What kinds of products, and what kinds of pictures?

hhp

> It is boring technical manuals...
> I don't know much about fonts...

If you don't mind a suggestion, you might consider getting a graphic designer to help out; someone who has experience working on technical manuals and has good examples of them in their portfolio (not all designers like those kinds of technical projects).

They could help present the information clearly and in a more visually interesting manner. Well designed manuals would be appreciated by your customers and would reflect well on your company.

I recommend Skolar.
http://www.rosettatype.com/Skolar
http://www.fontshop.com/fonts/downloads/rosetta_type_foundry/skolar_pe_b...

This is if you are making a printed manual or a pdf manual for viewing on screen. And if your software will allow this type of font. (Madcap Flare does not work with OpenType Postscript flavor fonts.)

What software are you using and what outputs do you envision?

hrant,
The products are small and big fan heaters and electrical cabinets.
In our manuals there are mostly black and white line drawings.

JamseM,
You are probably right, but before that I would like to gather some information and thoughts so I have a better understanding in discussions with a designer.

J. Tillman,
The intended use is printed manuals. They will be available on our website as a pdf file but the users will probably print the anyway.
We use the latest Indesign version to produce the manuals.

This is a rare case where I can't recommend spending money on a font. If you're on Windows just use one of the great system fonts - just make sure it covers all the required languages.

hhp

For a technically-oriented manual I'd be inclined to go for something conservatively plain and unobtrusive, with well-disambiguated characters (e.g. no O/0 or 1/l/I confusion) that nonetheless reads fairly comfortably.

If, as Hrant suggests, you don't want to spend money, there are some good free (open source) options. To name three: Linux Libertine, TeX Gyre Schola (a version of Century Schoolbook), or Bitstream Charter. I imagine any one of those would do well.

Georgia might work well too, although if your manual makes heavy use of tabular numbers you might find the old-style figures awkward. (Though there are ways around that, of course.)

See Georgia Pro: http://www.myfonts.com/fonts/ascender/georgia-pro/

hhp

I think Hrant is on the right track with using a good windows font.

You can do very nice work, with a surprising tonal range, using the following:

Calibri
Consolas

That's for the body copy (Calibri) and the technical data (Consolas).

For making nicer headlines, you can go to Lucasfont and license a single weight of The Sans.

It's one big Lucas de Groot family!