait.

I am confused with the ratios. 1:8 implies, for me, 16x more light! No?
maybe I should crawl back into my den to think this thru!

Regards.

fahim mohammed said:

I like the portrait.

I am confused with the ratios. 1:8 implies, for me, 16x more light! No?
maybe I should crawl back into my den to think this thru!

Regards.

Click to expand...

No, I was wrong. This is more like a 1 to 4 or thereabouts.

Ben

Ben Jones said:

No, I was wrong. This is more like a 1 to 4 or thereabouts.

Ben

Click to expand...

Ben,

What matters is the picture and I like it. You final cut is effective and pleasing. Have you given her copies yet? That's something I try to remember!

Asher