Flash vs. ambient light...more questions.

mnealtx wrote in post #4969658
I've been reading the recommendations and tips here and over on shootsmarter (can't reach strobist from here, for some reason), and had a couple questions about how shootsmarter recommends having the ambient light 1 - 1.5 stops below the flash. Then, on here I see the stuff from Curtis, Neil, and others talking about entirely different methods.

The relative ratio of ambient:flash really depends upon what YOU (or your client) finds tasteful!

In some cases, you want main subject to be well lit, yet capture the ambient light just a bit darker in order to draw the viewer's eye to the main subject while still being able to see the environment that the main subject is in.

In other cases, you want the main subject to not be overly lit, but you are using the flash as a fill light. Like if you use flash because their back is to the sun, too much flash is too obvious when the subject is clearly standing in a shaded area and bright sunny areas are visible in the scene.

Curtis N wrote in post #4970824
That's a pretty general statement. Can you give us a link so we can read it in context?

Yessir... here's the link.

Here's the applicable sections:

And:

And here's the meat of it:

I admit, I'm confused. I thought that having the camera set for one stop less light than ambient would force the flash to be the main light for the scene - is this not the case?

This seems like it would be a good technique for me to use for family photos (siblings and their families), as most of the shots would be indoors and under varying lighting conditions.

John_B wrote in post #4970890
mnealtx,
I had the 420ex (I burned it out) and the 580ex and I didn't notice the 420ex over powering my photos any more then my 580ex.
The improvements I noticed was: full manual controls (an excellent feature) and stronger power.
But not an improvement on exposures

If you really want help in flash photos tell us more on how you used it ex. what mode was camera in? M, Av, Tv, P What metering mode were you in? You could post an example photo with full Exif that will also help.

You should be able to get great results for portraits and occasional use with your 420ex

Hi John -

To be honest, I haven't used my flash in probably a year - when I was using it, it was indoors around the office taking candid shots for a newsletter. I was bouncing off the ceiling, but there were still a lot of hotspots - I didn't know much at all about FEC then (still trying to get a handle on it now) and had no FEC applied. As I recall, I was in program mode, but I can't guarantee it.

What I'd like to do now is have the flash for the family pictures as described in the post above, and hopefully to be able to do at least a modicum of fill lighting for other outdoor shots, but I'm not holding my breath on that.

Mike (mnealtx)

I think you have made some faulty assumptions when you were reading the ShootSmarter website.

The article you were reading was about Will Crocket's (Mr ShootSmarter) "secret formula for making TTL work". This formula is ONLY for using TTL. Through The Lens metering is a very strange duck, and has given a lot of people fits, leading many to say that it just doesn't work.

Will and his crew have done extensive testing and found what they believe to be the secret formula that allows TTL to function in the manner it was intended. That formula is to have the amount of light illuminating the subject be 2/3rds from the flash and 1/3 from ambient light. Said another way, the flash needs to be set 1 to 1-1/2 stops above the ambient.

In one of your posts you use an example of the ambient being f/4 and setting the camera to f/5.6 (one stop above ambient). This might work, but you are now in a manual situation and not using TTL.

Re-read the article on ShootSmarter.com. It can be quite helpful.

Regards

I've re-read it about 15 times now and it's still not any clearer for me - I thought that setting the camera for 1 stop less light than ambient would force the flash to be the primary light source for the scene, is this not true?

The ambient at f/4 and camera set at f/5.6 is exactly the situation in his article - is that not still TTL in respect to the flash?

mnealtx wrote in post #4971362
I admit, I'm confused. I thought that having the camera set for one stop less light than ambient would force the flash to be the main light for the scene - is this not the case?

It's important to be specific about what we're metering, and how. But here's a theoretical example:

You use an incident meter to measure the light falling on the subject. The reading is f/4. Now if you set your camera at f/5.6 then the ambient will be underexposed by 1 stop.

Then you turn the flash on and adjust the power so that the incident reading of combined ambient and flash is now f/5.6 - The flash is now adding one stop to the total illumination and therefore providing half of the light on the subject. Neither light source is predominant in this case.

You don't need to use an incident meter to accomplish this. It can be done with reasonable consistency with your in-camera meter and E-TTL flash.

Now I don't know if there's anything magical about that formula. I will say that I have sometimes followed a similar strategy in some large banquet halls that were reasonably well lit. But when the dancing begins and the lights go down, there just isn't enough light to make this work.

If you want to try that strategy, you must also understand that the ambient light will have a very different color temperature than your flash, and you'll need to gel the flash to get consistent color throughout the image.

Keep in mind that in relatively small rooms, bounced flash alone can light the entire room in a very pleasing way. By setting your shutter speed at flash sync with a moderate aperture and ISO, you can eliminate the ambient. I almost always use this strategy in residential settings because:
1) I almost always have a white ceiling.
2) I have only one exposure to worry about (simplicity is good).
3) I have one light source and one color temperature (simplicity again).
4) I never have to worry about motion blur when flash is the only light source.
5) I have total control of the light. I can aim the flash where I want, and vary the height of my bounce card for fill.

MarKap77 wrote in post #4971437
Mike (mnealtx)

I think you have made some faulty assumptions when you were reading the ShootSmarter website.

The article you were reading was about Will Crocket's (Mr ShootSmarter) "secret formula for making TTL work". This formula is ONLY for using TTL. Through The Lens metering is a very strange duck, and has given a lot of people fits, leading many to say that it just doesn't work.

Will and his crew have done extensive testing and found what they believe to be the secret formula that allows TTL to function in the manner it was intended. That formula is to have the amount of light illuminating the subject be 2/3rds from the flash and 1/3 from ambient light. Said another way, the flash needs to be set 1 to 1-1/2 stops above the ambient. Of course, then we have the ETTL oddity of chronic underexposure, so we have to use FEC +1, or so, in order to get the main subject to be truly exposed correctly!

In one of your posts you use an example of the ambient being f/4 and setting the camera to f/5.6 (one stop above ambient). This might work, but you are now in a manual situation and not using TTL.

Re-read the article on ShootSmarter.com. It can be quite helpful.

Regards

I disagree with the statement that this technique is "only for TTL". It would work fine even with a flash unit under photosensor Auto control if it has the ability for the user to tell it what aperture was set on the lens (f/4 or f/5.6, for example).

I'll also disagree that TTL is a strange duck...'ETTL' is indeed a real strange duck but TTL in film cameras is, absolutely and truly, a very predictable duck.

'The formula' is merely a standard balancing of ambient to flash output, for the 'flash dominant' shot (as they call it). The 1EV difference is not a sacrosant difference, which is why they say 1-1.5EV difference (flash dominant)...any greater ratio makes the ambient lit scene close to black, any lesser ratio makes the scene too low in relative difference to draw your eye to the main subjects.

I have used the techniques documented in Smartshooter.com for decades, when using flash. With TTL film cameras, or with ETTL digital cameras....With the ambient metered at f/4, the lens set at f/5.6 results in the ambient scene being UNDERexposed by -1EV. Then the ETTL controlled flash makes the main subject be exposed correctly with the f/5.6 shooting aperture, so the main subject is 1EV brighter than the underexposed ambient light scene.

Thanks, Wilt and Curtis - that explanation helps a lot... I was definitely floundering around in deep water trying to figure it out!

I'm still confused over which way to go about this....arghhhh. I don't want that plastic 'deer in the headlight' look....

mnealtx wrote in post #4971388
What I'd like to do now is have the flash for the family pictures as described in the post above, and hopefully to be able to do at least a modicum of fill lighting for other outdoor shots, but I'm not holding my breath on that.

mnealtx,
My suggestion is try this:
Put your camera in M (manual) set your shutter speed to 1/200th or 1/250th and set your aperture to get the desired DOF ex. f/8

If you photo has too much light there are ways around this:
You can use FEC this will reduce the power of the flash.

You can FE Lock (flash exposure lock) and lock on something lighter in color, this will set the flash at a lower power.

You can use FEB (flash exposure bracketing) which will give three photos with different flash amounts

mnealtx wrote in post #4971626
I'm still confused over which way to go about this....arghhhh. I don't want that plastic 'deer in the headlight' look....

Here are some simple ways to try to avoid that:

Use a much slower shutter speed, as this will give more exposure to the background.

Bounce off the ceiling

You can use a diffuser ex. a cheap method is put a paper towel over the flash.

However like I said before, in my opinion upgrading your flash will not really fix any of this, but it does offer more power and functions

Can't hurt to try and you waste no film learning

Thanks for the reply, JohnB - I'll give everyone's suggestions a try. I'm just trying to wrap my head around what adjustments need to be made for the various scenes. I've got tomorrow off, so I'll figure out something to take shots of at various settings to test it out...

I mulled over the SSU example last night and I understand (now) that since the camera was set to admit 1 stop less light than ambient, that the flash had to fire at a higher power in order to correctly expose the scene. Would the same thing happen in reverse, i.e. if the camera were set for one stop more light than ambient, would the flash then fire at low power for fill, or would I have to dial in a bunch of FEC to get the right output? (Using a 420EX).

Getting a 580EX II would definitely be worth it if I didn't have to constantly futz about with FEC...I've had a 580EX II and an L358 sitting in my B&H shopping cart for the last several days, trying to decide whether or not to pull the trigger...

mnealtx wrote in post #4976303
Getting a 580EX II would definitely be worth it if I didn't have to constantly futz about with FEC...I've had a 580EX II and an L358 sitting in my B&H shopping cart for the last several days, trying to decide whether or not to pull the trigger...

If you're using E-TTL flash, the camera tells the flash what to do. It doesn't matter if you're using a 420EX, 580EX II or something else. E-TTL isn't any easier with a more expensive flash.

On the other hand, if you want to use manual flash, then you'll need one with manual capability such as the 580EX II, and a light meter like the Sekonic L-358 makes it a whole lot easier.

Different tools for different situations.

Thanks, Curtis - I apologize for all the questions, and I've been reading up on your sig links like crazy, but how is manual flash different, and why (or in what situations) would I use manual flash vs. TTL flash? (this, of course, *if* I were to buy the 580EX vs. the 420EX that I already have)

E-TTL is one of the many forms of automatic flash metering. It fires a pre-flash, meters the light reflecting off the scene and back through the lens, and computes the amount of flash power required for the shot.

Automatic flash metering is useful for dynamic situations where the distance from flash to subject is different from one shot to the next, since the amount of power required is directly related to that distance (among other things).

Manual flash means you adjust the power of the flash unit yourself. This is the method used with studio strobes. It's useful for situations where you're taking many shots with the same distance from flash to subject. It's more consistent than automatic flash metering, but generally requires a flash meter to help adjust the flash power and camera settings (there are other methods but they are less accurate and more time-consuming).

The power on the 580EX II can be adjusted from full power down to 1/128 power (an eight stop range) in 1/3 stop increments.

Ok, I think I'm understanding a little bit better...thanks, Curtis!

It seems that for the most flexibility in shooting, I need to get some sort of adjustable flash, then...although I imagine my 420EX will still work for most indoors stuff that I'm currently considering.

Mike, if you are interested in Lighting 101 from Strobist it is available in .pdf from http://www.mediafire.c​om/?4fn1gynlk9c

If that fails I am sure it can be emailed if you provide an address.

Brian