There is only one way to know how your roll of redscale film will behave in different conditions and camera settings. You have to experiment. Here's what I did and found out.
Redcale films are unpredictable. But if you want the confidence of knowing the probability of a certain color result from your photos then you must shoot a test roll.
Every camera will produce a different redscale result. With SLRs to Rangefinders to the cult classic Vivitar UWS, not to mention the LC-W in my camera library, I decided to experiment with my Yashica GSN as one possible camera dedicated for shooting redscale. This was also due to being influenced/encouraged by plasticpopsicle ’s use of her Yashica Electro for redscales.
As such, for the purpose of my experiment I used a roll of Kodak Colorplus 200 film which I redscaled myself. I deliberately selected ISO 50 as my film speed setting because I felt that it would the lowest handheld speed that I can manage with this camera. As this was an aperture priority camera I selected f1.7, f4 and f8 to experiment with.
Here are the results when used in a bright but fairly covered open space around noon.
As you would expect, you will get orangy hues when used in a well shaded place.
Based on my experiment and experience with Kodak films, I think I will stick to the f1.7 setting when i want vintage/washed out colors. For deeper orange/reds, f8 and above works for me.