Im planning a shoot of a model in front of a fireplace and wanted to do a few shots of her lighted just by the fire...i know im going to have to slow shutter down, up the iso, and the such but i was wondering if there was a gel that came close to firelight to kick it up a little ...not looking to replace the fire glow.. but not sure how slow i would need to go so i was looking for alternatives in case it was too slow for her to not move.
fastest lens would be a 50mm 1.8 on a 40D and id either use my AB800s or one of my speedlights
Rosco actually makes a gel named flame, or at least they did at one time. But I actually prefer just using varying strengths of CTO gels. Perhaps starting with a 1/2 cto (tungsten), and adjusting to taste. Works great. Good luck.
Perception of skin tones in photos is tricky. What looks OK in the context of the scene in real life, such as when shooting a portrait at sunset or in front of the fire, can wind up looking exaggerated in a photo which lacks the context of being surrounded by, and having the eyes adapt to, the ambience. In a photo if the skin tones get too far away from normal the skin starts to look jaundiced. That's a common problem with gold reflectors. The light looks great by eye when shooting because of the way the eye adapts, but the subject looks like they have a bad case of Hepatitis in the resulting photo.
If you gel the flash to warm the light the results you see on the monitor when editing might not look natural and it will be difficult to reverse it in editing. A more foolproof approach would be to shoot with a tripod and start with time exposure baseline shot of just the fireplace balanced for a warm glow, then add the model with lighting balanced for normal skin tone based on custom WB with your flash off a gray card. After setting WB then shoot the model holding the card near her face (in the same light).
Shooting in RAW you will be able to balance the look of the foreground lighting for the best perceptual balance of warmth and natural skin tone. Once you find the balance you like you can paste those WB settings in all the other RAW files non-destructively. Because you have the baseline shot of the fireplace you won't need to worry about dragging the shutter. Just paste the baseline shot into the ones of the model you select then use an mask and eraser to add the glow of the flames. Because the firelight would naturally spill onto the model your masking wouldn't need to be very precise and should only take a minute or two.
