Category: Lenses and Optics
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Everything but the Sharpness
About 614 times a day I take a phone call or answer an email that is essentially the same question: “How sharp is this lens?” It’s no different in online forums (ok, actually forums are a lot worse) where pages of arguments drone on comparing the results of this bench-test lab review, these MTF…
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“This Lens Is Soft” and Other Facts
## In 2008, I wrote an article This Lens is Soft, and Other Myths that pointed out that lenses and cameras all have tolerance ranges and sometimes a given lens can be sharp on one camera body, and soft on another. At the time, autofocus micro-adjustment was a fairly new feature on camera bodies and…
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Fast Lenses: A Primer
by Stephen Michael Garey ## What is a Fast Lens? A fast lens is any lens of any type and focal length that has an aperture design capable of opening to f/2.8 or wider. There are fast lenses currently available that open as wide as f/1.2, and there are any number of popular lenses that open to f/1.4…
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Have You Seen My Acutance?
## Have you seen my acutance? A few words about sharpness and MTF charts Many of you know one of my pet peeves is strident internet arguments between photographers who are splitting hairs or misinformed. One major cause of these arguments is terminology: people use a nonspecific term which means…
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Optimus Prime
Today’s topic is prime lenses, those lenses that (GASP!!!) don’t zoom! Wait, don’t leave. This is really worth your time. (OK, those of you who already shoot entirely or mostly with primes can leave, there’s probably not much for you here.) About 10 times a week, in discussing the best lens for the…
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Teleconverters 101
The problem, I think, is that it seems so simple. “If I add a 2x teleconverter I’ll get that closeup shot I want.” We all know what a teleconverter’s purpose is: it magnifies the image by a factor of 1.4x or 2×. A 300mm lens with a 1.4x converter becomes a 420mm lens. With a 2x converter its a…
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"This lens is soft" and other myths
One of the most common examples of anti-logic we see at LensRentals is the statement The lens is soft/front focuses/back focuses. Now don’t get me wrong, there are bad copies of lenses out there, as best we can tell ranging from 3% to 7% of lenses. And we know, despite our checkout procedures, that…
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Front Element Scratches
We had a chance to make a pretty fun demonstration today, and here it is. As most of you know, we’re very finicky about our gear. We don’t like even tiny scratches on front elements or dust in a lens (although a bit of that is inevitable). We’re like you. We want the lens to look as good as the…