[zoeybird]

Hey Guys,

First time poster but long time reader.

I have a question about lenses in general...hopefully this is the right place to post this.

I'm a little confused on what makes a good lens. I understand the bigger the F stop the more $$ and the type of lens itself equals more $$ (ie digital vs manual) but what about clarity? How can you tell the lens your looking into purchasing has better clarity or resolution vs another??

Thanks in advance...

[ftpaddict]

First of all welcome to the forums. I'm sure you'll enjoy posting as much as you enjoy reading.

Sadly, there is no easy answer to your question, because there is no easy way to find out, unless you try the lens out for yourself. Or read reviews written by owners of the lens. Or read reviews such as the ones you can find on Welcome to Photozone! .

But it's all just measurebating, really.

[kristoffon]

Optical lens design - Wikipedia, the free encyclopedia

[Just1MoreDave]

One way: a lens that only does one (optical) thing is almost always better than a lens that does a lot of optical things. I have a lens here, let me give you its full name:

Tamron AF Aspherical XR LD IF 28-300mm 1:3.5-6.3 Macro

If I test this lens against just about any other lens I have, it won't have the best image quality, because it's designed to do so many things. I own it for when I don't want to carry all 15 better lenses that could do the same job. But don't buy a lens like that and expect it to be more than average at anything.

This is the catch when looking at lens specs and trying to "cover" all possible focal lengths at a reasonable cost. If you can define one area where a lens needs to be great, you can narrow your choices greatly before getting caught up in 1000 choices.

[zoeybird]

Thanks guys or gals

I feel sometimes like I can ask a trillion questions and still have a trillion more to ask everyone to be honest. I've had cameras for a while but as I get older, I just don't wanna take pictures, I wanna take really good pictures....I wish they had digital cameras a while ago and the cash I spent developing the film back in my pocket. But, who doesn't right?

Thanks again for each of the answers and if someone else has can add to it, please do...

Steve

[Ole]

This forum also has a review section where you'll find reviews of most current and past Pentax lenses:

Pentax Lens Review Database - Main Index

[newarts]

One good way to get a judgement on a newer lens' quality is to read its review at photozone.de

Almost all pentax lenses have less quantitative (but good) reviews here, in the pentax lens reviews database.

There is fair correlation between lens cost & quality from a contrast/resolution standpoint but it isn't an sure thing. There are many bargains and many overpriced lenses out there in used lens land.

[Marc Sabatella]

I'm a little confused on what makes a good lens.

Lots of things. Large maximum aperture, high sharpness, high contrast, "good" color, "good" bokeh, lack of chromatic aberrations, lack of barrel or pincushion distortion, lack of vignetting (all terms you can look up for yourself if you are unfamiliar with them). Some of these are more subjective than others, and some of these factors are more important to some people while other factors are more important to other people (for instance, I don't care as much as some about bokeh, color, or vignetting, but am very sensitive to sharpness).

the type of lens itself equals more $$ (ie digital vs manual)

That doesn't really make sense. "Digital" isn't a type of lens. It just means someone decided the lens was appropriate for use on a digital camera. And the lenses marked "digital" aren't always more more expensive than lenses *not* marked "digital". The most expensive lenses available new for Pentax include that FA77 and FA31, neither of which is "digital". It is true that lenses marked "digital" are almost always autofocus and autoaperture, and these often are more expensive than corresponding manual focus, manual aperture lenses. But not always - again, there are some manual lenses that are unbelievably expensive too.

but what about clarity?

That's not really a well-defined photographic term. You are probably referring to some combination of sharpness (more or less the same thing as resolution) and contrast. And the only way to know is to read reviews.