The Shocking Truth About Depth of Field: What Everyone Gets Wrong!

[@yawningmarmot]

Dare I say, the circle of confusion is indeed confusing :)

[@johanankarback6821]

Great video! Finally someone who explains it correctly and in a way that´s easy to understand. A lot of people just don´t get this...

[@extrashot]

I appreciate that!

[@Stephen.Bingham]

The Physics research and optical engineering communities are giving you a standing ovation, sir! So difficult to get this material over clearly to a general audience. The physical size of a camera's aperture is probably its single most important technical parameter. By working in terms of it - or further the cone subtended by it at the light source - one is able to make simple statements that are always true irrespective of other parameters. This process of looking for the simplest most general statement is the core activity that we call "science". By the way - as I'm sure you are well aware of - aperture size is also the most important factor in determining low light performance as it determines the light gathered by the lens. This is why when recording the same image - with the same depth of field - sensor size makes very little difference to low light performance. One could go on - aperture size is also the factor that determines the maximum theoretical resolution of an image (in MPixels etc). Perhaps someone should make a video called "In photography and videography it's the size of your hole that really matters"?

[@extrashot]

Thank you for the comment Stephen... it's really great to see others get what I was trying to describe. and yes, the hole is everything! 👍

[@fourcornerseducation8828]

Hi Stephen- I teach this to grade 10. We build from card 5x4 cameras which focus - box inside box - and use standard 50mm physic class lenses in a simple neoprene and balsa mount. Students calculate image size focal Point to film plane distance etc by scale ray diagram and then discover their images are out of focus when we develp them - paper negatives- then we introduce a simple diaphragm set which came out of an old plastic point and shoot with three selectable holes on a sliding plate - by using Edison bulbs and a ground glass they see the actual effect of light cones. Luckily I am an educator in the IB Middle years. - actually Im a Head of School- and we can take our curriculum where we want. There is just not enough optics anymore in any National curricula design - but there is also too little mechanical engineering. Its great fun and students understand how a camera works and the joy of silver halide. :)

[@Stephen.Bingham]

@@fourcornerseducation8828 Bravo, to you also, sir/madam! I wish I was a better educator- my background is in Physics research. I think this kind of knowledge is so useful and important. In this particular context it allows one to think critically about the marketing hype and spin of camera companies, and make rational informed choices when purchasing equipment. Even more importantly perhaps, it allows one to take better pictures - by understanding how to choose the right settings to get the "look" one is after, and mitigate issues such as low light levels.

[@joelpennmedia]

Thank you for such a clear explanation of DoF. I've been behind cameras for over 20 years and never come across a cone used to describe the resulting depth of field. I've learnt something new today, so thank you!

[@extrashot]

You're welcome - thank you for watching and the kind comment... much appreciated!

[@danielx555]

Oh my gosh, you're going to correct the internet. I'm getting all of my friends and family in the room to watch. This could be exciting ❤ Edit: I finished the video and this was very helpful. I am a hobbyist photographer and when I first bought a DSLR a few years ago I thought I would have to do all of the math (or maths) for every shot and it was just too much. And so I didn't pay a lot of attention to the numbers and calculations, etc. Now that I've spent some time figuring out all of my controls and doing a lot of study on the artistic side of composition, etcetera, I'm going back to the basics. This was really helpful.

[@extrashot]

That's great... thank you! 👍

[@juliancroot]

You have a rare combination of gifts....a wonderfully silly sense of humour (right up my street), decent acting abilities, and some top notch 'Attenburgh-esque' teaching chops. I won't lie, I got a little lost in the 'basic' maths' bit (due to my tiny brain, not you), but still thoroughly enjoyed the lesson :). I can see some considerable effort went into the script and illustrations too, so I hope this video gets very widely appreciated. It is from my corner anyway.

[@extrashot]

Thank you for all the kind words... much appreciated! (As someone who's trying to learn the keyboard, I'm loving your channel) 👍

[@UndertakingCinema]

Great video. I'm more convince than ever that there is actually no such thing as "Depth of Field". If you look closely, the object that's in focus is really the only thing that' IS in focus. The rest is an illusion. We just say "Well, that's acceptably in focus."

[@extrashot]

True! ... and the problem is, what's acceptably in focus is now different for everyone and every display device!

[@marktrued9497]

The magazine, Popular Photography, exhaustively covered this exact same issue over fifty years ago. Showing the math, replete with photographic examples. They demonstrated the exact same conclusion. People now are making the exact same assumptions and poor methodologies to lead them to the exact same incorrect conclusions. It seems to be an unavoidable process in the human learning curve.

[@extrashot]

Thank you so much for your comment Mark, I really appreciate it. I must be honest, after reading so many alternative descriptions, I was starting to doubt my own experience!

[@nelsonclub7722]

Pro here 35 years in and still going - you are not wrong - in the studio I always focus around the centre of the subject not the front of it - it does get more complicated with T+S, F+R and swing but the principles remain - good stuff

[@extrashot]

Good to hear... thank you!

[@fourcornerseducation8828]

Great video - as someone who teaches optics to 15 year old students - it is so nice to find a video that uses physics rather than mystics to explain this. But also as some one who has played with cameras for almost 50 years now - it seems to be something that used to be understood but is now in a melange of general ignorance. I think the first time it was ever explained to me was within a book published by focal press - and probably written by Ivor Mantle - wow that was a long time ago. Now to convince the Noctilux buyers a Tessar is better :)

[@extrashot]

Wow... you've brought back some memories mentioning focal press... My bible when I was starting out was " The technique of the television cameraman" by Peter Jones. I worked with him when he'd started studio directing. Simpler times! Thanks for the comment, much appreciated!

[@fourcornerseducation8828]

@@extrashot yes much simpler - you may like this its my alter ego: not technical and a hope of being a bit more philosophical - ps not a plug, but think you will understand! kzbin.info/www/bejne/sKvZoJaAotyVqJIsi=XnWMqZ_X7ydeWCWP

[@Jerry10939]

I never worry about the technical aspects too much in photography as long as I understand them. Just like I don’t need to worry about the gear ratio in my car with a standard transmission. I drive the car in the gear I need to be in. Same with photography. I know around what my depth of field is for a photograph for that aperture I can get the shot I want. I check the depth of field. If it’s not right. I change my aperture just like changing gears in my car.

[@extrashot]

... and that works for me too 👍

[@afriquelesud]

Love this analogy indeed. ❤🎉

[@garethwilliams976]

I was always taught that given a set circle of confusion the only two changes which affect depth of field at a given distance were the mathematical aperture of the lens (not light transmitted by the lens which can vary depending on its construction) and the reproduction ratio of the object focused upon and the actual size of its image on the sensor or film.

[@extrashot]

Perfect! 👍

[@the_rat_run]

Bah Humbug! I'm an elderly photographer (took up the hobby 52 years ago at 18!) and I really enjoyed your presentation. Over all of those years, as I'm just a hobbyist, I've looked at DoF as the 'slot' where focus is acceptably sharp, it works for me without having to over think it! Thanks for an enjoyable 13 mins (almost) viewing. I like Macro Photography, which is a great illustration of aperture & distance for DoF, my 60mm Macro lens has tiny DoF at 5 cm from the subject when compared to 5 M, even though the ratio appears to remain constant.

[@extrashot]

Thank you for the kind comment.... Macro photography is a whole other level of difficult !!!

[@trapromo]

You are the David Attenborough of youtube photo channels, which is obviously a very good thing. Peering with interest into the lifes of cameras, figuring out what makes em tick :)

[@extrashot]

Oh no.... so old !!! 😂

[@trapromo]

@@extrashot Hahaha, even mr. Attenborough was young like you once :D

[@Bo_Hazem]

Watching this while being extremely sleepy is a bad idea, but managed to understand. Now it's time for a nap.

[@extrashot]

😂

[@mickymack1230]

Excellent Video as always from Extrashot I appreciate the effort and creativity you have put into this video, highly professional. Thank you 👍

[@extrashot]

Thank you, kind of you to say so.. 👍

[@deaniweenie]

I've seen this 'argument' and explanation in other videos on KZbin but this (ironically) is the clearest to understand, even if I will have to watch it a few more times for the info to sink in ☺

[@extrashot]

That's good to hear... thank you.

[@HenriPierreChavaz]

I would recommend 'Depth of Field Outside the Box' by Richard F. Lyon for a comprehensive presentation.

[@extrashot]

Thank you for the recommendation.... I've just read his draft paper which is online, and it's great. What I was trying to do here is pair everything down to such a basic (maths free) level, it would be easy for visually biased creatives to simply picture what's going on. Cheers.

[@b991228]

One aspect I find confusing is that in a line of people in a group-shot if you focus on the subject that is dead center in the image the subjects at the extreme outer edge of the photo are somewhat out of focus. You come to realize the focus point is actually not a plain but rather an arch. Anyway the sharpest focus point of any lens is at its center. You learn that the subject of interest is best placed toward the center and to expect some degree of softness to occur at the edges. It’s best to shoot alot and learn the idiosyncrasies of your equipment.

[@extrashot]

True, and maybe another video on diffraction would be worth making... thank you.

[@StephenStrangways]

The focus point is an arch if a lens has field curvature, but it's a flat plane if a lens does not have field curvature. The amount of field curvature will vary from one lens design to another - and sometimes sample variation in assembly tolerances can change it from one copy of the same lens to another!

[@sclogse1]

I LOVE the circle of confusion. It just needs a 3-D animation to display it. More importantly, we miss our shots wirh auto focus because of the lack of contrast in our subjects. And thinking IBIS will let us shoot at 1/30th. Try natural view when focussing.

[@simonpayne7994]

I hate his click-bait title but his explanation is spot on.

[@AndyJonesPhotographer]

Rather than angle of view I've always said magnification which is really the same thing but I think is easier to visualise for most people and also helps clear the mist of sensor size.

[@extrashot]

True 👍

[@ooltimu]

Bravo! Spot on! The only thing that I visualize differently is that cone. It helped me better understand DoF by visualizing how light rays go into the camera and tracing them. A larger aperture or a closer object will have rays of light that spread faster (are less parallel) than an object further away. Conversely, a smaller aperture will let less divergent rays go into the camera and let only the more parallel rays in, creating a sharper image.

[@extrashot]

Thank you for the comment... and to be fair, anyway that works for an accurate visualisation has got to help. 👍

[@SMGJohn]

Finally someone who uses science instead of armchair experts on DPReview forum 50000 word posts to describe DoF

[@AgentBlackCrow]

Superb! Could you deal with the topic of ‘Larger sensor gathers more light’ please. 🤯

[@extrashot]

That's a good subject - thank you!

[@andrewlutes2048]

Thanks for the explanation and for suggesting a test.

[@lukewinsbury6516]

You lost me at ‘Hello’

[@BassPlayerAvailable]

Lol. Same here

[@extrashot]

😂 ...

[@colinb.5638]

I'm building some kind of automated large focal capturing device and this video is exactly what I needed to know 👌🏻👏🏻 Thanks !!

[@extrashot]

Thank you... and I'm intrigued ???

[@sunflowerdeath]

My field of view is reeeeally DEEP 😅

[@StreakyP]

As a follow-up I think covering hyperfocal distance could blow some minds too

[@extrashot]

True...

[@LadyBovine]

That was great! I thoroughly enjoyed that presentation, and even learned something! Well done!

[@extrashot]

Thank you... much appreciated!

[@yawningmarmot]

Could you share how you make those 3D animations where you demonstrate the lens, the sensor and the circle of confusion?

[@extrashot]

Hi, just using (and learning) Blender. A week ago I'd never used it, but I managed to watch enough KZbin videos to give me enough tips to make this video. It's a steep learning curve but I'm starting to love it ! 👍

[@TaoCovillault]

Totally agree there 👍 I often try to explain this to people and I often see them very confusing and distrustful 🙄 Now I have an amazing video to link them, thanks a lot !

[@extrashot]

Thank you... that's great to hear! 👍

[@Kirk-Monteux-Production]

A real good piece of education. Thank you.

[@extrashot]

Really appreciate your kind comment, thank you!

[@palesmichael]

12 minute video on "focal length changes the depth of field" ?

[@extrashot]

But it doesn't ???

[@phallicusoblongus]

Guess you missed the entire point of the video huh? He literally covers this by the end.

[@JoATTech]

Nice explanation. But I'm waiting for the comments that will say you are wrong :D (I know you are are not). I stopped arguing about DoF long time ago. I stopped also arguing shallower DoF = more cinematic look :D.

[@extrashot]

I'd also stopped arguing, but then I watched another video with a photographer getting it all wrong... I couldn't help myself !!! 😂

[@JoATTech]

@@extrashot 🤷🤷‍♂🤷‍♀

[@marcogiai-coletti354]

Thank you! Someone had to say this.

[@extrashot]

...and thank you for saying that! 👍

[@tomgilchrist553]

I would love to watch a video dive into Sharpness beyond the usual fare, including Coring, frequency dependence, and what have you. I'd love to understand that better with visual examples. The three of us who would watch such a video thank you in advance!

[@extrashot]

😂😂😂... are you into macro photography by chance?

[@DaddyDaughterMovieNight]

​@@extrashot Well...I do like close ups of bugs...😄

[@johnsammonds]

Brilliant video and a hard one to produce, reading through the comments there is a big missunderstanding of what this was about. I don't think the age of a photographer is a problem it's the lack of open mindedness of photographers. I get so frustrated with the crop sensor syndrome where people think it is a zoom function. for me a great video....John age 71

[@extrashot]

Thank you John, to be fair, I've been pleasantly surprised at how few people have misunderstood what I was attempting to visualise. It's difficult because so many of the traditional ways of looking at this have been superseded by ever increasing tech and display resolution! Take care.

[@OhhhhhhhBugger]

I mean, crop sensors essentially function as a zoom tool. They change the apparent angle of view and create a functionally new focal length. Doesn't matter what you THINK. The only thing that really matters here is the results.

[@extrashot]

@@OhhhhhhhBugger But the results of cropping an image don't create the functionality of a new focal length? There's no change to the perspective, no compression and no change to the depth of field... all you've done is crop an image in the same way as if you'd done it in post? Changing the angle of view is all you've done!

[@lighthackerslimited]

If Paul was a Physics Professor.. I'd join the class.

[@afriquelesud]

I write books, of the coffee table travel encyclopaedia type. DoF can ruin my books, for example: I need to add a photo to an article about Melkvlei waterhole in the Kgalagadi. If I then take a photo, displaying doves in focus, with an entire blurred out desert in the background, will my readers be able to understand what they're reading about? There is a niche for DoF, but the pixel snobs are really too excited about it. In life, I see the bigger picture, be it literal or figure of speech. I don't tell fractional tales, which is why DoF is for a niche (pron neesh) market, not for everyone. Therefore, I don't even listen when the supposed pro's discuss it. Photography is an art, the art of storytelling. Then tell the entire story. I don't need to isolate a lion from the grass to see a desert full of wildlife.

[@extrashot]

I couldn't agree more... DoF is just another tool in the story tellers box. In many ways, since the Canon 5Dm2, it's also been a victim of film makers fashion! Take care

[@clausgiloi6036]

It's important to realize that "depth of field" is a qualitative and relative term. Depth of Field as a measurement given by a calculator is always a somewhat arbitrary calculation dependent on the notion of "acceptable sharpness", which - as you pointed out - depends on multiple factors. There is no hard measure of "acceptable sharpness" and therefore no hard measure of "depth of field".

[@extrashot]

True... that gets to the heart of the matter... and probably why so many people argue the point!

[@marineforces3214]

what is so shocking ?, it is simple : the larger the room is , the deeper the depth 😀

[@extrashot]

Obvious, now you say it... 😂😂😂

[@OKuusava]

Or: there is always only one sharp plane, but what the orher looks to be, matters. Are they plenty blurred or nearly on focus. -and vise versa: dof is more usually used as "what the blurred looks like" not how blurred it is. ...and yes, lens cannot change the perspective. It is ipossible task for it.

[@extrashot]

Good point, I should of stressed your point about there only being one truly sharp plane... everything else is blurred, we just can't see it!

[@williamwilson5127]

Being familiar with the sensor size and lens you are using at any given time, can yield predictable outcomes without experiencing an academic crisis of faith. The physics are one of the key considerations for designers, while the end result is the key for the vast majority of end-users. Social media has enveloped the thoughts of many people's minds, sending them on a never ending quest for the perfect gear, rather than using the equipment they have in hand. If you find the theoretical difficult, don't think about it until you absolutely need it to overcome a problem.

[@extrashot]

Well said... and I'm getting quite bored with the quest for the perfect camera. It's probably the least important thing to worry about!

[@tomgilchrist553]

The visualizations truly helped my brain. Cheers.

[@extrashot]

That's nice to hear... thank you.

[@analogdesigner-Jay]

You did a good job explaining this. Thanks!

[@extrashot]

Cheers

[@alberteinstein3148]

Bravo for these perfectly clear explanations (and yet I am not a native speaker - as you can read here!). My only regret is the poor definition of the focal length, which only applies to a set of thin lenses side by side. Consult any advanced optical treatise (e.g. Kingslake, Applied Optics and Optical Engineering), you will see that it's in fact the distance between the focal planes and the principal planes - and not the optical center (and this is why a lens can be shorter than its focal length!).

[@alberteinstein3148]

edit : "native english speaker"

[@extrashot]

Thank you for the comment and the explanation... seems I need to research principle planes! 👍 (and your English is great)

[@HGQjazz]

11:20 I always learn something from your videos! I literally sat in a moment of silence after your closing statements. Then I let out a long sigh.

[@extrashot]

hope that's a good sigh! 😂 - Thank you.

[@PetCactusA_HarmlessLittlePrick]

Hyper focal distance kicks ass! 📸

[@luzr6613]

Whether or not it is directly relevant to my own practice, there's always value in knowing that there is much one doesn't know - if only because it acts as a brake on being obnoxious and ignorant in the comment section of YT videos. Thanks for the vid - plenty to mull over and the 'cone angle at source what's-it' might just stick in my melon for another day. All the best from a cabin in a swamp in a rainforest in New Zealand.

[@extrashot]

Thank you for the wise comment... As someone who's hoping to visit New Zealand next year, I'm intrigued by the cabin in a swamp? All the best from Bournemouth!

[@carlosgarcia9225]

Please Expand topic In future videos! Thanks

[@computerjantje]

why should he expand it? will expanding change the depth of field? :)

[@OrigEntertainmentOfficial]

Based on the comments you will get or are already getting, you probably have to make a follow up video that debunks or shows why the other explanations don't fully tell the whole story or get it wrong completely. And you will probably have to show real examples with different sensor sizes (m4/3 vs full frame), different focal lengths, aperture sizes, etc.

[@extrashot]

That's sounds like a good idea... this video probably didn't have enough real-world demos. 👍

[@videopromike]

How dare you correct the Internet! The Internet does not lie. Good stuff as usual. Thank you

[@extrashot]

Sorry my bad... (however, I'm impressed with how much kit you carry when shooting solo... respect Sir 👍)

[@phallicusoblongus]

Lots of people in the comments who get frustrated about not understanding simple physics and people who don't like to look deeper and understand a concept better. It's a shame.

[@tomingrassiaimages8776]

Excellent description!

[@robinprobyn1971]

Life was much simpler when I had my Samcine DoF calculator back in 83 ! ..

[@extrashot]

True!

[@etherealbolweevil6268]

Was there not a button in '83 that allowed the photographer to close down the aperture and see the depth of focus through the viewfinder, from which simple 'preview' mechanism the photographer could establish the necessary aperture to attain the most reasonable depth of focus. Thence compensate with shutter speed to obtain a reasonable exposure, leading perhaps to a different camera back loaded with a different film. Throw in digital everything with a few dozen extra variables and it becomes as simple as nukelar reactor design.

[@melvilib]

@@etherealbolweevil6268 I just used to unlock the lens and twist it to see DoF in my Pentax ME Super back in 1979. Was a bit dark at small apatures 🙂

[@Fuchs85DE]

@@etherealbolweevil6268 Even modern mirrorless cameras have this to my knowledge

[@comeraczy2483]

This is incredible! I can't believe I am seeing this on youtube. Thanks a lot for this one. Any chance that you would also debunk the "smaller sensors perform worse in low light"? I am dreaming of a world where photographers would talk about angle of view, aperture diameter, and exposure compensation. To the question "how to get 2 identical image on two different systems?", the answer would be around the lines of "use identical angle of view, identical aperture diameter, and identical exposure compensation, and shoot the exact same scene, from the same distance". Then people would stop having these pointless (and mostly incorrect) discussions about imaginary importance of sensor size.:-)

[@extrashot]

Hi, and thank you. You're the second in the comments to mention the "sensor size in low light" issue. I should make that. Matching shots on completely different camera systems is not a problem, especially when you get the 'cone' thing! 😂 I did a similar thing some time ago here: kzbin.info/www/bejne/q3XCkGB-h8hkjKMsi=uQ0f3qJVF9PJbRok&t=212

[@comeraczy2483]

@@extrashot Thanks for the link. I love the title! Yes, matching shots on completely different cameras is trivial and I am surprised that so few photographers understand the mechanism, especially considering the number of photographers who also have a phone. The 'cone' thing could certainly help. What also really impresses me is that, so far, you have only one comment in the line of "no, you're wrong". A great testimony to your excellent content and high level of credibility.

[@brugj03]

Smaller sensors do perform worse in low light, what`s to debunk about that.

[@comeraczy2483]

​@@brugj03, if you take two cameras, equip them with native lenses that have same angle of view and same aperture diameter, and shoot the same scene with the same shutter speed, with no exposure compensation and in auto ISO, you will have very similar images (same depth of field, same noise, same dynamic range, etc.). The differences will mostly come from the quality of the lens and from the cost of the technology used for the sensor. The only caveat is that in good light, the camera with the larger sensor can usually have a better dynamic range because the camera manufacturers (as opposes to sensor manufacturers) don't care that much about lowering the base ISO, and that cos-cutting decision typically affects cameras with small sensors more severely. For instance, a Galaxy S20 Ultra has a crop factor of 3.58, a lens that is a full frame (FF) equivalent of 23mm with an aperture diameter of 3.5mm. Besides the 3:4 vs 3:2 form factor, the images from that phone will be very similar to images taken with a FF camera with a 23mm lens at f-6.3, using the same shutter speed on both (comparing raw images and ignoring the sharpening the phone will do anyway). One big difference will be in the metadata: the ISO on the phone will be about 13 times lower than on the full frame camera. This is where the caveat for "low light" comes in: the minimum ISO on the phone is 25, which is the "equivalent" of ISO 325 on the FF camera. So, any scene where the FF would shoot at ISO less than 325 will blow the highlights on the phone. This is easily verifiable by anyone who has a phone and a camera. In addition, there are benefits that are inherent to smaller sensors. For instance, small sensors generate less heat, and heat generates noise in the images. Also, the quantum efficiency (QE - the proportion of photons detected by the sensor) can be higher in cameras with smaller sensors. For instance, typical modern full frame cameras and cheaper MFT cameras usually have a QE between 50 and 58%. The R3 is the best of all full frame cameras at 68%. The OM-1 II has a QE of 81%. That is a major advantage compared to any full frame camera.

[@brugj03]

@@comeraczy2483 Allllllllll right........ It seems it`s something big for you. I keep it simple, bigger at the same pixel count is better. That`s my unquestionable logic, that`s why i shoot FF and Medium format. It shows, that`s all that counts.

[@brugj03]

I`m a simple man, i take an FF f1.2 lens put it on 1.2 and i get extreme shallow depth of field. That`s what want and what i like. Now i`m gonna take some pictures to get this out of my mind.

[@extrashot]

Perfect... do what works for you! 👍

[@mxfxdlg]

I’m still a bit confused…………..circularly, that is.

[@skymakai]

I’ve really been trying to figure this out and had just given up. It’s really helpful to take sensor size out of the equation, or at least consider it a less prominent factor… after aperture and subject distance. Have you spoken with the PhotoPills guys about adding this method?

[@extrashot]

I haven't, and I hope nobody thinks I was criticising their app. Not at all, I use it regularly!

[@skymakai]

@@extrashot I’d love it to be added to the app.

[@DavidBattistella]

But we all know that the hyper focal length is far more important than depth of field in relation to subject distance.

[@extrashot]

Especially if you like landscapes! Even then, I think we need to re-asses the common figures currently used for Circle of Confusion. I'm not sure 0.03mm is good enough now we're all using high resolution monitors while sitting with our eyes so close to the screen! 😂

[@DavidBattistella]

@@extrashot 😂😂😂

[@AABB-px8lc]

still, diffraction pattern especially near focal plane have significant factor of actual depth of field. That is main reason good lenses are so expensive.

[@extrashot]

True... and diffraction gets really complicated, especially when we're talking colours! Good point.

[@andrewharrington7435]

You only need to worry about diffraction on the green pixels if the sensor has a standard Bayer filter. The red and blue pixels are all 1.4 times further away from each other than the green ones. So diffraction impacts the green pixels first.

[@bcomhaire]

Shocking!

[@computerjantje]

Thank you for another very nice video.

[@josdenis3684]

Or: How to turn something simple into something utterly complicated.

[@extrashot]

Sad to hear you found that utterly complicated... that's my bad!

[@phallicusoblongus]

@@extrashot Not your bad at all. If he didn't understand it, after you summed it up quite well, he wasn't using his brain.

[@phallicusoblongus]

So by that logic, scientists venturing to understand every facet of a "simple" phenomenon is a bad thing. The more you understand about a concept, the more you can inform yourself on how to use it.

[@Democratiser]

Very interesting. Thank you. I wonder whether LIDAR or another system which can measure the distance of objects in a scene from the camera will enable ‘fake bokeh’ software to be developed which enlarges objects according to their distance from the sensor? I guess one problem is that the effective resolution of objects would deteriorate the further they are away from the camera because it is effectively a process of selective cropping and enlarging those areas.

[@extrashot]

Fake bokeh (or DoF) is already available in software and some phones using depth maps or LIDAR, although I haven't seen software enlarge the background to mimic longer focal lengths? Might be an interesting project to pursue? Thanks for your comment.

[@Democratiser]

@@extrashot Indeed the current fake bokeh replicates a wider aperture at the given focal length whereas what your analysis made me wonder is whether it could be faked by replicating compression: a zoom effect. Just thinking aloud really!

[@youravantgarde]

Well i found this interesting. I don't know why so many people are angry in the comments. Maybe they're just dumb.

[@jlwilliams]

It seems to me that all this video does is replace a poorly organized and over-complicated set of beliefs with a highly organized but still over-complicated set of beliefs. It all seems a bit silly considering that DOF is simply an optical illusion caused by the limitations of our goopy little eyeballs! As Kingslake noted after summarizing many of the uncontrollable variations that affect the result, “hairsplitting arguments about depth-of-field data become absolutely worthless.”

[@extrashot]

In a sense, I agree with you about pointless arguments, although we can see that Kingslake also struggled with specific CoC numbers in the days of printed film. The problem I have is when I see so many people summarising the many indirect effects as if they are the real cause of the phenomenon. That's misleading in that it doesn't help our understanding of what's going on. It's a shame that you think the idea of a single angle at the apex of a cone of light over-complicated because it means my video has failed to explain it adequately, which is my bad.

[@ariesmight6978]

I have found your video to be. A lot more comprehensive about the subject matter then most other youtubers explanations. Thank you for all that you have done.

[@ricban1950]

Depth of field is an illusion. How "out of focus" parts if the image is depends on the size of print and viewing distance. All lenses have the same depth of field when focused at the same distance using the same aperture. As an example take a photo of a bottle using a 100mm lens at f/8. Take another using 25mm at f/8 from the same position. Produce an image from each such that the bottle is the same size in the print. You will notice that the "out of focus" areas are identical (ignore any pixelation if there is any).

[@extrashot]

Are you sure that's right? If you change from 100mm to 25mm both at f/8, you've reduced the size of the entrance pupil by 4. ie. it's now 3.125mm rather than 12.5mm. That would definitely change the depth of field. If you don't change the subject distance then you should see a difference. By my reckoning, at 2 meters subject distance, it's the difference between 18cm and over 7 meters !!!

[@marcelryser]

Thanks 👍

[@Patto2276]

If it looks like a duck, walks like a duck and quacks like a duck, it's a duck. My point: who gives a shit?

[@phallicusoblongus]

Apparently you. You watched the video and commented, after all.

[@the_black_douglas9041]

It’s surprising to read so many dismissive remarks here. Thank you for sharing your considerable knowledge. I’m going to have to watch this another 5 times to understand the concepts though.

[@extrashot]

I'm not so surprised, but thank you for the kind comment, it does help! 👍

[@Leicashootr]

First thing it’s not depth of field is depth of FOCUS.

[@extrashot]

Depends if you're talking about lateral resolution or longitudinal resolution (parallel to the optical axis)... although the difference is relevant, especially in macro photography or optical microscopy, most cinematographers seem to use the term interchangeably. I'm happy that everyone knows what we're talking about with 'Depth of Field'. 👍

[@deanhomer8469]

Depth of focus is behind the lens; Depth of field is in front of the lens

[@nathanielcashjr.732]

I simply set my aperature for the amount of light needed to keep my iso at a reasonable noise level or simply starting at F1.2. I autofocus to sharpen the image at a point. With Nikon, I turn the focus ring allowing focus peaking to show in the frame, turning it until peaking shows the depth of field that I want. Put another way, I step on the accelerator until I get the speed that I want without worrying about the mechanics of the engine or its relationship to the fuel pump. It's about the final image.

[@extrashot]

True! 👍

[@Eikenhorst]

Well, obviously the result from a DoF calculator should be taken with a massive grain of salt. It is all about what distance in front and behind the point of focus is 'acceptably' sharp. If you then want to apply a huge ton of math around something as vague as 'acceptable', I personally think you kind of lost the point already. Basically, if you want it sharp, you need to have it exactly on the point of focus (and a theoretical perfect lens and a perfectly still subject and sensor), if it is off, it is certainly not sharp. It might still appear sharp depending on many different factors (aperture, focal length, viewing distance, etc.), but mainly on your personal opinion on what is acceptably sharp, and no calculator is ever going to help with that.

[@extrashot]

Very true... and with so many different display devices, who knows what's acceptably sharp!

[@BleliEli]

Agree!

[@BobN54]

Circle of confusion is not a standard, it's always been a choice a photographer makes, though most photographers don't know. Also, you say that the aperture being the size of the entrance pupil is not 'technically true' - yes it is, that is the actual definition of aperture. Aperture and f-number are different things. Anyhow, what you've done is re-invent Harold Merklinger's object field method. Google for his name and 'the ins and outs of focus'.

[@extrashot]

I've just googled him as you suggest and pleased to agree that the principles do sound very similar. although, my maths ability is not up to understanding many of the equations he uses to prove the point he's making. I must admit that I was probably trying to over simplify these thoughts by condensing it down to just the one angle... but it works for my small brain! Thank you Bob for pointing me towards his method.

[@BobN54]

@@extrashot I think that the key takeaway from Meklinger is that he provides a very simple method which can be used even if you don't do the math. It works like this. Focus on the furthest point within your chosen depth of field. Then look at the closest object in your DOF and visualise the actual size of details you want rendered. So, for instance if the closest is a tree and you want detail in the bark then 5mm might be appropriate. Then you set the aperture (fl/f-number) to that.

[@Behnam_Moghaddam]

lux et veritas 🙏

[@extrashot]

cogitandi .........

[@Behnam_Moghaddam]

@@extrashot as we love to do! can certainly help if your information works beyond the webs, right? prefer some labora to proof :) thank you for the extra shots! value on YT...

[@Tony-c7z9t]

It's all just an illusion regardless.

[@etherealbolweevil6268]

A matter of optics yes. Plus more delusion more than illusion.

[@spectr-t4b]

It's so... lame. I wish you get better.

[@extrashot]

I hope your name means you're something to do with spectrometers, in which case, I can sort of see why you might think it lame. If not... 😂

[@80-80.]

Sensor size DOES affects depth of field...If all other factors being equal: Angle of view, aperture, distance to subject.

[@extrashot]

How do you keep the angle of view and aperture equal if you're changing the sensor size? If you maintain angle of view you've changed focal length, which changes the entrance pupil size. What you're describing is impossible to do without changing that cone !!! The sensor size is simply cropping the image, it's doesn't change DoF at all. On most cameras you can now crop the sensor size as you shoot... what does that do to your DoF?

[@coin777]

No

[@mickymack1230]

[@3DEditor]

You mostly put together this presentation just for the sake of wanting to be right. No matter how you present your material and thoughts, the results will always come out the same, no matter how someone represents it. While it's nice to hear different perspectives, there's always going to be someone out there who feels they have to be the one with all the answers.

[@extrashot]

Not so much a case of wanting to be right… more a case of trying to balance all the misleading info out there. If anyone would like to demonstrate how sensor size or focal length can directly change depth of field, then I’m more than happy to be corrected?

[@michaelsanfilippo7433]

Thank you for wasting twelve minutes and fifty seconds of my life.

[@extrashot]

Plus the time it took to comment... sorry you found it a waste!

[@phallicusoblongus]

You sat through 12:50 and didn't understand any of it? Yeah that truly is a waste of time. Should have paid more attention.

[@ryan63rd]

Well that's 12 minutes of my life I'm not getting back.🤔 a monumentally smug explanation, possibly accurate, but of no practical value.

[@extrashot]

I’m sorry you felt it a waste of time and couldn’t derive any practical value. Please accept this virtual voucher to stay up an extra 12 minutes before bedtime! 😂

[@thomaswentworth6433]

Other than to help people who find DoF confusing. Your comment is so profoundly pathetic and of absolutely no value to anyone other than you.

[@noenken]

Nobody is getting anything wrong by describing things in a simplified manner. You are not revealing information unknown to mankind. So the only person objectively wrong here is you by implying that everyone else doesn't understand.

[@extrashot]

Okay, 'everyone' is probably a bit strong... but I can only judge by all the misleading information presented by most of the photography channels I watch ???

[@colinstock325]

Well if everyone gets depth of field wrong then there’s absolutely no point in listening to this video as this content creator also must get it wrong.

[@extrashot]

Good point... well made! 😂

[@TaoCovillault]

​@@extrashot Nicely answered 😅

[@matrixate]

This has explained in under a minute by others with greater understanding. No offense, but much of this video doesn't explain the why and how. You just explained that what.

[@threepe0]

Starting off by saying sensor size doesn't affect depth of field isn't a great start. You either know that it effectively does and are being obtuse, or don't know and shouldn't be weighing in on the topic. It's surely the former in this case. Yes, you can absolutely faff around for ages and kinda sorta get the same picture with a different sized sensor IF there is an equivalent lens for your sensor. For a shot I needed a couple of years ago, there just wasn't an equivalent lens available for aps-c or m43 sensors. It was literally not possible to get the shot with any sensor smaller than full frame. It was frustrating as a beginner to see people who had been doing this longer just talk past and correct others, and tell you why the calculators and tools you find are useless, but give you no more complete understanding to what was going on because they had nothing to add aside from smugly "correcting" others (actually being uselessly pedantic.)

[@exitar1]

Sensor size doesn’t change depth of field it changes field of view…

[@PyzaMadeInPoland]

​@@exitar1exactly.

[@threepe0]

@@exitar1 as he says in the video, it is part of the puzzle. It allows putting a lens on with a larger aperture relative to the sensor, which isn’t always available for a smaller sensor size. Saying it “doesn’t effect” depth of field is like saying ISO doesn’t effect exposure. Technically, it doesn’t. But it’s also a mind-numbingly stupid and useless thing to say. If sensor size doesn’t effect depth of field (it friggin does,) let’s hear you explain why webcams and phones all need to fake depth of field. Hint: it’s because their sensor size is tiny

[@threepe0]

@@PyzaMadeInPoland 🤡

[@extrashot]

@threepe0 A larger sensor allows you to use a larger entrance pupil with an equivalent lens. The fact that you didn't have an equivalent lens doesn't mean it's the sensor size that's changing the DoF. I wasn't trying to talk past anyone, and I made a point of saying PhotoPills was great. I'm sorry that my smug efforts to add to the collective understanding didn't work for you.

[@jonjanson8021]

So what, who cares?

[@extrashot]

I was going to say 'not you'... but then you care enough to comment, thank you! 😂

[@KennethRosenstroem]

You did obviously!

[@TaoCovillault]

@@extrashot 👍 Champ ✨

[@dongee1664]

We all know that the accepted techniques work. Know it alls get in the way of enjoyment, and they're boring. Bye.

[@dongee1664]

@joepublisher166 We all see things in different ways. I don't feel that photography should be made to sound difficult, there are very few things involved in controlling a camera. Composition is king to me.... All the best.

[@extrashot]

Thank you Joe... exactly what I was hoping for!

[@TaoCovillault]

@@dongee1664 I mean... If you were hoping for a video about composition, maybe clicking on a video called "The Shocking Truth About Depth of Field" is not the best place to go 🙏

[@leeds-yoga9265]

Made up nonsense.

[@extrashot]

Go on... I'll bite... do you mean 'nonsense' as in you can't make any sense out of it or is there something in particular about this visualisation you don't agree with?

[@phallicusoblongus]

Not too bright are you?

[@paularger2841]

To hell with apps and calculations. Use your eyes and the experience you gain through experimentation.

[@extrashot]

True!

[@paularger2841]

@@extrashot you have made a very good and thought provoking video sir! Thank you.

[@FoarteMisto]

correcting the Internet sounds like the perfect suicide mission !

[@extrashot]

True1

[@cannibalculture3016]

Once this sinks in, and my brain catches up, I'm sure it will be very useful 🥸