What is a Normal Lens?

[@ThioJoe]

Love these types of technical videos

[@BThings]

I love the way that you went into the nitty gritty details and then say that it doesn't necessarily matter that much for making art. It satisfied both my love of knowing about just *how* things work, while at the same time preferring to make movies (and other artsy things) more by the feel of it. Of course, what I *really* love is when people manage to create things that feel organic and naturalistic while also being very precise. You don't get it often, but it's really cool when you do!

[@edwinhenderson863]

Thank you for getting back to doing the filmmaker IQ technical info series of videos. I watched all of the older ones and learned so much!

[@laservampire]

In regards to a "normal" lens on old SLR cameras, it was defined by the size of the image in the viewfinder in relation to what your unaided eye sees at the same time. When the both eyes show a nearly 1:1 image, that's the "normal" lens. For example Pentax had a 55mm lens for their Spotmatic cameras which provided 1x magnification compared to your naked eye. Different cameras might have a different magnification in the viewfinder, so the Normal Lens focal length will vary from maker or camera model. An Olympus Pen F half frame camera (which is pretty close to the size of 35mm cinema film) has a 40mm normal lens.

[@FilmmakerIQ]

Makes sense - from a pragmatic point of view, that is a normal lens in that situation (looking through a viewfinder)... but ultimately it's the print size and viewing distance that matters in the end for determining what a normal lens is.

[@MarceloTezza]

You are awesome! So hard to have a straight foward video, with a little bit of comic jokes and a well explained complete info. I feel like if i ever tryed to make videos on youtube would be just like yours. Thanks!

[@RythmGkwd]

Very well explained, thank you for this video !

[@sclogse1]

Suggestion: If you're heading to an Imax theater, try to reserve the center seats in one of the last three rows. Sweet. By the way, the reason the Tron sequel was my favorite Imax experience was because much of the surrounds in the imagery were dark..Dark etched by light, not filled by it. This kept the stray light from the projection and the bounce off the screen from illuminating the room and kept the contrast up. As soon as the first Avatar got under way I immediately knew it would look better at home on Blu-Ray. Much better contrast and saturation. This is a stimulating talk I'll watch again. If you've talked about the circle of confusion before, I'd like to see the 3-D diagram you had to make for it. I remember learning it in my Photo Lab Tech class in the Army in 1971..boy, you didn't want to sit in the front row of those classes, the instructors had the worst hangover breath...

[@aliendroneservices6621]

Black velvet smocks should be issued to all IMAX patrons (to keep contrast levels high).

[@AllanHambrick]

Long time subscriber here. You have a gift for explaining technical things! I would love to see you deep dive into all things cinematography including modern developments with regards to "volume" and it's back screen roots and filming technique etc. Would make a great series that I would likely watch and re-watch. Massive ask for sure, but you are extremely good at this :)

[@FilmmakerIQ]

I've never heard it called volume before... Unless I had unfettered access to such a set, I won't be able to do videos on it... :(

[@AllanHambrick]

@@FilmmakerIQ Sorry :) I just watched the making of 1899 on Netflix and that's what they called it ... Could be called something else by the people who made the tech. I think it would be interesting to see the progression of rear screen projected sets and even some of the in camera set extension tricks that were devised over the years. I know you don't get into SFX stuff much on your channel, but if you did, with your communication skills and attention to detail, I think it would be very popular. Thanks for the response :) Love your channel.

[@FilmmakerIQ]

I think the set Disney uses is called volume because when I googled it, that's what came up. I've just seen it called "virtual production" :)

[@Gorkab]

Finally a new explanation video! I missed those here!

[@lizbetharzeta9128]

Yes he does explaining a lot of good things!

[@RCAvhstape]

The technical videos are my favorites.

[@ricardoconti3868]

May I suggest you to make a video showing a comparison between the size of the crew of old movies ex: Stan Laurel & Oliver Hardy, until today's blockbusters, and in the same way the changes in the equipment explaining all the devices attached to camera.Thanks again young Hess. Greetings from Brazil.

[@britcom1]

Great stuff, John!

[@simontrickfilmer]

what a coincident: I'm sitting here with your "I life in 24 frames" TShirt and a new Video pops up 🙂

[@Xplozhun85]

3:56 "Card in the corner" Does KZbin still support this feature? Don't see any recommended thumbnails embedded in the video (or on any other video on KZbin anymore).

[@FilmmakerIQ]

Works on my phone, and I literally set it up on KZbin. How are you watching?

[@delfipina7393]

I swear to god all my film school teachers show us your videos, ur a G

[@FilmmakerIQ]

Your teachers are wise!

[@wakkowarner8810]

I love your videos. I learn so much from your videos.

[@samuelh5]

So, a normal lens is whatever causes the picture to appear the way it would to the human eye in that portion of our field of view that the image occupies? Such that we could seamlessly extend our angle of view past the screen and into the shot and have it match the angle of the camera. It becomes pretty clear that screen size and viewing distance would matter a lot here! Great video!

[@FilmmakerIQ]

Exactly!

[@aristotle_4532]

Yes. 28mm for APS, 16:9 material, best seat in movie theater with standard screen size. A 23 inch monitor at 50cm distance is about the same, so you can use the same standard for computers. You can test by taking photos of a room from the seat, showing some objects behind the monitor, the room geometry, etc, then put the monitor back qnd show the images on the monitor. It will match with a normal lens, so the monitor will appear transparent. The normal lens is lomger for tv, and even longer for old tv directed for much smaller screens at similar distancee. But a normal lens is only important for shots that include camera motion. You can go much longer in static shots and it will still look natural.

[@FilmmakerIQ]

It's almost like you should watch the video where it's properly explained rather than this half baked explanation! The motion angle is nonsense though. Lots of great motion in any focal length.

[@aristotle_4532]

@@FilmmakerIQ You have a very bad attitude. Your explanation contains less information, is less accurate and I can tell you do not have university education in engineering or any actual experience in professional imaging. You are also wrong about motion. You can rehash the articles of others and do the semi informed popular science thing, but you have to watch your attitude.

[@FilmmakerIQ]

I love it when idiots give me crap about having an attitude when they spout off their idiocy. Bitch please, my stuff is used for teaching at University. I also teach myself. Nothing you said is correct (shades of incorrectness best described as half baked). You even conflated metric and imperial measurements which I guess is common but should irk anyone who thinks they have an engineering background. There's a reason why you're on my channel watching my videos, and you have nothing to show on yours.

[@ralfbaechle]

I tend to shoot at a well larger resolution than I actually need so I can crop to the exact resolution I need. For shooting that means I need a lens that's a good bit wider For some of the stuff I shot that also helps me to avoid the annoying 28-70 / 70-200mm border - shooting the exact resolution would mean I'd be too close to 70mm so whatever I lens I pick will turn out to be wrong for sure. Perceptually the final result is pretty close to a normal lens which gives the intended effect of "I'm in the middle of the action".

[@lizbetharzeta9128]

Wow I didn’t know that their was so much different kind of lens Iam new to all this! I learn good stuff to in this video today!

[@ToddSurber]

I've done a lot of testing on this to see what field-of-view lens gives the most natural/closest feel to the human eye. From a filed-of view perfective, I found a 28mm-35mm range on a full frame feels the closest and most natural looking when you're right in the action giving you the feeling you're right there. In real life, our eyes don't isolate objects and people as we do with pictures and video. We may focus on something or someone briefly but our eyes are constantly shifting. Sit in a room with a 50mm on a full frame and you'll find it feels way too zoomed and not wide enough to match the human eye FOV. Then put on a 28mm or 35mm. You'll see what I mean. The focused area might feel closer to 50mm but our peripheral is always there. So 28-35 is more accurate. In photography and video, we are isolating subject matter, to remove distractions so we need more zoom or we'll most likely crop it out later anyway. So in these situations, for full-body portraits, the 50mm looks best and most natural, and for upper-body portraits and headshots an 85mm looks the most natural.

[@FilmmakerIQ]

You're missing the variable of how we watch it. You've tested it in under your particular viewing experience. A bigger or smaller screen would change what feels natural.

[@ToddSurber]

@@FilmmakerIQ True, it can, but how close you are to the subject matter will have the largest impact. We normally stand much farther apart from each other and items in real life than we do for pictures or movies. Everything is moved closer to look more natural. There are a lot of factors that can affect how natural it looks. Many famous directors use wider lenses based on how close they shoot to the subjects. There really is no one definitive right answer. Each situation will have its own variable that will affect what looks most natural.

[@FilmmakerIQ]

There actually is a right answer - it's in the video ;) Did you watch it?

[@ToddSurber]

@@FilmmakerIQ Hi, of course, I did. I'm simply saying our human field of view is not 50mm, it's much wider. A more accurate way of saying this would be that our FOV is closer to a range between 28-35 but the area within that that we focus on is closer to 50mm. Our peripheral is still there and our eyes are always shifting focus within the wider area of view. From my experience as a pro photographer for the last 20 years is that the range of 28-35mm will give you a more true-to-life immersive feel looking back at an image or video like you were there than a 50mm. A 50mm cuts out most context. It's good for focusing on the subject, keeping the heads natural looking, spacial distance, etc., but it cuts out the additional width we feel in person. I understand from a technical standpoint you're explaining why that range is called normal in the film but there's a reason why photojournalists typically use a 35mm and most filmmakers prefer the 28-35 range lens over the 50. Thx again for the great videos.

[@FilmmakerIQ]

I think we're on the same page - but there's a couple nuances I would add. Whatever our human field of view is - unless we're dealing with VR, the images we produce will never cover the entirety of our field of view. So it wouldn't really make sense to match the angle of view of the camera with the angle of view of the eye. There is this normal lens math that does find the exact perfect match of field of views between camera and observer. But that math sits precariously on the exact viewing distance and screen size. So as an exact function, it's interesting but just as easily dismissed in favor for artistic reasons. No one says we _have_ to be "normal"

[@xpucmogrozdanov6391]

What do you think about compression? What is the normal lens regarding the compression of the human eye?

[@FilmmakerIQ]

The normal lens IS when there no "compression" ... A normal lens is the lens in which the display medium will result in unaltered perspective lines - essentially looking out a window. As for what the "compression of the human eye" - that's sort of a circular question. Since a normal is lens is defined as what appears natural, by very definition the human eye is a normal lens. There is no compression happening in the eye.

[@Crlarl]

I'm doing the calculations for myself. Earlier, I calculated the same 53.1° as you did with the formula FoV=2atan([diagonal]/[focal length]÷2). I'm at 6:27 and can't get the same numbers as you: 2.5x-›22.6°, 1.6x-› 34.7°, 1.2x-›45.2°. Correct me if I'm wrong, but the numbers should be 20°-›2.8x, 30°-›1.9x, 40°-›1.4x.

[@FilmmakerIQ]

I pulled the numbers straight off wikipedia which we all know is right on everything: en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance#Fixed_distance Your numbers are more accurate mathematically. I didn't check on them so shame on me, but realistically, that kind of accuracy not really useful.

[@Crlarl]

@@FilmmakerIQ The Wikipedia numbers work but they use horizonal field of view, not diagonal. It's an adjustment of ~1.147.

[@FilmmakerIQ]

That makes sense...

[@TimofejNenarokov]

Pentax has a lens which is 43,3mm and not "industrial". One of favorite lenses I had ever used.

[@FilmmakerIQ]

I thought they made one but I guess they're not selling anymore

[@TimofejNenarokov]

@@FilmmakerIQ they still sell them. they actually updated it couple years ago, with new glass coating more suitied for hi res digital sensor and new diafragm with more blades.

[@FilmmakerIQ]

I see them now... They're like pancakes lens.

[@TimofejNenarokov]

@@FilmmakerIQ yes it's. They also made same formula lens for leica l39 mount.

[@sheldonnorton9035]

Where can the films you make be viewed? Thanks!

[@FilmmakerIQ]

Used to have a bunch on Vimeo but they deleted everything when I downgraded my account. You can see a lot of my body of work on this channel. Otherwise I do corporate and government stuff...

[@herrreinsch]

you are allowed to use any focal length you want if you shoot 24fps. :P ........ amazing content as usual.👌

[@FilmmakerIQ]

For cinema ;) Use whatever frame rate you want for anything else.

[@maxheadrom3088]

Excellent! I'm almost sure you have a video about anamorphic so I'll look for it. An observation about watching films from a guy who never watched The Godfather nor Apocalypse Now because he does not have a good tv nor had the chance to watch it in the theater: some films should be watched closer to the screen and some farther away. "The Graduate" is a film one should watch a bit farther from the screen while "Death in Venice" should be watched closer. (imho)

[@FilmmakerIQ]

My one video on Anamorphic: kzbin.info/www/bejne/lWnLdJ2FYsisp6c

[@reddcube]

I wonder what the angle of view for IMAX is. Probably some crazy like 90°

[@FilmmakerIQ]

Interesting question: 54-70° soundworkscollection.com/post/imax-101-theatre-geometry-video

[@aerhaer]

Sorry, I'm confused on how the figures of 2.5x at 20 degrees and the other two were calculated. Could someone please explain?

[@FilmmakerIQ]

Which ones? Sometimes the calculations are made for only the horizontal, sometimes the calculations are for the diagonal

[@aerhaer]

@@FilmmakerIQ For example how did you obtain that at 30 degree SMPTE standard, the focal length would roughly equal to 1.6x the diagonal of the sensor?

[@FilmmakerIQ]

30 degrees is just a standard. To derive it use trigonometry or just an angle of view calculator. en.m.wikipedia.org/wiki/Optimum_HDTV_viewing_distance www.pointsinfocus.com/tools/depth-of-field-and-equivalent-lens-calculator

[@aerhaer]

@@FilmmakerIQ ah yes I see, thank you for the response and the links

[@bruinflight]

I love sitting up front at the theater

[@cavalrycome]

A small quibble: I think what you mean is that one's perception of a 'normal' view is "context dependent" rather than "subjective". There's no reason to think that two observers looking at an image from the same distance would have different subjective experiences of the normalness of the view, right?

[@MarceloTezza]

Every single person has a subjectivity that alters its percepicion about everything. Everyone has its own filter.

[@cavalrycome]

@@MarceloTezza And how could you possibly know that?

[@MarceloTezza]

@@cavalrycome Art

[@MarceloTezza]

@@cavalrycome individuality

[@MarceloTezza]

@@cavalrycome How about every single person has different traits, even gemini?

[@diplomatfromspace]

Love ya John....!!!

[@mr.b6789]

You're back!! 👍😉

[@sungrakchoi]

just great! thanks

[@gurratell7326]

I've always thought that 50mm on a 35mm camera is to narrow and 35mm on a 35mm is to wide, so when I found a old Minolta 45mm f2 for my Sony A7 it felt at home. Sure I wanted a tiny bit wider still, but it was waay better than that awkward 50mm lens that I had before. And lo and behold, apparently that 45mm is quite close to that "scientific" definition of 43.2mm., so tbh I think there really is some truth to that :)

[@FilmmakerIQ]

After all that, I don't think you understood the point of the video ...

[@gurratell7326]

@@FilmmakerIQ I understood it, but I just wanted to give my view on it, because I very mush feel like a 43mm give the most "normal" perspective, while a 50mm is to narrow and 35 to wide. And btw, this ain't the first time I'm seeing this, but you tend to be bit rude in you're answers for no apparent reason. I like you're videos, but I'm loosing respect in you because of your comments. Maybe think your answers through a bit more if you don't want to lose viewers.

[@FilmmakerIQ]

In your follow up you insist that you don't actually get the video. In some context the 35mm is normal, in other context the 50mm is normal... It depends entirely on the viewing perspective. THAT'S the point... Not that 43.4mm is the proper normal lens. Maybe I think your comment completely missing the point of the video is a bit rude in the first place. I have no problem if you'd like to stop watching because I challenge my viewers.

[@gurratell7326]

@@FilmmakerIQ I'm not trying to say you're wrong or anything, I just mean that in MY context and viewing perspective a 43mm is a normal, that's what I'm saying. And please just try to be nicer if you think someone missed the point or try to give you another perspective. Going hard like that for no reason ain't a smart way to discuss with your viewers.

[@FilmmakerIQ]

Seriously - you just do not get AT ALL what this video is saying do you? Your understanding of normal lenses is completely wrong - "your opinion" is the reason I made this video. Sorry, I'm not being mean - you make stupid points and I give you pushback on them. Take some advice and listen to someone trying to help you understand the topic rather than just thinking people are being mean when you spout off the OPPOSITE of what the video you're commenting on is trying to teach you.

[@m4nc1n1]

Ok, nobody else sees the booger?

[@FilmmakerIQ]

It's normal.

[@morinc75]

leaving a normal comment here for big Al

[@IsaacRC]

I can perceive 210 degree horizontal I'm not normal 🤭 Source: USA's army docs on 360 VR for combat training 😱 Cool video 👍

[@FilmmakerIQ]

It's okay not to be normal.

[@IsaacRC]

@@FilmmakerIQ Ok but not the 24 fps stutter effect :-)

[@Olearius]

Sorry, I am not convinced by your explanations. Normal lens has nothing to do with the size of the picture/screen and viewing distance.

[@FilmmakerIQ]

I'm not convinced you have an actual definition of what a normal lens is. If you think it's unrelated, it's because you don't have an understanding of what it is. Start here: en.wikipedia.org/wiki/Normal_lens

[@Olearius]

@@FilmmakerIQ I know this Wikipedia article and the "formal" definitions of a so called normal focal length (some say Normal=sensor diagonal, others say normal=2 x sensor height and there exist some other exotic calculation models). I also know, that this is a very complex and contentios theme. What I can say: A photo or a video shot with a normal lens will always look normal, authentic or natural, independant of the size of the screen/print/monitor and independant of the viewing distance to the screen/print/monitor etc. Short question: We see you most of the time in some kind of midshot (we see most of your torso behind a desk and your head with some head room like at 5:17). Could you tell me with what focal length and sensor format you made this scene?

[@FilmmakerIQ]

Why are you arguing with me? You don't actually have an argument... This subject isn't that complex - I've laid EVERYTHING out in the video. The problem is you don't have a working definition of what "normal" is. How do you explain why some people say 1x diagonal and some people say 2x sensor height??? There's a reason, and I just presented it in the video. There's no such thing as "it will always look normal independent of the size of the screen" - What does that even mean? What does "normal" even mean in your definition??? You see, once you actually define what "normal" is... you immediately faced with the problem of perspective. For example: Say you take my image on this video and blow it up to the size of the Empire State Building... now stand on the sidewalk across the street. Does my chest up shot look "normal" - do I regularly appear the height of a skyscraper? No. Now go across town and look at my skyscraper sized image from a mile or two away - from a certain distance, my skyscraper sized image will actually look "normal" - meaning I could stand next to it and it would look like I'm standing next to a life sized cut out. Viewing distance and image size 100% plays into what a normal lens is... If you want to disagree, you can just freely be wrong about it. If the truth is "unconvincing" - that's not my fault -it's your own ignorance.

[@Olearius]

@@FilmmakerIQ In one comment you state, that you teach also yourself. Have you ever heared the term „robustness of perspective“, and if yes, do you really understand what is meant by it? Have you ever asked yourself, why for crime scene or evidence photography (where spatial relationsships and authentic distance documentation is the critical task) a focal length that matches the diagonal of the sensor is recommended (some recommend 50mm on full frame, instead of 43mm)? Why oh why? If the normal lens is a matter of viewing distance and print size, then each focal length could be normal, as far as viewing distance and print size are correct. But why the heck do they not insist on a correct viewing distance when showing the photographs to a jury or judge? Instead they harp on about the sensor diagonal or the nifty fifty. What is the reason for this dogma? Think about it and get smarter. When I see a midshot of you in the video, I always perceive you 1.5 - 2 meters away from me, indifferent how small or large the size of the video is or the viewing distance to my screen. Even as thumbnail I have this impression or perception that you are 1.5 - 2 m away from me, if I were in the scene. And even - as you suggest - if I would take your image on this video and blow it up to the size of the Empire State Building and I would watch it from the sidewalk across the street or a few streets farther away, I would have the same impression: This „midshot“-guy is 1.5 - 2 meters away from me, period. One last point: Do you believe me, that the at 7:37 mentioned Kowa LM28LF lens has a focal length of 28 mm and not as stated by you 43.3 mm? Think about my hints, teach yourself and hopefully you get a deeper grasp on what a normal lens substantielly is.

[@FilmmakerIQ]

Robustness of perspective? Now you're arguing that distance and screen size play it a role? But seriously there is no perspective needed here. You are just plain wrong about normal lenses. This is a scientific objective term And I have demonstrated all the principles that you need to understand it. You only have perception of 1.5m because you have a life time experience of interpreting images as such (really closer to 2m). You can develop that expectation with any focal length - shoot enough 200mm portraits and you recognize how far the camera is from subject. The issue is what is the definition of "Normal" and there is nothing "normal" about holding me in the palm of your hand on a phone. Re: crime scene photos. Have you ever served on a jury? The photos are 8x10s viewed from a "normal" distance of about a arms length. That equates to the 1xthe diagonal of the sensor standard... Why is it that cinematographers use 2x the diagonal. Why the discrepancy? (hint, it's screen size and viewing distance) If you think a medium shot of me blown up to a skyscraper is still 1.5m away when viewed on the street next to it... What can I say, you're full of it. You'd be looking at a Giant and probably unable is even see the whole entire picture. To think that's a normal angle is a ridiculous interpretation. It would look completely out of proportion and anything but normal. As for the Kowa lens, that was just a mistake as I googled 43.3mm lens and that was what came up. I'm sure such exact lenses exists, doesn't alter the point I'm making. Sorry but you have no clue what you're talking about because you haven't done the homework. You brushed off the Wikipedia article as a "formal" definition (which happens to be the correct definition). You havent actually sat down and defined "normal", you just base your assumptions on "feelings" - what feels right... Rather then an objective measure Really think about it and get smarter....

[@MeekAndBackFirE]

is that a booger in ur nose?

[@FilmmakerIQ]

It's my new nose ring.