RGB to grayscale?

If when printing, you can change the Color Profile to "Black & White". I have not experimented with this on any of my printers to then see how it matches to the paper I would choose to use.

You can, however, make a duplicate version and in adjustments you can take saturation down to zero.

I would probably not do either of these, but rather use Photoshop as an external editor and do it way you always have done.

UPDATING -- in the Adjustment sidebar, you can click on the arrow in the button menu at the top, and choose to add the Black and White section with controls much like those in PS.

Ernie

Message was edited by: Ernie Stamper

I'd use the Black and White / monochrome Mixer Adjustment -

Press "Control-M" to turn it on, and use the RGB sliders to change the channel mixing for the grayscale conversion.

Then yes, when you export a version you can assign the color profile so it is not RGB

That is correct, nothing in aperture is "permanent" until you export a version of the file (this includes color profiles and color space).

In the export versions dialog, you can edit the presets, and make a custom one called "grayscale" and set it to save a TIFF or PSD or whatever you need - then change the color profile to 2.2 grayscale and the file opens in Photoshop as a grayscale image, not an RGB one (I just tested to confirm).