I am using ISO 100 35mm slide film (camera Minolta x700, with a dedicated flash unit). Pictures taken indoors with flash have come out insipid and almost too cold (white).
How can I add a bit of yellow or orange or basically warmer tone? Would bounce flash help (even though the ceiling is also white)? If yes, would I need exposure compensation?
Put a gel filter over your flash. Golden or orange (especially the CTO) will be best. These filters are available from various manufacturers and holders are also available,if you desire one. There is a product from Rosco that includes variety of pre-cut filters for this purpose that includes various effect colors, but also balancing ones. It is called The Strobist Collection.
There are warming and cooling filters that can be mounted atop the lens. The warming series is 81A – 81B – 81C – 81D. These are pale salmon, 81D being the strongest. All require you to increase exposure 1/3 stop. Alternately, you can warm up the flash with gel filters. Gels are likely your best bet as they are available from theatrical supply houses as they are used to alter the colors of stage lighting.
Let me add that electronic flash is generally a good match for daylight balanced slide film. It is highly likely that the cool results are due to improper processing at the lab. Should you apply warming filters base on this one experience, next time your results may be too warm.
