- Joined
- Oct 15, 2008
- Messages
- 2,749
- Car
- wme451 a124 r129 s211 r230
The thing to bear in mind is that nothing will beat the quality of a fixed, ie prime, lens. So a non zoom lens with a fixed focal length, say 50mm, will produce better images than a zoom lens which has a variable length of say 15-85mm, set at a focal length of 50mm. A simple analagy is if anything, generally, is made to do one thing only, it will do it better than something else which is made to do several similar things.
With zoom lenses, the greater the range of focal lengths, the greater the compromise of their capabilities, depending on budget and manufacturer, but the principle is the same, so some lenses set at 80 will give a different perspective to others. Just think of the way a picture looks taken from a distance, but zoomed in close, and then the same picture taken up close with a wider angled lens, and you will see the difference. Also, outer edges may start to degrade in image quality etc.
The f numbers refer to the aperture of the lens, which is like the iris of the eye. The more the iris or aperture is open, the more the amount of light you let in. The shutter speed on the camera is like the eyelid, and will determine how long you let the light in for. The more light you let in, the less amount of time you need to let it in for etc, so fast shutter speeds for moving objects require more light to be let in, and the smaller the f number, the more light it will let in. Your 2.8 lens will let in about twice the amount of light on full aperture as the 3.5s your are considering, and is therefore 'faster'. It would be better for landscapes in lower light, for example, so don't compromise that for the 15-85 lens. If you can, I would look to get a second lens, going upwards from 50mm.
I won't get invloved with depth of field etc, 'cos I haven't had breakfast yet, but your camera will be programmable anyway. I woke up early this morning, all excited, 'cos I'm picking up the replacement for my old 124 estate later today, an S211 E500 estate, so you'll know how I'm feeling! Good luck with the sale of yours, btw. Time for breakfast!
Edit for previous post in red.