Is there a noticeable difference between 1.8 and 1.4 prime lenses?

  • I have been shopping around for a prime lens for my Nikon D50. I noticed that the 1.8 is hundreds of dollars cheaper than the 1.4 AF-S. What will I gain for that cost difference? Is it really noticeable?

  • It's an extra two-thirds of an f-stop, with all that comes with it:

    • Narrower depth of field (perhaps marginal in comparison to the f/1,8)
    • Brighter viewfinder; great in low-light situations
    • Might be the difference between getting the shot or not, also in low-light situations
    • Lenses tend to get sharper when stopped down. At f/1,8 the f/1,4 lens is stopped down two-thirds of a stop, while the f/1,8 is wide open. I don't know if there is any actual difference in sharpness between the lenses here, but I would assume that the f/1,4 is sharper at f/1,8 than the f/1,8 lens.

    Is it worth the price difference? Only you can tell...

    I'm on the canon side but the sharpness and the low-light capabilities really blew me away when I upgraded from the f/1.8 to the f/1.4 50mm lens.

    There's also a difference in bokeh due to the number of blades used to form the aperture. The f/1.4s have a nicer bokeh.

    Just to clarify, the f1.4 is 2/3rds stops faster than the f1.8, so that means 2/3rds stop faster shutter speed. With most viewfinders, lenses above a certain speed (not sure, like f2.8?) are imperceivable in brightness in the viewfinder due to the way the light is split between the AF sensor and the viewfinder. Sharpness definitely depends on the brand. E.g. the Pentax 50mm f1.7 is reportedly sharper and more contrasty than the Pentax 50mm f1.4 at common apertures until around f2.8. Read reviews: fredmiranda, slrgear, photozone.de. For vintage: pentaxforums, mflenses, manualfocus

    The Canon 50mm f/1.8 cheapo in particular has some pretty shocking bokeh at times.

    A f/1.4 lens at f/1.8 is not necessarily going to be sharper than an f/1.8 wide open. I'd say that it may often be the opposite. Let's say the lenses are a *similar price* (unlikely in practice) - the f/1.4 will probably be less sharp at f/1.8 than an f/1.8 lens. Only when it's a fairly cheap f/1.8 lens (like the Canon) compared to a more expensive f/1.4 would I expect the f/1.4 to be sharper at the same, widish aperture. To put it another way, making an ultra-fast lens involves more comprimises than just adding a new, less sharp f-stop to the bottom. It affects your other apertures too.

    Just to be clear, as @Reid says below, 1.4 is 2/3rd of a stop bigger than 1.8.

    @thomasrutter is right, i've read something of the sort. it's due to the fact that f1.8 50mm lenses use some slight variation of a time tested design (cheap to make, tack sharp), and usually, f1.8 lenses at f1.8 are sharper than f1.4 lenses at f1.8.

    @JoséNunoFerreira Most 50mm are basically "Double Gauss" designs. See http://www.lensrentals.com/blog/2011/08/lens-geneology-part-1

  • I'm not sure about with Nikon, but one of the biggest differences I see mentioned between the Canon 50mm 1.8 and 1.4 lenses is the build quality - plastic vs metal among other things. This is probably what accounts for most of the price difference.

    I bought the f1.8 and it was a great lens, notice the word *was* though, I dropped it and the glass fell out. I now have the 1.4.

    From about f/2.5 or so onwards, they're essentially identical in sharpness, but below that the f/1.4 is sharper. Also, of course, its USM focus is much faster & quieter than the f/1.8.

    This is the _really big_ difference btw the 1.4/1.2 and 1.8 aperture lenses.

    Not to mention the difference in aperture blade count. The 50 1.8 has nice images (for it's price), but it's bokeh is trash.

  • Here's the Thom Hogan review: http://bythom.com/Nikkor50AF-Slensreview.htm

    His take is: yes, the f/1.4 is somewhat better, but not by a whole lot, so save your money unless you really do need the extra 2/3 stop. Consider boosting the ISO by a stop instead (and you should be ignoring the pixel-peepers and their 100% crop noise tests anyway).

    Also note that the f/1.8 D does not have an internal focusing motor and thus is not compatible with some bodies. I don't recall if the D50 is such a body, but check this.

    I wouldn't worry about depth of field, because it makes focusing that much more critical and also having too narrow DOF is a much more common technical error than too deep DOF.

    The D50 has an internal focusing motor, no problem.

  • Assuming this is a 50mm lens than for DOF the difference would be:

    As far as shutter speed goes, f/1.8 to f/1.4 is a half-stop, so:

    • if your shutter speed was 1/30 at f/1.8, it'd be 1/45 at f/1.4.
    • if your shutter speed was 1/100 at f/1.8, id be 1/150" at f/1.4
    • You can calculate other shutter speeds by just multiplying the shutter speed at f/1.8 by 1.5 to get the shutter speed at f/1.4. Or divide to go the other way. (Full stops double as the aperture value gets lower, so a half stop is 1.5X. Just divide to go the other way.)

    To correct a slight mistake: f/1.8 to f/1.4 is not half a stop, but 2/3rds of a stop, because f/1.8 is sqrt(2)^(5/3), while f/1.4 is sqrt(2)^(3/3). The shutter speed must be converted equivalently: it should be 2/3rds slower.

  • Yes, there is a noticeable difference between the 1.8 and 1.4. My thoughts on the subject in a few bullet points

    • Ignore the light difference, there are more significant differences between those lenses
    • The focus on the 1.4 AF-S is much faster and more accurate
    • The focus on the 1.8 does quite a bit of hunting in low light
    • Image quality is also better on 1.4 AF-S but my experience here is a bit limited. I have only used that lens in the shop.

    I usually shoot the 24-70 2.8 and when I occasionally switch to the 50 1.8 it is always a bit frustrating. Once I wanted to avoid intimidating kids during a birthday party and went with the prime. I regretted it so much when the focus couldn't keep up with fast moving non-cooperating objects. If you can afford the 1.4 go for it, I regret that I didn't and I will as soon as I can afford it.

    I've seen conflicting stories about the IQ. Many seem to consider the 1.8 to yield more pleasant images, but that might refer mostly to bokeh and other subjective things (colour balance etc.) rather than sharpness and distortion (which are pretty good on the 1.8, no need to buy the 1.4 for that unless you're a theorycrafter who looks at his images through a microscope).

    I have compared the f/1.4 AF-S G, the f/1.8 AF-D and the f/2.8 24-70 AF-S zoom (at 50mm). All lenses were wide open, focusing done manually via live view on a tripod and the subject was a flat newspaper. I could not put a hair between the 24-70 and the f/1.4 on centre or corner sharpness. The f/1.8 is slightly sharper in the centre but _significantly_ worse in the corners.

  • You can compare the technical results from reviews such as those at photozone. It is interesting to see that the AF 50/1.8 D has less distortion than the AF-S 50/1.4 G. The centre resolution of the f/1.8 is also higher at all apertures, although the f/1.4 is more consistent out to the borders.

    However you have to work out what you want from such a lens and at what apertures you expect to use it.

    Also consider that the price difference reflects the design & manufacturing cost rather than the value or quality: it is that much more difficult to make an f/1.4 lens.

  • Yes, but until you master the 1.8 lens I wouldn't recommend spending the money on the 1.4. The wider the lens the more precisely you have to focus to get good results. I've taken photos of a person's face where the eyes were in focus but the nose is blurry with the 1.8. So get the 1.8, and get good at manually focusing it. Even with AF-S on the D50 you will want to manually focus a lot to get really good results with this lens.

  • Heh, that's the same camera I use!

    I don't have a nifty-fifty, but my understanding is that you don't get even a full extra stop when moving from 1.8 to 1.4. Also, I've read that the 1.4 version introduces more distortion. Unless you really need the best max. aperture, save your money and get the 1.8 version.

  • Besides the DOF questions, i'd like to point out that the effective focal length of a 50mm FX lens when used on a DX camera (like the D50), will be about 70 or 75mm. Make sure you consider that when thinking about this lens. I happen to like it, as the lens feels a little like a "portrait" lens, and the DOF control is very nice. Buying the Nikon FX 35mm lens puts you at about 50mm on a DX camera, but it also has a minimum aperture of f/2, thus different DOF characteristics:

    http://imaging.nikon.com/products/imaging/lineup/lens/singlefocal/wide/af_35mmf_2d/index.htm

    some of the pictures on my web-site, like this one:

    http://bobplotts.com/galleries/Floral/aai.jpg

    were shot with the 50mm 1.4 on a Nikon D90.

    -- bobp

  • It's quite a bit of difference if you are shooting indoors or at night...which is why most people get it. For daylight in portraits it won't be as much. I'd rather have a 35mm 1.4 but it's way too expensive for me. I shoot on DX with a sigma 30mm 1.4 for a normal lens and a nikon 50mm 1.8g for portraits. If you are on FX, get the 50mm 1.4g and the 85 1.8g for portraits. The sigma 30mm 1.4 is supposed to be equivalent to the 50mm 1.4g... Nikon doesn't make a 1.4 for dx, b/c they want you to upgrade to FX...Same thing at other lengths. They don't make a 24mm 1.8, only the super expensive 24mm 1.4. So it's either sigma 1.8 or nikon 2.8 at that length.

    The bulk of your answer is really not relevant to the question, which was whether the extra cost of the 50mm f/1.4 was worth it over the f/1.8, and whether any difference was noticeable.

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Content dated before 7/24/2021 11:53 AM