The Never-Ending Quest
But How Sharp Is it Really!?
One of the most common questions that I'm asked is,
|Is the ... lens sharper than the ... lens?|
A variation on this theme is...
|What do you think of the ... lens? Is it sharp?|
Or there's the more generic...
|Is a zoom lens as sharp as a prime lens?|
That's enough! I'm about to answer your questions, (as well as a few that you didn't ask), and from here on, until the end of time, you need ask them no more. And, if anyone asks you these questions, you'll now know where to refer them. Right here.
Photographed with a Hasselblad ArcBody and 35mm Rodenstock lens on Provia 100F.
What's All This About Sharpness Anyhow?
There are photographers who love to test and compare things. When they make prints or examine their slides under a loupe, they are not looking to see if they have properly captured a special location, light or subject. They are first and foremost concerned with technical quality rather than image quality.
Consequently they fret and fuss. They choose primes over zooms. They buy the most expensive brands of bodies and lenses. But then when they have them, what do they do? Do they settle down to pursue their photography? No, they fuss and fret some more, worrying that if only they had a sharper lens their photography would somehow improve. Sound familiar?
There isn't a photographer alive who doesn't care about how sharp his or her lenses are. It's one of the primary manias of anyone playing this game. We buy and sell different brands of cameras in search of the holy grail of sharpness.
Should I trade in my Nikon gear for Canon?
Should I trade in my Canon outfit for Nikon glass?
Damn, maybe I should buy a Leica system. I hear Leica lenses are fantastic.
But, how about Contax? Those Zeiss lenses have great reputations.
But boy, are those lenses ever expensive. Are they worth it?
I know you've never had these thoughts, but you have heard from lots of other photographers who have. Go to any of the on-line discussion boards. You will find that talk about lens sharpness represents probably half the discussions — most of it filled with unsubstantiated opinions and mistruths.
After 40 years as a professional photographer as well as an ardent amateur, as a teacher and as a journalist, I've learned certain things about photography and photographic equipment, and specific to this topic — about lens sharpness, its importance as well as, frequently, its lack of importance.
Here then is what I know about the subject, shorn of as much bafflegab and BS as I know how to make it.
Some Cosmic Truths
Photographed with a Rollei 6008 and Schneider 40mm Super-Angulon lens on Provia 100F
I'm now going to let you in on the great truths. The ones that all true cognoscenti know, but that are hidden from newcomers and the otherwise uninitiated. If you're really observant you may notice that this piece has some scattered evidence of the use of irony, (some would call it sarcasm.) Ignore the man behind the curtain. I stand behind every statement.
Finally, note before you enter the inner sanctum that I have occasionally used the word "Usually". That's because to be a universal truth, there must be an exception that makes it so. Otherwise, what would we have to argue about?
Prime Lenses are Sharper than Zooms Lenses (Usually)
The title says it all. There is no free lunch! If you want the utmost in sharpness, don't buy a zoom lens. But, if you want greater shooting versatility by all means do buy a zoom. You'd be a fool not to.
Why are primes sharper? A number of reasons. Zooms lenses by necessity have more elements than primes. This makes them more difficult to design, increases the risk of various forms of optical aberration, and can reduce contrast and increase flare.
Prime lenses usually have larger apertures than zooms, and the laws of optics say that all other things being equal (which they often aren't) a wider aperture lens will be sharper than one with a smaller aperture — the issue being diffraction effects.
Having made the case for prime lenses, let me say that three of the sharpest lenses I own, the Canon 70~200 f/2.8L IS zoom, Leica's M series 28-35-50mm Tri-Elmar, and the Pentax 67's 55~100mm f/4.5 zoom, are as good as any primes in their formats that I've ever used. As I said — "usually" sometimes defines the rule.
Photographed with Leica M6 and f/4 Tri-Elmar lens @50mm on Ilford XP2 Super
Camera Manufacturer's Lenses are Sharper than Third Party Lenses (Usually)
Camera manufacturers want you to buy their lenses. They don't want you to buy a lens from a third party. If you do they don't make as much money, and making money is why they're in business. Therefore they have to make some of their lenses as inexpensive as possible. But, professionals and other serious photographers want the finest lenses possible, which are expensive to make. What to do?
Most major brands therefore make two lens lines, sometimes so indicated (like Canon's "L" series glass), and sometimes just differentiated by price. This allows them to cater to both markets.
Third party lens makers usually aren't interested in selling camera bodies. They want to sell you lenses. And since most amateur photographers make their buying decision based pretty much on price alone, it isn't hard for these companies to figure out what to do to get this business.
If you want the finest lens of a given type, buy the manufacturer's top-line lens. If your priority is to save money, then buy the third party lens. No matter how hard you try and imagine it to be so, that $200 lens (including a free skylight filter) from Sigma, Tamron or their brethren just isn't going to be as sharp, free from flare and optical aberrations, well designed and sturdily constructed as a $900 optic from Canon, Nikon or one of the other majors.
Are there exceptions to this. Yes, maybe, sometimes. Some types of lenses are easier to design than others, so low-cost third-party lenses can be quite decent. But, this brings us to our next cosmic truth.
Taken with a Canon EOS3 and Canon 24mm L T/S f/3.5 lens on Provia 100
You Get What You Pay For
Test drive a BMW or a Lexus. Now test drive a Chevy or Nissan. Notice any differences? Of course you do. Compare the prices. Now you understand why better costs more.
What applies to cars applies to lenses as well. Quality costs money. When is "good enough", good enough? Only you can answer that. If you can afford a Mercedes, good for you. If a Leica prime lens is within your reach, go for it. But if you can't afford one don't delude yourself that a lens that costs 2-3 times as much as another isn't worth the money. It is. For those that can afford it! For those that can't — get over it, and live happily with what you can afford.
Please read my parable on coveting high-end equipment for further thoughts on this topic.
Good Technique Trumps Sharp Optics
Now for one of the biggest truths of all. You can fret all you want about how sharp a given lens may be, but if your photographic technique isn't first rate, having a lens capable of producing high resolution and high contrast is hardly worth a damn.
To get the best from any lens here are some things that you should be doing:
Use a solid tripod. For 95% of the landscape, nature and wildlife work that I do I use a tripod. Religiously. I own three; big, bigger and biggest. Just about the only time I hand-hold a camera is when I'm doing documentary-style street shooting. Hand-holding usually leads to inferior images, particularly in landscape and nature photography.
Use mirror lock-up and a cable release. Vibration; any vibration, is a sharpness killer. Don't hand-hold a lens at a slow shutter speed and a wide aperture and then worry about whether the lens is sharp or not. What are you thinking of?
Image Stabilization. Whether it's Canon's IS or Nikon's VR, this is one of the greatest innovations in lens design of the last quarter century. It works, and it works damn well. For serious long lens work, even when working on a tripod, Canon's family of Image Stabilized "L" series lenses are worth their weight in gold (which partially explains their price).
Canon D30 @ ISO 100 using a 400mm f/4 IS DO lens.
Use the lens' optimum aperture. This is typically not with the lens wide open, and never when stopped all the way down. Only the finest lenses are as sharp wide-open as when closed down somewhat, and no lens is at its best when stopped down to f/22 or f/32, due to diffraction effects. Most lenses have their optimum aperture at 2-3 stops down from wide open.
Use fine-grain, high-resolution film. You want to be able to see what you've paid all that money for, don't you? Of course using such film means ISO speeds of under 100, which means that a tripod, cable release and mirror lock-up are a necessity when combined with the use of the lens' optimum aperture.
Your image processing technique and equipment must be as good as your photographic technique and your lenses. Whether in the chemical or the digital darkroom; whether using an enlarger or a computer, anything less than the finest tools and techniques will obviate whatever investment you've made in fine lenses.
Can you honestly say that your prints match your hopes for a given image? It may not be your lens that's at fault. It may be what you're doing and the tools that you're using after the photograph was taken that's limiting your ultimate image quality.
If all of the above are not part of your everyday shooting technique then you're likely not getting the most from your expensive lenses. Only when you've given a lens every chance to show its best do you have the right to determine if its performing at its best.
Think about the variables standing between a scene in front of the camera and a print hanging on the wall. A large number of factors determine whether or not the print will be sharp.
The lens' resolution capabilities The film's resolution capabilities Camera and/or subject motion Aperture used and consequent depth of field as well as use of optimum aperture Film flatness — is the pressure-plate doing its job properly? Film thickness — are all layers in the film (colour) bringing the image into focus Film grain — sometimes grain makes images look sharper — sometimes the opposite! Enlarger parallelism — many aren't, and sharpness suffers Negative carrier precision and film flatness Enlarging lens quality and aperture used Resolution of the printing paper used
Of course digital post-processing has its own issues, including...
The film flatness capabilities of the scanner's carrier The native resolution of the scanner chip and firmware The Sharpening level applied in post-processing The native resolution of the printer The resolution of the printing paper used
For digital cameras many of the same issues as for film cameras apply, as well as those for digital image processing.
See what I mean? The sharpness of a given lens is just one of a myriad of factors, and usually not the most important one, in determining if a print will look "sharp".
The Bottom Line
Pentax 67II and 55~100mm f/4.5 zoom. Provia 100F.
Are you ready for this? Here's the big one. The one big truth that I've learned about this subject after more than 40 years as a photographer, and which summarizes the points above.
"Most Lenses are Better Than Most Photographers"
Does this idea make you uncomfortable? Good. That's what it's meant to do. Think about it.
Yes, there is a difference between brands. There definitely is something special about many Leica lenses, and Zeiss lenses are generally superb. Top Nikon and Canon glass can be as good as it gets. On the other side of the coin, some Sigma-Tamron-Tokina lenses are indeed so much junk. Some though are pretty good.
All of these statements are based on personal experience. None though are universal truths. But it's my unquestionable experience that it is rare indeed that I ever see photographs taken by folks that fret about these issues that even come close to matching the capabilities of even the least pretentious of lenses.
This is why there are those folks that makes the claims that they do about some lenses or brands, or countries of origin, while there are others who say that they don't see the differences. This isn't a case of "the emperor's new clothes". It's often just a matter of experience and skill, each of which can be acquired if one has the will.
So, unless you are utilizing all of your photographic skills and know what to look for and how to achieve it, stop worrying so much about sharpness. Buy the lens that fits within your budget and that meets the needs of the type of shooting that you do. Most of all, stop worrying and just enjoy doing your photography.
Now that you think you've got it figured out, it's time for some more reading. Here are four articles on related topics.