What gear should I take with me?

This is my advice for a small format SLR setup suitable for Paris. Hopefully, it will also prove useful to medium format or point and shoot users.

All around zoom

You probably have this kind of lens in your bag. If you do not, consider it seriousely before your trip. 
Of course, you can shoot everything with quality fixed lenses, but this will mean changing lenses often.

Be careful when choosing it: especially check distortion at the wide end. This is a killer when shooting architecture.  

Wide angle

When you start shooting in Paris, you soon find that 28mm (or equivalent) is often too tight. You cannot always move back to get full buildings.
In that case a 10-20mm, 12-24mm or 11-18mm zoom will be useful on an AP/SC camera.
On a full frame camera, a 17-40mm, 17-35mm or 16-35mm lens will come handy. You will often find yourself using the wide end, at the risk of having extreme perspectives! 
If you can afford it and have a tripod, a tilt shift wide angle will be fine to reduce the perspective distorsion (I wish I had one).

Long focals

I use these less often but can be interesting to isolate interesting things or capture architecture details.
A 200mm is generally enough on an AP/SC camera.
It will be a tad short on a full frame, but all in all you will have very limited occasions to use a 300mm unless you want to shoot the gargouilles of Notre Dame or sculptures on the Louvre or the Opera.

Keeping your bag light

If you head to Paris with photography in mind, be prepared to walk a lot. Many photo opportunities will not be just out of the metro. Packing light is therefore important.
Here is an example of what to take:
  • wide angle zoom 
  • all around zoom / 50mm fixed focal
  • 70-200mm or 70-300mm zoom
  • one camera
  • CF card / batteries
For night photography add:
  • A middle sized tripod
  • A bubble level
  • A cable release

Bag choice

The choice of a bag will depend on what you plan to do as well as on the amount of gear you are carrying.

If you plan photo sessions without too much walking, and change lenses often, sling backpack such as the LowePro SlingShot series will be fine.

If you plan to walk a lot, but do not carry a lot of gear, a mid-sized bag such as the LowePro FlipSide series is the choice.

If you carry more or heavier gear, or if you want to add a tripod to it, you will have to invest in a larger backpack.