Slow lens

SLOW LENS -A lens with a relatively narrow maximum aperture -ƒ/8, for example.
SLR - Abbreviation for Single Lens Reflex.

Slow lenses look dim
SLR viewfinders get dim with slow lenses.
With the popularity of slow zooms, SLR finders made since about 1979 are optimized for brighter screens with slow lenses, ...

Slow lens
A lens with a small maximum aperture. (i.e. f8)
(see Aperture & Fast lens) ...

Slow lens
Film which has a small maximum aperture. (i.e. f8 )
Slow Sync
A flash technique for using the flash at a slow shutter speed.

Rather slow lens (in terms of aperture) by traditional G series standards
Movies limited to VGA resolution
High ISO images lose saturation and detail (and offer no control over noise reduction) ...

What is a slow lens or a fast lens?
These are colloquial expressions describing the maximum aperture value or values of which the lens is capable.

For good viewing of the image with slow lenses, I have found that a second velcro is called.

When you hear about fast and slow lenses, reference is being made to a lens's maximum aperture, which is the maximum amount of light that a lens can let in.

So the fast lens is the type of lens that allows more light and the slow lens is the opposite. The speed helps in defining the results of your shots. The f/stop numbers are the measurements referring to the maximum aperture.

Should you buy a fast lens or a slow lens? I'd say that a fast lens only makes real sense if you intend to shoot it wide open. If you're going to be shooting at f/8, you'll be paying a lot more for capabilities you never use.

Slow Glass Slang term for a slow lens. Slow Lens A lens that has a relatively small maximum aperture, usually in the range of f/3 to f/4.

I own both fast and slow lenses and use them depending on the situation. I don't bother carrying my heavy 300mm f-2.8 when my smaller and lighter 400mm f-5.6 can give me the results I want.

Adding a teleconverter extender to a slow lens especially, may cause you to loose automatic focus. For obvious reasons this may be problematic for photographers who want to focus quickly on a moving bird.

"Slow lenses" will have apertures of f/4 or f/5.6. If you want to shoot sports or action, especially in low light, fast lenses are your friends. They are, however, more expensive than their slower brethren.

A fast lens transmits more light and has a larger opening than a slow lens. Determined by the maximum aperture of the lens in relation to its focal length. The speed of a lens is relative to it's focal length.

Fast lenses transmit more light and have larger openings than slow lenses. Determined by the maximum aperture in relation to focal length. Lens speed is relative: a 400 mm lens with a maximum aperture of F/3.

Lens Speed
The largest lens opening, e.g. f2 not f16. A fast lens transmits more light and has a larger opening than a slow lens.
(see f-stop & Slow lens)
Light meter
(see: Exposure meter) ...

George 5.3 6.3 are kinda slow lens.
Yes, they are. However, I tried to answer the question meds martin actually asked.
1. Meds specifically asked about the Canon 18-200mm f3.5-5.6 IS, which is in the same general range as the others I mentioned.

A lens with a maximum wide aperture (f/1.4, f/2, f/2.8) allowing it to gather more light than a "slow lens" which has a less wide maximum aperture (f/3.5, f/4 and smaller).
Nikonians Photo Glossary ...

Lens Speed is a semi-technical designation that rates or compares a lens' maximum f/stop value; i.e. a fast lens might have a maximum f/stop of f/1.4, conversely a slow lens might have a maximum f/stop of f/4.5.
Light Meter ...

Lens Speed The largest lens opening (smallest f-number) at which a lens can be set. A fast lens transmits more light and has a larger opening than a slow lens.
Light meter (See Exposure meter) ...

lens speed
the largest lens opening (smallest f-number) possible for a specific lens. (A fast lens transmits more light by way of a larger opening than a slow lens).

Slow lenses and entry level cameras can’t equal the capabilities of pro equipment. And given the situation, even the top pro equipment can’t net a tack sharp image every time the shutter is pressed.

6 to 11, while a "fast" lens (one that can pass more light through) might have a maximum aperture from 1 to 4. Fast lenses are typically larger than slow lenses (for comparable focal length), and typically cost more.[citation needed] ...

In addition, there is a less obvious drawback that with slow lens + teleconverter combinations (f8 or above) your camera may only auto-focus with the center sensor.

It also prevents many slow lenses from focusing in dim situations. So the first lesson to learn in using a polarizer is that it should be taken off until it is needed, and never left on the lens for convenience.

See also: Lens, Light, Slow, Camera, Image