f/1.4 vs. f/1.8

[jmtonkin]

Hey everyone,

I'm looking at adding a 50mm fixed lens to my bag, and I'm looking for some advice. I've done some research on the f/1.4 vs f/1.8, and I'm not really getting any solid answers. I'm looking for some real-life experiences with these two. Is there a huge noticeable difference in the 1.4 to 1.8? I've read that there is quite a bit of vignetting at 1.4, have you experienced this? I heard that the build of the 1.4G is much better than the 1.8, is that true?

There is just such a huge price difference, but I don't know which route would be the best. I mostly shoot portraits (engagements, senior pictures), and I have done a few weddings.

Thanks for your advice!


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[Derrel]

I looked at the 50/1.4 AF-S G, then the 50/1.8 AF-S G. Side by side, on my camera. I bought the 50/1.8 AF-S G.

The "rap" on the 1.4 model is it focuses kind of slowly, and the 1.8 is maybe 90% as good, but focuses more rapidly, and is sold for significantly less money than the 1.4 model. I almost never shoot wider-open than f/2.8, so the max aperture is meaningless to me. Vignetting? I do not mind a little in-camera vignetting...I often ADD some in as a matter of fact. The newer Nikon bodies have user-adjustable degrees of built-in vignetting control, or OFF. Lightroom has lens correction profiles for both new G-series 50mm lenses. Vignetting is a FILM-era problem to me...I don't care if a fast, normal-length, NON-macro lens vignettes.

 

[jmtonkin]

Thanks Derrel! That's good information to know!


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[Gavjenks]

Get the 1.4 if you intend to shoot a lot of photos at f/1.4. Otherwise, get the cheap one that is virtually just as good for apertures 1.8 and up

 

[jmtonkin]

I suppose I probably won't shoot as many pictures at f/1.4 as I'd think. I looked at my DoF app and punched in some numbers and at 5' the difference between f/1.4 and f/1.8 is a whole one inch. To some people, that might mean all the difference in the world, but for me, not really at this point.


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[Patrice]

As Derrel has observed, and I suspect many others as well, not many portraits get shot at f/1.4 or f/1.8, so the choice between 50/1.4 and 50/1.8 is not one primarily made on maximum aperture, rather the choice is based of the more aesthetic attributes of the lenses. Differences in bokeh, contrast, colour and such might be the determining factors in the final choice.

When I was shopping for an 85 the choice of the 85/1.4d over the 85/1.8d was not based on aperture, build or price.

 

[yioties]

I don't think the 50 1.4g isn't worth the price difference with the 1.8. go to a camera shop and shoot them both wide open and decide if it's worth it to you

 

[Gavjenks]

I suppose I probably won't shoot as many pictures at f/1.4 as I'd think. I looked at my DoF app and punched in some numbers and at 5' the difference between f/1.4 and f/1.8 is a whole one inch. To some people, that might mean all the difference in the world, but for me, not really at this point.


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It's true that that's not a huge difference in the "wdith" of DOF. But you have to keep in mind that that's not really what DOF is all about in that context. The out of focus-ness of the ENTIRE frame increases from 1.8 to 1.4. As in, if you're focused at 5 feet (which you really shouldn't do btw unless you desire to exaggerate noses and get weird proportions), a point of light out at 1/3 of a mile away will obviously be out of focus at 1.8. But it will be noticeably MORE out of focus at 1.4. It's not just a binary in vs. out of focus. Increasing aperture gradually makes already out of focus areas that much smoother and creamier.

But of course 2/3 of a stop is still not a dramatic difference, even given that.

 

[Derrel]

I suppose I probably won't shoot as many pictures at f/1.4 as I'd think. I looked at my DoF app and punched in some numbers and at 5' the difference between f/1.4 and f/1.8 is a whole one inch. To some people, that might mean all the difference in the world, but for me, not really at this point.


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It's true that that's not a huge difference in the "wdith" of DOF. But you have to keep in mind that that's not really what DOF is all about in that context. The out of focus-ness of the ENTIRE frame increases from 1.8 to 1.4. As in, if you're focused at 5 feet (which you really shouldn't do btw unless you desire to exaggerate noses and get weird proportions), a point of light out at 1/3 of a mile away will obviously be out of focus at 1.8. But it will be noticeably MORE out of focus at 1.4. It's not just a binary in vs. out of focus. Increasing aperture gradually makes already out of focus areas that much smoother and creamier.

But of course 2/3 of a stop is still not a dramatic difference, even given that.

Gav brings up a really good point about how the human brain "perceives" out of focus backgrounds. It's actually a subject that not many people talk about or think about. We can easily quantify depth of field with any of a dozen or more on-line depth of field calculators, but the way we perceive and mentally process the quality of the blur, and the degree of out-of-focus subject matter, is very difficult to pin down with numbers, or even with lengthy descriptions of how pictures look, or how we "feel" about them.

A good case in point is the 85mm f/1.8 AF-D versus the 85mm f/1.4 AF-D lenses that Patrice mentioned choosing between in post #6. The 85mm f/1.4 AF-D has very creamy, very pleasing and favorable out of focus background rendering; the 85/1.8 AF-D does not, not nearly to the same degree. And the brand new 85mm f/1.8 AF-S G lens has EXTREME sharpness across the frame, but the way it renders out of focus background items is not nearly as pleasing as the way the older 85 1.4 AF-D does. The way DOF is rendered, qualitatively speaking, does not show up in DOF calculators.

In the 50mm lens category, one of the sharper 50's is the Zeiss 50mm f/2.0 Planar design, produces simply harsh, hashy, God-awful background rendering. Head to PixelPeepers.com and look at the big sample pics from the 50 Zeiss Planar. Full-size sample photos from Zeiss 50mm F/2 "uggg!"

 

[Gavjenks]

Derrel, I am pretty sure you could simply calculate the exact size of the blurry circle from a distance out of focus point of light, given aperture and distance (maybe some other number).

It's not mysterious so much as it is that just nobody bothers to publish information that detailed and/or nobody has programmed an online calculator to do it for us yet.



There's also stuff like how much of the light is toward the edge of the OOF disk versus the middle or evenly distributed. And the shape of the disk (i.e. how rounded are the aperture blades), etc. These things are more subjective in terms of what's better. Although you could also measure them if you wanted, and I'm fairly confident that almost everybody would find "circular shape" and "even distribution of light in that shape" to be the most pleasing bokeh. But mainly what I'm talking about is just plain of degree of blur, which is pretty straightforward and bigger discs are probably universally desirable by anybody trying to shoot a portrait at f/1.4 in the first place.

These are not my photos, but they are all creative commons, so I think it's fine to post them.

(carlosluis)
^Pretty pleasing bokeh. Notice circular shape (from blades), medium-large-ish discs (somewhat wide aperture combined with distance from plane of focus), and relatively even distribution of light wihtin discs (things like spherical/aspherical lens design, etc.)


(Jean-Jacques MILAN)
Weird "donut" bokeh from a mirror lens. The aperture is donut shaped, so you get donut shaped OOF points. Usually perfect circular is preferred to this (or to hexagons, etc.) in most cases.


And I can't find free images for distribution of light, but see the photos near the bottom of this page:
http://photo.stackexchange.com/questions/7044/how-do-soft-focus-or-defocus-control-rings-work

 

[boomer]

Just a reminder, Nikon has the instant rebates going on for a few more days...the 50mm 1.4G is only $339 right now. Not too bad! Only about $140 dollars more than the 1.8G.

 

[Derrel]

Derrel, I am pretty sure you could simply calculate the exact size of the blurry circle from a distance out of focus point of light, given aperture and distance (maybe some other number).

It's not mysterious so much as it is that just nobody bothers to publish information that detailed and/or nobody has programmed an online calculator to do it for us yet.



There's also stuff like how much of the light is toward the edge of the OOF disk versus the middle or evenly distributed. And the shape of the disk (i.e. how rounded are the aperture blades), etc. These things are more subjective in terms of what's better. Although you could also measure them if you wanted, and I'm fairly confident that almost everybody would find "circular shape" and "even distribution of light in that shape" to be the most pleasing bokeh. But mainly what I'm talking about is just plain of degree of blur, which is pretty straightforward and bigger discs are probably universally desirable by anybody trying to shoot a portrait at f/1.4 in the first place.

Yes, the mathematical, quantitative aspects of out of focus areas is pretty simple stuff, but I was thinking more about the aesthetic appeal or lack of it, in the way lenses render OOF areas.

One of the most-annoying types of out of focus rendering to me is "onion bokeh", in which out of focus points of light are rendered with a series of concentric rings, like a slice of onion. A good example of a modern, sharp zoom lens is the new Tamron 24-70mm VC lens...it renders OOF point light sources with classic "onion" bokeh. Other people dislike "condom ring" or "bright-line" bokeh characteristics.

Many people do not care about bokeh, but the SIZE of the OOF discs is not nearly as critical as their shape and or their characteristics.

Flickr: Discussing Best "non-condom-ring" bokeh 50mm lens? Please chime in! in 50mm (The original 50mm group)

 

[sifelaver]

I shoot a 1.4 at 1.8 or 2.0 to get a sharper image from stopping down. Dunno if it really matters.

 

[djacobox372]

The f1.8 is a newer aspherical design which makes it sharper with better contrast than the 1.4 at wide apertures which is basically unchanged in optical design for 40 years (they improved lens coating that's about it).

 

[jmtonkin]

Update: I picked up the 1.8G today, and I'm in love! From having my first lens that I can shoot that wide, to the colors, to the sharpness of this lens, I am very pleased with my decision!


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