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05-06-2010, 10:53 PM   #1
alphalt
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Prime and zoom lenses quality difference

Hello,

I've heard rumors that prime lenses has more optical quality than zoom lenses. Is this true ? Should I avoid buying zoom lenses when I want excellent quality ?

05-06-2010, 10:58 PM   #2
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QuoteOriginally posted by alphalt Quote
Hello,

I've heard rumors that prime lenses has more optical quality than zoom lenses. Is this true ? Should I avoid buying zoom lenses when I want excellent quality ?
It depends on the lens. Some zooms are doorstops and so are some primes.

05-06-2010, 11:03 PM   #3
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Jeff has a point, I suggest you look at the lens review database to get an idea
I prefer primes; if you get a really good prime (like a DA or FA limited for example) the quality can be hard to match with a zoom. However, some zooms are also excellent quality, so it depends on the lens.
05-06-2010, 11:05 PM   #4
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I would say that generally speaking primes have better IQ than zooms. Of course there are exceptions. The Pentax 17-70 is a very sharp lens but not as sharp as the DA 40 limited, actually any pentax DA limited is probably sharper than any zoom out there but definately not all primes are sharper than every zoom. That is going to far.

05-06-2010, 11:09 PM   #5
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QuoteOriginally posted by alphalt Quote
Hello,

I've heard rumors that prime lenses has more optical quality than zoom lenses. Is this true ? Should I avoid buying zoom lenses when I want excellent quality ?
JeffJS is right, it depends on the lens. Generally, primes are cheaper and have better IQ since they're easier to produce/design. Zoom lenses are far more complicated to manufacture. Pentax is known for its amazing prime lenses, so it's pretty hard to go wrong with most primes. It's really a matter of personal preference, do you value IQ or convenience more? Primes are cheaper in terms of individual lenses, but you would need 2-3 primes to cover the focal length of most zooms, so the cost quickly adds up.

I use primes exclusively. I care about IQ first and foremost. The only zoom I use is the A35-105mm f3.5, that lens definitely has prime quality.

The kit zoom lenses today are no match for the prime kit lenses of yesteryears in IQ.
05-06-2010, 11:18 PM   #6
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You already received some good advice. Let me add that a zoom lens has to be 'tuned' for a compromise over the entire zoom range, while a prime lens can be optimised more easily since it deals with a single focal length. Overall, and for the same price, a good prime lens will give you an excellent IQ, often better than the zoom lens. But it will not match the convenience of the zoom lens.

At the end, it is a matter of convenience, usage and needs. I use both zoom and prime lenses. They have both their uses and advantages.

Last edited by hcc; 05-07-2010 at 12:27 AM. Reason: Typos
05-07-2010, 12:33 AM - 1 Like   #7
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it really depends.
Let's put it this way:
new zoom will always (99%) be better than old zoom! Technology moved a lot forward and here is where you can see it.
This is not necessarelly true with primes. Many of the old ones are just as good as the new ones.
One think to look out for is price tag. Most of the time you get what you pay for. Please exclude Helios 44 and various M42 Takumars from this rule. Those go for next to nothing and provide excellent optical quality.
Main difference between zoom and prime is on wide f stops. MOST primes beat MOST zooms up to f4! And of course primes provide faster option (there is no zoom for K mount faster than f2.8). There are notable exceptions between zooms though. Lenses like DA*50-135 which by f4 proved (at least for me) nearly impossible to tell from my F50/1.7
If you shoot f stops smaller than f4 you won't see much difference if any as a general rule... at the end of the day it's as much about optical quality as about your habbits/eyes.
I have had some great zooms (DA*50-135, Tamron 70-200/2.8, Sigma 100-300) but ended up with mostly prime line up. I see zooms as two lenses (wide end and long end) and very rarely use the entire range... but you may see it differently and there are definitely some great zooms out there...

BR
Peter
05-07-2010, 01:54 AM   #8
alphalt
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Thank you all for this good explanation !

05-07-2010, 02:10 AM   #9
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Another good idea is to visit the Pentax Gallery and view some pics of various zooms.

PENTAX Photo Gallery

I have both the DA*'s and can swear by them both to give great quality results.... I am now however more keen on primes... Pentax primes


Cheers

Neil
05-07-2010, 05:14 AM   #10
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It's not a "rumor"... it's a fact of optical design.

All things being equal (quality design and optical materials), a prime will be optimized for ONE single focal length, and tweaked for that focal length. A zoom must be balanced, and compromises must be made, for a range of focal lengths. So in theory there is one focal length where a zoom will be at its best, and it degrades as you move away from that focal length.

A short zoom, well designed, will be nearer what you can achieve with a prime. A long zoom will involve more compromise. And a cheap consumer zoom will NOT be designed as neatly as a Limited prime.

In real life, SOME zooms mostly equal some primes. But the best prime will always be better than the best zoom. Except at one focal length.
05-07-2010, 05:35 AM   #11
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QuoteOriginally posted by bdery Quote
It's not a "rumor"... it's a fact of optical design.

All things being equal (quality design and optical materials), a prime will be optimized for ONE single focal length, and tweaked for that focal length. A zoom must be balanced, and compromises must be made, for a range of focal lengths. So in theory there is one focal length where a zoom will be at its best, and it degrades as you move away from that focal length.

A short zoom, well designed, will be nearer what you can achieve with a prime. A long zoom will involve more compromise. And a cheap consumer zoom will NOT be designed as neatly as a Limited prime.

In real life, SOME zooms mostly equal some primes. But the best prime will always be better than the best zoom. Except at one focal length.
I think you need to reword this just a little.

I do not believe that the "short" and "Long" zooms refer to focal lengths, in the way that short and long are normally useed with respect to photography.

I believe the challenge is not focal length, but focal length range.

There are many fine and very sharp long zooms in the 70-200 mm range, but image quality suffers significantly when you look at 28-200mm zooms.

It is not the focal length that is the challenge but the zoom range.

Additionally many wide or ultra wide zooms have additional challenges, that can make a prime a better choise at the wide or "short" end.

In fact I believe it is really only materials that have permitted high quality really wide zooms., where as high quality telephoto zooms have been around for some time
05-07-2010, 06:20 AM   #12
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In my experiŽnce primes were almost always better than my zooms.
Exeptions : m75-150/4.0 as good as m135/3.5
DA 16-45 better than my Sigma 24mm (and the Sigma better than Pentax 24mm).
Sometimes less is more : K45-125 in the centre as good as many primes, softening outside the centre section is functional in portrait photography. My K55/2.0 is almost constant from centre to corner @ F4 / F 5,6. Thats not always what you need.
05-07-2010, 07:44 AM   #13
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The theoretical answer is, that high quality primes would be better than any zoom lens. The practical answer is, whether the difference in image quality is visible in the final image!

Any lens design involves compromises. Zoom lens design affords more compromises, as the zooming introduces more variables. That's true.

But a really good zoom lens can deliver pronouncedly better image quality, than a poor or mediocre prime lens. And poor zooms can be very inferior ion performance to even a mediocre prime.

In my experience, when using a high quality zoom lens the image quality is not so much limited by the lens, but by other factors, which would affect prime lenses just as much (wheather/atmosperic condition, when using longer focal lengthes over a distance, camera shake, motion blur, subject contrast etc.)

Ben
05-08-2010, 07:11 AM   #14
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QuoteOriginally posted by Lowell Goudge Quote
I think you need to reword this just a little.

I do not believe that the "short" and "Long" zooms refer to focal lengths, in the way that short and long are normally useed with respect to photography.

I believe the challenge is not focal length, but focal length range.

There are many fine and very sharp long zooms in the 70-200 mm range, but image quality suffers significantly when you look at 28-200mm zooms.

It is not the focal length that is the challenge but the zoom range.

Additionally many wide or ultra wide zooms have additional challenges, that can make a prime a better choise at the wide or "short" end.

In fact I believe it is really only materials that have permitted high quality really wide zooms., where as high quality telephoto zooms have been around for some time
You are correct that by "short zoom" I meant "zoom with a short range"...

I'm not sure I understand what you mean by"materials have permitted ..." If you mean that new types of glass have made the job of the lens designer easier, it's true to some extend. When designing lenses the designer starts with a known design, then works on the parameters to improve. His levers are glass types, lens element thickness and curvatures (or you can add or remove elements, but that's a new design).
05-08-2010, 12:00 PM   #15
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I recommend you grab a DA limited of your choice focal length and experience it
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