paco_rosso

<p>Look at the eyes, it seems to be illuminated with natural light, in a street. Not a beauty</p>

<p>(Mira los ojos, los brillos delatan una calla en casi todas las fotos, luz natural. No parece que sean beauty).</p>

<p>After all, see this photo, is a beauty (that of bowens) a little far away.<br>

(De todas maneras mira esta foto, es la beauty de bowens pero algo alejada, unos dos metros)<br>

http://www.24x36mm.net/jeyzar/slides/prjeyzar0203_lr.html</p>

<p>The sun throught a blind.</p>

<p>This RF sounds like Profoto have abosrved Creativle Lights ¿Don't you think? Suddenly there is no more Creative Lights and, curiously, Profoto launch exactly the same equipment... Suspicious.</p>

<p>Last week I was shooting a fashion catalogue and use the Bowens octabox. Now I want one for my studio, but ¿What octa to buy?<br /><br />I would loke to hear ("read") from your experience. My laternatives:<br>

Bowens (1,5m)<br>

Creative light (1,5 m) but It seems there is no more Creative lights anymore ¿Are they been abosrbed by Profoto?<br>

Aurora (I think this will be, but... 60cm octa, 90cm octa or 150cm ok ¿Any sugestion?)<br>

Fomex ¿Is thereis anybody who have used the Fomex 150cm octa?</p>

<p>The only way (I think) to get a "open flash" (this technique) with a 1/125 obturation time is to move the camera (or the subject) at a quick speed... (/set mode ironic on) ¿Did you shoot from a car in movemetn? (/set mode ironic off)</p>

<p>In response to:<br>

"<a href="../photodb/user?user_id=5180877">John McCosh</a>, Dec 05, 2012; 12:58 a.m.</p>

<p>This happens in both Landscape and portrait format and only happens when using the wireless flash triggers."</p>

<p>Then I guess it is a delay in the transmission, the flash is emiting light for a long time, ¿Maybe thereis TWO shoots too near in time?</p>

<p>But the receptor can be a simple photoelectric celule, It can detect IR light.</p>

<p>The wireless transmisor is a infrared flash ¿Isn't it? Not a radio one, but a IR flash. (I think the wireless flash system in nikon run in infrared, not in radio, so it can be a preflash exposed by the IR sensitive of the sensor).</p>

<p>Think in a horizontal clock around the model, the six is in the camera, the three in her left shoulder, the nine in her right shoulder, the twuelve in her back.<br>

<br />In the first image you have:<br>

two lamps at 11 and 1 ("kickers"),<br>

One overhead, big, maybe a softbox.<br>

One at the 8, maybe an octabox.</p>

<p> </p>

<p>The real reason for the octabox is the size of the softbox. When you reach about 1 meter in the side the structure becomes less rigid than with other sizes. So the solution is to change the rectangular form to a circular one. The 8 side is the solution, it intercales one sitck beetween two of the rectangular one.<br /><br />The effect is very similar to that of the 1mx1m, but without the chance to change the rendering of the shados when you rotate the frontal plane over the light axis.</p>

<p>Matt, if you get a f:8 at 1 meter then at 2 meters you have a f:4. The consecuence of inverse law is the guide number. Your illustration say at 1 meter, f:8, so that's the guide numbef of this source, at 2 meters, f:4 (because 4=8/2).</p>

<p>What I said about the inverse law and fresnel is a translation of the tables in the ASC Manual to the International System of Units. I calculate the tables as curves, not as tables, as you can see in the Manual. And it is almost a parabolic curve.<br>

Other thing: the data in the ASC Manual are not so correct as it should be. There is some extranges numbers for the more powerfull lamps.</p>

<p> </p>

<p>Fresnel are inverse squared rules. Parabolic, when the lamp is in the parabole focus are not. If you read the tables of the ASC Manual see the fresnel are inverse squared.</p>

<p>You are right, Jay. There is a near field wich is almost lineal, a medium field, where the response of the light is beetween lineal and parabolic and a far field where the response is parabolic. I wrote about this in my book "Técnicas de iluminación en fotografía y cinematogragía".<br /><br />About the light there is TWO laws: the inverse square law and the "solid angle projection".<br>

The inverse aplies when the source of light is caracterized by intensity and the solid angle when the light is caracterized by luminance.<br>

What the solid angle projection say is the illuminance in a point in the space is E=L*w*cos(a)<br>

<br />Where E is the illuminance, L is the luminance of the source, w is the solid angle with vertex in the point of the scene and base the source oflight. a is the angle beetween the axe of the light beam and the normal vector to the plano of measure.<br>

What the law say is: go to the scene and look at the source. Imagine the visual field you have and the portion of this visual field wich is filled ocuped by the source. The proportion beetween the surface of the hemisphere arounds you and the surface ocuped by the source is the proportion beetween the illumination due to the hemisphere and the illumination due to the source of light.</p>

<p>Imagine the girls is in the center of a horinzontal clock. The camera is at 6. One of the light is at 9 and the other at 3 (actually about 1 minute near the 12 in both cases).</p>

<p>I do not thing ina strip light. But the shadows of the feet decay quickly...</p>

<p>The light in this image is the typical light used in dance. In spain we call this a "calle" ("street") o" luz de calle" ("light of street") I do not know the translation in english theatrical argot.<br>

The scene in a theatre scene is divided in rows called "calles" (in Spain), the division are made by vertical panels out of the sight of the public in the sides of the scene. The phocus are bettwen this panels. What you see is the usual light for a ballerina.<br /><br />The spot in the floor I think is made with an spotlight, which has some blades which lets you the form you want to the ligh beams.<br /><br /><br>

As it is in the image is very difficult way to illuminate the figure, for the little size of the coberture. So two posibilities:<br>

a) It is not a scene photo but a studio image (you illuminate the space and put the ballerina there, not illumante the scene and let the ballerina dance).<br>

b) It is a scene photo and there is some postporcess to dark the enviroment.</p>

<p> </p>

<p>Do this:<br>

"As an example, I'm photographing a sunset scene I point my camera at the sky and get my light reading i will use on the camera, then i point it at the bush in the foreground 20 feet away I want the flash to illuminate and get a second reading to see what work the flash needs to do. I get a difference of 3 ev from the sky. how do i convert that into flash settings?"<br>

¿What is the difference beetween the two readings?<br />If difference is 1 stop, then adjust the power of your flash to produce the f number of the figure ("the bush").<br>

If difference is 2 stops, then adjust the power to produce the f number one stop and a half over the figure.<br>

If difference is 3 or more stops, adjust the power to produce the f number you have read in the background.</p>

<p>For example: Background (sky) is f:16. Then:<br>

If figure is f:11, adjust the flash to produce a f:11.<br>

If figure is f:8, adjust in the flash a f:13 (f:11+1/3)<br>

If figure is f:5,6,,. adjust the flash to produce a f:16.</p>

<p>¿How can you adjust your flash?<br>

There is three ways: Change the power,change the distance, change the emision pattern.<br>

CHANGE THE POWER: If you flash can do it change the power.If you have a modern model of flash. Set the flash to maximun power (1:1), now aim the camera to the figure, and press the shutter button, focues the scene. Now in the display of the flash you have the distance where you get the f number adjusted in camera. So, only change the power until you see in the display the distance from the flash to the figure.<br>

If your flash is a old model, without screen, then it has a table. See in the table what is the power to get the f you want for the distance. Or by the guide number: multiply the distance from the "bush" to the flash for the f number you have calculated. It is the guide number you have to use. See the difference beetween this number and the original guide number and that's the amount of power you have to change.</p>

<p>CHANGE THE DISTANCE: if you flash do not can change the power, chage the distance, you know, the guide number again. or the display in a modern flash.</p>

<p>CHANGE THE LIGHT DISTRIBUTION: cover the flash with a fabric, or use a diffuse filter. But you have to know the amount of change in the light you get BEFORE you use it. it is, try in your home first and remember what you achieve.</p>

<p>Yhe power of the flash is related only to the amount the electric energy the unit can store, not the power of light emited. It depends on the light shaper you use, the distance beetween the flash and the scene and what is the enviroment of the scene. You need a flashmeter to know the f light the flash give you.<br>

With the 1mx1m softbox in my black-painted studio I get a f:16 with a Gemnini 500R at a distance of about 2 meters.<br /><br /><br>

The bestu you can do is adquire a flashmeter and measure the light.</p>

<p>Erick, it is a little strange than a t: 1/250 you get a displaced image ¿Could it be a self-shadow of the hand (the dark tone the figure takes when its surface change its angle to the light beam)? (Yur photo of the girl in black gown.<br>

For the red one, it is a gohst... ¿Are you sure it was at 1/250?</p>

<p>I have been writing about this issue in the past, here in photonet and other places.<br>

To equilibrate the ambient light do this:</p>

<p>First: shoot in manual, not in automatic (you can shoot in automatic but the method is slightly different).</p>

<p>FIRST: Read the light (no flash) in the background for a exposure time compatible with flash whooting (p.e. 1/60)<br>

SECOND: Read the light in the figures (with NO flash).<br>

THIRD: Adjust in camera the exposure for the background (f ant t).<br>

FOURTH: Change the f number in camera in this way:<br>

If the difference beetween the figure and background is 1 stop, adjust in the camera the same f number you read for the figure.<br>

If the difference beetween the figure and the background is 2 stops, use in the camera a 1+1/2 stops grater than the figure.<br>

If the difference beetween figure and background is 3 or greater stops, adjust in the camera the same f number you read for the background.<br>

FIFTH: Adjust in the flash the power. To do this aim the camera to the figure with flash on. Focus the figure. Now read in the flash display the distance from the flash to where it will give you the f adjusted in camera.<br>

Change the power until you can read in the flash display the distance beetween the flash and the camera. <br>

So you now have the power adjusted exactly to reinforce the light of the background.<br>

SIXTH: now change the f adjusted in camera to the f for the background.</p>

<p>So, you end with the camera adjusted for the background (f and t) and the flash in manual with the correct power to equilibrate the ambient light (I prefer call this "reinforce the light" than "fill the light").</p>

<p>Thanks John, but I am traying to find the "qualification" in other countries. he qualiiations are a deinfinition of a proffesion to permit the free movement of workers in the european area. Each country of the european community must to write their own "proffesional qualifications" to clera waht some job is. For example, ¿Are the same a plumber in theUK than in Germany than in Spain? The way to know it is the qualification. This is not a title neither a curse, is a denition of the proffesion to let the educational system stablish a target to program the courses.</p>

<p> </p>

<p>I would like to know about the proffesional qualification of photographer in the European Community ¿Is there anybody who can help to find the prof. qualification in Germany, France, UK, England and other european countries?</p>

<p>¿Why do you think 50% is medium gray? You are think in "arithmetical average" but this is "geometrical average".<br>

Think in this way: black is 4%,white is 80%.<br>

The ratio beetween G (medium gray) and B (black) must be the same as the ratio beetween W (white) and G (medium gray) to see the same "jump" in luminosity. It is:<br>

G / B = W / G<br>

So:<br>

G^2 = B * W<br>

So:<br>

G = SQRT (B*W)<br>

If you calculate the square root of 80 and 4 it is 17.88%<br>

You know, almost 18%.</p>

<p>You can translate lux into f and t and iso in this way:</p>

<p>E = 270 * f^2 / (asa * t)<br>

Where E is the iluminance in lux.<br>

f the number f<br>

asa is the asa part of the ISO photographic sensitivity (not the DIN).<br>

t is the exposure time. TIME not Speed. (1/60 not 60)</p>

<p>As rule of thumb: 1000 lux are f:2,8 for t 1/50 with ISO 100/21<br>

(This is the base for cinematography calculations).</p>

<p>BUT: if your lightmeter can measure luminances (what in old photographic books are called "reflected light", actually brillance) then the equation is this:</p>

<p>L = 15.41 * f^2 / (asa * t)<br>

Where L is the luminance in candles per sqare meter (Cd/m2)</p>

<p>I do not understand any ¿Why do you want turns orange the light of a flash? In CTO the O stands for "Orange".</p>

<p>If you are trying to give some yelloish character to your flash best look for a CTS filter than a CTO.<br>

(S for straw).</p>