Doing The Math with Flash

[flyinglentris]

flyinglentris wrote

I don't use Amazon. They seem to want to force the Prime card on me and I'm not game for that. The 5th edition PDF I found is $12.99 at some outfit called SetMalls.

Did you actually get the PDF? Lots of complaints against that company and a number of others that are all at the same address.

I have not gotten it yet, no. It says that the e-mail for download will be sent out within 24 to 48 hours. If there is a problem, I will lodge a complaint with my card vendor.

How do you know about these complaints that you refer to?

 

[BAK]

For the OP

RE >> The shutter speed should be your camera's highest sync speed so that you don't get light pollution from ambient sources. <<

Your camera's highest sync speed may be a little slower for studio strobes than for camera-maker flash guns. If you get a dark, probably see-thru, bar across one edge of your picture, lower your shutter speed one or two notches.

BAK

 

[BAK]

The Sekonic meter has an electrical socket.

Take a long flash sync cord and plug it into one light and plug the other end into the socket on the meter.

Walk over to the subject, hold the meter in place, press a button on the meter.

The connected flash will go off, and the burst of light will set off all the other flash guns.

The meter will tell you the exposure.

Walk over to the camera, set the f stop on the camera and plug the flash cord into the socket on the camera.

If there's no socket on the camera, buy a Nikon AS-15 hot shoe socket adapter. Works fine on a Canon. I use one) and plug the cord into the socket on the AS-15

This system has worked for me (different meters) for three decades. No automation.

BAK .

 

[john isaacs]

flyinglentris wrote

I don't use Amazon. They seem to want to force the Prime card on me and I'm not game for that. The 5th edition PDF I found is $12.99 at some outfit called SetMalls.

Did you actually get the PDF? Lots of complaints against that company and a number of others that are all at the same address.

I have not gotten it yet, no. It says that the e-mail for download will be sent out within 24 to 48 hours. If there is a problem, I will lodge a complaint with my card vendor.

How do you know about these complaints that you refer to?

Google.

 

[flyinglentris]

For the OP

RE >> The shutter speed should be your camera's highest sync speed so that you don't get light pollution from ambient sources. <<

Your camera's highest sync speed may be a little slower for studio strobes than for camera-maker flash guns. If you get a dark, probably see-thru, bar across one edge of your picture, lower your shutter speed one or two notches.

BAK

Thanks guys ...

I am aware of the workings of DSLR focal plane shutters, how the first and second curtains work and that at the camera's max sync speed, the shutter slit will be wide open and at faster speeds, a traveling slit. It is only with HSS or FP that faster shutter speeds can be used because the flash will fire multiple times in tune with the slit travel and expose the entire sensor. HSS is not available (to me at least), except as a function of my speedlites. Second curtain sync. is not something that I would find myself using as I don't need (at least yet) to create photographs with light trails. For the same reasoning, stroboscopic flash is not something I currently have much use for.

This ambient light thing comes to fore when considering the additive properties of light and a member answered a question I had on that about how to set the camera up to eliminate or ameliorate ambient exposure and let flash do the job without fussing about calculating additive energies.

 

[flyinglentris]

flyinglentris wrote

I don't use Amazon. They seem to want to force the Prime card on me and I'm not game for that. The 5th edition PDF I found is $12.99 at some outfit called SetMalls.

Did you actually get the PDF? Lots of complaints against that company and a number of others that are all at the same address.

I have not gotten it yet, no. It says that the e-mail for download will be sent out within 24 to 48 hours. If there is a problem, I will lodge a complaint with my card vendor.

How do you know about these complaints that you refer to?

Google.

I have just googled about a hour or two ago and confirm what you refer to. I can't talk to my CC vendor until after 4 or 5 days and this company doesn't live up. If they are scammers, I am out $12.99 and have advised my CC vendor not to honor anything further from this company and they will dispute the charge. Until then, I don't have a copy of the book and will have to wait to source it from a different source.

 

[flyinglentris]

The Sekonic meter has an electrical socket.

Take a long flash sync cord and plug it into one light and plug the other end into the socket on the meter.

Walk over to the subject, hold the meter in place, press a button on the meter.

The connected flash will go off, and the burst of light will set off all the other flash guns.

The meter will tell you the exposure.

Walk over to the camera, set the f stop on the camera and plug the flash cord into the socket on the camera.

If there's no socket on the camera, buy a Nikon AS-15 hot shoe socket adapter. Works fine on a Canon. I use one) and plug the cord into the socket on the AS-15

This system has worked for me (different meters) for three decades. No automation.

BAK .

I can't wait to get my meter. But, alas, I have to.

 

[Brooke Meyer]

I looked for Fresnels and wondered whether the LiteMode mainframe would mount a Fresnel, but it appears that Buff's lights don't support Fresnel lenses.

Completely different animals and I didn't explain myself very well. Which is a common complaint from my wife. I have 3 different bags of lights:

One has a half dozen manual speed lights. With remote, triggers, flags, grids, snoots and gels. Larger modifiers are 43 " convertible umbrellas with diffusers, Wescott Apollo Strip Boxes & grids, Orb & grid plus a sml soft box with a dual speed light L bracket.



Two has a pair of Einsteins and a Digibee. With CC, Cybersense, xcvrs, std reflectors, umbrella reflector, grids, snoot with grid, barn doors and gels. PCB specific modifiers are an Omni, discontinued Razor and a 26 China ball with balcar insert plus homemade skirt/flag. All the Wescott Apollo stuff works with these.





Three has 4 Mole Richardson 2801 Tungsten Fresnels . Other bags has a pair of 2351's . All have umbrella stand adapters, barn doors, scrims, gels and snoots. And a pair of leather gloves becasue are they hot. Ironically, the lamp in the Fresnels is the same as the modelling lamp in the Einsteins. You can't stop action or kill much ambient with these like speed lights or monolights. They are essentially theater lighting and that is a place I feel most at home.



The speed lights and monolights are like peanut butter and jelly and work together very well. The tungsten fresnels are a a different mind sets, like piston engines and jets .

 

[Ellis Vener]

There many used copies of Light Science & Magic for sale on eBay.com

Loading…

www.ebay.com

at quite reasonable prices.

The best piece of advice I ever had about lighting came from a terrific photographer I met on the set of a movie. He was shooting the poster and I was doing the production stills. This was back in 2000 before everything went digital but his advice still applies and it goes something like this:

You start with a picture in your mind of what you want the lighting to look like so you set the light where you think it should be with the modifier you think will be best for that look. Take a meter reading And then you shoot a Polaroid (now days, test frame). Then you move the light or change the modifier to better fit the picture you want to make and shoot another test. You keep going like this until the test shot either looks the way you imagined the shot or betters your imagination. Then you bring the talent in and start shooting. Keep it as simple as possible.

To that I’ll add: make notes including either sketches pictures of the set up with your iPhone/Android phone.

As you build your own lighting vocabulary, expect to screw up and make mistakes - that’s part of the learning process. The more regularly you do it the faster everything moves.

Also start keeping a notebook of photos you think you want to basically emulate. Study them.

There are many lighting cookbooks and formulas out there. My advice is to ignore almost all of them.

Light Science and Magic does a very good job of not being a lighting cookbook and instead concerns itself with the science and mechanics of how light works.

 

[Ellis Vener]

Mr. Issacs is right as usual.

 

[rfsIII]

Yes. Firing strobes from your meter is a fundamental tool of studio photography. They all work the same way; you use either a cord or a radio remote to fire the flashes with the button on the meter. I'm not as familiar with the Paul Buff Cybersync system but it might offer the same functionality.

If you don't have a meter for the moment, Paul Buff has a calculator on its website that shows how to set their strobes to get the f/stop you want.

http://s196259524.onlinehome.us/output.php

Others have explained the math quite well. Allow me to address how to learn to use "big" flashes with a light meter. First off, don't use any of the automation for the time being. Use the manual settings because won't have enough experience with the lights to know what the automatic modes are doing. Also, forget everything you know.

To use strobe efficiently you start by deciding what ISO and aperture you want to shoot with. Studio photographers generally use the camera's lowest ISO and an f/stop somewhere between f/4 and f/11 depending on what's being shot. The shutter speed should be your camera's highest sync speed so that you don't get light pollution from ambient sources.

I know that deciding on the f/stop first is completely backwards from the conventional internet wisdom, but it's the way professional photographers work and will save you many hours of frustration.

Here's a really good basic overview of how to set your lights—he's using an L358 but it applies to other Sekonics as well.

So let's say you decide you want to shoot at f/8. Bring in the main light, set it at 1/2 power and hook it up to your light meter; stand where your subject is going to be, point the light meter at the strobe and hit the flash button. You'll get a reading; adjust your light until the meter reads f/8.

Turn the main light off and then set the exposure of your fill; let's say you want it half as bright, you would use your flash meter to measure the strobe output and adjust the power till the meter reads f/5.6.

Continue metering and adjusting whatever other lights you choose, remembering to only fire one light at a time.

As a last step turn on all your lights, put your meter in the subject position and fire everything at once. You should still get a reading of f/8 but depending on how the light bounces around your shooting space you may have to go up or down on either your power or your aperture to get a solid f/8.

Voila! Perfect exposure and your sanity remains intact.

I won't have the Sekonic until about 3 weeks, maybe 4. I'll try things out then.

Your post hints that the Sekonic can be attached to the flash unit to fire it. Is that correct?

 

[flyinglentris]

There many used copies of Light Science & Magic for sale on eBay.com

https://www.ebay.com/sch/i.html?_fr...C0.A0.H0.X.TRS5&_nkw=Light+Science+and+Magic+

at quite reasonable prices.

The best piece of advice I ever had about lighting came from a terrific photographer I met on the set of a movie. He was shooting the poster and I was doing the production stills. This was back in 2000 before everything went digital but his advice still applies and it goes something like this:

You start with a picture in your mind of what you want the lighting to look like so you set the light where you think it should be with the modifier you think will be best for that look. Take a meter reading And then you shoot a Polaroid (now days, test frame). Then you move the light or change the modifier to better fit the picture you want to make and shoot another test. You keep going like this until the test shot either looks the way you imagined the shot or betters your imagination. Then you bring the talent in and start shooting. Keep it as simple as possible.

To that I’ll add: make notes including either sketches pictures of the set up with your iPhone/Android phone.

As you build your own lighting vocabulary, expect to screw up and make mistakes - that’s part of the learning process. The more regularly you do it the faster everything moves.

Also start keeping a notebook of photos you think you want to basically emulate. Study them.

There are many lighting cookbooks and formulas out there. My advice is to ignore almost all of them.

Light Science and Magic does a very good job of not being a lighting cookbook and instead concerns itself with the science and mechanics of how light works.

Thanks Ellis,

I do keep a photographer's notebook for much the same reason you cite here, along with other reasons, like keeping tabs on details of the shot.

The Light Science and Magic book definitely has my interest. I'd prefer to get it as an eBook or PDF so that I can read it on my laptop. I find it easier on my eyes which went south on me after going un-diagnosed with severe sleep apnea about a decade ago. That's one of the reasons I don't pilot GA airplanes any more. But if I have to buy the book in paper, I guess paperback would suite my library better than hard cover. Right now, I will wait to see if I got burned for $12.99 by this company I ordered the PDF from.

BTW: tugwilson referred me to the book and then seems to have gone upset when I replied that I didn't shop Amazon and said he was "muting" me. Too bad. He seemed to be a good bounce for opinions and reflections on lighting topics.

 

[Ellis Vener]

1. flyinglentris wrote:

There many used copies of Light Science & Magic for sale on eBay.com

https://www.ebay.com/sch/i.html?_fr...C0.A0.H0.X.TRS5&_nkw=Light+Science+and+Magic+

at quite reasonable prices.

The best piece of advice I ever had about lighting came from a terrific photographer I met on the set of a movie. He was shooting the poster and I was doing the production stills. This was back in 2000 before everything went digital but his advice still applies and it goes something like this:

You start with a picture in your mind of what you want the lighting to look like so you set the light where you think it should be with the modifier you think will be best for that look. Take a meter reading And then you shoot a Polaroid (now days, test frame). Then you move the light or change the modifier to better fit the picture you want to make and shoot another test. You keep going like this until the test shot either looks the way you imagined the shot or betters your imagination. Then you bring the talent in and start shooting. Keep it as simple as possible.

To that I’ll add: make notes including either sketches pictures of the set up with your iPhone/Android phone.

As you build your own lighting vocabulary, expect to screw up and make mistakes - that’s part of the learning process. The more regularly you do it the faster everything moves.

Also start keeping a notebook of photos you think you want to basically emulate. Study them.

There are many lighting cookbooks and formulas out there. My advice is to ignore almost all of them.

Light Science and Magic does a very good job of not being a lighting cookbook and instead concerns itself with the science and mechanics of how light works.

Thanks Ellis,

I do keep a photographer's notebook for much the same reason you cite here, along with other reasons, like keeping tabs on details of the shot.

The Light Science and Magic book definitely has my interest. I'd prefer to get it as an eBook or PDF so that I can read it on my laptop. I find it easier on my eyes which went south on me after going un-diagnosed with severe sleep apnea about a decade ago. That's one of the reasons I don't pilot GA airplanes any more. But if I have to buy the book in paper, I guess paperback would suite my library better than hard cover. Right now, I will wait to see if I got burned for $12.99 by this company I ordered the PDF from.

BTW: tugwilson referred me to the book and then seems to have gone upset when I replied that I didn't shop Amazon and said he was "muting" me. Too bad. He seemed to be a good bounce for opinions and reflections on lighting topics.

 

[flyinglentris]

1. flyinglentris wrote:

There many used copies of Light Science & Magic for sale on eBay.com

https://www.ebay.com/sch/i.html?_fr...C0.A0.H0.X.TRS5&_nkw=Light+Science+and+Magic+

at quite reasonable prices.

The best piece of advice I ever had about lighting came from a terrific photographer I met on the set of a movie. He was shooting the poster and I was doing the production stills. This was back in 2000 before everything went digital but his advice still applies and it goes something like this:

You start with a picture in your mind of what you want the lighting to look like so you set the light where you think it should be with the modifier you think will be best for that look. Take a meter reading And then you shoot a Polaroid (now days, test frame). Then you move the light or change the modifier to better fit the picture you want to make and shoot another test. You keep going like this until the test shot either looks the way you imagined the shot or betters your imagination. Then you bring the talent in and start shooting. Keep it as simple as possible.

To that I’ll add: make notes including either sketches pictures of the set up with your iPhone/Android phone.

As you build your own lighting vocabulary, expect to screw up and make mistakes - that’s part of the learning process. The more regularly you do it the faster everything moves.

Also start keeping a notebook of photos you think you want to basically emulate. Study them.

There are many lighting cookbooks and formulas out there. My advice is to ignore almost all of them.

Light Science and Magic does a very good job of not being a lighting cookbook and instead concerns itself with the science and mechanics of how light works.

Thanks Ellis,

I do keep a photographer's notebook for much the same reason you cite here, along with other reasons, like keeping tabs on details of the shot.

The Light Science and Magic book definitely has my interest. I'd prefer to get it as an eBook or PDF so that I can read it on my laptop. I find it easier on my eyes which went south on me after going un-diagnosed with severe sleep apnea about a decade ago. That's one of the reasons I don't pilot GA airplanes any more. But if I have to buy the book in paper, I guess paperback would suite my library better than hard cover. Right now, I will wait to see if I got burned for $12.99 by this company I ordered the PDF from.

BTW: tugwilson referred me to the book and then seems to have gone upset when I replied that I didn't shop Amazon and said he was "muting" me. Too bad. He seemed to be a good bounce for opinions and reflections on lighting topics.

He wasn’t upset at you for not liking to use Amazon. He was upset at you for buying an apparently pirated version.

Good Morning,.

The company represented itself as reputable and we all take our chances, not just on the web, but in the world. It may turn out that this company didn't pirate the book, but scammed me for $12.99. I wanted a PDF as I said, to read on my computer. It looked good and well, it'll be the fist time in a long time that I stumbled into a scam, if it is one. And I believe right now that it is.

I've located textbook.com and they have the paperback for $36.84. I'll look to that in about 5 days after I'm certain that I got screwed for the $12.99.

Humor tugwilson and let him know that I apparently, have been scammed for the PDF. It ought to get a smile.

 

[Michael Fryd]

...

Thanks guys ...

I am aware of the workings of DSLR focal plane shutters, how the first and second curtains work and that at the camera's max sync speed, the shutter slit will be wide open and at faster speeds, a traveling slit. It is only with HSS or FP that faster shutter speeds can be used because the flash will fire multiple times in tune with the slit travel and expose the entire sensor. HSS is not available (to me at least), except as a function of my speedlites. Second curtain sync. is not something that I would find myself using as I don't need (at least yet) to create photographs with light trails. For the same reasoning, stroboscopic flash is not something I currently have much use for.

This ambient light thing comes to fore when considering the additive properties of light and a member answered a question I had on that about how to set the camera up to eliminate or ameliorate ambient exposure and let flash do the job without fussing about calculating additive energies.

It's easy to tell if ambient light is affecting your images. Just disable the flash trigger and take a shot. That shot will only be lit by ambient. if the frame looks black, then your ambient isn't noticeably affecting your image.

When I shoot in the studio, I have my normal room lights on so I can see what I am doing, and the model can move without tripping. I shoot at base ISO, around f/8, a little below my camera's sync speed.

If I take the radio remote transmitter off my hot shoe, I get a black frame. I don't worry about the ambient room light affecting the image at all.

 

[rumple]

[...]

So let's say you decide you want to shoot at f/8. Bring in the main light, set it at 1/2 power and hook it up to your light meter; stand where your subject is going to be, point the light meter at the strobe and hit the flash button. You'll get a reading; adjust your light until the meter reads f/8.

Turn the main light off and then set the exposure of your fill; let's say you want it half as bright, you would use your flash meter to measure the strobe output and adjust the power till the meter reads f/5.6.

Continue metering and adjusting whatever other lights you choose, remembering to only fire one light at a time.

As a last step turn on all your lights, put your meter in the subject position and fire everything at once. You should still get a reading of f/8 but

That's not correct - fotowbert explained it earlier.

Total exposure = SQRT( key^2 + fill^2 )

So in your example the total exposure will be about f/9.8, not f/8, which is quite different.

 

[rfsIII]

Excellent eye. I hit the button before thinking all the way through.

But when you do the math what values are you using for full and key? The amount of light in stops? Foot candles? EV?

[...]

So let's say you decide you want to shoot at f/8. Bring in the main light, set it at 1/2 power and hook it up to your light meter; stand where your subject is going to be, point the light meter at the strobe and hit the flash button. You'll get a reading; adjust your light until the meter reads f/8.

Turn the main light off and then set the exposure of your fill; let's say you want it half as bright, you would use your flash meter to measure the strobe output and adjust the power till the meter reads f/5.6.

Continue metering and adjusting whatever other lights you choose, remembering to only fire one light at a time.

As a last step turn on all your lights, put your meter in the subject position and fire everything at once. You should still get a reading of f/8 but

That's not correct - fotowbert explained it earlier.

Total exposure = SQRT( key^2 + fill^2 )

So in your example the total exposure will be about f/9.8, not f/8, which is quite different.

--
"THINK" - Watson

 

[fotowbert]

Measurements are made in F values, the direct output of the flash meter.

Key light is adjusted to give f/8 reading, fill is f/5.6 , or half as bright as the key. Square these to get 64 and 32. Note that the square values agree with the intensity ratio between key and fill. Sum the squares to get 96 for the total intensity. The SQRT of 96 is 9.8, the F value for both lights acting together.

Excellent eye. I hit the button before thinking all the way through.

But when you do the math what values are you using for full and key? The amount of light in stops? Foot candles? EV?

[...]

So let's say you decide you want to shoot at f/8. Bring in the main light, set it at 1/2 power and hook it up to your light meter; stand where your subject is going to be, point the light meter at the strobe and hit the flash button. You'll get a reading; adjust your light until the meter reads f/8.

Turn the main light off and then set the exposure of your fill; let's say you want it half as bright, you would use your flash meter to measure the strobe output and adjust the power till the meter reads f/5.6.

Continue metering and adjusting whatever other lights you choose, remembering to only fire one light at a time.

As a last step turn on all your lights, put your meter in the subject position and fire everything at once. You should still get a reading of f/8 but

That's not correct - fotowbert explained it earlier.

Total exposure = SQRT( key^2 + fill^2 )

So in your example the total exposure will be about f/9.8, not f/8, which is quite different.

 

[rfsIII]

What an elegant solution. Thanks for sharing.

Measurements are made in F values, the direct output of the flash meter.

Key light is adjusted to give f/8 reading, fill is f/5.6 , or half as bright as the key. Square these to get 64 and 32. Note that the square values agree with the intensity ratio between key and fill. Sum the squares to get 96 for the total intensity. The SQRT of 96 is 9.8, the F value for both lights acting together.

Excellent eye. I hit the button before thinking all the way through.

But when you do the math what values are you using for full and key? The amount of light in stops? Foot candles? EV?

[...]

So let's say you decide you want to shoot at f/8. Bring in the main light, set it at 1/2 power and hook it up to your light meter; stand where your subject is going to be, point the light meter at the strobe and hit the flash button. You'll get a reading; adjust your light until the meter reads f/8.

Turn the main light off and then set the exposure of your fill; let's say you want it half as bright, you would use your flash meter to measure the strobe output and adjust the power till the meter reads f/5.6.

Continue metering and adjusting whatever other lights you choose, remembering to only fire one light at a time.

As a last step turn on all your lights, put your meter in the subject position and fire everything at once. You should still get a reading of f/8 but

That's not correct - fotowbert explained it earlier.

Total exposure = SQRT( key^2 + fill^2 )

So in your example the total exposure will be about f/9.8, not f/8, which is quite different.