Portraits - What's the point of f/1.2 - 1.8?

[Le_Soleil]

Hey all,

Firstly; I hope I didn’t cause too much distress in the community with the provocative title. It’s 50-50 tongue in cheek and serious

Beginner at photographing others here!

I’m aware of the basic physics that e.g. a f/1.4 lens will let in more light than a f/4, making it ideal in low light conditions. I’m also aware that “bokeh” is more pronounced with a 1.x lens than a 2.x or 4.x lens.

I've been practicing with a nifty fifty f/1.8. I’m very happy with the lens, but find myself rarely shooting at 1.8 for headshots. There are two reasons for that:

1. Nailing focus on just one eye (or eyes) is hard. Are both eyes in focus? Just one? Is it the eyebrows that are sharpest? The tip of the nose? A lock of hair?
2. Even if the closest eye is in focus, the other won’t be, never mind the rest of the face.

Trial and error has led me to believe that f/2.8-4.0 is more flattering where the entire face is in focus, while still getting adequate “bokeh”.

When looking at reviews for your average portrait lens (e.g a 85mm 1.4) there are usually portrait examples at both 1.4 and stopped down to 2.0 - 4.0. Whichever review I look at, portraits shot at 1.2-1.8 has a tendency of having just one eye in focus, sometimes two. Sometimes the focus isn’t even there, but on some piece of hair or a cheek.

From what I can surmise:

F/1.2-1.8: Very shallow DoF, not the entire face will be in focus.

F/2.0-4.0: Not as shallow DoF, but both eyes and parts of the face will be in focus.

When do you decide to shoot at f/1.x for portraits? If you want more than one eye to be in focus, stopping down to f2.8 seems like the better choice, no?

Are there any other benefits with the 1.x lenses compared to their 2.0 or 2.8 counterparts if you shoot in the 2.0-4.0 range with the 1.x lens?

 

[Trk]

You also need F1.x if subject is further away (e.g. full body portrait) and want blurred background.

Otherwise unfortunately as hobbyist I am only able to focus with 1.x with camera with very good autofocus. Sony A7R V allows me to use F1.x lenses without skill and embarrassment.

 

[J A C S]

You mentioned headshots. I take those once every few years when it is time to renew a passport. Then I use f/8. My other portraits are framed much differently - half body or full body, etc. DOF increases fast with distance.

 

[FrancoD]

If you buy a lens that you will probably use at , say ,f/ 3.5 but has a maximum aperture of f/ 1.4 , all those that like or need to shoot at f/ 1.4 or f/2 or f/2.8 ... can also buy the very same lens.

in a way it is the same reason why most cars can carry 5 passengers....

BTW, most often the wider aperture lenses also have the best glass, best coating and strongest built.

Same reason as above, one lens will work for all that are after one or more of those features.

 

[Tom Axford]

Use a depth of field calculator to find the DoF. DoF is strongly dependent on whether you are taking full body, head and shoulders, head only or less.

Here is a shot taken at f/10.6 (FF equivalent) and yet still only one eye is in focus, because the shot is head only.

 

[David5833]

...Are there any other benefits with the 1.x lenses compared to their 2.0 or 2.8 counterparts if you shoot in the 2.0-4.0 range with the 1.x lens?

You seem to have mostly answered your own questions, at least for the way you like your portraits to look. However, the most important benefit is that not everyone wants a portrait to be in perfect focus from tip of nose to back of head. If you want the soft look of the thin DOF of, for example, an f/1.2 lens then you need such a lens or be skilled at editing.

For any genre, having a fast lens gives you added options for control of exposure (especially if you need faster shutter speed in low light) and DOF and all that comes with those things compared to a slower lens. Finally, the fastest lenses often are sold as "professional" gear, ostensibly with better build quality and overall performance compared to consumer lenses.

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https://www.flickr.com/photos/143821723@N06/

 

[Greg Edwards]

Why make road cars capable 150mph if the speed limit is 70mph? A car that can move at 150mph will be more efficient (and have better brakes) than a car only built to go at 70mph.

Likewise, most lenses need to be stopped down a little to achieve optimum sharpness, reduced vignetting and less distortion. A f1.2 50mm lens will usually be sharper stopped down to f1.8 than a f1.8 50mm shot wide open.

 

[yardcoyote]

I'm no portraitist, and my only practical reason to have any fast lens is purely to gather light, mostly for indoor shooting in museums and such. (There, narrow depth of field can be a bug, not a feature.). One fastish prime in 50 or 85mm is enough for me.

But it can be very hard to find an f/2 or f/2.8 lens that is of high quality and is sharp wide open, even though that is the kind of lens I would prefer. Many manufacturers have historically assumed that the only reason people buy a slower lens is because they can't afford a faster one, and they have been designed strictly to keep prices down. If you want the best optics your only option is often to buy the faster lens and shoot it stopped down.

It seems like this trend may be reversing a bit. Fast prime lenses have gotten so big and heavy that they really aren't a lot of fun to carry around for everyday shooting, and you are starting to see some nicer "small slows" being offered. Some even have aperture rings!

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Instagram: @yardcoyote

 

[Dick Dastardly]

Your observations are correct, there's no point to f1.8 for example on a apsc or FF sensor.

For portraits, f1.7 on a M43 camera is ideal, and not only. It's the best compromise in terms of DoF and iso, on my FF camera i need f3.5 or more to achieve the same look and in low light, it means i have to use iso 12800 and above. Not great.

As for why people prefer blurry images and videos, don't know. Whenever i see a video on YouTube shot at very low f numbers, i quit looking because it's all a blur.

 

[DirkPeh]

I remember when I started to get more serious, I bought my first prime, a 80 mm equivalent, and shot everything at f/1.4 for the “pro” look .

A bit later and wise, I am mostly between f5.6 and f8.

As others have mentioned in this discussion and I found a bit tougher to learn: distance plays a huge role. I often prefer 135 to 85 for portraits and this dictates a huge distance to the subject, changing the DOF. If 50 or 85 mm are used esp. at closer distances, the aperture is often much narrower.

There is a trend to use wider lenses and closer distances for portraits. One of the results of gazzillions of smartphone portraits and selphies we have come accustomed to. Many shudder about the distortion. I don’t even recognise it, as if my brain simply takes the distance into account.

 

[Michael Fryd]

Hey all,

Firstly; I hope I didn’t cause too much distress in the community with the provocative title. It’s 50-50 tongue in cheek and serious

Beginner at photographing others here!

I’m aware of the basic physics that e.g. a f/1.4 lens will let in more light than a f/4, making it ideal in low light conditions. I’m also aware that “bokeh” is more pronounced with a 1.x lens than a 2.x or 4.x lens.

"Bokeh" and "Depth of Field" are different things.

"Depth of field" refers to the range of distances where the subject appears to be in focus.

"Bokeh" refers to the quality of the out of focus regions. Imagine that there is a small white circle that is out of focus. Depending on the lens, that out of focus circle might look like a pentagon, a doughnut, a nicely blurred circle, or something else. That's Bokeh. Often, for a portrait, you want the out of focus areas to be creamy smooth.

With wide apertures, you get shallower depth of field. That makes the areas behind the plane of focus blurrier.

Wider apertures do let in more light, but the tradeoff is that shallower depth of field. Depending on what you are shooting, that shallower depth of field might be a problem, might be an advantage, or might not make a differece.

I've been practicing with a nifty fifty f/1.8. I’m very happy with the lens, but find myself rarely shooting at 1.8 for headshots. There are two reasons for that:

1. Nailing focus on just one eye (or eyes) is hard. Are both eyes in focus? Just one? Is it the eyebrows that are sharpest? The tip of the nose? A lock of hair?
2. Even if the closest eye is in focus, the other won’t be, never mind the rest of the face.

Trial and error has led me to believe that f/2.8-4.0 is more flattering where the entire face is in focus, while still getting adequate “bokeh”.

This is a stylistic question. When creating art, you might want only one eye in focus. When do a tradition portrait or headshot, you may want both eyes in focus.

A scientist might tell you that when the camera is focused at 5 feet, only things that are exactly 5 feet are in focus. 1mm further or closer and the object is not in focus.

An engineer might point out that while something a little further/closer is not scientifically in focus, it's close enough that it will look in-focus in the final print. The range of distances where the object appears to be in focus is the "depth of field". As objects move away from the plane of focus they get blurrier. We can measure the amount of "blur", but we can't easily measure the "bokeh". Remember, with real world lenses, the blur is often not a pure Gaussian blur. "Bokeh" refers to aesthetic quality of how the blur deviates from the ideal.

When looking at reviews for your average portrait lens (e.g a 85mm 1.4) there are usually portrait examples at both 1.4 and stopped down to 2.0 - 4.0. Whichever review I look at, portraits shot at 1.2-1.8 has a tendency of having just one eye in focus, sometimes two. Sometimes the focus isn’t even there, but on some piece of hair or a cheek.

From what I can surmise:

F/1.2-1.8: Very shallow DoF, not the entire face will be in focus.

F/2.0-4.0: Not as shallow DoF, but both eyes and parts of the face will be in focus.

How much will be in focus depends on a few factors including: focal length, sensor size, aperture, and subject distance.

The human eye is attracted to the parts of the photo that's in focus. With a portrait you often want that to be the person. The background will be out of focus if it is outside the depth of field. You can do this by having the background be further behind the subject, or by using a shallow depth of field.

As to how much of the face you want in focus, that's an artistic question. What style image are you trying to create?

When do you decide to shoot at f/1.x for portraits? If you want more than one eye to be in focus, stopping down to f2.8 seems like the better choice, no?

There are lots of online Depth of Field calculators. Use one to determine what settings you need to get the depth of field you want for your image.

Are there any other benefits with the 1.x lenses compared to their 2.0 or 2.8 counterparts if you shoot in the 2.0-4.0 range with the 1.x lens?

Focus and framing tend to happen with the lens wide open. If you have a DSLR with an optical viewfinder, the viewfinder tends to be brighter with an f/1.8 lens than an f/3.5 lens.

As wider apertures have shallower depth of field, focus is more critical with wider apertures. With a wider aperture, the camera can focus a little more accurately.

Thus there are some advantages to using an f/1.8 lens even if you are shooting at f/5.6

If you are shooting something flat, or far away, you may have sufficient depth of field, even when the lens is wide open. In that situation, opening up to f/1.8 can allow you to use faster shutter speeds in lower light.

 

[Tom Axford]

As others have mentioned in this discussion and I found a bit tougher to learn: distance plays a huge role. I often prefer 135 to 85 for portraits and this dictates a huge distance to the subject, changing the DOF. If 50 or 85 mm are used esp. at closer distances, the aperture is often much narrower.

It is worth looking into this a bit more. It is the framing that is most important.

For example, a tight head shot has about the same DoF at the same F-number, whatever the focal length used. So, a tight head shot at 150mm f/5.6 will give much the same DoF as a similarly tight head shot at 50mm f/5.6, although for the former, the camera will be three times as far away as for the latter.

A head and shoulders shot will always give you a lot more depth of field (four times as much if the size of the frame is doubled).

 

[A Marcus]

You are working in too close to the subject. Too close and the nose reproduces too big and the ears too small. Also, the whole face will not be in good focus at large diameter aperture settings.

As a rule-of-thumb, portraiture is best if you mount a lens that is about 2X longer than "normal". A "normal" lens is one with a focal length about equal to the diagonal measurement of the format. For a full frame camera that's about 50mm. For the APS-C that's about 30mm.

The ideal portrait lens for the full frame is about 100mm. The ideal portrait lens for the APS=C is 60mm.

Find your camera's "normal" lens and multiply its focal length by 2.

What does this do for you? It forces you to step back (more distance between camera and subject. This will solve your focus problems when working with the aperture wide open. This extra distance also reduces the likelihood of facial distortion.

There are no rules in art, you are free to follow your heart. If you want to make good portraits, try a lens 2X longer than "normal", you will like the results.

 

[Le_Soleil]

Fantastic replies to everyone here, thank you all for the in depth explanations you've all provided. There's a lot to process and go through, but I really appreciate all your replies.
Haven't really heard or used a DoF calculator before, but I'll check it out!

Will also look at getting a lens with a bit more reach at some point, an 85mm lens or above. Seems that it's worth going for a slightly faster version even if I stop down a bit.

Thank you folks!

 

[Michael Fryd]

Fantastic replies to everyone here, thank you all for the in depth explanations you've all provided. There's a lot to process and go through, but I really appreciate all your replies.
Haven't really heard or used a DoF calculator before, but I'll check it out!

Will also look at getting a lens with a bit more reach at some point, an 85mm lens or above. Seems that it's worth going for a slightly faster version even if I stop down a bit.

Thank you folks!

Faster lenses tend to be more expensive. They are often bundled with other useful benefits.

For instance, Canon has their regular lenses and their "L" lenses. The "L" lenses are their professional or "Luxury" line. Wider aperture lenses tend to be L lenses. They are more likely to have be more tolerant of weather and/or rough handling. They are more likely to have a physical distance scale on the lens for completely manual focusing. They are more likely to come bundled with a lens hood and/or lens storage bag/case. High end lenses may also have fewer aberrations.

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When discussing focal lengths, it is important to mention the sensor size that the lens will be mounted on. Focal length is a physical property of the lens. Angle of view is determined both by focal length and by sensor size.

For instance a 50mm lens has a 46° angle of view when mounted on a full frame camera. Mount that same lens on a 1.6X crop body, and it is still a 50mm lens, but the resulting angle of view is only 30°.

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There is a lot of confusion in this area. This is because with the introduction of digital, camera manufactures started advertising angle of view in units of "focal length needed on a full frame camera in order to get this result". That's a lot to say, so it gets abbreviated to "equivalent" or "effective".

When a camera manufacturer tells you that a certain camera/lens combination has an effective 50mm focal length, they are not describing focal length at all, they are telling you that the angle of view is 46°.

A 25mm lens on a 2X crop body has an angle of view of 46°, so that gets marketed as 50mm equivalent focal length. However it's still a 25mm lens.

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When it comes to portraits the general rule is to first pick your subject distance. If the camera is only 1 foot from the tip of the nose, the ears are 50% further away. That perspective is generally not pleasing. If the tip of the nose is 5 feet from the camera, the ears are only 10% further away. That generally provides a more pleasing perspective.

Once you have chosen the subject distance, pick the focal length for your camera that gives you the framing you desire. What this means is that if you take a shot from waist to the top of the head, and you want to take a second shot with only the face, you may want to move to a longer focal length, rather than getting closer to the model.

On a full frame camera, 85mm is a popular focal length for portraits. Personally, I like a little more distance between the camera and a model, so I generally use a longer focal length. My favorite full frame portrait lens is a 70-200mm f/2.8 zoom.

I find that f/2.8 yields more than sufficient shallow depth of field for my style of portraits. I also find the focal range meets my full frame needs.

True, an f/1.8 prime can yield shallower depth of field, but I find that I don't need that. Others may find that f/1.8 isn't shallow enough, and they need f/1.4 or f/1.2.

Prime (fixed focal length) lenses have a reputation for being sharper than zoom variable focal length) lenses. However, lens technology has gotten much better in the last few decades. High end zoom lenses (like Canon's 70-200 f/2.8 L) provide excellent quality. They seldom are the limiting factor in image quality. Moving to a prime lens may not yield a visible difference in the final result.

 

[Bob A L]

100% agree that too shallow of dof does not make good portraits. I suppose it's like much in photography that is all up to personal taste and that's fine. But my personal taste just can't get satisfied with such shallow dof especially on portraits. If I want the background blurred out I have plenty of other ways to do that and still maintain the entire face and ears in focus.

 

[David5833]

...Will also look at getting a lens with a bit more reach at some point, an 85mm lens or above.

You haven't said what camera you are using. For example, on Canon crop cameras a 50mm lens will have the same field of view as an 80mm lens on a full frame camera, so it may have acceptable foreshortening because you will be farther away for the same framing.

Seems that it's worth going for a slightly faster version even if I stop down a bit.

That depends on your assessment of need/cost/benefit. For me, in most situations, "slightly faster" is virtually never a big deal. OTOH, if I often found myself in situations where the fastest aperture actually made a difference in being able to shoot at a usable shutter speed or having satisfying background blur or being able to focus in low light, then it would be "worth it." However, I know from my history that I just don't find myself in those situations often enough to matter, so I would usually rather pay a lower price and carry less size and weight.

 

[Martin_99]

This is a little bit weird question for me, like no other portrait style exist, only headshots.

My favourite is half body portrait, where f1.8 provide nice separation from background (meaning common focal lenghts 35-85mm) without effect of "too much blur" (at least for me). Not mention full body portrait, where sometimes separation effect is relatively low.

 

[Johan Borg]

Fantastic replies to everyone here, thank you all for the in depth explanations you've all provided. There's a lot to process and go through, but I really appreciate all your replies.
Haven't really heard or used a DoF calculator before, but I'll check it out!

Will also look at getting a lens with a bit more reach at some point, an 85mm lens or above. Seems that it's worth going for a slightly faster version even if I stop down a bit.

While a fast lens is useful for subject separation at longer distances, it's not entirely obvious that a faster lens is better stopped down than a slower lens wide open.

Especially in the 85-105mm range there are several F2.8 macro lenses that are optically superb and make for good portrait lenses as well.

 

[MarkInSF]

Why make road cars capable 150mph if the speed limit is 70mph? A car that can move at 150mph will be more efficient (and have better brakes) than a car only built to go at 70mph.

Likewise, most lenses need to be stopped down a little to achieve optimum sharpness, reduced vignetting and less distortion. A f1.2 50mm lens will usually be sharper stopped down to f1.8 than a f1.8 50mm shot wide open.

Eh, cars designed for high speeds are almost always _less_ efficient. They need more powerful engines, and that typically means more displacement - though turbochargers have evened things out a bit. Even in those cases the more powerful variants have worse fuel efficiency. One of the main limitations on automobile top speed is tire ratings. That's why so many cars top out at 155 mph, a common tire rating.