Fast glass plus high ISO... or Flash

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[Original post @ esfotoclix.com/blog1/?p=2146]

A common query on Internet forums asks how fast of a lens and how high of an ISO one needs to capture family candids without the use of flash. May folks deem the latter intimidating (to family members), awkward and for the most part impractical, so I thought it would be interesting to show how flash would compare against wide open fast glass with high ISO in a lighting environment where one could possibly entertain such a comparison.

Since I did this handheld, the compositions won't match exactly, but they will still be close enough to compare. See how you think things turned out here in this family play-night scene.



Nikon D700 @ ISO 3200 with 24-70 @f2.8


Nikon D700 @ ISO 800 with 24-70 @f8
SB-900 (TTL) bounced from camera right



Nikon D700 @ ISO 3200 with 24-70 @f2.8

Nikon D700 @ ISO 500 with 24-70 @f5.6
SB-900 (TTL) bounced from camera right


As you can see, these are quick grabs, the types of family, slice-of-life photos people want to catch without too much complication. The flash lighting isn't optimal, but with a quick bounce, the flash doesn't wash out and flatten out the scene, as direct flash would do. Notice also that when the flash becomes the predominant (main) light, shadow locations generally shift from the right side of faces to the left.

This is all a matter of personal taste; there's no right or wrong here. The ambient lighting has a warmer, quieter feel to it, so it's definitely capturing the moment more naturally. In this case, though, I prefer lighting the broad side of the face with flash, as opposed to the relatively harsher shadows that the ambient (lamp at camera left) light created. And this brings up a good point: when you shoot with ambient, you can't slide or move the light around (not simply anyway). You are more or less at the mercy of the ambient light you have and will constrain your shooting angles accordingly. Depending on the situation, fewer options for shots may be available to you.

For full disclosure, I'll also point out that for the ambient lighting shots I had to perform white balance correction to mitigate overly red/orange skin tones, and I also lifted the shadows a bit to lessen some of the harshness I noticed.

At any rate, there you have it: fast glass with high ISO vs. flash. You decide which you like best and which works for you.
 
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one of the most obvious differences and I think the one most people will notice first is the colour differences, the colour of the wall totally changes in the last two with the non-flash shot much warmer. This is not really a product of 'flash' per se but of the chosen white balance, if you were to gel the flash I think the two versions would be much closer
 
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one of the most obvious differences and I think the one most people will notice first is the colour differences, the colour of the wall totally changes in the last two with the non-flash shot much warmer. This is not really a product of 'flash' per se but of the chosen white balance, if you were to gel the flash I think the two versions would be much closer

Yup, either gel the flash or decide which "look" you want. Sometimes I find the incandescent skin tones too red and orange, no matter how much WB correction I do in post. It comes down to preference and taste.
 
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Which wall color most closely matches what your eye sees, flashed or ambient?

Ambient: the wall is a very pale slate green color. However, I find the flash shots to have the best skin tones. Sometimes we must prioritize and compromise.
 
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As with your examples, flash is often going to permit smaller apertures and of course a lower ISO. As you can see, the children on the couch are OOF in one shot, likely due to the f/2.8 aperture. However, if that's unimportant then of course it's not an issue.

Also, under artificial light, as was the case here with the table light for instance, gelling the flash helps balance the flash light with the ambient room light. This makes it easier to color correct as you only have to deal with (ideally) one color temp.

Although the images with and without flash both 'work', if accurate colors are a requirement (wall color for example) then other things need to be taken into account.
 
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What does the wall color look like in direct sunlight if you have windows? The type of light you see the room in matters too. Your door casings look orange in ambient but white in flashed pic. You may think ambient is more natural, but the casings show otherwise.

I think your ambient pics look better, but you need to adjust your WB if you want better skin tones under the room lighting.

A better question is what looks like the actual setting than what is the actual correct colors.
 
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Joined
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North of Seattle, South of Canada
There are a lot of variables when it comes to color accuracy with color temperature being a predominant factor. Not all scenes have the same lighting and therefore the same color temperature light sources. The term for this being 'mixed lighting'.

As with these images you have the natural room light, that being without any artifcial light sources, as well as artificial light sources such as table lamps. If you also have a flourescent light source in addition to a strobe you then have four light sources to deal with, each having a different color temperature.

To complicate things further, wall color also plays a role since they reflect light, as well as add their own color cast to it. This can result in any light source having a color cast that is different than its own native color temperature. For example a strobe may have a color temperature 5500K, but when bounced off a colored wall can end up being something quite different.

You can deal with this by eliminating all, or as many light sources light sources as possible, and then subsitute your own light/s which you can control. In that way you have only one light source and its color temperature to deal with.

If mixed lighting can't be avoided then gelling your strobe/s so they have the same color temperature as the existing light makes keeping color accuracy easier by helping to balance color temperatures.

If color casts are still an issue then you may have to prevent the surfaces which are causing the color casts from doing so by the use of flags or wall coverings, etc.

In short, you may have to create an environment where there is only one light souce, that being what you supply, and where there are no surfaces which cause color casts other than those you erect, supply or somehow control.

It's not technically difficult to accomplish and it need not be expensive either. For example, you can use white bed sheets to cover walls in order to prevent a color cast and simply not include those surfaces in the shot. Thus, photography rewards creativity in more ways than just composition.
 
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