my print results are not as expected

[CVSebastian]

Hi guys, I am currently creating an ad with Affinity Publisher and Photo. Unfortunately the print results are not satisfactory and I don't know what to do. As it looks like there seems to be a problem with the layers. Maybe I am doing something fundamentally wrong when creating the document? 
I have attached some photos to show you where the differences are (even if it is only photographed, you can see the color differences well).

I look forward to your thoughts on this! 

Sebastian 

[mac_heibu]

Looks like the difference between screen colors (RGB) and print colors(CMYK) in combination with a greyish paper color.

Which color profile has your document? Which color definition has, for example, the „red“ of the text?

[CVSebastian]

Thank you mac_heibu. You are right, the color format is CMYK/8, the profile is U.S. Web Coated (SWOP)v2, but the colors are taken from the RGB color space. 
This might explain the problem with the colors. My problem is that our corporate design colors are expressed in RGB, but the printing house needs CMYK. What can I do there? 

In your opinion, does this also explain the problem with the photo used? As the screenshot shows, it is designed to be cut off from the curve, but the print makes it appear again. And why only over the width of the text frame and not over the whole width of the photo (see lower left corner).

 

[BofG]

Ideally you should ask the printing house for the profile they will be using - you can then use this as a soft proof layer at the top to see what the colours will come out like. You can then make adjustments to get the colours better. This does rely on you having a properly calibrated monitor.

The photo cropping issue is not related to the colours. What format are you providing this to the print house in?

[CVSebastian]

Unfortunately there is no exact specification, but I'm going to ask for it. They would like it as PDF/X-1a. Do you think there is a problem with exporting? 

What I don't understand either: I have consistently used RGB colors. Then the colors would have to be consistently wrong? How is it possible that the same RGB grey is output differently when printed? 

Thanks for your patience!  

[BofG]

Firstly I would open that x-1a pdf in Adobe Reader and see if it's rendering correctly with the photo in there. If it is, then the print house RIP is messing it up and you should ask them to resolve it. If it's wrong on there then it's an issue with Affinity export.

As for the colours, it's a very complex field, but essentially you haven't done anything 'wrong' in using rgb, I'd actually recommend working in an rgb colour space for the document as a lot of presses can exceed the cmyk gamut, so no point limiting yourself to a smaller set of colours. The print colour profile will define the translation between the colour formats, and on top of that there are different methods - usually a 'perceptual' approach is done.

If you cannot get a profile from the print house, I'd recommend converting your document colour space to srgb iec6..2.1 and setting up a soft proof layer as ISO Coated v2 (eci). You will most likely not be able to hit that vibrant red you have in print, at least the soft proof this way will give you a realistic expectation of what the print can manage. Also, before exporting always turn off the soft proof layer.