Simple question-Is there really a need for f1.4 or faster prime lenses ?

[pendennis]

To get the 1.4 aperture, lens makers have to make larger glass, which increases the odds of distortion for glass that's not as sharp as smaller aperture versions. GOODGUY makes an excellent observation that the f1.8 is sharper than the f1.4, and you pay more for the "lack" of sharpness. (Adage here - Faster, Cheaper, Better....Pick two).

In the film days, with the practical limits of film ISO's (6-400), photographers needing low light exposures could push films like Tri-X to as high as 1600, and using a f1.4 lens still get acceptable results. News photographers bought f1.4 lenses by the gross. Today, with very acceptable results at ISO's up in the thousands, the need for the f1.4 lens is less than before. I just sold my 50mm f1.4 AIS because it sits in the bag, unused. I can "push" my ISO, and shoot wide open at f2.8, even f3.5 when I need to.

I distinctly remember my Canon FD 50mm f/1.4 had much higher IQ than the FD 50mm f/1.8 ... it more than just a wider aperture.

Well with modern lenses I think the gap isn't so big, as an example Nikon 50mm 1.8G is actually rated to be sharper then the Nikon 50mm 1.4G
Another example is Nikon 85mm 1.8G which is so sharp that frankly even if the 1.4 version is sharper I don't see much of a difference if there is any.

 

[AlanKlein]

F1.8 is lighter and cheaper than f1.4 because there's less glass. When I shot film that had an ISO of 200, you might need 1.4. But today, with ISO running much, much higher without noise, the advantage of 1.4 is imaginary. Optical viewfinders once "saw" better in darker viewed areas with f1.4. So back then because of film, brighter lenses had their purpose. But with LED backs now unlike film cameras of the past, that advantage is diminished as well. Now you can shoot digital at 1600 ISO instead of film at ISO200.

Also, the DOF on 1.4 lenses is awfully small, maybe 3". Focusing is a problem and out-of-focus areas due to the narrow DOF often messes up some portrait shots as noses and ears are blurry.

Save your money, carry a lighter camera and shoot just as well with an f1.8.

 

[Scatterbrained]

If the f/1.4 renders in a way that pleases you and the f/1.8 doesn't then that should be it. Of course, for me it's all about the f/1.2.

 

[petrochemist]

If the f/1.4 renders in a way that pleases you and the f/1.8 doesn't then that should be it. Of course, for me it's all about the f/1.2.

Shooting with MFT with it's smaller sensor there are times I'd like faster than f/1.2. There are f/0.95 lenses available in that format, some of which a highly regarded. Of course they're also highly priced so I have to make do

 

[fmw]

Slower lenses require less correction to get a flat undistorted image. That means faster lenses are more complex, bigger, heavier and sometimes not as well corrected as slower lenses. The point of the faster lenses is clear but there is a price to pay in their design.

At the moment I have a couple of AI Nikkors that I tested recently - the 180mm f2.8 and the 200mm f4. In terms of image quality they are the same. They have the same resolution and the added contrast of the 200 is barely discernable. But to get that same image quality an f stop faster, the 180 is big, heavy and expensive as well as being a little bit shorter in focal length.

It is one f stop. Does it matter? Maybe and maybe not. It depends on the photographer, the light and the goal. Most amateurs will do just fine with the 200 and a notch up on the ISO setting. The pro may need that extra stop. I would recommend the 200 to an amateur and the 180 to the pro. Different requirements.

 

[ruifo]

Unless you need f/1.4 for extreme low light conditions, the f/1.8 prime family does just fine (just excellent).

Another reason for the f/1.4 family is the character they bring, but that's subjective. I love the 85mm f/1.4D because of that. Neither the f/1.4G, f/1.8G, or the f/1.8D versions of the 85mm give the same character, but the f/1.8G is the sharpest among them all, no doubt.

Another reason still is using the f/1.4, on their earlier D, AI-S and AI versions on film SLRs, together with your modern DSLR.

The f/1.8 primes are just excellent, overall, specially the G versions.

 

[astroNikon]

If you use the argument of strictly a larger aperture for low light advantage then there isn't much of an advantage.

If you use f/1.4 for more artistic shots that you can't get with a f/1.8 then you have your justification.
This excludes the rendering of different lenses compared to one another.

I guess you could also push the justification of why use fixed aperture lenses at all especially f/4 type lenses.
For me, the aperture lets' me isolate subjects which is more important than the low light ability, though having FF I have more flexibility too.

 

[chuasam]

I distinctly remember my Canon FD 50mm f/1.4 had much higher IQ than the FD 50mm f/1.8 ... it more than just a wider aperture.

Well with modern lenses I think the gap isn't so big, as an example Nikon 50mm 1.8G is actually rated to be sharper then the Nikon 50mm 1.4G
Another example is Nikon 85mm 1.8G which is so sharp that frankly even if the 1.4 version is sharper I don't see much of a difference if there is any.

The Nikon 50/1.4 is a dog of a lens. The sigma version is much better. The 85 1.8g isn't too bad. Much better than my old 1.8D.
I plan to get the 105mm f/1.4G. I wish it had VR.