(I also posted this question in the Photoshop forum...)
I am writing an article for a magazine that will be offset-printed on matte paper without spot colours (< 5000 copies). I am a fairly new CS5 user and also fairly naïve about commercial printing. Anyway, I would like to include some greyscale images in the article but convert them to one colour (15/100/100/0 Red). Right now, I can achieve this two different ways, but I get different results....
Method 1: I opened the original greyscale TIFF image in Photoshop, changed the mode from Greyscale to Duotone, changed the preset to custom, changed the type to Monotone, selected the colour swatch for Ink 1, selected "picker," and set the CMYK values to 15/100/100/0, respectively, and named the Ink 1 value as "RED." I then placed the image in InDesign.
Method 2: I placed the same greyscale TIFF image in InDesign, selected the image with the white arrow, and chose CMYK red 15/100/100/0 from the swatches panel.
Compared to the monotone, the TIFF is a much darker, deeper, almost orangey red (see below). I would like to know if there is a "standard" way to achieve this monotone effect (without spot colours), or if it makes any sort of difference to the printer. Also, any clarification as to why the images are so different would be greatly appreciated!
I tried with both the CMYK mix you used, and with Pantone 185 (bright red).
I got the same appearance by colorizing an image in InDesign as I did from the Photoshop monotone when the Duotone curves are left at default (45 degree angle straight line)
In Photoshop, are sure didn't adjust the Duotone curve. That could produce the results you show:
Also, when I woke up this morning, it occurred to me that you didn't say what format you saved the monotone (Duotone mode) in. I saved as a PSD file. An older format (DCS or EPS) may not preview correctly when placed in InDesign unless you turn on View > Display Performance > High Quality Display. The best way to view the page is to choose View > Overprint Preview (although this might take a little longer on an older computer).