Why do I get a colored shadow behind shadow and feather transparency areas when printing?

Question

Hello,
I've been pulling my hair out over this and finally went to my printer to ask if they had insight as to why this is happening. I'll include his reply here but would like to hear your expert opinions too!
When laying out a file in InDesign, I do a lot of overlapping, feather and some drop shadow and always get a colored shadow behind the transparency area when printing out from a pdf. These files are being designed for print, which is what I thought InDesign was created for - as an updated alternative to Quark and Pagemaker? Here is what the printer says:
"Ive taken a look at the file in question and the issues this lady is experiencing can not be resolved in InDesign. What she needs to do is build the background image with color overlays all in Photoshop as a Layered PSD. Then flatten it and pull it in to InDesign as a Tiff. Then she can place her text over the top of it. She needs to use image masks on the color overlays - for the areas she does not what the color to violate.
What it comes down to is these fancy design effects out of InDesign and Illustrator should never be used for printing. They can be used for web design. Reason is, they cause RIP problems. Things fall off the file and transparent areas go away just to name a few. This happens all the time."
I would appreciate any other viewpoints here. Can I really NOT use the shadow and feather functions in InDesign for print? Are there any other ways to approach this problem other than what is being advised here. It is SO much easier to produce the entire file in InDesign.
Here is a link to the pdf. If someone would like to see the original indd file, I can post it somewhere.
http://displaysunlimitedinc.com/test/panel_3_text.pdf
There is a 1 inch blur drop shadow on the black and white temple image; a 1 inch feather on the black and white screened back image behind the main text box; and no drop shadow or feather on the map at top right, yet I get a colored shadow behind all 3 of these areas when I export the indd file to pdf and print that out. The fact that I get a shadow behind the map puzzles me.
Thank you very much in advance.

Answer 1

Horgycat,
The CMYK/RGB question is actually pretty complex, and depends to a great extent on how the final output is going to be produced.
If the files are destined for a printing press, all RGB elements must be converted to CMYK prior to printing. You have the option of doing that before placing in ID, or during export to PDF, and there are pros and cons to both methods, but if you don't know until the last minute what the print conditions will be, the convert on export path is more flexible.
Spot colors are a different matter. As far as I'm concerned, you should NEVER specify a spot color unless you are actually using spot ink on a press. A lot of inkjet and laser devices claim to be Pantone certified, but the reality is that even with expanded gamuts available using more than four inks, I'd estimate that better than half the Pantone solids are not reproducible as simulations that would satisfy me or my clients. The convert spot to process route should only be used, in my opinion, when you've designed a job properly to be printed using spot colors, and suddenly you have an output change or an added image that forces you to move to a process output. The last time I tried it, by the way, I had issues at the printer (the regular prepress guy was out of town, so I'm not sure what went wrong) and I ended up re-building the file with real process colors to get the transparency to work.
But you mentioned that you are doing exhibition panels, which implies to me that they are probably NOT going on a press -- you need to do hundreds, or sometimes even thousands, of copies to make a press cost-effective compared to digital printing. I used to work in a large-format output bureau doing just this kind of work, and we used large inkjet plotters. In this case, mixed RGB and CMYK files are less of an issue since most plotters will handle either, and depending on if they have an internal or external RIP or none at all, you may actually get better color fidelity using RGB as CMYK colors may get converted in the RIP to the RGB values that the plotter understands, and then get converted back a second time to CMYK (CMYKOG or whatever ink combination is used) internally before the ink is sprayed. Only the print provider would be in a position to tell you the correct color space for the equipment.
Which of course puts you at a bit of a disadvantage working with a client out of state who isn't supplying you with such necessary information as the correct output profiles for the job. It will be a miracle if the color is close.
A final word about looking funky on screen. Just as many spot colors can't be well simulated in CMYK, many also cannot be displayed adequately on a monitor. The ONLY way to choose spot colors is with a swatch book, and that's what the press operator will be using to verify his work. Clients need to be educated about the differences in technology and the limitations of soft proofs.