I have a printer capable of printing high res photos on photo paper, and duplex documents on plain A4.

I have set the printer up twice (i.e. two separate printers pointing to the same URI) using the CUPS interface at http://localhost:631, once called Documents, once called Photos. For each of these instances I have set up the appropriate defaults (media type, size, print quality, duplex...). CUPS seems to remember these fine but applications (e.g. LibreOffice, EOG, firefox ... under Gnome Shell FWIW) seem to have some weird other default that bears no resemblance to either the defaults I set up, nor the last settings I used with any particular application.

It's a problem because there are so many settings to change that it adds a couple of minutes to each and every print job. Inevitably I forget one or two and end up having to reprint the job.

Seems there must be somewhere that these defaults get stored? Anyone shed any light on it?


Question: What creates this strange flare and how to prevent it?
Answer: Your other choice is to use a hood.  That will help avoid the flares from off the frame.  

It also appears that the flare is accentuated by some CA as well.  Stopping down a little or using a brighter lens that is better corrected may help.  

Lastly, don't use UV filters indoors/at night unless they are multi-coated to remove such reflections.  When in use, they provide two additional surfaces for flaring.  It's better to leave them off in these situations.

Still, having flares used for dramatic/visual effect (eg: Star Trek) is in vogue.  If you like this look, do all the reverse!