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defocus a fresnel


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#1 Sing Lo

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Posted 23 July 2006 - 09:50 AM

Hi, This is my first post. I am a still photographer and lurker here, trying to learn and seek inspirations from cinematographers. I am a big fan of hard lights. I have been researching and practising the lighting techniques of 1930-40 Hollywood Silver Screen style still portraits. I have a 14" and 8" fresnel spot attachments for still photography strobes.
I hardly found any information on fresnel usage techniques in still photography forums; most folks there only know how to use soft lights.

I have read a literature somewhere that a fresnel spot can be made out of focus or defocused and the feathered beam can be used to light the subject. I am very familar with the technique of feathering but I can't get round in my head how can you make a fresnel out of focus?????

in other words: What is the exact definition of a fresnel being in focus??? :unsure:

You cannot say a fresnel is in focus or out of focus by looking at the shadow sharpness, because the shadow definition depends on several factors: the shadow sharpness is continuously changing from soft to hard when it is moved from spot to flood positions, and also it is affected by the subject-to-light distance and the size of the fresnel lens. Unlike a hard-edged spot attachment for gobo projection, a fresnel has a gradual soft beam edge, so the concept of a out-of-focus fresnel is very puzzling for me. thanks.
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#2 Tim J Durham

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Posted 23 July 2006 - 10:20 AM

Hi, This is my first post. I am a still photographer and lurker here, trying to learn and seek inspirations from cinematographers. I am a big fan of hard lights. I have been researching and practising the lighting techniques of 1930-40 Hollywood Silver Screen style still portraits. I have a 14" and 8" fresnel spot attachments for still photography strobes.
I hardly found any information on fresnel usage techniques in still photography forums; most folks there only know how to use soft lights.

I have read a literature somewhere that a fresnel spot can be made out of focus or defocused and the feathered beam can be used to light the subject. I am very familar with the technique of feathering but I can't get round in my head how can you make a fresnel out of focus?????

in other words: What is the exact definition of a fresnel being in focus??? :unsure:

You cannot say a fresnel is in focus or out of focus by looking at the shadow sharpness, because the shadow definition depends on several factors: the shadow sharpness is continuously changing from soft to hard when it is moved from spot to flood positions, and also it is affected by the subject-to-light distance and the size of the fresnel lens. Unlike a hard-edged spot attachment for gobo projection, a fresnel has a gradual soft beam edge, so the concept of a out-of-focus fresnel is very puzzling for me. thanks.

There are many different sorts of lenses for fresnels. Some lenses scatter the light, others "focus" it into a beam. I'm not sure that "focus" is the best term, maybe concentrate. What is it you want to do?
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#3 Chris Keth

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Posted 23 July 2006 - 01:06 PM

There are many different sorts of lenses for fresnels. Some lenses scatter the light, others "focus" it into a beam. I'm not sure that "focus" is the best term, maybe concentrate. What is it you want to do?



I would guess that "focused" in this case means "full spot." If that's not it, someone doesn't know what a fresnel is.
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#4 Stephen Williams

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Posted 23 July 2006 - 01:22 PM

I would guess that "focused" in this case means "full spot." If that's not it, someone doesn't know what a fresnel is.


Hi,

Wide open is the hardest light, so maybe that is what is meant by focused.

Stephen
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#5 Hal Smith

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Posted 23 July 2006 - 01:36 PM

I have read a literature somewhere that a fresnel spot can be made out of focus or defocused and the feathered beam can be used to light the subject. I am very familar with the technique of feathering but I can't get round in my head how can you make a fresnel out of focus?????

I'm guessing that your reference was talking about using the "fuzzy" edge of a fresnel beam to light perhaps a face. The edge of a fresnel's beam has a rapidly changing light gradient, one could light a face from the front and have one side of the face brighter than the other, a different "look" than side lighting a face. I'm not certain if that would be usable in motion photography where precise positioning as in a still studio isn't as practical. I'd be more apt to try scrims to attain such a look. But it's certainly an idea and something I'm going to test.
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#6 Sing Lo

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Posted 23 July 2006 - 02:59 PM

I'm guessing that your reference was talking about using the "fuzzy" edge of a fresnel beam to light perhaps a face. The edge of a fresnel's beam has a rapidly changing light gradient, one could light a face from the front and have one side of the face brighter than the other, a different "look" than side lighting a face. I'm not certain if that would be usable in motion photography where precise positioning as in a still studio isn't as practical. I'd be more apt to try scrims to attain such a look. But it's certainly an idea and something I'm going to test.



I first read about the description of "defocused spot" in "Hollywood Portraits" by Roger Hicks and Christopher Nisperos; can be bought from Amazon:

http://www.amazon.co...0...ce&n=283155

Here a paragraph from the book:

"Feathering: Very often, though far from invariably, movie stills were not made with spotlights focused tightly and shining directly onto the subject. Rather, the spot was defocused somewhat, and the edge of the light beam was used, a technique known as feathering."

After thinking about it, I believe " defocusing a spot" means setting it to flood position in Roger Hicks' own terminology, which is misleading and incorrect in my opinion. A fresnel is not out of focus even in full flood position for sure!

I often use feathering technique with softboxes and beauty dishes to create controlled fall-off and dramatic transitions from highlights to shadows on people's face or to accentuate texture of the clothes. I am yet to try it with fresnel. But I would imagine a double open scrim can do the same job, even though the shadow-highlight edge transfer is not neccessary the same effect as feathering.
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#7 Sing Lo

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Posted 23 July 2006 - 03:18 PM

There are many different sorts of lenses for fresnels. Some lenses scatter the light, others "focus" it into a beam. I'm not sure that "focus" is the best term, maybe concentrate. What is it you want to do?




Yeah, I own two type of fresnels and they behaves very differently; my 14" fresnel has conventional focusing by moving the lamp backward or forward relative to the lens like what you use in cinematography. The 8" fresnel has variable iris focusing system which I have never seen being used in motion picture. In convetional focusing fresnel, the light quality is soft and brighter in spot position with soft shadows; the light is hard and dimmer in flood position with hard shadows. This is to do with the change in apparent size of the light sources when you move the lamp closer or far away from the lens. Now the interesting thing is that the irs focusing fresnel behaves the exactly the opposite; the light is hard and dimmer at the spot position with sharp shadows, the light is soft at full flood!!
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#8 Chad Stockfleth

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Posted 23 July 2006 - 04:46 PM

...the light is hard and dimmer at the spot position with sharp shadows, the light is soft at full flood!!


Am I missing something? This is how I would expect a fresnel to act.
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#9 Sing Lo

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Posted 23 July 2006 - 06:34 PM

Am I missing something? This is how I would expect a fresnel to act.


Well, the explaination is: In conventional fresnel, the lamp is very close the the lens at full flood position. If you look at the fresnel lens with a sun glasses, you can almost see the bright shape of the lamp itself at full flood. So the apparent size of the light source is almost same as the lamp. Now the hardness of the light and the sharpness of the shadows depend on the size of the light source. At flood position, the light is harder and dimmer.If you set the fresnel to spot, you can see the whole lens is bright so the size of the light source is the same as the diameter of the lens. At spot position, the light is softer and brighter. People think the shadows of fresnel set to full spot is sharper with naked eyes, because the contrast between the highlight and shadows is larger when the beam is brighter.

With iris focus fresnel, the distance between lamp and lens is fixed. The spread of the beam is controlled by variable size iris that looks the same the as the aperture blades in a camera lens. At spot position, the iris is closed down to smallest hole, so only the inner circles of the fresnel lens is being used and the apparent size of the light source is small and hence hard light...etc and vice versa. ...at least this is my theory anyway.
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#10 Alex Haspel

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Posted 24 July 2006 - 05:39 AM

Well, the explaination is: In conventional fresnel, the lamp is very close the the lens at full flood position. If you look at the fresnel lens with a sun glasses, you can almost see the bright shape of the lamp itself at full flood. So the apparent size of the light source is almost same as the lamp. Now the hardness of the light and the sharpness of the shadows depend on the size of the light source. At flood position, the light is harder and dimmer.If you set the fresnel to spot, you can see the whole lens is bright so the size of the light source is the same as the diameter of the lens. At spot position, the light is softer and brighter. People think the shadows of fresnel set to full spot is sharper with naked eyes, because the contrast between the highlight and shadows is larger when the beam is brighter.

With iris focus fresnel, the distance between lamp and lens is fixed. The spread of the beam is controlled by variable size iris that looks the same the as the aperture blades in a camera lens. At spot position, the iris is closed down to smallest hole, so only the inner circles of the fresnel lens is being used and the apparent size of the light source is small and hence hard light...etc and vice versa. ...at least this is my theory anyway.


this is all right.
it has also been partially discussed here:
http://www.cinematog...showtopic=15250
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#11 Chris Pritzlaff

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Posted 24 July 2006 - 06:21 AM

"Feathering: Very often, though far from invariably, movie stills were not made with spotlights focused tightly and shining directly onto the subject. Rather, the spot was defocused somewhat, and the edge of the light beam was used, a technique known as feathering."


what is being said here is that the edge of the beam of light is used on the subject, so the light is not "focused" or aimed directly at the subject. The light is aimed slighty away and the edge of the lights beam is hitting the subject. Im not sure why this would be done since I don't think this would make the light any softer. My only thought would be that it would perhaps reduce contrast as seemed popular in the stills of the old movie stars.
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#12 Sing Lo

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Posted 24 July 2006 - 08:36 AM

what is being said here is that the edge of the beam of light is used on the subject, so the light is not "focused" or aimed directly at the subject. The light is aimed slighty away and the edge of the lights beam is hitting the subject. Im not sure why this would be done since I don't think this would make the light any softer. My only thought would be that it would perhaps reduce contrast as seemed popular in the stills of the old movie stars.


The reason for feathering is to create light fall-off, shadows and hence drama. This technique is useful in low-key lighting to bring out form, texture or mood. I think feathering makes the light harder not softer. If you light subject with the edge of the beam, the effective size of the light source is smaller looking from the subject's view point. Usually the feather beams of light from a fresnel or softbox covered with eggcrates have less wrap-around effect, sharper edge transfer ( rapid transition from highlights to shadows) than a softbox by itself.
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#13 Michael Nash

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Posted 25 July 2006 - 05:02 PM

Of course the easiest way to soften a fresnel is to put diffusion in front of it. You can maintain a relatively small pool of light with a softer quality by using a very light grade diffusion right on the barn doors. Hampshire Frost or Opal Frost work well; anything heavier than that and you'll start spreading the light too much. A larger frame of Hampshire Frost close to the subject will also soften the shadows a bit without spreading the pool of light very much.
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#14 Sing Lo

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Posted 26 July 2006 - 03:15 PM

Of course the easiest way to soften a fresnel is to put diffusion in front of it. You can maintain a relatively small pool of light with a softer quality by using a very light grade diffusion right on the barn doors. Hampshire Frost or Opal Frost work well; anything heavier than that and you'll start spreading the light too much. A larger frame of Hampshire Frost close to the subject will also soften the shadows a bit without spreading the pool of light very much.


Incidentally, I saw this was done in an outdoor location film set directed by Woody Allen today. They filmed Evan Mcgregor right under Brighton pier using two giant HMI fresnels (possibly 600mm 18K) with diffusion screens on barndoors mixing with daylight. They used hugh white reflector to bounce the light from the fresnels as fill. It was very interesting to watch the lighting set-ups in big budget film...I kept a sketch of the lighting diagram...
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