advantage of prime lens

Started Aug 31, 2012 | Discussions
ennemkay
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advantage of prime lens
Aug 31, 2012

i've always assumed the main advantage of a prime lens is the larger aperture for a given size/weight/price. is there anything else? i notice some people use primes exclusively. does it become tedious to change lenses frequently? my only prime is the 16mm.

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GaryW
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Re: advantage of prime lens
In reply to ennemkay, Aug 31, 2012

ennemkay wrote:

i've always assumed the main advantage of a prime lens is the larger aperture for a given size/weight/price. is there anything else? i notice some people use primes exclusively. does it become tedious to change lenses frequently? my only prime is the 16mm.

In general, a prime lens doesn't need as many internal elements as a zoom lens, and there aren't as many compromises, so you can get a higher quality result. The 16mm has compromises to allow it to be so small, but still, it has few elements and IMHO is still pretty sharp. I have a Minolta 28mm prime lens and it's probably the worst of the Minolta primes, and it's still as good or better than the Nex 18-55 as far as sharpness is concerned. Bokeh, not so much. I also have a Minolta 50/1.7, and I'm pretty sure it's a lot sharper than the18-55, although I don't think I've bothered to make hard comparisons. (Years ago I compared it to my 17-50/2.8, and they seemed pretty equal on my 10mp A100.)

So, I see primes as fewer compromises and higher quality, generally.
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kev777zero
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Re: advantage of prime lens
In reply to GaryW, Sep 1, 2012

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

I've read articles explaining how old SLR lenses or early DSLR lenses can't compete with lenses of today in sharpness since lens manufacturers back then wasn't expecting sensors with 16 or 24megapixels.

That being said, there is much more to a good lens than just being sharp, so old lenses do have their value (I own a couple as well).

GaryW wrote:

ennemkay wrote:

i've always assumed the main advantage of a prime lens is the larger aperture for a given size/weight/price. is there anything else? i notice some people use primes exclusively. does it become tedious to change lenses frequently? my only prime is the 16mm.

In general, a prime lens doesn't need as many internal elements as a zoom lens, and there aren't as many compromises, so you can get a higher quality result. The 16mm has compromises to allow it to be so small, but still, it has few elements and IMHO is still pretty sharp. I have a Minolta 28mm prime lens and it's probably the worst of the Minolta primes, and it's still as good or better than the Nex 18-55 as far as sharpness is concerned. Bokeh, not so much. I also have a Minolta 50/1.7, and I'm pretty sure it's a lot sharper than the18-55, although I don't think I've bothered to make hard comparisons. (Years ago I compared it to my 17-50/2.8, and they seemed pretty equal on my 10mp A100.)

So, I see primes as fewer compromises and higher quality, generally.
--
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EinsteinsGhost
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Re: advantage of prime lens
In reply to ennemkay, Sep 1, 2012

ennemkay wrote:

i've always assumed the main advantage of a prime lens is the larger aperture for a given size/weight/price. is there anything else? i notice some people use primes exclusively. does it become tedious to change lenses frequently? my only prime is the 16mm.

Size and weight are generally an advantage also. But then, you're limited to just one focal length. But largely a non issue when I personally consider my Minolta 200mm f/2.8 G and compare it to Sony 70-200 f/2.8 G. The former is considerably smaller and lighter.

And Image Quality. Primes don't require as many compromises as Zoom lenses.

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JohnK
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Re: advantage of prime lens
In reply to kev777zero, Sep 1, 2012

kev777zero wrote:

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

Old lenses can sure be sharp, but IMO, modern coatings make for better contrast and saturation, and stabilized lenses generate more keepers, for me anyway.

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sean lancaster
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Re: advantage of prime lens
In reply to EinsteinsGhost, Sep 1, 2012

I like having one focal length and being forced to think more about how I am going to compose my shots within the limitations of the prime lens I am using. As I survey scenes for potential shots, I imagine my shots given the focal length on my 5N. I never think about it as a disadvantage. I haven't used my kit lens since last year (or maybe January). Once I get above 50mm (or about 75mm on full frame) then I like zooms because I am often shooting a particular subject and I probably have less control over how close I can get (e.g., wildlife).

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forpetessake
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Re: advantage of prime lens
In reply to kev777zero, Sep 1, 2012

In reality you'll find quite the opposite. The old manual glass was well designed, manufactured, and tested. They were built to last long, and it's not surprising I have 30-50 y.o. lenses that still work very well. The modern consumer lenses have different objectives: lower manufacturing costs, and thus due to high cost of labor, minimal manual operations, smaller size, weight, as wide as possible zoom range, image stabilization, quick AF, etc., they aren't individually adjusted, and only statistically tested, leaving 3-5% defective. They are designed for a few years obsolescence. It's funny to see how all testing web sites would report similarly mis-aligned lenses.

Not all old lenses are great on modern sensors, but there are very many that easily beat in resolution, contrast, build similar modern lenses within 10x of the price. As to the coatings, lenses have been coated for the last 80 years, for the last 40 of them they had really good multi-coating. The only thing you can expect from the modern lenses is cheaper coating, not better coating. I personally have tested a lot of old primes and zooms, and I kept mostly those that were fast, had good contrast and resolution: primes - wide open, zooms - one stop down, and all having at least 60 l/mm @ center. Some lenses I have tested better than 80 l/mm @ center, some lenses I don't have, but other people tested reproduce as far as 100-120 l/mm (MTF50)-- good luck finding anything like that in modern consumer segment. I went through testing several dozens of old manual glass and kept about 20 of them, and there many more good manual lenses I haven't even touched. In my experience, if you want to buy modern lenses of the same quality you need to look at a lot more expensive professional glass, you won't find them in consumer segment.

kev777zero wrote:

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

I've read articles explaining how old SLR lenses or early DSLR lenses can't compete with lenses of today in sharpness since lens manufacturers back then wasn't expecting sensors with 16 or 24megapixels.

That being said, there is much more to a good lens than just being sharp, so old lenses do have their value (I own a couple as well).

GaryW wrote:

ennemkay wrote:

i've always assumed the main advantage of a prime lens is the larger aperture for a given size/weight/price. is there anything else? i notice some people use primes exclusively. does it become tedious to change lenses frequently? my only prime is the 16mm.

In general, a prime lens doesn't need as many internal elements as a zoom lens, and there aren't as many compromises, so you can get a higher quality result. The 16mm has compromises to allow it to be so small, but still, it has few elements and IMHO is still pretty sharp. I have a Minolta 28mm prime lens and it's probably the worst of the Minolta primes, and it's still as good or better than the Nex 18-55 as far as sharpness is concerned. Bokeh, not so much. I also have a Minolta 50/1.7, and I'm pretty sure it's a lot sharper than the18-55, although I don't think I've bothered to make hard comparisons. (Years ago I compared it to my 17-50/2.8, and they seemed pretty equal on my 10mp A100.)

So, I see primes as fewer compromises and higher quality, generally.
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ennemkay
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Re: advantage of prime lens
In reply to ennemkay, Sep 1, 2012

thanks for the responses. very useful. i just ordered a legacy prime for my nex 3...

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El Matadurr
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Re: advantage of prime lens
In reply to kev777zero, Sep 1, 2012

kev777zero wrote:

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

Mine are plenty sharp.

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GaryW
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Re: advantage of prime lens
In reply to JohnK, Sep 1, 2012

JohnK wrote:

kev777zero wrote:

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

Yes. And 80s. At least the primes. Old zooms may not fare as well; at least some of the older consumer-grade ones I've seen and used. The newer zooms I've gotten have all been pretty good.

Having said that, all lenses aren't universal in quality. Some big-name brands are going to be more consistent than budget brands. You can consult web sites for info. on relative lens quality. (Dyxum for Minolta lenses, for example.)

Old lenses can sure be sharp, but IMO, modern coatings make for better contrast and saturation, and stabilized lenses generate more keepers, for me anyway.

Some older lenses have a different look, but if you like the look, that can be good. I really like the look from some lenses, even if they might be thought to be not as sharp, etc. I can think of some photos I have that just look great, even though the lens needed to be stopped-down to get great results. I think my Minolta 50/1.7 might be sharper than any of my e-mount lenses, and makes very pleasant portraits. Sometimes I need f2.0 or f2.8 to get more keepers, if there's some motion in the scene; stabilization can help in some situations, although, I find AF to be the biggest winner in making keepers, so I don't use my legacy lenses too much. A bit sad, really, but it's just too hard to see the difference some times, so I might as well use the e-mount for most activity, with the 50/1.7 for special occasions/uses. There's almost no point in the 28/2.8, but sometimes I think I should give it more of a try just to get a different look.

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GaryW
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Re: advantage of prime lens
In reply to forpetessake, Sep 1, 2012

forpetessake wrote:

In reality you'll find quite the opposite. The old manual glass was well designed, manufactured, and tested. They were built to last long, and it's not surprising I have 30-50 y.o. lenses that still work very well.
..

More thoughts.... Some of the really old glass had radioactive elements that improved its performance. Until they come up with something equally performing, there could be some advantage there, still. We're not getting that anymore.....

At least for primes, I think the technology was well understood many decades ago. For zooms, I've read that computer benefited the designs in the 80's.

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Jerry R
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Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is
In reply to ennemkay, Sep 1, 2012

Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is a good example.
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sean lancaster
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Re: Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is
In reply to Jerry R, Sep 1, 2012

Jerry R wrote:

Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is a good example.

As guess that's true depending on what you're measuring. I typically want my primes to be faster than zooms, so even an f/2.8 zoom isn't as good in low light as the primes I like to use. Give me a Canon FDn 50/1.4 or even the Zeiss 24/1.8. If I am going to get a prime that is f/2.8 then it had better be much smaller than the zooms, so it's better than a zoom in that regard.

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davect01
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Re: advantage of prime lens
In reply to JohnK, Sep 1, 2012

I think at least for me it is the value. I can pick up a very nice old lens for a whole lot cheaper than a modern lens.

This being a side hobby, I am not about to drop $600.00 on a lens. However that $10-30.00 lens on Ebay is no problem. I have three lenses that are super nice and result in great shots, the most expensive being $35.00.

As said above though not all old lenses are good. I have picked up a couple of lenses that just were either in bad shape or never produced a clean, crisp shot.

As for prime versus zoom, I think it is a personal preference as well as a location based decision. I have a 45mm that I put on when going to a place where I know intimate pictures will be wanted. A 28-70mm and the 18-55mm kit lens when think I might need a bit of options and a 70-150mm when going places that will primarily be distance shots such as the zoo or a ball game.

JohnK wrote:

kev777zero wrote:

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

Old lenses can sure be sharp, but IMO, modern coatings make for better contrast and saturation, and stabilized lenses generate more keepers, for me anyway.

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astrosandy
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Re: Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is
In reply to sean lancaster, Sep 1, 2012

What do you guys think about the cropping ability of the primes on N7? I found my sigma 30 2.8 could be very well used as 30-90 mm given the rigorous cropping ability. Yes it is true that the photos of kit lens can also be cropped, but I think primes are better than zooms since primes are sharper. And when I crop my photo so much, can I say I have 30-90 mm f/2.8 lens? I generally keep that precision zoom on my soft b button when using prime. I found it handy to compose my shots and then I revert to normal before taking the photo.

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D Cox
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Re: advantage of prime lens
In reply to kev777zero, Sep 1, 2012

kev777zero wrote:

While I do agree primes should be better due to more simplistic designs, I wonder if it's actually true that the SLR primes from the 70s can beat the sharpness of modern lenses.

I've read articles explaining how old SLR lenses or early DSLR lenses can't compete with lenses of today in sharpness since lens manufacturers back then wasn't expecting sensors with 16 or 24megapixels.

They were expecting high resolution films such as Kodachrome (ISO 25), Panatomic-X or NP-15. For some uses, even Microfilms (or the similar Tech Pan).

All these have comparable resolution to a NEX, or even better.

However, it is true that some lenses were designed more to give high contrast up to a certain resolution limit, while others were designed for very high resolution even if contrast fell off steadily at the top end. Nikon generally went for contrast, for instance, and Leitz for resolution.

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D Cox
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Re: Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is
In reply to Jerry R, Sep 1, 2012

Jerry R wrote:

Zooms can be as good as primes, the 16-70 Zeiss lens on the Sony R1 is a good example.
--

They can be as good, but the more elements there are in a lens the greater the chance that one will be slightly off spec.

The commonest fault in lenses is not bad design but faulty assembly - elements slightly off centre or slightly tilted.

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BasiliskPhoto
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Re: advantage of prime lens
In reply to ennemkay, Sep 1, 2012

I love an aperture ring on a lens, rather than fiddling with on camera controls. I might be tempted by some of the upcoming Sony emount lenses, but sadly I doubt they will have an aperture ring.

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maurus_e
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Re: advantage of prime lens
In reply to ennemkay, Sep 1, 2012

Besides being faster (usually), which is a significant advantage, the main photographic advantage of a fixed focal for me is that I think more about composition and perspective.

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ProfHankD
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Definition of prime, engineering differences
In reply to ennemkay, Sep 1, 2012

ennemkay wrote:

i've always assumed the main advantage of a prime lens is the larger aperture for a given size/weight/price. is there anything else?

Just to be official, "prime" traditionally means designed as a single optical entity (as opposed to using an add-on converter), but it is commonly used as you used it, to mean "of fixed focal length."

There are many different types of optical designs that can be used in lenses and each has specific characteristics that tend toward particular image qualities; see Cicala's blog at LensRentals:

http://www.lensrentals.com/blog/2011/08/lens-geneology-part-1
http://www.lensrentals.com/blog/2011/08/lens-geneology-part-2

There are many optical design options for fixed-focal-length lenses with a focal length similar to or greater than the mount flange-to-image-plane distance (which was about 45mm for SLRs and a mere 18mm for NEX) for which the lens was designed. Tuning for various properties, such as large apertures (usually with double Gauss designs) or shorter-physical-than-focal-length (telephoto), is relatively easy. Also, the small number of elements makes coatings less critical... so old lenses can be excellent in this range.

Shorter focal lengths generally use a retrofocus design that essentially packages a wide angle lens together with an inverted telephoto design to project the image further back -- roughly doubling the number of lens elements needed. Minimizing reflections and light loss at each surface becomes more important and the optical defects from the two component lens systems compound. Making such a lens have good IQ with a large aperture is difficult (expensive).

Zoom lenses generally have many more design constraints, especially if the zoom range spans wide to tele. Typically, there are at least three component lens systems inside a zoom, with the middle one moving back and forth to zoom. Maintaining IQ is very difficult and secondary goals, such as not shifting focus while zooming, often result in complex mechanical movements within a zoom lens. Zooms are difficult to correct for large apertures, so f/2.8 is about as fast as you'll see. More elements also make coatings, alignment, etc., affect IQ more... and modern computer design helps.

In summary, the penalty for zooms is less in the wide angle range because retrofocus wide already required lots of elements. Especially around 50-100mm, fixed focal length lenses can be much better than zooms in speed, cost, size, and various IQ properties. Choose wisely.

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