What's the point of 1.2 and 1.4

[IronMaskDuval]

Serious question because I don't know. Is there a practical usage? I can't find any reason why 1.4 is usable unless I wanted a blurry mess. Please enlighten me because I'm having a nikon 50/1.2 itch.

 

[cherylynne1]

Well, for one thing, most lenses are best when stopped down a bit. If you stop down on 1.4, you're still at 1.8.

Embrace the blur.

 

[tirediron]

More light = faster shutter speeds and/or lower ISOs in low-light situations. Granted DoF becomes a huge issue, but if you're careful, it works.

 

[IronMaskDuval]

Well, for one thing, most lenses are best when stopped down a bit. If you stop down on 1.4, you're still at 1.8.

Embrace the blur.

Yea, I use my zeiss at 2 or slower. Although it really starts to shine at 2.8. I guess I'll just pass on the Nikon. My wife told me to quit buying camera stuff and remodel the kitchen... Sigh

I embrace the blur all the time with my awesome cell cam.

 

[JonA_CT]

Well, for one thing, most lenses are best when stopped down a bit. If you stop down on 1.4, you're still at 1.8.

Embrace the blur.

So you get sharper images at 1.8 than you would on a 1.8 lens?

 

[cherylynne1]

Generally speaking, yes. Of course there are some really high quality 1.8 lenses that are pin sharp wide open, and there are some cheap third party 1.4 lenses that have to stop down to 3.5 before they're sharp. But for the vast majority, I'd say that's the case.

 

[ruifo]

Serious question because I don't know. Is there a practical usage? I can't find any reason why 1.4 is usable unless I wanted a blurry mess. Please enlighten me because I'm having a nikon 50/1.2 itch.

The 50mm f/1.2 AI-S is a especial lens. It has a dreamy look at f/1.2 and at f/1.4, that very few lenses can reproduce. Also, it's said to prodece the sharpests f/2 images among all 50mm lenses out there, at f/2.

Having said that, to master the manual focus at f/1.2, f/1.4 and f/2 can be a challenge, on modern DSLR, once their eyepice prisma, and their dot confirmation system, is optmal fom f/2.8 aperture and smaller. But the more you practice, the better you understand how to achieve focus with your copy.

Here shots of mine with the 50mm f/1.2 AI-S and the D810:
Nikkor MF 50mm f/1.2 AI-S

I love this lens and the results it's able to produce. But I'm someone who loves old lenses character.


Some samples of dreamy look at f/1.2 and f/1.4:

f/1.2

Lluvia by ruifo, on Flickr

f/1.4

Long Play by ruifo, on Flickr


And some samples of f/2, f/2.8 and f/4 sharpness:

f/2 - even two galaxies became visible: Andromeda (top) and Triangulum (bottom)

Andromeda Galaxy Star Trek by ruifo, on Flickr

f/2.8

Sol y lluvia (MEX) by ruifo, on Flickr

f/4

San Francisco-Oakland Bridge Skyline by ruifo, on Flickr

 

[IronMaskDuval]

I don't have a problem with focus wide open, it's just the depth of field is so shallow...I guess it just doesn't suit my taste

 

[Solarflare]

Generally speaking, yes. Of course there are some really high quality 1.8 lenses that are pin sharp wide open, and there are some cheap third party 1.4 lenses that have to stop down to 3.5 before they're sharp. But for the vast majority, I'd say that's the case.

Well, there is no law of optics one way or the other.

However as a general rule of thumb if a lens offers less maximum aperture, the optical design gets simpler.

And if the construction of a lens gets simpler, assuming same standards and tolerances as before, the overall image quality tends to increase.

This is why for example the Nikon 50mm f1.8 are always slightly sharper than the corresponding 50mm f1.4, no matter which version (AI, AI-S, AF, AF-S, ...). Same for the 85mm f1.8 [f2 for AI/AI-S] and 85mm f1.4. Same for the AF-S 70-200mm f4 VR vs the AF-S 70-200mm f2.8 VR2.

Mind, many people accept willingly a slight loss in sharpness if they get the additional possibilities of more light and less depth of field.

And theres exceptions of this rule of thumb. Quite a lot of them, actually. For example for some reason the Zeiss 25mm f2.8 is supposed to be the worst lens of the Zeiss lineup of DSLR lenses, only about average in performance, and inferior to the 25mm f2.0.

 

[Solarflare]

Serious question because I don't know. Is there a practical usage? I can't find any reason why 1.4 is usable unless I wanted a blurry mess. Please enlighten me because I'm having a nikon 50/1.2 itch.

Well the depth of field is controlled by

(a) aperture
(b) focal length
(c) distance to subject

So for example if you have a 28mm f1.4 and keep 5m distance to your focal plane, the depth of field is 1.76m according to Online Depth of Field Calculator

With 50mm its still 0.53m, with 85mm its 0.18m.

So yes, avoiding razor thin without stopping down is simple. Just keep your distance.