how to judge a lens' quality?


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lingfoo

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I'm new to photography, and I am wandering in what sense will a lens be consider good? is the Canon 28-105 USM II a good lens?

Why is some lens so expensive, and some cheap? even within the same zoom length and same USM?
 

Ah Pao

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#2
Few factors to consider.

Purely from an optical viewpoint, things to look out for are:
- "Sharpness" or resolution
- Colour balance
- Contrast
- Flare control
- Chromatic abberation control
- Bokeh (not to be confused with Depth of Field)
- etc.

Some can be qualitively measured, others are simply a matter of personal preference/tolerance.

Then there are other technical aspects of a lens (e.g. USM, IS, overall construction) that will add to the cost of a lens.

Very often a lens purchase is subjective and you'll need to do a bit of research on opinions before making a decision.
 

justarius

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#3
A lens is good if you are happy with the results it gives you.

Lens comparison is very subjective. A lens might have the best bokeh in the world, tack sharp, excellent contrast, zero chromatic aberration but can still be classified as a lousy lens because it weighs a ton and proves impractical to use in the field.
 

sriram

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#4
The mid range Canon zooms such as the 28-105, 24-85 etc are very capable performers. I've made several 8x12 enlargements from my 28-105 and they show very good sharpness and definition. Gotta shoot these lenses at their sweet spots.
 

ST1100

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#5
lingfoo said:
I'm new to photography, and I am wandering in what sense will a lens be consider good? is the Canon 28-105 USM II a good lens?

Why is some lens so expensive, and some cheap? even within the same zoom length and same USM?
The thing is, where lenses are concerned, improvement in performance does not scale linearly with cost. A lens that is 10% better optically can cost 2 to 10 times as much. Especially fast aperture lenses.

A one-stop increase in aperture (eg f4 to f2.8) means theoritically a minimum of double the surface area, and practically a lot more than double the amount of glass, as well as a lot more aberrations to correct.

If you're new to photography, i'd suggest you go easy on the purchasing. But stay away from the bottom of the barrel lenses, those very cheap kit lenses and those super-zooms (28-200, 28-300). The lens you mentioned (28-105) is considered a good lens, but i think there are two versions: one starts at f3.5 (the good one), the other f4 (the, um, not-so-good one). Which one is yours?
 

lingfoo

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ST1100 said:
The thing is, where lenses are concerned, improvement in performance does not scale linearly with cost. A lens that is 10% better optically can cost 2 to 10 times as much. Especially fast aperture lenses.

A one-stop increase in aperture (eg f4 to f2.8) means theoritically a minimum of double the surface area, and practically a lot more than double the amount of glass, as well as a lot more aberrations to correct.

If you're new to photography, i'd suggest you go easy on the purchasing. But stay away from the bottom of the barrel lenses, those very cheap kit lenses and those super-zooms (28-200, 28-300). The lens you mentioned (28-105) is considered a good lens, but i think there are two versions: one starts at f3.5 (the good one), the other f4 (the, um, not-so-good one). Which one is yours?
haven't got any except for a Kit lens. am looking at a 2nd hand 28-105, f3.5-4.5, and am still considering should I spend the money on lens at tis early stage or not.
 

Canonised

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#7
lingfoo said:
I'm new to photography, and I am wandering in what sense will a lens be consider good? is the Canon 28-105 USM II a good lens?

Why is some lens so expensive, and some cheap? even within the same zoom length and same USM?
when i first started buying lens, the "old birds" at SEED told me this:
lens with a RED ring at the end of the black barrel & those white barrel lens ARE the good lens .... not cheap but proven to be the truth. So if you are SERIOUS with this new hobby, then save up to get the good lens.
BTW, the 28-105 USM II is my first and favourite lens ... light, handy and sharp at this price.
 

lingfoo

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#8
Canonised said:
when i first started buying lens, the "old birds" at SEED told me this:
lens with a RED ring at the end of the black barrel & those white barrel lens ARE the good lens .... not cheap but proven to be the truth. So if you are SERIOUS with this new hobby, then save up to get the good lens.
BTW, the 28-105 USM II is my first and favourite lens ... light, handy and sharp at this price.
Approx how much is a new 28-105 USM II's market price anyway? I've been using my KIT lens all these while, no chance to try out other lens just of yet. what is the difference between the 28-105 lens and the EOS 300D Kit lens?

And if I were to buy 2nd hand, what are the things i should take note? thanks a bunch...
 

lauLEE

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#9
lingfoo said:
Approx how much is a new 28-105 USM II's market price anyway? I've been using my KIT lens all these while, no chance to try out other lens just of yet. what is the difference between the 28-105 lens and the EOS 300D Kit lens?

And if I were to buy 2nd hand, what are the things i should take note? thanks a bunch...
no kit lens so dont know the quality/comparison.

if you have no experience buying secondhand, then maybe you need :
1. a friend who can help you to inspect the lens,
2. buy cheap, so if worse come to sorse, sell again and u dont make much losses,
3. make a good judgement on the seller, find out the reason for him to sell,
4. a lot of luck .... hehe
 

lingfoo

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#10
lauLEE said:
no kit lens so dont know the quality/comparison.

if you have no experience buying secondhand, then maybe you need :
1. a friend who can help you to inspect the lens,
2. buy cheap, so if worse come to sorse, sell again and u dont make much losses,
3. make a good judgement on the seller, find out the reason for him to sell,
4. a lot of luck .... hehe
:sweat: :sweat: :sweat: Why does it sounds so scarry?

Just need some advise, a Canon EF 28-105 USM II f3.5-4.5 2nd hand no warranty for 200? is that a good buy?
 

kvp11

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#11
Someone told me..
1) A heavy lens is a good Lens.. :dunno:
2) See the coating.. Purple Colour is good..:dunno:

To me till now.. still:think:
 

oeyvind

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#14
IMHO, most lens are capable of better photos than most of us can, myself included.

Buy what you can afford, and as megaweb said "try to take interesting photo with it."

Cheers.
 

sebastiansong

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#15
oeyvind said:
IMHO, most lens are capable of better photos than most of us can, myself included.

Buy what you can afford, can try to take interesting photo with it.

Cheers.
:thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:

well said :cool:

express urself through your eqpt...

soft lens express softly.. sharp lens express forcefully... :think:
 

rncw

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#16
oeyvind said:
IMHO, most lens are capable of better photos than most of us can, myself included.

Buy what you can afford, and as megaweb said "try to take interesting photo with it."

Cheers.
:thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:

what you posted made the most sense.
 

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#17
I have that lens.... one. it looks very good... esp with a flower hood.

USM is damn good as usual, has rear focusing, means the front does not turn...

great for travelling.... it has followed me to vietnam, cambodia and rugged places like that and its a nice range.

at 28 there is distortion... but i like the lenght. it is heavy compared to a normal kit lens... but its part of canon's travelling pair, made of poly carbonate. his other half is the 70-210, however this lens will give u darkened edges with 2 or more filters and even with one filter at 28mm u shld be prepared to see the corners slightly darker.

price
28 135mm has USM also but its more ex. because it has an image stablizer in built, or other lenes my be faster like F2.8 for the 24 -70, while this one is 3.5 - 4.5., others may have a bigger zoom range like sigma 24 - 135 so price will vary,

The reasons can range from brands... to built.... to features... to image quality, but more ex does not mean a better buy

good lenses are apllied correctly:

1.) fiind out what u want to use it for, indoor all the time? outdoor?
2.) picture quality (sharpness , Contrast, Saturation of the image)
3.) Auto focus performance
4.) bokeh is the out of focus areas, personally this lens has nice bokeh lah.. and at night for long nite shots the lens gives u a natural 8 point star for the bright spots...
 

Prismatic

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#18
In technical terms, the parameters that defines a good lenses are:
1) Resoluting power
2) Clarity
3) Parity
4) Colour fidelity
5) Ergonomics.

Resoluting power is how well the lenses can show fine details.
Clarity is how clear or bright the lenses is.
Parity is how much contrast the lenses can resolve.
Colour fidelity is how the lenses reproduce colours. (whether it's true-to-life)
And lastly ergonomics includes things like how fast the AF is, the feel and build of the lenses, special features etc etc.
 

lingfoo

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#20
Canonised said:
Hi, you can consider this one, quite reasonable:

http://forums.clubsnap.org/showthread.php?t=65725

this lens shld be a very good start ...
Thanks for the recomendation. Saw that one. Another question I have, saw a couple of 28-105 USM for sale, some are USM, some says USM II, what are the difference? USM II have Macro right?

And for the same focal length range, what other brands besides canon is there?
 

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