I just went through an exercise to get proper color when shooting simple work with speed-lights. In particular, when using the technique of "dragging the shutter" to open up backgrounds while using TTL flash in low light ... which involves a color temp mix that results in too much post work and possible file degradation.
I used the Leica S2 for these tests, with an ISO of 640 in fairly dark or very dark ambient conditions that were lit by tungsten bulbs or lamps. The lens was the S70mm. Many DSLR users can move the ISO up to 800 or even 1600, which increases the problem even more.
These comparison shots are not color corrected ... color temps are straight from the camera, converted to jpgs and attached here.
I used a Graslon Prodigy Dome diffuser which has interchangeable white and amber domes.
In the tri-panel image with Exif info below, a manual shutter speed of 1/30 @ f/2.5 was used to open up the backgrounds (dragging the shutter). When doing this, the ambient color temp exerts a more dominate role in the over-all image.
When AWB was used with the white diffused flash, the images goes quite warm.
Then, when a custom WB was employed with the white diffused flash, the situation improves, but still exhibits a warm cast.
When a custom WB is used with the amber diffused flash the colors are then true. A slight exposure tweak would render the scene as it really was.
This was demonstrated even more dramatically when the tungsten source was a bit more isolated as in the bed-side lamp shot ... Custom WB set off pillow, walls are blue.
-Marc
I used the Leica S2 for these tests, with an ISO of 640 in fairly dark or very dark ambient conditions that were lit by tungsten bulbs or lamps. The lens was the S70mm. Many DSLR users can move the ISO up to 800 or even 1600, which increases the problem even more.
These comparison shots are not color corrected ... color temps are straight from the camera, converted to jpgs and attached here.
I used a Graslon Prodigy Dome diffuser which has interchangeable white and amber domes.
In the tri-panel image with Exif info below, a manual shutter speed of 1/30 @ f/2.5 was used to open up the backgrounds (dragging the shutter). When doing this, the ambient color temp exerts a more dominate role in the over-all image.
When AWB was used with the white diffused flash, the images goes quite warm.
Then, when a custom WB was employed with the white diffused flash, the situation improves, but still exhibits a warm cast.
When a custom WB is used with the amber diffused flash the colors are then true. A slight exposure tweak would render the scene as it really was.
This was demonstrated even more dramatically when the tungsten source was a bit more isolated as in the bed-side lamp shot ... Custom WB set off pillow, walls are blue.
-Marc
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