Focal Lengths and Zoom Lenses

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This topic contains 7 replies, has 3 voices, and was last updated by  tfandrew 5 months ago.

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  • #27757

    tfandrew
    Participant

    Having just looked at “The White Stocking Dungeon Blues” (“What’s New” for 28th January), I would like some more advice on focal lengths. First, of course, I want to thank you, Hywel, for including with the set the information about lens and lighting that both fascinates me and makes it possible for me to write this post. I must also make clear that the star of the set, Rachelle Summers, is a fabulous model who consistently creates great looks. My wife and I spent a week shooting with her in the French Alps last month and have other shoots booked this year.

    Turning to focal lengths, Hywel, you say you were using a 28-70mm zoom lens and I admit to using a lens of similar range on the Sony Alpha 7 full frame camera (although in my case only the f4 verson). In your “Focal Lengths for Bondage Photography” tutorial video, however, you speak favourably of prime lenses of 50 or 55mm or even 85mm and seem to say it is rarely acceptable to go below 35mm. You demonstrate how distortions can occur on the model’s body at low focal length shots. So, when I use my lens with models, I find myself frequently checking where I have it set, so that it does not often go much below about 50mm.

    I know and support the point that great artists in any medium know the rules so they know when to break them. That applies to Hywel, but not to me. Apart from lacking your experience, Hywel, I have very poor eyesight and know I do not pick up on subtle details. I am sure the illustrations of distortions on the tutorial video were clear, but I had difficulty seeing them. I am not confident when a “distortion” would actually improve things (eg sometimes it may be good to make legs look longer). I fear I may be shooting with “distortions” others would dislike but I do not see.

    The starting point in the tutorial is that some of your trainees have used the zoom to compensate for loss of field of view as they approach the model. The lesson is that, as photographers, we should remember to step back (if we can) to increase field of view rather than reduce focal length on the zoom.

    What do others think? Are there circumstances where the distortion of the short focal length is eliminated or minimised – or even desirable? Are “distortions” reduced if the overall distance to the model is greater? Has Hywel cleverly improved even the lovely Rachelle? Is it time for an advanced tutorial?

    Oh, a word on the lighting. I don’t see colours at all and admit I thought the lighting a little flat, but my wife says the blue light on blue rope was very effective and she liked it a lot.

    #27758

    Sablesword
    Participant

    Coming in from a Nikon crop-sensor point of view…

    First, let me add my thanks to Hywel for the tech notes and tutorials, and for including EXIF data in the photos he uploads.

    Second, “Distance.” When photographing a model, I try to keep a good distance away and let the zoom focal lengths fall where they will. It helps that I seem to be naturally immune to the “creep closer, zoom wider” syndrome that Hywel mentions in the focal-length tutorial. If anything, my impulse is to do the opposite, whenever I have room to back up.

    It turns out that most (90%+) of my shots are 35mm or longer – which on a Nikon DX (crop sensor) is “equivalent” to 52mm on a full-frame camera. The shots that are wider I don’t worry about; usually I’ll have had a good reason for it. E.g. I’m standing on a chair looking down at model lying on the floor.

    One place a photographer might want to use a wider focal length is for a shot that takes in the entire room, with the model occupying a relatively small part of the frame. Or if the room has two or three models.

    My current three-lens kit is a 35mm f/1.8 prime, a 50mm f/1.8 prime, and a 24-120mm f/4 zoom. Multiply by Nikon’s 1.5 DX crop factor to get the full-frame equivalent focal lengths. I use the primes when I need to deal with ambient light, and the zoom when I need to deal with an improvised studio.

    As for deliberate distortion, my inclination is with the fashion photographers who take distortion in the opposite direction, using extreme telephoto lenses to get a very “flattened” view of the model.

    #27759

    Hywel
    Keymaster

    Hi,

    As with all photographic “rules”, the “no wider than 35mm on full frame” rule is just a pointer to pay attention. The critical part is not actually the focal length of the lens. It is where you are standing.

    RULE REFRAMED: If her nose is significantly closer to the camera than her eyes are, as a fraction of the distance from camera to subject, it’s going to produce perspective, geometrical distortion which risks appearing unflattering. (The same effect can produce really ugly looking photos of other parts of the body, too.)

    So generally it looks bad having some parts of the model’s body significantly closer to the camera than other parts by accident. If she’s deliberately reaching out to camera that’s a different matter- sometimes you’ll want to exaggerate that for effect, but even then I find a 35mm lens produces a more natural-seeming effect.

    My “avoid the focal lengths from hell” rule is a rule of thumb derived from that based on observation of what combination of factors most commonly leads photographers on tutorials to provoke this distortion: zooming out and walking in.

    As Sablesword says, if you’re shooting the entire room with the model relatively small in the frame, a wider angle lens will not only be fine, but very possibly be required in smaller UK shooting spaces.

    Think about the geometric effect of standing close to the model, especially in cases where parts of the model’s body are significantly closer to the camera than other parts. This produces the “big foot tiny head” distortion effect one can see in some foot fetish photos- giant feet filling the frame, with a tiny head much smaller in pixels on the image than the feet, because the camera was 30 cm from the feet, the model was on a sofa, and her head was about 180 cm away from the camera- six times as far as the feet. So naturally the feet look big in frame, the head comparatively tiny.

    In my experience, this effect is not very disruptive to the viewer because it is obvious. The brain fills in “oh, feet are close, head is far”. Therefore it’s not unflattering, because we recognise what has caused it. Get down there and shoot it on a 14 mm lens and it’ll look kinda funky, but not like the model is misshapen.

    Shoot an ordinary head-and-shoulders portrait with a 14 mm lens. Now you’re standing so close to the model that the tip of her nose is significantly closer to camera than her eyes are- and if it is a 3/4 shot, her eyes will be significantly different distances from the camera. One eye will look bigger than the other, the nose will seem oddly protuberant, ears will recede and look small. Again, with a 14mm lens (on full frame) the effect will be sufficiently exaggerated that most viewers will probably spot “aha, it’s a distorting lens, not an ugly model”.

    Shoot it on a 24 or 28 mm lens though and the result is naturalistic enough for the eye not to notice, and for most viewers to just think the model doesn’t look very good. In longer shots it can make thighs look fat, bodies look uneven, invoke asymmetry, appear to lengthen noses and just generally make the model wince when she sees the photos afterwards.

    Back off to a full-length shot and the effect is diminished, because the model’s nose is no longer significantly closer to the camera. Remember: significant difference between distance to eyes and nose, as a fraction of the distance from camera to subject. Nose is maybe 5 cm in front of eyes. If shot from 30 cm away this is a big difference (1 part in 6), if shot from 2 m away this is trivial (1 part in 40) and from 4 m away negligible (1 part in 80). That’s why a model small in the frame with a 28 mm lens looks fine- you are standing in the same place you’d be standing to shoot a head-and-shoulders shot with a 50 mm lens.

    It’s actually nothing to do with the lens. This geometrical distortion is purely an effect of perspective, of where you are standing. Standing in the same place, you see the exact same view. A 24 mm lens will fit a wider slice of that view onto the camera sensor than a 50 mm lens will, but the perspective effect will be identical- zoom in to the 24mm image to match the field of view of the 50 mm lens, and the views will be (*nearly) identical, if you were standing in the same place.

    (* Nearly identical, because there are other sources of distortion, from the lens optics, which will likely be more severe from the 24 mm lens).

    So the reason for choosing a 35 mm lens is that it allows you to shoot full-length shots in a average size room whilst forcing you to standing far enough away from the model to avoid excessive perspective distortion. When I have a big enough space, I like to shoot everything on an 85mm lens, because IMO it’s the most flattering- it makes me stand far away to get the compositions I like.

    But you can definitely use lenses like 28mm, 24mm so long as you are conscious of the need to remain far away from the model. One needs to resist the temptation to step in to get a tighter shot- that’s when one really needs to change focal length instead.

    Hope that helps?

    Cheers, Hywel

    • This reply was modified 5 months, 1 week ago by  Hywel.
    • This reply was modified 5 months, 1 week ago by  Hywel.
    • This reply was modified 5 months, 1 week ago by  Hywel.
    #27763

    Sablesword
    Participant

    One thing I still have to consciously think about avoiding is the “big head, small feet” distortion when the model is standing. If I’m standing 10 feet – OK, OK, 300 cm – away, then my camera is 300 cm from the models head and 340 cm from her feet. The standard fix, of course, is for the photographer (me) to crouch or sit and so make the distances from the camera to the model’s head, feet, and waist more nearly equal. Plus backing up (if I can).

    #27764

    Hywel
    Keymaster

    Yes, totally! My knees tell me about the need to keep doing this when I’ve done several shoot days in a row, but there’s just no getting around the fact that shooting from waist height causes less geometrical distortion and therefore looks better, most of the time. Knee height looks good too (it makes people look heroic, and Hollywood uses it all the time for that reason).

    Annoyingly, the photographer on-the-floor distortion (bigger feet, smaller head) looks quite nice as long as it isn’t too overdone, which is a literal pain in the neck to shoot. But does nice things to long legs 🙂

    One other time I reach for the 28 mm lens is shooting overhead stuff, where the length of my arms may be the limiting factor. This produces something of the big head small feet distortion, but also I think tends to make the model look big-eyed and anime-waif-like, so usually works for BDSM. Love shooting in spaces where it is possible to get proper overhead shots with an 85mm lens, but there aren’t many of them around!

    The other main time I reach for 28 mm is shooting video on a handheld gimbal. Much though I’d like to be able to use a 55mm lens, it’s just too hard to get the framing right when grabbing unrehearsed shots of a moving model with a lens that tight and get focus something like right too. The 28mm gives more forgiving depth of field and wider field of view whilst allowing one to get close enough to produce some separation from the background (a bit from boken, but more from parallax as the camera moves).

    Interesting discussion chaps, thanks. Have decided on next shoot to practice using the funkier focal lengths in my lens case for 20 shots at the end of each set, to see what I can come up with using stuff like a 14mm f/2.8, 300 mm f/5.6 catadioptric or 180mm macro lens.

    Cheers, Hywel

    #27769

    Hywel
    Keymaster

    Posting for tfandrew:

    Thank you both for replying, but I regret, Hywel, your responses did not take me very far. My apologies if I was not clear enough.

    I appreciate the point that “distortion” is reduced if the distance between the parts of the model is small as a proportion of the overall distance to the camera. It was a point I raised in the original post and I am grateful for the confirmation. I can understand general theories of geometry, optics and perspective. My problem is that I have disabilities that include a severe visual impairment. I was hoping for help with the things I can’t work out with the general theories: what do fully sighted people actually see when you look at the pictures.

    I think I can see deliberate “distortion” when it gets extreme, as you mention in foot fetish shots, or in pictures like this:-

    Ariel and Tillie

    Correct me if I’m wrong, but I didn’t think there was anything like that in “The White Stocking Dungeon Blues”.

    My problem is where there is more subtle “distortion”. How, if at all, can someone like me make use of the good and avoid the bad. Without going to extremes, some people like to lengthen a leg or enlarge some other part of the model’s body. Conversely, some observers seem sensitive to perceived distortion. I was once asked to produce shots I admired for a local photography group. One of the shots I offered was one of Hywel’s (pre-bondage) of a model sitting on a chair. The group leader immediately dismissed it, saying the legs and feet were distorted large. I hadn’t been aware of this and the incident was somewhat upsetting. I know I will never see things as fully sighted people do but I hope it will help to look at examples in real pictures and to hear what fully sighted people see and think.

    I therefore hoped someone would offer comments on the set of “The White Stocking Dungeon Blues”. I did not want to comment on pictures in my original post because my whole point was that I distrusted my eyesight. Hywel, are you saying there is no visible distortion in the set? My first thought was that DSC07049 was one of Sablesword’s “whole room” shots and the background may be distorted but Rachelle is standing sufficiently upright that no part of her body is significantly closer than any other and the lighting is sufficiently straight on to her to tend to flatten her face. But there are later shots – with shorter focal lengths – where she is pushing part of her body towards the camera (DSC07074 to DSC07078). These are the sort of shots I would avoid based on the tutorial advice I described in my original post. Should I be seeing anything out of proportion? Do others see it? If so, do others like it?

    Thank you and hoping things are more clear now.

    (End of tfandrew post)

    • This reply was modified 5 months ago by  Hywel.
    #27771

    Hywel
    Keymaster

    Shot 07049 – 38 mm full length, not particularly tilted up or down, flat on lighting as you say.
    Not as flattering as I’d maybe like in an ideal world- it’s not the most flattering on her thighs,
    but conversely she’s not posing either, it’s a test/behind the scenes shot. In an ideal world I’d
    have moved backwards and shot on my face 85mm focal length, but as you know in the dungeon
    there’s walls and doors and so forth in the way, so sometimes one compromises.

    Shot 07074 – 24 mm full length. There’s definitely some distortion to my eyes in that shot, her bum
    looks a bit big, her legs a bit short. It’s on the borderlines of what I’d consider acceptable myself, but
    there’s no absolute criterion I’m afraid. 07079 has definitely got big head small feet distortion going on,
    and is only borderline acceptable for my personal tastes. I probably left them in because:

    A) the whole set is quite stylised with the blue lighting etc. so isn’t meant to have a particularly natural or
    neutral rendition.

    B) I tend to accept more distortion with the dungeon because of the physical constraints of the space.

    C) It wasn’t bad enough for me to throw the photo away at first glance, and I learned years ago that
    being over-selective on photos for full photosets can end up short-changing customers who are
    place different emphasis on what’s OK and what’s not. When I did an experiment a very long time
    ago with a full set of 36 images (from a roll of slide film) and with just the 20 or so I’d selected.
    pretty much everybody preferred seeing all 36 images, even if some were to my eyes less than optimal.
    That even applied to focus being in places which I don’t like – if I’ve accidentally focussed on fingernails
    where I was aiming for eyes or cuffs, I leave the shot in because the fingernail fans might love it beyond
    all others in the set. So I only throw stuff away if there’s a gross error – nothing sharp, or nothing on the girl
    or the bondage sharp, or excessive camera shake, flash didn’t fire, gross over or under exposure etc..

    D) There’s a sense in which I guess I intend my photos to be seen as sets, rather than as
    individual shots too, so I’ll keep stuff in if it tells a story or is the only shot of a certain angle or
    style in the set (eg the only landscape shot or the only closeup of something).

    E) By the looks of it, later on in the set I’ve decided to embrace it and go for weird angles,
    probably emboldened by standing in places I don’t usually stand in in the dungeon. For example
    DSC07151 has big old head small feet distortion made deliberately more stylised by the cock-eyed
    composition. I personally accept the distortions more easily in that sort of shot than in a
    “normally composed” shot which looks like it is trying to be more lifestyley/naturalistic. I may
    even have decided “oh, I can shoot from inside the dungeon with this lens, I wonder how that
    looks?” (My memory is in no way up to recalling what I was actually thinking BTW, so this
    is all pure post-hoc figuring out the process by reverse engineering looking at the shots I took).

    F) If I need to keep the number of photos in the set up and I’ve cocked up and need to
    keep as many shots as possible (doubt it was the case here).

    G) It was a mistake – I was doing exactly what I warn people about using a zoom at its
    widest setting, and I should have removed the shots but didn’t for some reason. I do tend
    to process and leave shots in and learn my lessons for the next set, rather than be too
    cruel on culling a set with errors. See C) and recall that none of this actually goes through my
    mind in a cold blooded way when I shoot- I evolved the “focal lengths from hell” rule through
    trial and error, making mistakes and figuring out ways to avoid making them without noticing
    in future, like only using prime lenses and never going below 35mm if I could possibly help it!

    Sensibilities are different I guess when aiming for single shots, especially if the shots are to be
    submitted to individual comment or judging. I guess because we all recognise that photographs can
    have whacky distortion, everybody is probably different in what sorts of distortion they find
    aesthetically pleasing and what sorts or what amounts they dislike? I’ve not thought about
    it particularly deeply before, beyond my own rule of thumb which I sometimes break when
    I feel like it or the physical situation seems to call for it.

    So I’d rather guess that there isn’t any rule which can guide you, beyond the general
    rules of thumb. Shoot for oneself and if it doesn’t bother you well why should one care
    what other people think about it, really? One can learn technique from others of course,
    and emulate artistic works we like and find out how they were created, but technique
    segues into artistic choice pretty quickly when you start digging deeper.

    I’ve been very lucky that my personal bondage artistic vision appeals to enough people that I can
    make a living from it, but I didn’t start doing it to appeal to others. (Parenthetically,
    it looks like my landcape photography does not appeal to others enough for me to
    make a living from it, at least not with my (utter lack of) salesmanship and woeful
    marketing ability,

    It’s nice when it does appeal to others but I don’t really care when it doesn’t.
    I’m going to keep doing landscape photography for my own pleasure, like I have been
    since I was a teenager.

    The sort of photos that do the rounds at local photography club competitions
    usually send me right to sleep. There’s nothing wrong with them. The judges are
    usually all very correct and nit—picking and to my personal tastes utterly fail
    to spot a work of art with an ability to provoke an emotional response in me.
    But maybe they get the same thrill from a well-turned macro shot of a screw
    focus stacked to get a completely sharp photo of something completely boring
    that I get from a mountain sunset or a girl in barefoot bondage. I dunno. It seems
    to appeal to plenty of people, and if they are having fun, fantastic! I’m probably just projecting
    my hatred of competitions in general and hatred of closed group art competitions in particular.

    I don’t mean to diss photography groups, they’re just not my thing. I managed a single
    meeting of the local Welshpool group. I was more patient in my younger days when Kate
    dragged me to a few in the early days at Paul’s group in Reading, back in 2001 or something like that,
    but she lasted a lot longer there than I did.

    Cheers, Hywel

    #27772

    tfandrew
    Participant

    Thank you, Hywel, for the further detailed and helpful response. It was what I was looking for and gives me hope that – in the right circumstances and when I look carefully – I may be able to see and work with “distortion” effects.

    One aside on “photography groups”: we are probably very much together on groups in the sense of camera clubs, but the group I was at was a tutored enthusiasts group. My upset was not that the tutor didn’t like the picture – that’s his problem – but that I had not seen the effect he didn’t like.

    There’s a known effect under which visually impaired people, when asked what they can see, will say what they think should be there or what they think the questioner will like. This is not an attempt to please but a subconscious attempt by the brain to interpret the incomplete information it receives. With your latest reply, I have more confidence that I may genuinely be seeing things.

    Thank you again.

    Andrew

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