I keep looking at different cameras and all they bleat on about is pixels.. grrr

What exactly makes up a good lens as the specs for some of the digi cameras are less than useless.. and I can find little info on the actual differenences in the lens that make it bad better or good.

Cheers
(have my eye on the ixus 400 anyway but would like at least a bit of background info :D)

Andy

There are two things to consider here: specification and performance. Problem with compact cameras (digital or analogue), is that it is more difficult to test lens performance, because you can't remove it.

In terms of specification, maximum aperture (larger aperture / smaller f/stop = better) and zoom range are really the only 'numbers' you can look at. For digicams, also worth checking what the minimum aperture (larges f/stop) is, because sometimes the range is quite small. A 'good' (subjective) specification might be f/2 max aperture and a 8x or more zoom range, covering the 35mm equivalent of 28-200mm.

In terms of performance, there are a huge number of factor that can be tested: resolution, contrast, astigmatism, geometric distortion (pin/barrel etc.), edge fall-off (darkening at picture corners), chromatic aberation (colour fringing) etc.

If you have a friendly local dealer, why not take a memory card and try out a few cameras, and print the images?

I have a NIKON COOLPIX2100, cost about £170 and takes some brillant pictures.Loads of special features including being able to take a 10 second video.

I have the Dimage 7i because it has the very good Minolta GT lens. I don't know much about photography, but it's a big lens with a lot of glass in it so it must be good (thinking back to my astronomy days -- big lens=more light).

But to complicate things more, you need to get a lens with good bokeh ;) (the Minolta's is terrible).

Oh, forgot about that one. IIRC, Bokeh is a measure of how the out of focus highlights appear. Ideally they should be nice, evenly lit, fuzzy circles, but sperical aberation and the blades in the aperture diaphram can make them appear darker in the middle, and non-circular (octagonal or whatever, depending on the number of blades in the diaphram).

Less spherical abberatoin and/or more diaphram blades give better Bokeh.

[Edited by dr_ming - 11/27/2003 10:14:54 PM]

More than that, they should be brighter in the middle than they are at the outsides. IMHo the shape is less of an issue (I don't mind hexagons, personally), but the Minolta's have sharp edges and look horrible. Unfortunately there's no way to measure bokeh :(

With any camera where the lens is built in, there's not a lot of point discussing it separately - you may as well just read reviews of the camera as a whole. They'll mention whether the finished image is sharp or fuzzy, what noise levels are like and so on.

Given that digital cameras with small sensors tend to have huge depth of field, it's unlikely that bokeh will get much of a mention, though - it's more of an issue with SLRs, where you have the ability to throw things a long way out of focus.

A.

good description of bokeh here before someone asks

clicky bokeh

I cant add anything to the answer,too many boffs in here [smile] but you shouldn't read and believe all the hype about Leitz,there are others and imo its more about personal taste.I say that using Zeiss becuase i cant afford Leitz,if i could i would agree with all the silly myths,like they can resolve a flies arse on the moon,amongst others :)

45mm Zeiss V Summicron 35mm version 2 million? both got quality glass,and are made well,thats all i know :)



[Edited by dba - 11/27/2003 10:40:28 PM]

Here is another article, which is a bit more... um... intense. I couldn't help but think that maybe it was something more of interest to lens manufacturers than to photographers.

interesting site that,just been a huge ruck in a Contax bbs regarding a contributor