All About Lighting - Ask Anything V2.

[LBPhotog]

VI - Do you have the exposure information for that image that you posted? Maybe if I see the settings it'll finally *click* with me (pardon the pun)

So, what I am hearing is that you expose for the background, then under expose it the selected number of stops and compensate with flash compensation (or by turning up the power of your strobe) and adjusting ambient control with shutter speeds ... sorry, sometimes the simplest of concepts is tough for me to grab, and it's the more complex ideas that make the most sense to me.

 

[Village Idiot]

VI - Do you have the exposure information for that image that you posted? Maybe if I see the settings it'll finally *click* with me (pardon the pun)

So, what I am hearing is that you expose for the background, then under expose it the selected number of stops and compensate with flash compensation (or by turning up the power of your strobe) and adjusting ambient control with shutter speeds ... sorry, sometimes the simplest of concepts is tough for me to grab, and it's the more complex ideas that make the most sense to me.

Exactly. I'll post another photo done with one light that will be easier to explain.

The below photo was shot at ISO 100, shutter speed 1/250, and f/2.8. This was shot as the sun was going down and the lens used was a Canon 15mm f/2.8 Fish Eye. If I wanted the sky to be brighter, all I would have had to do was use a slower shutter speed to let in more light. The 5D MKII's x sync is 1/200, so I generally start at 1/160. I probably wanted less ambient at the time, so I started using a faster shutter speed to get what I wanted. Even though the 5DII's x sync is listed at 1/200, I know I can push it 1/3 to 2/3 of a stop without getting too much of the black bar from the shutter speed encroaching into the exposure. Also, with my subject in the center of the frame, I could have probably pushed it further with no ill effect.

If I didn't want to use that technique and I wanted less ambient from the starting point of 1/160, I could have dropped my aperture down to f/4 from f/2.8. That's one stop of light, which lets in exactly half as much light as f/2.8. So to compensate with the flash, I would have had to double the power. If I was shooting at 1/64 power, I would have had to turn the flash up to 1/32 power to compensate for narrowing the aperture down a stop.

 

[Big Mike]

As for what has been throwing me off was that I always under the impression that shutter speeds had very little to do with the exposure when it came to artificial light source and that apperture values always controld the amount of light ... now that the shutter effect has been explained I will have to play around and see what I can come up with. Thanks.

I think you're starting to get it, but here is another explanation that might help.

Every photo taken with flash, is actually two exposures. One from the flash and one from the ambient light. Most of the time, the two exposures line up, or one of them is much more powerful than the other, so you don't notice that there are two. For example, in a dark situation, with little ambient light, the flash has to provide lots of light for the exposure of your subject, but the background probably won't be lit by the flash. So unless you expose for the ambient (background) light, the background will be dark while the subject is bright. There is probably some ambient exposure of the subject, but it would be so faint, that it's hard to see and the flash exposure of the subject overpowers it in the photo.

In the opposite situation, out in bright conditions, there is lots of ambient light, so the ambient exposure is likely nice and bright. And if we use flash, it's probably only adding a little bit to the exposure, usually used for fill. The two exposures will probably line up very well and it looks like a single exposure/photo.

So now that we know that there are two exposures...we need to know how to control them. The ISO affects both equally. The aperture affects both equally. The shutter speed affects only the ambient exposure (because the flash burst is faster than the shutter speed). So therefore, we can use the shutter speed to change the ambient exposure, without changing the flash exposure. Lastly, there is the flash power/output...it affects the flash exposure but not the ambient exposure. So we can use the flash power (or distance to subject) to control the flash exposure without changing the ambient exposure.

So the practical application of this, is to find the right balance between flash & ambient exposure. Going back to your 2:1 ratio, you might want the subject to be one stop brighter than the background. So first you meter your ambient light and dial in setting to underexpose by one stop. Then set your flash power to expose the subject properly. If you are using the flash in TTL mode, you can use FEC to change the flash exposure.

 

[LBPhotog]

MIke, VI - Thanks for the clairification on this one - I think where I was getting stuck was thinking that shutter speed played little to no part in equation when dealing with flashes/strobes and that it was only apperture, ISO, and distance to subject that effected the exposure.

Now it's just a matter of playing and practicing ....

 

[gsgary]

MIke, VI - Thanks for the clairification on this one - I think where I was getting stuck was thinking that shutter speed played little to no part in equation when dealing with flashes/strobes and that it was only apperture, ISO, and distance to subject that effected the exposure.

Now it's just a matter of playing and practicing ....

Get a flash meter and it is easy

 

[LBPhotog]

Get a flash meter and it is easy

Have one, but, it's still fun to just shoot and play.

 

[Village Idiot]

Get a flash meter and it is easy

Have one, but, it's still fun to just shoot and play.

I have photos from this weekend I'll post here. I was shooting outside with a beauty dish, a 1200w/s pack, and a 6 stop ND filter. Great way to kill the ambient and highlight your subject. Unfortunately, I left most of my lightstands in the trunk of my car and it's at the body shop, so I could only use one light.

 

[Village Idiot]

C'mon, where's the lighting questions, give me something to occupy my time here...

 

[fsquare]

Well i created a thread of my own for some critique and like usual got nothing so i'll post here. I just got my small portable studio up and running and was testing it out the other day. Can you give me some critique on the lighting from this pic?

silver umbrella with strobe high camera left and a white reflector camera right at about 90degree from the subject.

 

[Village Idiot]

That's because it's amazingly bland. The photo itself is soft. The lighting is soft and flat. It's a portrait of a kid with a **** eating grin on his face. Sharpen it up and it might help. The light is ok. It's not edgy, it's not unique, and it's perfectly safe. That's not entirely a bad thing, but people don't tend to comment on photos here unless they're absolutely terrible, amazing, stolen, or the poster is an ass. The background is completely underexposed and the color temperature difference between ambient and your strobe is really evident. If you shoot under ambient light and want to mix ambient in with the flash, you should use gels on your flash and adjust your WB accordingly.

 

[fsquare]

That's because it's amazingly bland. The photo itself is soft. The lighting is soft and flat. It's a portrait of a kid with a **** eating grin on his face. Sharpen it up and it might help. The light is ok. It's not edgy, it's not unique, and it's perfectly safe. That's not entirely a bad thing, but people don't tend to comment on photos here unless they're absolutely terrible, amazing, stolen, or the poster is an ass. The background is completely underexposed and the color temperature difference between ambient and your strobe is really evident. If you shoot under ambient light and want to mix ambient in with the flash, you should use gels on your flash and adjust your WB accordingly.

Thanks for the feedback. I think the softness lies in my PP because, in my opinion anyway, the eyes look sharp. I was also aiming to have the background underexposed so as to have the main subject pop and not distract the eye with random chairs and tables lying around.

Anyway, back to the drawing board

 

[Derrel]

So, how are you finding working with power pack and head (aka 'box and cable') studio flash units, as opposed to multiple monolights? I know a while back you were pretty opposed to pack-and-head systems, but that now you have a decent one that features Variable Focusing flash heads. How do you find the system working out for you? Do you like the 202 VF flash heads with their ability to throw a wider or a narrower beam of flash?

 

[OrionsByte]

If you shoot under ambient light and want to mix ambient in with the flash, you should use gels on your flash and adjust your WB accordingly.

This is something that I've always wondered about, and honestly I haven't done any experimenting. testing, or googling regarding it, but how do you know which gels to use to match the ambient properly? I mean I know that CTO gels are generally for tungsten, and window green gels are generally for flourescent, but that's obviously not going to fit every situation. I picked up a pack of gels, and tried using them once or twice but was so unhappy with the results (I didn't even keep them so I can't post them as examples) that I kind of gave up until I learned more.

So I guess what I'm asking is, is there a way to determine the color temperature of the ambient light in order to choose a matching gel, or is it mostly experience and/or experimentation?

 

[Village Idiot]

So, how are you finding working with power pack and head (aka 'box and cable') studio flash units, as opposed to multiple monolights? I know a while back you were pretty opposed to pack-and-head systems, but that now you have a decent one that features Variable Focusing flash heads. How do you find the system working out for you? Do you like the 202 VF flash heads with their ability to throw a wider or a narrower beam of flash?

It's not bad with multiple packs. With a single pack, I wouldn't have been able to do some of the shots I've wanted to. Power adjustment is somewhat lacking, but it would have cost about $6,000 for a nearly equivalent Profoto setup.

 

[Village Idiot]

If you shoot under ambient light and want to mix ambient in with the flash, you should use gels on your flash and adjust your WB accordingly.

This is something that I've always wondered about, and honestly I haven't done any experimenting. testing, or googling regarding it, but how do you know which gels to use to match the ambient properly? I mean I know that CTO gels are generally for tungsten, and window green gels are generally for flourescent, but that's obviously not going to fit every situation. I picked up a pack of gels, and tried using them once or twice but was so unhappy with the results (I didn't even keep them so I can't post them as examples) that I kind of gave up until I learned more.

So I guess what I'm asking is, is there a way to determine the color temperature of the ambient light in order to choose a matching gel, or is it mostly experience and/or experimentation?

That's probably the cheapest way. There are meters that measure color. Sekonic has one for $1,200.

Sometimes you want to mix colors though or use gels for effects. I know David Hobby, the writer of Strobist, uses 1/4 and 1/2 CTO gels to warm up his flashes to give a warmer fuller skin tone to his subjects in some of his photos. I use them for effects.

Red gel on the flash behind the guy in the background: