85mm or 127.5mm (on crop factor)

Discussion in 'Nikon' started by raffal, Jan 20, 2014.

  1. Maybe this is silly question but when one talks about for example 'perfect' focal lengh for portraits and suggest 85mm 1.8 lens -has in mind FF or FF and
    DX...because this lens on Nikon crop factor will be more like 127.5 mm rather than 85mm...thanks
    Raf
     
  2. Rafal:
    When I was shooting film and when I shoot FX now. I still consider 105mm as the ideal for portraits. This would equate to 70mm when shooting DX.
    -O
     
  3. pge

    pge

    It is hard to say without the context of the quote. The "perfect" focal length for portraits, speaking strictly FX has often been suggested to be somewhere between 85mm and 135mm. So, your 85mm lens would fall within that definition either on an FX or DX camera. Really the best way to decide for you would be to take shots yourself, either with the lens or with a kit lens zoomed to that focal length.
     
  4. I have a good sized nose so I like my portraits taken with a 800mm lens :D
     
  5. As Owen, I prefer 105mm on FX.... On DX, using primes, I much prefered 85mm over 50mm - the latter is really just a bit too wide and not flattering, in my view.
     
  6. There's no such thing as a perfect portrait focal length. It depends on the subject, your style, how much of the person you
    want to show, etc. I've seen anything from 58mm to 135mm (on FX) described as an ideal portrait lens, and I remember
    one guy on here a while back who couldn't possibly shoot portraits without a 200mm.

    It's really up to you to decide what the criteria for a good portrait lens are and shoot with what you like best.
     
  7. Hi Rafal - if you shoot outdoors or if you have a very large studio, the 85mm is better. You will have better subject/background separation
    those shots were all at 135mm http://500px.com/ElenaShumilova
     
  8. Perspective is dictated solely by the distance from camera to subject, and not by the focal length of lens used. It would be better to think "I need to be a minimum of 2m (6.5ft) away from my subject's face to get a nice flattering perspective with their rather pointy face and big nose" rather than "I'll just use my favourite 105mm lens for this shot".
    Edit: Sorry Al! just noticed your own comment on the subject of noses. I ain't no oil painting myself. Blessed be the big noses.
    Also, hasn't the DX format been around long enough that we no longer have to relate it to Oskar Barnack's randomly chosen double cine-frame from the 1920s? After all, those of us that shot roll and sheet film never did a mental flip-flop to convert from our 110mm or 210mm lenses back to the 35mm film format, whose inferior quality was generally despised.
     
  9. While there may be no "perfect" focal length for portrait work, tradition has often worked in the range from 75mm to 105mm. Some of the world's greatest lenses, period, have been in this range:
    Biotar 75mm f/1.5 and the Nikkor-P 105mm f/2.5, to name just two.
    but as for
    hasn't the DX format been around long enough that we no longer have to relate it to Oskar Barnack's randomly chosen double cine-frame from the 1920s? After all, those of us that shot roll and sheet film never did a mental flip-flop to convert from our 110mm or 210mm lenses back to the 35mm film format​
    And How!
    Simply remember that a 85mm is a medium telephoto on DX, a short telephoto on FX, and you know all you need to know.
     
  10. For portrait of a baby I would use something like a 35mm lens shot at about 1 to 2 feet away. That's the way mother sees her baby. So basically pick the distance you want to do the portrait at and then pick the focal length for the framing you want.
     
  11. 85mm f1.4 lenses are sometimes called ideal for portraits.
     
  12. Nikon originally considered the 85 and 105mm focal lengths optimal for portraiture, being optimized for this task in different developments. Since the 40s-50s.
    But also they made a 135mm lens with similar specs, so it could be also considered another portrait focal lengtht.
    If you translate it to the DX field of view, you have the right focal lengths... the issue is that this lenses were made for FF (now FX), and there isn`t DX lenses with identical design, but maybe with a "versatility" idea on mind.
    But I have never understood the reasons of being a true "portrait lens" and why it should be the fastest one.
    Well, I have my own explanation:
    Older, vintage, original "portrait" lenses were made fast to avoid long exposures; portrait studios used to use natural daylight, plate emulsions were not so light sensitive, and they have a hard time trying to get their subjects steady while exposing the plates... so the faster aperture the better to avoid motion blur. This were the first portrait lenses... they even have engraved "Portrait Lens" over the barrel.
    About the focal length, the one that fit the format at a reasonable sized room, pleasant perspective and framing.
    Faster apertures (e.g. f3, f5) on that bigger formats delivered a very shallow depth of field, and therefore, a noticeable high background blur.
    So my understanding is that nowadays, portrait specialist lenses are the ones that look for that very same effect... shadow DoF and heavy background blur. The duration of exposures are not of an issue, because "emulsion" speeds are much faster.
    But the formats we use right now are much smaller, so the background blur is not as pronounced. We need fast lenses, much faster, and even so, the background is not as blurred. Lenses are sharper, so we need a trick that make that backgrounds "unsharp", to get that effect.
    Long focal lenght lenses are difficult (and expensive) to make with fastest speeds, so it`s easier to make a 85/1.4 than a 105 or 135 with the same aperture.
    So the "most portrait lens" of the portrait lenses, right now, could be the 85/1.4 (and specially, the 85/1.4AFD and on), because the aperture.
    Another could be the 105/2DC, which is not as fast, but to blur the background in a "similar manner" they used the trick of modifying the aberration correction with a ring that can be actuated by the user. Same with the 135/2DC.
    There are also a 105/1.8 and a 135/2 MF lenses, but I wonder if like the 85/1.4 MF, can be considered fast lenses but not pure "portrait specialists".
    The focal length of the lens is not as important, as like Andy says, it depends on each one`s preferences; maybe we could say that if they fit into reasonable perspective (say, from 1.5 to 4 meters), any focal length will work.
     
  13. But I have never understood the reasons of being a true "portrait lens" and why it should be the fastest one.​
    I think nowaday people need fast lens for portrait so that they can have sharp eyes and blurry nose and ears.
     
  14. When I was shooting film and when I shoot FX now. I still consider 105mm as the ideal for portraits. This would equate to 70mm when shooting DX.​
    agreed! I like my 105 on DX for outdoor portraits, though.
     
  15. A so-called "normal" lens for 35mm format is often an excellent portrait lens on a DX body, especially with the wider f/1.4 and f/1.2 apertures that give such smooth and buttery out-of-focus highlights ("bokeh", sometimes called "brokeh" here on P.net).
    On FX, 135mm focal length lenses are used for portraiture (e.g., Canon's soft focus version), but that can be a little too "flattening" to be "flattering" for those with smaller noses. :)

    close to the lens makes nose large, far away makes it look flatter
     
  16. Peter ..when he said '105'- he
    meant on FX...u talkin 105 on DX
    which would equal 157.5 on FX..so
    ..thats what he didnt mean...you
    would have to have 70 -to get 105
    angle of view on DX...
     
  17. when one talks about for example 'perfect' focal lengh for portraits and suggest 85mm 1.8 lens -has in mind FF or FF and DX...
    ... I think they have on mind by default the 85/1.4AFD lens for reference, which is a FF (or FX) lens. They don`t think on the focal length, but on an specific lens designed for portraiture. And for closer shots (there are no full body "portraits"?), people use to like 105mm or longer (FF/FX), so for DX they could consider it right for their needs (they don`t mention if full body or tight heads shots, BTW).
    But as mentioned, the focal length does`t matter at all; what really counts as a portraits specialist lens is the rendering quality and the background blur quantity and quality. Any focal length (that fit your perspective) will work.
    So for DX, an 85/1.4AFD or AFS will work, a 105DC will work, and the 135DC too (but a bit on the long side, maybe).
    There are no 50mm "nominated portrait specialists", but to my taste, maybe the new 58/1.4AFS, or the older 50/58 f1.2 MF versions, or even the Sigma 50/1.4HSM (with its very high center&very low corner resolution), could be worthy of this title. It`s obvious that a 50mm focal length lens could fit the needs of DX shooters.
    Again, from my point of view, there is not a unique and "perfect" focal length lens for portraits. It does`t make sense.
     
  18. There are no 50mm "nominated portrait specialists"
    Either the 58/1.4 AF-S or 60/2.8 AF-S Micro work nicely for portraits from the rendering point of view in my opinion and are fairly close to the field of view on a DX camera that one would obtain using an 85mm on an FX camera. The 58mm is clearly intended for portrait use though I think most users will be using it on FX (simply because it's such an expensive lens).
    In any case the portrait rendering (a bit softer skin, with sharp outline of the face) is mostly a useful feature for tight head and shoulders and head shots, as in wider views with 2/3 or full body in view, it is not necessary to soften anything; the blemishes on the skin are so small in the image that they do not matter. Only for the head and shoulders and tighter shots in my opinion is any extra treatment of skin useful. I do see some wedding and portrait photographers post-process the skin heavily and I detest this look. However, apart from softer and less harsh rendering of skin, many portrait lens designers have put emphasis on achieving the nicest out of focus rendering. In recent times this has extended towards the wide angle sector as well, with the 24/1.4 and 35/1.4 Nikkors being more bokeh-optimized than wide angles used to be, and the newer 50/1.8 also seems to produce quite nice bokeh. For DX, on budget, my choice for head and shoulders would be 50/1.8 AF-S, 58/1.4 AF-S or 60/2.8 AF-S; for wider angle than those, i.e. for full body shots, with some environment, the 17-55/2.8 DX is excellent for a zoom (but doesn't quite give that wide an aperture, but the rendering is very nice for portraits), the 18-35/1.8 Sigma may also be good.
    I think on FX anything from about 35mm to 200mm can be used for portraits depending on what is meant by a portrait, this would translate to 23mm to about 135mm on DX. I tend to have a preference for lenses from 35mm to 105mm myself (FX; that would translate to 23mm to 70mm on DX). Quite a lot of the time the 24-70 (or 17-55) do what is needed quite well without having to resort to a prime. In particular, when I'm using lights, I'm likely to use a zoom so that I don't have to deal with lens changes while I need to also adjust the lights and move them about. However for head and shoulders, I almost always use a prime (because they offer a more optimal "look" for the purpose and a closer minimum focusing distance than the telezoom that I have).
    I find very curious that people often take "portrait" to mean head or head and shoulders. To me, the much more interesting portraits often include more of the body, the language of the body, posture, use of hands tell more about the person than the face alone. Also, hints about who the person is are given by the environment. It is for these 2/3 and full body shots that the wide aperture (e.g. f/1.4) is often needed, not for the head shots, which I typically shoot at f/4 to f/8.
     
  19. I've heard it asserted (by this forum's favourite non-authoritative source) that the perspective that "looks natural" is the view of a person from about 15', call it 3m, away - supposedly this is how we remember people, and it's about the distance where we recognize someone entering our personal space enough to register details. It's probably not far off the average distance in a small crowd. The perspective effect on a face is pretty subtle unless extreme, anyway. Erring on the long side does have the "shrink the nose" effect (although, sadly for me, it also has the "grow the ears" effect).
    Focal lengthLong edge
    on FX
    at 5mLong edge
    on DX
    at 5m
    35mm​
    5.1m3.4m​
    50mm​
    3.6m2.4m​
    85mm​
    2.1m1.4m​
    105mm​
    1.7m1.1m​
    135mm​
    1.3m0.9m​
    200mm​
    0.9m0.6m​
    (Calculation: 36 x 5/focal length for FX, 24 x 5/focal length for DX.) Note that you probably don't want to fill the frame completely with the subject, so using an 85mm lens on full frame just about allows you to get the whole person in or an upper body shot with plenty of breathing room, a 135mm is head-and-shoulders plus some breathing room, and 200mm is getting very tight. The shorter lengths (50mm and below) are often used in landscape mode to get a group shot. 105mm obviously splits the difference between the two "classic" lengths.

    A moderately long telephoto tends to be better for isolating the subject from the background - partly because you don't see much background, partly because the background blur from a fast lens is magnified. The same is even more true of a longer lens (such as a 400 f/2.8), but those lenses make communicating with the subject harder, they tend to be horrendously expensive, and they're arguably a higher priority for sporting events and wildlife (meaning they'll be branded more for that purpose). I use a 200 f/2 for (candid) portraits - Joe McNally uses one for staged shots - but I suspect Nikon would struggle to sell one primarily for that purpose.

    What's the "best" portrait lens depends on the look you want - if you want to include lots of background or have a deliberately distorted effect, even an ultrawide works. But on FX, the 85-135 range tends to be the cross-over point between limiting distortion, isolating from the background, and being vaguely affordable. Shorter has limited background isolation, tends to start having more distortion if you get close, and is probably better suited to including some more environment (it becomes "normal"). Longer starts to get expensive fast, starts being more useful for sports and wildlife, and offers relatively limited gains over the 135mm range for a classic portrait perspective - you get roughly the same look for a lot more money. (But the 200 f/2 does make the background go away beautifully.)

    Bear in mind that the DX crop also effectively makes the lens slower. An 85 f/1.4 used on a DX camera behaves - from a depth of field perspective - like a 127.5mm f/2-ish lens would on FX. You still get the ability to isolate the distracting bits of the background from the frame, but you don't get any more background blur than you would with the same lens on FX.

    But I'm not a professional portrait photographer. YMMV.
     
  20. I find very curious that people often take "portrait" to mean head or head and shoulders. To me, the much more interesting portraits often include more of the body, the language of the body, posture, use of hands tell more about the person than the face alone. Also, hints about who the person is are given by the environment.
    Agree, absolutely. In fact, one of my favorite portraitists is Arnold Newman, a master with this behavior; in many of his portraits, the subject is merely a fraction of the frame, even a very small one (check Igor Stravinsky, or Ming Pei, or Salvador Dali, amongst others, by Arnold Newman). I love this "environmentally immersed" portrait style.

    What is really odd to find in the masters, is that "one eye in focus, the other don`t" kind of portrait.
     
  21. "so using an 85mm lens on full frame just about allows you to get the whole person in or an upper body shot with plenty of breathing room, a 135mm is head-and-shoulders plus some breathing room, and 200mm is getting very tight. The shorter lengths (50mm and below) are often used in landscape mode to get a group shot. 105mm obviously splits the difference between the two "classic" lengths." --- so to make long story short those "values" are on FX. on DX is gonna be minus crop factor then ...55/70/90 respectively ...am i right?:)
    raf​
     
  22. Keep in mind that most modern lenses do change focal length as you change focus. At closest focus, near where most portraits are taken, the 135/2 DC is about 115mm. The 85mm lens at closest focus is actually a 77mm lens, which makes it equivalent to a 115mm lens on DX.
     
  23. Ahh! The 'infernal focus' effect Luke. Having grown up with unit-focusing lenses that effectively grow in focal length as you focus closer, I still find it difficult to imagine the framing I'm going to get from a zoom or other internally focused lens.
    I recently compared the field-of-view of my old (unit focussing) 85mm f/2 Ai-S Nikkor with that of the Samyang 85mm f/1.4. The Samyang subject height at 1m distance is about 42cm. The Nikkor only takes in 34cm for the same camera distance - and will focus a bit closer than 1m. That's a substantial loss of magnification by the Samyang, which makes tight head shots impossible.
    Mathematically there's a difference of almost 24% in subject height between the unit and infernal focused lens. For that to happen, my optics spreadsheet tells me that the Ai-S Nikkor 'grows' to an EFL of nearly 94mm, while the Samyang shrinks to around 79mm.
    So where does that leave the idea of an "ideal" portrait length now?
    I'm not knocking the Samyang here, as much as internal-focusing in general. The Samyang is still a very good 80mm(ish) lens at portrait distances. The only thing I can say in favour of internal focus is that fast apertures generally stay fast, even close up, and there's less exposure compensation needed if you work from an external flashmeter.
     
  24. Rafal: Yes. The "conventional" numbers refer to an FX field of view - though, frankly, it's all so based on heuristics that being off by 50% may not be all that critical! Also bear in mind that the short edge of an FX frame is the same size as the long edge of a DX frame, so a lens that you'd use in "landscape" mode on FX to get some extra background in might be the lens you use on DX for a "portrait" orientation crop. 85mm on DX is very close to 135mm on FX, making an 85mm a good "portrait" lens on either format, for different concepts of portrait.

    You may notice that there aren't many 55mm, 70mm and 90mm lenses. I've heard it said that a genuine 50mm lens is a little shorter than ideal for many portraits on DX, and that a 60mm lens is nicer; the Tamron 60mm f/2 is one choice. Or there are the recent, expensive, 55 and 58mm f/1.4 lenses, obviously. Frankly, a 50mm is probably close enough - you can always crop the result a little. Sigma make a 70mm macro, but I'm not sure it's an obvious portrait lens. I've always thought of 105mm as splitting the difference between the obvious portrait lengths (on FX), and since I have a (Samyang) 85mm and have a 135mm Nikkor, I've never felt the need to fill that gap; if I had to pick just one lens, I'd be more tempted. The 90mm Tamron macro is a pretty nice portrait lens on either DX or FX, so long as f/2.8 gets rid of enough background for you - I used mine until I felt the need for speed and got the 85mm.

    Luke: The close focus on the 135 DC is, according to Photozone, 1.1m, at 1:7.1. I'll trust your maths on the equivalent focal length, but 25cm across the FX frame is awfully close. I'd expect most portraits to be some distance away, though I'm sure the focal length change applies somewhat.
     
  25. More examples;
    Hasselblad users (amongst other 6x6 format shooters) have the 150mm Sonnar as a popular portrait lens (96mm FoV in FF/FX, longer side of the format, so if we crop to a 2:3 ratio, it become 80mm), the 180s are for Mamiya RB/RZ (94mm FoV on FF/FX), 4x5" press cameras used to have 270mm telephotos (81mm FoV), Cooke still made a portrait lens in 229mm (68mm FoV on FF/FX), and Leica have made different 75mm versions for the M system...
     
  26. I find very curious that people often take "portrait" to mean head or head and shoulders. To me, the much more interesting portraits often include more of the body, the language of the body, posture, use of hands tell more about the person than the face alone.​
    Do a Google® image search for "portrait" ( e.g., link ) and nearly 100% of the images are more-or-less "head and shoulders".
    For one of the most highly respected (aside from a few old Mortensen admirers) portrait photographers, look up portrait +Karsh ( link )
    Again,almost entirely head and shoulders, so it's not just some quirk of a few people to see this as the most usual portrait composition.
     

Share This Page