Red turns orange

I recently purchased a digital rebel XT. I was shooting several red barns the other evening with an 81B filter attached to my lens. The images of the barns wound up with a slight orange cast. Is this common with the digital rebel, or could it have been caused by the warming filter? After all, red and yellow do make orange.

A warming filter will add a yellow/orange cast to colors. That is what it is meant to do, to "warm" the light color toward the yellow (higher K) end of he spectrum. So, it will make red look orange.

After you learn about what you can do with RAW files, you'll leave your filters at home. With a RAW file you can create the same effect, adjusting the color temp to your heart's desire.

How would you suggest learning RAW?

You should have received a copy of Canon's Digital Photo Professional software with the camera. Install it and read the PDF manual for it.

Set your camera to record RAW files ("image quality" in the menu). Download them to your computer. A card reader makes this much easier.

No need to be intimidated by RAW. In a nutshell it only allows you to do two things you can't do with a JPEG in Photoshop. You can change the white balance and you can adjust the exposure, within limits. These are probably two of the easiest things you can do in the world of image editing.

Give it a try, experiment, have fun! If you get stuck, post a question in the Post-Processing forum here.

Set your camera to raw, shoot some pictures, process them. I don't know what software you use for post processing but at the very least Canon's DPP is available free. It does a rather good job of converting raw IMO.

There are also some pretty good books available and some great tutorials online. Canon has one for DPP here: http://www.photoworksh​op.com/canon/index.htm​l

Well, not ALL of your filters, but you can certainly avoid warming/cooling ones and do that in RAW processing. You can't simulate a circular polarizer in PS, and you can't really do the same thing as a graduated neutral density in PS, but many PS experts can approximate that ( I think a real filter does it better). You definately need a ND filter to get slow shutter in bright light for things liek smoothing moving water.

Yeah, I overgeneralized. I meant warming/cooling filters. Sorry if I caused any confusion.

On the other hand, the effects of a UV/haze filter can easily be rendered in photoshop by reducing the contrast and adding ghost lights.