Is 85mm really ideal for portraits?

Discussion in 'Beyond the Basics' started by adamhiram, Sep 28, 2020.

  1. adamhiram

    adamhiram No longer a newbie, moving up!

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    When I first started learning portraiture, I went out and picked up an 85mm lens. Everything I read said for headshots and above-the-waist portraits, 85mm was the lens to use. I eventually picked up a 50mm prime as well for full body shots. I was happy with the results with both lenses, and used them for years. The only catch was I was shooting on a crop sensor body, first with a Nikon D5100, then with a D500. Other than needing more space to shoot, I didn't think much of it.

    Having recently switched to full frame (Nikon Z6), I figured the same guidance applied, but I could stand a little closer to my subjects, and obtain a shallower depth of field with the same lenses if desired. However I decided to take some test shots, and the results weren't quite what I expected.

    First, I compared headshots taken at 50mm and 85mm, both on my D500. I typically don't take tight portraits at 50mm, but also didn't think it would be terrible. The results were as expected, albeit a bit more exaggerated than I would have thought. It is pretty clear that the face gets quite distorted shooting this tight with the 50mm.
    d500-50mm-d500-85mm.gif

    Since 50mm on a crop sensor is roughly the same field of view as 85mm on full frame (technically 75mm), I figured I would compare the two. Below, we can see that despite 85mm being the "ideal" focal length for portraits, it isn't all that different from 50mm on a crop sensor in terms of facial distortion.
    d500-50mm-z6-85mm.gif

    So does that mean same 85mm lens on both cameras would look significantly different? It turns out it does, with 85mm on the Z6 showing the same distortion as the 50mm did on the D500. Note that the D500 was a bit further from the subject to accomplish the same framing.
    d500-85mm-z6-85mm.gif

    Thenext logical step was to perform the same test with equivalent focal lengths from the same distance again. That meant 85mm on the D500, and 135mm (70-300 zoomed to 135) on the Z6. And look at that, the facial distortion is gone on both. Please excuse the head position at 135mm, I must have bumped it at some point.
    d500-85mm-z6-135mm.gif

    Lastly, I wanted to see if the difference really was so significant between 85mm and 135mm on the Z6. While not quite as pronounced as the difference between 50mm and 85mm on the D500, the facial distortion is still noticeable.
    z6-85mm-z6-135mm.gif

    That leaves me with two questions.
    • Is 85mm really the best focal length for headshots and above-the-waist portraits? Is the facial distortion something to be concerned about, or is that a normal perspective of how we see people from 4-6' away?
    • Would a longer focal length be more flattering if I have the space to support it? I've heard great things about some of Sigma's Art glass, particularly the 135mm f/1.8. I've also been curious about their 105mm f/1.4 and its comically large size, particularly on a smaller mirrorless body. It's worth noting that 85mm is currently the longest native Z-mount prime.
    I would love to hear from portrait photographers on here - what you typically shoot with, what you would recommend, and your thoughts on whether or not the perspective at these focal lengths is pleasing.


     
  2. Pixeldawg1

    Pixeldawg1 TPF Supporters Supporting Member

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    Twice the standard focal length of the camera is considered the "ideal" focal length for portraits. So a 105mm for your camera will do very well. This is because the perspective at this focal length makes people look "natural". At 50mm, the nose tends to look larger, less so at 85mm, but 105mm is the sweet spot. In 120 cameras, a 150mm lens is used and for a 4X5, 180 to 200mm.

    Cordially,

    Mark
     
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  3. Quassaw

    Quassaw TPF Noob!

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    The focal length makes no difference to the distortion - it's the distance between the model and the sensor. An 85mm allows you to stand a nice distance from the model to fill the frame on a full-frame camera. With a 50mm you can tend to get too close, and even closer with a 28mm. However, if you stand the same distance away with the 85mm and the 28mm you will see the same amount of distortion (although you'll have to crop in post for the 28mm shot of course - not what you really want to do). On a full frame, an 85mm give a pleasingly low amount of distortion. I tend to like something a little shorter (70mm) for my head shots. In the old days, some people used to shoot with 135mm, which to me can make the face look a little flat - try standing miles away from the model and shooting with a 500mm for a headshot and you should find that the face doesn't look too good.
     
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  4. Soocom1

    Soocom1 Been spending a lot of time on here!

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    Actually the distortion factor is something I have seen multiple times.

    The smaller the senors/ film area, the more distortion it takes to get an image, either through the lens itself or the image.

    This has to do with the registration distance vs. the focal length of the lens itself vs. the image capture area.

    Med. format at 110-185 mm is considered ideal as Pixledawg points out. The larger the image area the larger the image circle, and ergo a longer focal length to achieve full coverage. Plus the distance factor. The larger the format the more information collected.

    Standard portrait lenses on a 35mm typ. fall to the 80-105 range because almost all 35mm cameras have a registration distance of around 44 mm +/-.

    In a Med. Format that distance is around 75mm +/-

    Perspective control lenses (T/S) are capable of reducing the distortion (ironically by distorting the image), but bellows on a Large Format allows the movement to create the most flattering image.

    Its just that the modern world of photography has not been "focused" (pun intended) on the nuanced aspects of photography because of iPhones.
     
  5. wfooshee

    wfooshee No longer a newbie, moving up!

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    The notion of 85mm as the "ideal" portrait lens is based on its field of view on a 35mm frame, which your crop-sensor cameras did not have. The 85mm lens on those cameras gave you the field of view of a 130-ish mm lens on a 35mm (or full-frame digital) camera.

    Basically, what made the 85 to 105mm length good for portraiture was that at the distance needed for good framing, the perspective was such that facial features were neither exaggerated nor flattened. With a shorter lens placed closer (to get the same framing) features closer to the camera seem enlarged. With a longer lens placed more distant (again, to get the desired framing,) the subject seems flattened. you might get good framing from across the street with a 500mm lens, but it won't be a nice portrait. :)

    Perspective is a matter of distance from the camera. If you shot a "perfect" portrait with an 85mm lens, then switched to a 50mm lens and shot from the same distance, then cropped the image, you'd have exactly the same portrait. The original 50mm frame has a lot of useless area around the larger field it views, but cutting that out by cropping puts you in the same place that the 85mm lens had you seeing.

    Sensor (or film) size is what determines the focal length of the lens you want for portraiture. You need a higher focal length lens when using a larger area to capture your image; that lets you compose your framing such that the subject to camera distance yields a flattering perspective.

    In your comparisons, it looks like you moved the camera when changing lenses so you'd have the same framing. If instead, you left the camera where it is and cropped the image created by the shorter lens, you'd see what I'm saying about the perspective not changing.
     
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  6. Quassaw

    Quassaw TPF Noob!

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    Registration distance has no impact at all - how could it? My Z6 has a registration distance of 16mm, but a 50mm lens on that gives exactly the same image as a 50mm lens on a D850, which has a registration distance of 4.5mm.
     
  7. Quassaw

    Quassaw TPF Noob!

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    46.5mm of course!
     
  8. Soocom1

    Soocom1 Been spending a lot of time on here!

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    Your not understanding what I am talking about.

    Registration distance is the distance from the focal point to the image plain for those not knowing.

    The image from a 50mm on a SLR vs. a mirrorless will look exactly the same because the mechanical construction of the lens designed for the two need to make an image circle to match the respective reg. distance. You cannot attach a mirrorless lens on a SLR without some kind of optical adapter period.

    The core diff. I am referring to is the distance between a small and med. format.
    They have to be longer on a Med. format or have optical construction that allows for an extremely short distance to create the image circle.

    The resulting image is then constructed to match one another.
    so distance is a major factor.
     
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  9. Tropicalmemories

    Tropicalmemories Been spending a lot of time on here!

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    There's also a cultural dimension to consider. My 'model' is Asian and she much prefers portraits taken with a low cost 27mm lens on a crop sensor Fuji to ones taken with the 56mm 'portrait' lens that I bought specifically for portraits at a much higher cost! When I've taken portraits of her friends, they say the same .... 27mm best, 35mm OK, but they are not keen on the 56mm shots.

    I think there's two factors here ...... firstly the Asian obsession with caucasian facial features - they all think their noses are too small, almost all the popular models and actresses here are half European or have had nose surgery, and secondly the passion for selfies taken at close range on mobile phones have given people a particular perception of their appearance.

    So our views about was an ideal portrait lens may not necessarily be shared by our models.
     
  10. AlanKlein

    AlanKlein Been spending a lot of time on here!

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    The same things happens on Zoom or vlog type videos where people sit close to their computers or cellphones. Their noses are too big for their faces.
     
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  11. Designer

    Designer Been spending a lot of time on here!

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    Back in the film era, we always considered 105mm to be the shortest lens for good portraiture, with longer (135mm and up) being preferential. Yes, that usually means stepping back to get your subject with a little space around him, but that is where the longer lenses belong anyway.
     
  12. Soocom1

    Soocom1 Been spending a lot of time on here!

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    Remember also FoV aspects.

    The higher the number the narrower the actual capture image is going to be. Not just distance. Typ. speaking, and unless you're using a Macro specific long lens, the overall image begins to get washed out if shooting with a 200mm. But this is again dependant on the format size. A 180mm in Med. format is NOT the same as a 180mm in 35mm.

    Then consider speed: The faster the lens, there is the bokeh aspect that ties directly into the overall FoV. its subjective, but plays an important role in portraiture.
     

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