What is the slowest shutter speed that you can use with a wide angle lens for a SLR camera?

To elaborate on the rule of thumb, with digital cameras you also have to take the crop factor into consideration.

With a wide angle lens on a regular film camera, the rule of thumb works out to:
24mm lens --> 1/24th second max.
28 mm lens --> 1/28th second max.
35 mm lens --> 1/35th second max.
50 mm lens --> 1/50th secon max.
etc.

If you need keep the shutter open for longer, you should use a tripod to prevent blur.

However, with the exact same lenses on a digital body, with let's say a 1.5 crop factor, you get:
24 mm --> 1/35th second max.
35 mm --> 1/50th sec max.
50 mm --> 1/75th sec max.
etc.

If your camera or lenses have Vibration Reduction/ Image Stabilization/ etc., you can often get away with an exposure bonus of up to 2 stops. A TWO stop bonus means that you can keep the shutter open FOUR times as long.
You usually don't see this technology used in wide angles lenses however, because the rule of thumb makes wide angles more forgiving than long lenses.

Hope this helps!

The wide angle lens doesn't make a difference. You can use as slow as you need to get proper exposure. If it is very slow, make sure you have a tripod.

Shutter speed has nothing to do with lens size with the exception that, with a longer lens which generally has a wider aperture, one would need a slower speed to compensate for the lower light factor.

A "rule of thumb" I've heard for hand-holding a camera: The minimum shutter speed you should use for hand holding a camera is the inverse of the lens focal length in mm (35mm film camera equivalent). For instance, if the 35mm camera lens focal length is 100 mm, the slowest shutter speed you should use before going to a tripod is 1/100 second - any slower and use a tripod or risk having camera shake.

Most digital camera lenses are marked with the equivalent 35mm camera focal length, so this can be applied to digital cameras too. On the other hand, most newer digital cameras have anti-shake software built into them...

The rule described above is a very good one, which you should respect in order to make sure that you get sharp pictures.

A few things can alter it:

- When shooting, try to find support for your arms: on your chest when nothing else is available.

- If you can brace yourself and your camera against something solid, you can generally shoot at lower speed
The photo of Saint Sulpice (see link below) was shot at 1/15th of a second but I was resting against a stone pillar.

- Shooting vertical frames can sometimes be tricky as you are not as stable as when shooting horizontal

- A stabilized lens can help, but I do not think extreme speeds (under 1/8th or 1/4th of a second) are reached easily. Stabilized wide angles are not very common yet.