dgolfnut Loc: Bear, DE

I am an amateur enthusiast and shoot landscapes, nature - still and in-flight, night scenes and family events with a Nikon D850.
I have 24 & 50mm F1.8 primes. I've thought about a 1.4 or 1.2 for better low light performance but am concerned about DOF. As I've thought more about it, I realize I rarely even use the 1.8 wide open. I have gotten some nice night night shots handheld or minimally braced with the 1.8.
Maybe I just don't know enough about what tool to use in what situation.
So the question is - in what situations is an f1.4 or 1.2 the right tool for the job and what will it give you that a much less expensive 1.8 will not?

rmalarz Loc: Tempe, Arizona

Quite honestly, I'd save the money. If you consider that you can easily change your ISO, if needed, you've more than compensated for the slight difference in aperture.
--Bob

DaveO Loc: Northeast CT

I think you basically answered your question.

The real downside is not being able to say you have one here on the forum.

PHRubin Loc: Nashville TN USA

For me, those wide open lenses are most useful when you are shooting moving targets. Sports or wildlife come to mind. For these you need fast exposures, so in order to keep ISO down, you might benefit from wide open.

Then again, for portraits you want nice bokeh which calls for wide open. Whether 1.8 would be wide enough is a matter of personal preference.

I expect the need for as low as 1.4 or 1.2 would not be often.

Longshadow Loc: Audubon, PA, United States

Especially if your landscapes are predominately in daylight.

CHG_CANON Loc: the Windy City

In today's digital world, ultra wide apertures are artistic decisions rather than low-light tools. Your camera's abilities at higher ISOs negate the need for these ultra wide apertures. If you look at the reviews and example images of the newest wide-aperture lenses for mirrorless, you'll see eye-popping prices as well as performance at the max aperture as sharp as any aperture of the DSLR / SLR versions.

MW

The one thing F1.2 does that F1.8 cannot do is to produce a very, very thin DOF in order to isolate a subject whether it be a human subject or something else. There are work arounds for low light but if want a narrower DOF (even blurring the background via post processing software works poorly) only a wider aperture will do it.

BebuLamar

You gain little in term of low light performance. If you want shallow depth of field then go for it. If you're concerned about not enough depth of field then you gain nothing.

Kmgw9v Loc: Miami, Florida

I have one.

bleirer

...plus you can use the blur filter in Photoshop to add one or more stop's worth of that background effect. Not exactly the same, but close.

DaveO Loc: Northeast CT

Me too. Can't tell you how thrilled I am.

RWR Loc: La Mesa, CA

The wider apertures enable more accurate manual focusing in low light. The difference in depth of field between f/1.2 and f/2.0, or even f/2.8, is often minimal, depending upon your reproduction ratio.

larryepage Loc: North Texas area

This question almost never gets answered completely or correctly. The correct answer? "It depends."

In the past, I concurrently owned 50mm f1.8, f1.4, and f1.2 Zuiko lenses for my Olympus film cameras. All were current models at the time. I had bought them sequentially in that same order, and progressively upgraded to the wider apertures. Let me address a few things that might help you think intelligently about your choice here.

First...depth of field is not even a consideration between a f1.8 and even a f1.2 lens, especially at 50mm. The depth of field is so shallow at f1.8 that it is impossible to observe a meaningful difference when moving even all the way to f1.2. Now with a wide angle, there will be a bigger difference, but it is still not a significant issue. And you still have the smaller f stop available if you should need it. You don't have to shoot at f1.2 just because you have a f1.2 lens.

But the difference in exposure is a full stop, and that can be significant. I don't generally use a 50mm lens for night sky photography, but I could. The lens I use is an f2.8 wide angle, and my normal exposure is f2.8, 25 seconds, ISO 4000. If I had a f1.2 lens (2.5 additional stops of exposure), I could drop ISO to 2000 and exposure time to 10 seconds. That is a huge difference. And everything is at infinity, so I don't care about depth of field at all.

For a given focal length, lenses with larger f stops are generally of higher design and construction grades. I know that for my Olympus, there was a huge difference in quality and construction moving from the f1.8 to the f1.2. The f1.8 was clearly a "beginner" lens. Very lightweight, simple optical design, slightly sloppy operation, very soft corners, marginal sharpness and color transmission. The f1.4 was an "enthusiast" lens...better construction, very smooth operation, better image quality. But the f1.2 was a truly professional grade lens. Sharp all the way to the corners, beautifully sharp and colorful images, and built both like a tank and a fine watch. Of course, the prices for those lenses progressed accordingly.

So to really make a good choice between or among these lenses, you need to consider a lot more than depth of field (which doesn't matter). You need to decide whether your usage patterns would suggest a more rugged lens, and whether you would appreciate the performance of a higher grade lens. Also consider that a 50mm f1.2 may weigh twice as much as a 50mm f1.8. Does that matter to you?

BebuLamar

Today 1 stop extra exposure doesn't mean much with cameras that are capable of low noise at high ISO and with stabilization that allows you to hand hold camera at much longer shutter speed.

ClarkJohnson Loc: Fort Myers, FL and Cohasset, MA

This is a great, well-articulated analysis, larryepage. Thank you fo sharing.