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I have asked every lab and they prefer sRGB. Now when I shot some stuff for a brochure, the printers asked for Adobe RGB
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That is because most labs are not aiming for the (few) professional photographers outside. They choose to advice sRGB, because it’s a small color-space causing little difficulties with the average picture. The good labs (and there are not many) will give good advice and have first-class knowledge about color management. They profile their printers and let you use those profiles they created with your images for soft proofing and converting to the printer profile in the end.
Most printers can print way outside the sRGB colorspace; therefore, sRGB is not a good description and an unnecessary limitation. When you use adobeRGB, you can convert to a smaller colorspace, but you cannot convert sRGB to a larger colorspace (like the printerprofile) (well you can, but you will not gain anything). Some printmakers ask for aRGB, because they will do the converting for you.