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[goodcow]

I got this brief reply in another thread from nitewulf, but I want some elaboration:

the cheaper lens has 3 elemens in 3 groups. that means there are 3 seperate lenses w/ air space between them.
the expensive one has 4 lenses in 3 groups, that means 2 of the lens elements are glued together and the other two are seperate.

What's the difference between:

1 element glass lens
vs.
Lens design, 3 groups, 4 lenses

Now I know what the latter means from nitewulf's description, but for the former, is just 1 element of glass better then, since there's no air between them for the lens to breathe? Or are greater elements of glass better, as long as they're grouped as little as possible?

 

[GXAlan]

The groups/elements of a lens doesn't tell you much about final image quality. All things equal, the fewer elements the better. All things equal, the fewer groups the better. Things aren't equal. It's much better just to look at the finished output... Think of elements and groups as measuring console performance by "bits"

A long time ago, it was said that the more elements you have, the more freedom the designer had to control lens aberrations, improve close focusing, or vignetting. Sort of true. But each "corrective" lens has its own aberrations to deal with...

The number of groups tells you about the number of air-glass interfaces, which tells you about flare. The fewer the groups, the less the flare. Groups also deal with zoom lenses because you want to move multiple blocks of lenses to zoom. Some zoom lenses can be designed where the barrel doesn't extend, while others aren't designed like that.

Here's where it gets complicated. The flare from air-glass interfaces can be reduced by improvements in anti-reflective coating, and the invention of low-dispersion glasses meant that you could control your aberrations with fewer elements, and as I said corrective lenses add problems too.

Here's the better rule of thumb of lenses: the more low dispersion elements the better. On average, the wider the range of zoom, the more difficult it is to be sharp. The best fixed focal length lens will always beat the best zoom lens.

 

[goodcow]

Alrighty... can anybody recommend some good websites for lens reviews?

 

[GXAlan]

Are you talking about SLR lenses? No one "reviews" the lenses alone for standard digital cameras, although reviews of the product itself will comment on it.

If you're looking for SLR lens reviews, good places include:

http://www.photodo.com

hasn't been updated for years, but fortunately lens technology has been fairly consistent.

http://www.fredmiranda.com/reviews/
has good end-user reviews

and

http://www.wlcastleman.com/equip/reviews/
Canon lenses only, but exceptionally good data.

What exactly is your question? Or are you just curious?

 

[goodcow]

Basically, I'd like to get a 37mm lens for a Sony camcorder I own, and I'm unsure which one(s) to purchase.

 

[GXAlan]

Which camcorder? Wide angle or telephoto adapter?

 

[goodcow]

Which camcorder? Wide angle or telephoto adapter?

I'm going to take this to PM since it's really just us talking. Expect something soon.