Duane D. Loc: Kalkaska, Michigan

I have always faced my umbrellas open toward the subject opposite of the diagram. Am I nuts?
Duane D.

REJ Loc: Ontario Canada

My old fuzzy brain likes the diagram much better then lots of words. Good input. TK's

rpavich Loc: West Virginia

Do you mean that the key light is on camera right and not camera left, and that the fill is on camera left and not camera right?

Shakey Loc: Traveling again to Norway and other places.

I'll second that!

:thumbup: :thumbup: :thumbup:

Fotoholic Loc: Austin, TX

I like it!I am going to have to try it, thanks. What book were you reading

rpavich Loc: West Virginia

100% reliable flash photography

by Ed Verosky.

charryl Loc: New Mexico, USA

Thanks so much for posting. Just started a portraiture class today and that is exactly the lighting results I wanted to try to achieve.

Fotoholic Loc: Austin, TX

Thank you, I am going to check it out, looks like there is some good information

rpavich Loc: West Virginia

Very good! Post some of your results here when you do!

Macbadger Loc: Illinois

Ditto.

ianhargraves1066 Loc: NEW SMYRNA BEACH, Florida

Great portrait and the system works as you can see. One minor problem is in the math in that the second light at 6 feet is ineffect not half as bright! All artificial light sources work the same way as far as exposure goes. Unfortunatly digital only users are spoiled by having auto flash exposure so never ever learned the inverse square law or used guide numbers for calculating correct exposure.

All flash equipment has a guide number. A typical guide number might be 96. To get exposure spot on you measure or guess the distance from the light source to the subject, say for example 10 feet, you divide the guide number by the distance and the answer is the F stop you should set. In the above example 96 /10 feet =F9.6 . However if you do the same cal for a subject 5 feet away the answer would be F16.

The problem comes when the distances are closer in the postster's example of 3 and 6 feet you get the following results 96/3 feet = F32 while at 6 feet the calcs are 96/6 feet = F16 which is 2 whole F stops not double .

Look up inverse square laws. But when you get a result like this from a standardized set up who cares about the math haha. When you get it wrong with digital you can see its wrong and fix it, with a sheet of 10x8 film you get it wrong and it cost you in excess of $35 plus your subject has long gone by the time the transparencies are returned from the lab as most of the ex pro photographers will know! Congratulations on the portrait it is superb! Well done.

Ian
http://www.paulcbuff.com/sfe-inversesquarelaw.php



Inverse Square Law
The common misconception is to think that moving a light twice as far from the subject will result in half the light and a one f-stop difference in illumination. This is incorrect.

It must be remembered that light is projected in a 2D pattern – up/down and right/left. If you consider a reflector that illuminates, say, a 10-foot circle at a 10-foot distance, the area illuminated is pi times radius squared or 11,310 square inches. If the distance is doubled to 20 feet, the projected pattern will be a 20-foot circle and the area of that circle will be 45,239 square inches – four times as great as the first example. Since the light must now illuminate four times the surface area, its intensity is one fourth.

Thus the square law propagation of light:
The intensity of light varies according to the square of the change in distance from light to illuminated surface.

So, if you increase the distance by two, the light intensity becomes one fourth – 2 f-stops, not 1f. If you move the light in to one half the distance, the intensity increases by 2 f-stops.

ianhargraves1066 Loc: NEW SMYRNA BEACH, Florida

This post was for Duane but I clicked on the wrong post. Sorry!


No you are not insane haha you can use umbrellas, providing they are the translucent material, either way, the shooting through the brolly produces a softer light and less directional. Try doing it both ways, some umbrella mounts will only let you reflected light forwards though!

Ian

Daryl New Loc: Wellington,New Zealand

Thanks thats great info.

Duane D. Loc: Kalkaska, Michigan

thank you for that as my umbrellas are reflected and light does not go through them. Yes I also like the lighting in the photo very much and if something works I stick with it. lol

rpavich Loc: West Virginia

Oh...lol..you have reflective and not shoot through.

It doesn't matter which umbrella you have...both will work but the results look a little different.