Focusing on Depth of Field and Lens Equivalents

[@TutorialsJunction]

i freaking spent thousands of dollars at institutes and they could not teach me any of this properly, you teach everything millions time better and also for free !!! love your videos man, keep it up :)

[@SchardtCinematic]

Even if I could afford to go to film school I would probably fail. I have always been a slow learner. So I've always taught myself or if someone could teach me hands on. I could understand stuff faster. With John's teachings. I maybe have to watch his video maybe 3 times and I understand what he is saying. I love it.

[@gabrieltonatiuandrade8941]

This is so true. I've been studying film production for 3 years now and nobody ever explained to me this so didactically.

[@Apna-apnahoney]

Photoshop Tutorials | Photo effects impactguru.com/s/uxZ0zQ support us donate

[@dipaldesai6956]

This is because this person is a true TUTOR and a true TUTOR teaches everything keeping in mind Education as a Mission and Not as a Business

[@dogeongreenscreen]

yikes

[@sottozen]

This is one of those videos i regularly come back to watch...

[@TonyAndChelsea]

Nicely done! I'm glad to see these concepts are becoming more widely accepted! Even just a year ago, this was a really controversial topic. I'm constantly switching between 35mm, Super-35, MFT, and BlackMagic's mini-MFT sensor sizes for video, and this math has been critical to choosing the right lenses and settings for different scenes.

[@FilmmakerIQ]

Hi Tony! Your video changed how I perceived sensors size in relation to DoF. I really had to work hard to wrap my mind around it with physical experiments. There was a lot of myths that I needed to let go and at first I was hesitant to discuss this topic because of the confusion it can cause. But after I dug deep enough, I felt I could explain it my own way. Anyhow, Thanks for having the courage to stand up against an often ornerly photography crowd on this subject :)

[@omarquintana3481]

Tony & Chelsea Northrup i am confused here, please some assistance: 2x crop factor on focal length for a 50mm 100 (2x 50); 2x ISO is ISOxcrop factor^2... ISO 160 x (4) 640. But... what about of 2x aperture for f/4 is f/8 (2x8) or f/5.6 (as 2x(f/4)=f/5.6).

[@FilmmakerIQ]

It's a straight multiplication, not taking in consideration of stops. So 2*f/4 is f/8

[@omarquintana3481]

mr john: i really really appreciate your fast answer. So the four cases ( focal, focus, aperture and iso^2] are straight multiplication

[@FilmmakerIQ]

Focus does not change. Remember these are equivalents... What would be the equivalent on a full frame sensor.

[@Luciusse]

This type of videos are like The Bif Short of Internet. You don't understand the details, but you understand the big picture, and that's the most important thing and the most difficult thing to explain. Well Done Filmmaker IQ.

[@BasicFilmmaker]

As usual, fantastic stuff. Personally, I love the in-depth coverage - sent many a person over here when they have questions. Thank you.

[@Apna-apnahoney]

Kevin - The Basic Filmmaker impactguru.com/s/uxZ0zQ support us donate

[@ShaunakDe]

This is seriously the best video on DOF and sensor size in the world.

[@sparkybluefox]

"I can see clearly now" ...... Thank you Mr Hess for this sweet video! I love the work done on this channel!

[@nobnobnobnob]

Finally somebody who knows and explains the subject very well not is not from the manufacturer side(who wants to market us).

[@ingridfong-daley5899]

This was BRILLIANT... your demonstrations and re-wording of the concepts in multiple ways makes the concepts more easily accessible to everyone. This is quickly becoming a favourite channel--thank you so much for taking the time to do this!!!!!

[@victorbart]

Filmmaker IQ is always solid content! Thanks John :) The whole depth of field discussions will never stop. There are 2 ways to compare it both are right both are opposite :)

[@FilmmakerIQ]

+victorbart Not sure what the other way is, but this is the right way :P

[@zukaka84]

+Filmmaker IQ I am still confused. I don't understand how the depth of field calculated from the pixel size is related to the depth of field coming from the blurred back lights (or so called bokeh).

[@FilmmakerIQ]

Go back to the animation of the single point of light. If the point is in focus (6:08), it will be a point in the final image... Once it goes out of focus, it becomes a ball of light... Just like bokeh... The bigger the spot, the more out of focus it is.

[@zukaka84]

+Filmmaker IQ This is clear. But my confusion starts at 13:50 when you talk about bokeh of out of focus lights. Their sizes will not depend on the pixel size, they will depend only on lens focal distance and aperture. So everything you say after 13:50 using crop factor, focal length, field of view and aperture is clear but I cannot relate it to the pixel size and circle of confusion. Let's say we have 2 full frame sensors, one with 12mp and another with 48mp resolutions. If we use the same lens with same focal length and aperture settings we will get two pictures with identical bokeh even though 48mp sensor has the shallower depth of field.

[@FilmmakerIQ]

+Zuriah Heep The problem with your paradox is you're comparing apples to oranges ;) Two prints - one from a 12MP one from a 50MP camera, identical dimensions. They look identical right? What's the difference between the two? The Pixel Density. The pixels are much smaller on the 50MP than they are on the 12MP. But that's cheating ;) What happens when you match the pixel density - so that each pixel from the 12MP camera is exactly the same as the 50MP camera? Now the 50MP print will be much larger - about 2x larger. If you compare pixel to pixel, bokeh on the 50MP will be 2x bigger than the bokeh of the 12MP camera! That sounds stupid... but follow me here ;) This is exactly what's happening when we enlarge the image from a crop sensor. If we were to print out an 8x10 from a 12MP FF and a 8x10 from a 12MP crop sensor - we would have to enlarge each pixel of the Crop sensor so that they'e the identical size to the FF. And if we enlarge the image - the bokeh blooms will enlarge as well. :) Bokeh is affected by focus distance, aperture, AND the size of the sensor. Now to come back to try to explain why two images from the same FF sensor have the same bokeh even though _theoretically_ the higher MP count has a shallower depth of field. I may have been a bit quick to tie resolution to circle of confusion - there is obviously a link. But Circle of Confusion isn't defined by pixel size, it's defined as CoC (mm) = viewing distance (cm) / desired *final-image* resolution (lp/mm) for a 25 cm viewing distance / enlargement / 25 In the case of Full Frame they use d/1500 (d=diagonal of the lens) as short hand giving us 0.029mm as the CoC. Rough math puts a 12MP pixel at around 0.008mm and 50MP at 0.004mm - both of them are well below the CoC using d/1500 standard. Using that standard the 12MP and the 50MP FF sensors have identical DoF because both pixels are _smaller_ than the CoC. But if we continue to enlarge the image (the third variable in the CoC equation)- the CoC will get smaller and smaller. It's only when we enlarge the image so much that our CoC is inbetween 0.008mm and 0.004mm that we can start to say that that the 50MP FF sensor is shallower than the 12MP FF sensor. Until then, as long as the CoC is bigger than the pixel size, both cameras have identical Depth of Field.

[@jjcale2288]

And this concludes as the only valid demonstration of DoF, focal length and crop factor hysteria on YT. Thank you for a coherent and scientific explanation!

[@bg365247]

Brilliant! Kubrick would be proud. He was obsessed with tack sharp images.

[@HarleyPebley]

All your content is superb, but you went to even greater heights with this one.

[@GiuseppePipia]

YES!!! FInally a video where it is said that smaller sensors give actually a shallower DOF, if all the other variables are the same!!!! FINALLY!!!!

[@storysupport]

That's not correct because the scene composition is the most important variable. The field of view is the most important factor because the entire point is to create and image of a given THING. The field of view can't possibly be the same if the other factors are. Think about it, when using a camera, its to photograph something, right? The subject is the reason for the photo, not the camera's settings. If the field of view is different, then that "something" is not the same. Therefore, for a given field of view (with matching, lens, aperture and ISO) the larger sensor will have a shallower depth of field. He says this at 15:48

[@FilmmakerIQ]

Yes it is... it is an apples to apples comparison. it's just different which apples you want to compare.

[@storysupport]

@@FilmmakerIQ You may be responding to an incomplete comment. You wouldn't mind looking at what I wrote above and confirming if we have the same understanding, would you?

[@FilmmakerIQ]

KZbin is so screwy it's only showing me the most recent comments. It's not even showing your earlier comment. Basically everything in the video is correct. Same focal length same aperture... the smaller Sensor will have a shallower DoF AND a smaller FoV

[@storysupport]

It is @@FilmmakerIQ. I was speaking to what the commenter mentioned saying that for a given field of view (with matching, lens, aperture and ISO) the larger sensor will have a shallower depth of field as you mentioned at 15:48 or so. I just recently came across your page. These concepts are explained pretty well.

[@AGCipher]

Your videos are amazing and every photographer should watch them!! Wonderful explanation!! :)

[@WilliamParmley]

Thank you! After all these years... I never realized that crop factor effects *everything*, not just "equivalent" focal length.

[@chochmah]

I'm so happy every time you upload a video that I thumbs up it within the first couple of seconds.

[@STEHH87]

You truly are the master of the photographic math!!! I really enjoy your show, as there isn't anyone else out there (that I am aware of) who explains the math and logic behind all the aspects of photography that well!! Keep it up!!

[@WilsonWongWilzWorkz]

Your last point is the best summary. It is not about the sensor size, it is how you shoot.

[@SchardtCinematic]

I bought my 5D mark III because I was used to my 50mm lens being 50mm not 80mm. Although I like using my T3i to get that extra reach with my 300mm zoom lens once and awhile. This is one of my favorite videos you have done John. I understood depth of field from my 35mm photography days. But had trouble understanding it with my APS-C sensor on my T3i. You really brought it to life for me on seeing the difference now and I will be better at using both cameras more creatively now.

[@SoloFlightProd]

Your method of teaching is insanely solid John! I think im going to use your stuff to start off some ACs!

[@LiaoK]

Small correction: You can never get the same field of view by moving the APS-C camera back. You can match the framing on your subject, but the angle (field) of view stays the same so your foreground and background will be different (i.e. the perspective is different). The only way to match field of view is by using the equivalent focal length.

[@stephenvictor8961]

I Salute you! I honor and respect you and all you have gone through to get you to your levels of intelligence, wisdom and skillfulness in communicating (teaching) so effectively. I am new to photography and self taught. I did not know what I did not know. Inasmuch I remained niggled by a prompt to remove this ignorance of the physics you so eloquently explained / demonstrated. I now know what I do not know. I will avail myself of your body of work. Thank you!!!

Perfect explanation! :)

[@allissondiego1989]

I'm not even involved in filmmaking. I just watch this channel because the videos are extremely well made and entertaining

[@grudgin1877]

Thank you so much again. Best on KZbin truly.

[@djrbfmbfm-woa]

great info. best channel on YT. j.

[@SymonSaysTV]

Ironically this is the first tutorial you've ever made which is out of focus. ;-)

[@meta1884]

+Symon Says TV I noticed that too, glad to know it wasn't just me. I wholeheartedly believe he did it on purpose.

[@deBurrows]

same here, hope this was on purpose.

[@motogee3796]

its the nature of the subject material...circle of confusion

[@mirageleung]

You are magnificent, I've been so confused about focus vs depth of field for so long

[@biscuitsalive]

I have already praised this video. But I feel I need to again, I just had to share it to a few individuals that were arguing with me on the DOF sensor size issue. Your video explains it really well and helped me make my point perfectly.

[@FilmmakerIQ]

+biscuitsalive I was afraid to tackle this subject about a year ago because there was a point in my life where I would have been arguing with you on this matter. I had to make sure I was armed mentally for what this subject meant and how to explain it. This video has been one of the more controversial ones for sure. Thank you for sharing!!

[@biscuitsalive]

+Filmmaker IQ it's excellent! I occasionally make camera related videos. And if my videos were half as well thought out and delivered as yours I would be very happy indeed.

[@biscuitsalive]

+Filmmaker IQ can I get your opinion on something please? It may help settle an argument. I did a test video a couple of days ago. See "can you spot the camera sensor size from the shot" On my channel if you have time. Ok, so the point of contention is- the speedbooster is only changing the FOV allowing me to keep the same distance and framing. (Simulating a wider lens) (Others were arguing the booster was narrowing the DOF) But if you actually break it down. The booster is technically widening the "apparent" DOF. Just as it is widening the FOV. ( as the circle of confusion is reduced due to the widened FOV) The actual DOF of the lens is not changing. As I'm keeping the focal length. The distance. And the aperture the same throughout. Would you agree with my thinking here? Hopefully. Have been having a 3 hour argument over it. :D

[@FilmmakerIQ]

+biscuitsalive The technical name for a speedbooster is "Telecompressor" You're taking the image circle from the lens and making it smaller. So let's say you have a spot of light that's slightly larger than the sensor's Circle of Confusion. When we compress the image - we're make that spot of light smaller - therefore what was previously "slightly out of focus" will now be inside the tolerance for focus. Following that logic - the booster is widening the Depth of Field regardless of what sensor you use. What might be confusing is people would jump to the idea that a speedboster increases the fstop and therefore reduce the depth of field. The problem though is that ignores the relationship between the focal length and f-stop ratio. A speedbooster shortens the focal length but does not change the diameter of the aperture. So a 1.4x compressor would take a 50mm F4 down to a "real" 35mm F2.8 - it's no longer 50mm so you can't just look at the F4->F2.8 and make that conclusion. Actually if you look at depth of field charts - the depth of field widens exactly by the power of the compressor.

[@biscuitsalive]

+Filmmaker IQ great stuff. It seems I have the physics in my head working roughly ok now. But you explain things better than i can. (I'm a typical artist, visual based thinking, and can not write down my thoughts as well as I can draw them. :) ) So essentially the speed booster (metabones call it a "focal reducer" ) is widening the FOV, hence shortening the focal length. AND increasing the f stop due to how the maths works out with the new shorter FL. So in terms of apparent DOF on sensor, these two things cancel each other out don't they? So the "apparent" DOF we see in the captured the image remains the same. (As the shorter FL makes the COC smaller, but the new f stop also makes it wider... So the scales are balanced... No increase or decrease to the COC size) (Note- I realize the DOF of the actual lens does not change.) In which case the description of what the speed booster does on their site is very misleading, regarding allowing narrower DOF.

[@jacobyu5050]

the ISO crop factor is 1.6*1.6=2.56, so the iso is not 500*1.6=800, it should 500*2.56=1280 that will give the same look

[@DAVIDSDIEGO]

Always informative and entertaining! This is the only channel I watch long videos on YT. BTW, I still believe Mr. Grady was the real caretaker. :)

[@stefanosk27]

+DAVIDSDIEGO He's always been the caretaker..

[@lwanfry]

Your videos are amazingly interesting. Even the CGI videos which I probably master more than you do are absolutely brillantly explained and accurate. Well done

[@wookix]

Thank you for these videos! They made me see the process of 'taking a picture' in a whole different perspective. Keep doing these videos! :)

[@GetOutsideYourself]

NIce Shining reference on the sample photo.

[@atephoto]

Just fantastic video, explaining this whole concept with good examples.

[@F3sterJ3ster]

I'm definitely going to have to watch these videos on lenses and sensors a few times before I fully understand them but these are really helpful. thx.

[@Lot7ix]

Have just watched 10 seconds and already know it's gonna be something great! ;)

[@MattFromSMM]

Great explanation

[@techsavvydaddy5616]

John, Once again your wealth of knowledge and the way you breakdown everything is by far one of the best I have ever seen. Thank you so much I love your classes, truely educational. BTW where did you find the cartoon b-roll at 10:44 that is hilarious!!!! LOLz

[@zeghnal]

somebody give this man a tv show

[@stuntmanbob90]

I won't go to film school. I just watch all your videos :)

[@mahadihasanrichard2191]

i got many many many thing to learn in this video. it was a full of information and this video clears my lots of confusions. thank you so much sir i just love the way you describe.

[@januarioph]

Great content!! Tnks for all the support for the photography community!!

[@mgamm1]

What an excellent and informative video -really well spoken and laid out. I found this interesting and incredibly useful as someone who is moving from using only 120 & 35mm to 4x5 film. Your examples are grounded in digital sensors but everything is totally applicable comparing film formats as well (except for pixels vs grain). Great instruction, thank you for including the math.

[@FilmmakerIQ]

I've started to shoot 4x5 and it's so fun but intimidating

[@mgamm1]

@@FilmmakerIQ Yeah I think there are a lot of things that can go wrong! I have ordered an intrepid camera system with all the bells and whistles including the enlarger. I think the key with 4x5 is to plan how you are going to use the camera, write down all the steps and absolutely never rush. I am pretty careful and meticulous, but we will have to see how quickly I make my first mistake and toast some expensive film :) ** also if you are getting into 4x5, I highly recommend looking into Caffenol-C-L development if you haven't already. It's quite a game changer, and now how I exclusively am developing any BW film at home.

[@AlexPetrov108]

It's just perfect and what I was looking for, thank you so much!!!! =) BUT, one little point still needs to be cleared - perspective distortion in regard to the focal length, distance and crop factor for portrait shots e.g.

[@FilmmakerIQ]

Watch our forced perspective video for more on perspective distortion kzbin.info/www/bejne/pp2XkpuVfduKock

[@publius1564]

This is great! The visuals are a big help (cameraman banging his head on the keyboard was hilarious) Thanks!

[@MrKockabilly]

16:18 let's be frank here, image-wise smaller sensor is "inferior" (they are at extreme disadvantage in low light, hard pressed to get a bokeh). As for the depth of field (assuming same field of view), larger sensor can easily achieve what a smaller sensor can (such as a larger DOF) by simply closing down the aperture, but a smaller sensor is very limited on how it can achieve what a larger sensor can (a shallow DOF). Simply put, a larger sensor has that extra capability. One may not need that extra capability (it is extra cost, of course) but it would be good to be there when you may want to use it from time to time.

[@RCAvhstape]

John, I hope you're getting ready to do some talking about Super 8mm since Kodak is releasing a bran new camera and processing service this year!

[@FilmmakerIQ]

+Helium Road It just looks so expensive.... $75 a pop for 2-3 minutes for the 8mm look? Seems like its going after a very niche market.

[@joonaikonen6423]

+Filmmaker IQ Oh no! I was excited for this and hoping it would cost like 20-30 dollars. Obviously i had no knowledge about the cost of film today. I've never shot on film and was hoping i could use this for my short films. Too expensive for me. :/

[@FilmmakerIQ]

+Joona Ikonen even $20-30 would be high... It's hard to justify when you can get a very nice 64gb SD card for the price I'd 6-8 min of film. And it's 8mm look which is close to the look of 1/3rd inch consumer video cameras... I just don't see the point.

[@joonaikonen6423]

+Filmmaker IQ I guess you're right. Those videos shot on super 8 just have this nice look and feel, and i'd really like to have that on couple of short movies that i'm writing. Of course that look can be made in post, but idea of that just doesn't feel as rewarding to me. But yeah, maybe i'm just romanticizing the idea of shooting on film. And this is coming from a guy who collects impractical vinyl records, so thats probably the case :D

[@joonaikonen6423]

+Fyodor Chernych Are Nolan, Abrams & Tarantino hipsters cause they shoot on film?

[@Matony]

I wish I had stumpled upon this video (and channel) in 2016. Thank you sir! Very plain language, beautiful demonstrations 😊

[@omarquintana3481]

In the 8:50 minute you indicate the circle of confusion is marked by the width of a pixel, but today with the new film and photography cameras, monitors and devices, 6k and 8k that begin to have a resolution and sharpness much higher than the film should it be changed the definition of circle of confusion? Or we continue to maintain the traditional definition of 25 µm

[@FilmmakerIQ]

I should have stated that the pixel definition is only for thought analogy. as long as the pixel is larger than the circle confusion which in HD it usually is... Then it can be used to understand the concept. But now that the pixels are smaller than the circle confusion, it doesn't work. And the circle confusion isn't just traditionally 25 microns, it varies depending on the size of the sensor.

[@fuzzywuzzy599]

Fantastic enlightening. Only one thing. The statement - Don't worry about the full frame equivalence? The issue you haven't taken into consideration in making that statement - Relates to achieving the same sort of effect in a shot e.g. bokeh and field of view on a crop sensor as is achieved on 35mm / full frame. That's one of the reasons to understand the why and how - is it possible? While achieving this in a package that is more light weight and compact than full frame kit and more frugally. So that's physically not achievable given your video as a whole. So it's then a question of how close, how good enough. Speed boosters and 0.95 crop lenses and not quite the field of view but closer in micro 4/3rds. One clarification - so am I correct in taking it the reason for depth of field, bokeh etc. In the first place relates to the curvature of the lens so there are spots visible instead of points of light in those areas, hence why reducing aperture size blocks those out of focus rays from hitting the sensor cleaning up the light that is allowed through and therefore increasing what is acceptably sharp and therefore depth of field.

[@FilmmakerIQ]

I'm going to reinstate the sentiment. Don't worry about that. I can tell by your writing that you are not really approaching this with experience. Format sizes have real hard physical differences. What I'm showing you is how the math works. Learn to shoot with what you have.

[@Ilustre87]

Best explanation for this subject ever!!!👍👍👍

[@KenTanis]

This was super, thanks John.

[@paristo]

The only part that was left off (just slightly mentioned) was the final print size, as that and viewing distance and the person eye sight rules what is found to be acceptable sharp. As in video it was mentioned when talked about circle of confusion for film makers as they project on larger area, it would have been good to mention that everything is equal when final print and viewing distance magnification ratio is same. Meaning take the crop factor for the final print size in same viewing distance, or take the crop factor for viewing distance on same final print size, and everything is equal. Meaning depth of field, noise and so on being same regardless of the format. (in other words, 35mm print projected as 50" size and viewed from 200cm distance is same as 1.6x print projected as 31.25" size and viewed from 200cm distance, or both being 50" projections but 1.6x print is viewed from 320cm distance.) So why so? Because depth of field changes based 1) final print size 2) viewing distance 3) viewer eye sight So if you want to get two distances in focus, you need to calculate everything from those three factors to know what camera settings you are going to use. This is so called "magnification rule" and sometimes called as "format ratio" or "format factor" and some people know it as "crop factor", but it has nothing to do with the sensor size as it isn't based to it, but to three factors mentioned above and they affect what format should be used, what ISO and what F-stop for depth of field. And clever ones notices that is mathematically called "inverse square law". Aka magnification ratio. It works with the lights too and optics too. Like many wonders why moving light source distance to subject follows Inverse square law, making subject brighter or darker. But then your camera can be at any distance to subject and your subject is always at same brightness. But the same thing is with it, inverse square law. If you have 50mm, your subject is 2x1m and then you move camera from 10m to 20m distance, you receive 4 times less light from subject, because you increased the distance by 2 times, but same time the subject is 2 times smaller meaning it is by magnification same as 1x0.5m at 10m distance for the sensor. If you have camera moved from 10m to 5m distance, your subject is now magnified two times, and is by size same as 4x2m subject would be at 10m distance. You get more light by 4x but subject is 2x larger so subject brightness is same. The optics does same, why F-stop is a ratio of inverse square law. If 1x1m subject is at 10m distance and 50mm focal length is changed to 100mm, it magnifies the subject 2x and hence receives 4 times less light. Or if 50mm is changed to 25mm, then camera receives 4 times more light as subject magnification is 2x smaller than it was with 50mm. And to compensate this, aperture follows Inverse square law so same F-stop will transmit same amount of light trough it regardless of the focal length or sensor size in same exposure time. Why 50mm focal length with 12.5mm aperture is same as 25mm focal length with 6.25mm aperture, both being f/4. Many doesn't remember to calculate focal length (magnification) to light gathering and they only calculate aperture diameter and sensor area. Saying that 2x smaller aperture (diameter in mm) pass less light to 2x smaller area (sensor size in mm²) equals smaller light gathering. While leaving out that 2x shorter focal length (like 25mm instead 50mm) gathers 4x more light before it even enters to aperture and hits the sensor. Resulting equal exposure. But then magnifying final print from smaller sensor to same final print size as from larger sensor, magnifies noise, lowers sharpness and changes as well depth of field and dynamic range. Eventually all being equal if same magnification ratio is used = sensor size size ratios = final print size ratios, viewed from same distance and by same eye sight quality. Why f/2.8 is always f/2.8 regardless of the format, and why ISO 200 is always ISO 200 regardless of the format. And if you magnify other format 2x more than another (like m4/3 vs 35mm) to get same final print size, the smaller format will have increased noise, shallower depth of field and lowered dynamic range.

[@FilmmakerIQ]

+paristo Very thorough comment - thanks!

[@sidbrun_]

The bit around 15:30, I think you missed one very important thing; the perspective has changed too, the APS-C image has become more compressed

[@FilmmakerIQ]

+Sid Brunski Yes that's true - but I wanted mainly to focus on the depth of field which has become shallower :)

[@sidbrun_]

Yeah, but I think it's important to note because there's often a myth that the focal length decides the perspective, not where you're physically standing, since we're talking about lens equivalents.

[@FilmmakerIQ]

Maybe we'll dedicate a video just to that topic :)

[@sidbrun_]

@@FilmmakerIQ is there a video where you've shown that a higher pixel count/density, despite being on a crop sensor, could yield a blurrier background than a full frame sensor with less pixels? I'm so sure I've seen a video about that.

[@satanases]

Your practical examples with the magnifying glass are just insane! Thanks a lot for the video, helped my life out, hahahaha

[@Twobarpsi]

Best video I have seen on this subject!

[@PhilEVignolaJr]

Great explanations of very complex subjects. Very well done!

[@amsrremix2239]

Big question, for anybody on the thread. Very early in the video ,00.58, he's says" its the same for photography lens. " What I'm wondering is do any of these methods change when your using a Cinema lens and camera. You obviously move from F-stop to T-stop , but are there any other intricacies that might change ?

[@FilmmakerIQ]

+marcus cummings in terms of depth of field, the difference between motion picture and still is really resolution and print size... The fundamentals are identical. In my experience focus in motion picture is more forgiving because it's moving and you can't just sit and stare at it like a still picture.

[@bendermac]

What is the font effect you're using for the chalk-effect of your spreed sheets? i really like it :)

[@FilmmakerIQ]

+bendermac It's an animated font called "Blackboard" and then we use a script called "Characteristic" which will lay them in in After Effects. For a year before I discovered "Characteristics" each letter had to be laid in one by one like a printing press :P

[@bendermac]

+Filmmaker IQ - I've found it on videohive.net and thank you for the "Characteristic" tip :)

[@mahdi9364]

Finally I came somewhat close to understanding this topic.

[@epiphoney]

Are you saying a full frame sensor at 42" has the same depth of field as an aps-c sensor at 67.5" at 15:41 in the video, all other settings being equal?

[@FilmmakerIQ]

No it shouldn't be - that was an oversimplification on my part - just demonstrating that what people usually do is step back to get the same framing. If you step further back - you end up increasing the DoF more than the offset of the crop sensor.

[@theluxlyfe]

Can't wait for your paid photo and video courses. This is too good, to be free!

[@zerobizzy]

At 13:34 the APS-C and the full frame look equally bright given the same settings, this doesn't make any sense. I thought larger sensors capture more light therefore, resulting in a brighter image. Did you increase the shutter speed on the full frame or used ND?

[@FilmmakerIQ]

+zerobizzy no, you're seeing the image with no funny business. The idea is the larger sensor gathers more TOTAL LIGHT, but the way ISO works is that ISO 500 should expose the same way regardless of what lens in front of it.

[@YeagerFilm]

Another great video! This one had to take a while to make! Thanks!

[@baijunatarajan]

Thank You, Sir,,, I would say This is one of The most informative and well-presented videos I have seen...

[@helder4u]

Spot on facts, simply explained - You, Are, GREAT!!

[@Mark-wq7wd]

I know im like 5 years late to the party, but I love how you used the Stephen King theme while explaining.

[@max-28382hhfh]

I really appreciate the experiments you set up, thanks! I also thought dynamic range as it relates to sensor pixel size would be good to mention in the context of what is covered in this video. Take the a7r, a7 and a7s for example. Each one has the same sensor size but a different pixel size. Would be interesting to compare the dynamic range of the three (or the circle of confusion)

[@gamerN77]

Your videos are truely fantastic! Not only can a b*tchslap my fellow photo-nerds with science (lol), I also learn more of the fascinating aspects of my beloved hobby. Thank you for your great work! Btw. Nice Shining-carpet ;D

[@kaifu-d]

Hi John, I love this video, finally someone explained this so clearly and with plenty of evidence. I just wonder if you would expand the topic at the end of the video a bit, which is about different sensor sizes have different looks, I'd love to see if you could make a comparison between the look of different sensor sizes AND analyze them through a scientific way, for example IMAX, Alexa 65, Alexa LF, Super 35, and Super 16 etc.

[@davidjohnbalce1111]

Probably, one of the best explanations for depth of field and lens equivalencies. But, there is one thing that confuses me. As mentioned in the video "with the same lens the smaller sensor produces shallower depth pf field", does that mean that if the Micro 4/3 equivalent of a certain full frame lens have deeper depth of field?

[@FilmmakerIQ]

The equivalent has deeper depth of field on the M4/3 but the same focal length (ignoring equal framing) The m43 is actually a lot shallower. A cell phone camera would have even shallower focus than that. It's the focal length that makes up for the difference

[@thanhngo4697]

Thank so much, this is the best explanation about lens !

[@Japhgar]

Is it really true that 80mmf3.2 Full-frame and 50mmf2.0 crop have different depht of field? as you mention in 14:53 It seems to me that Bokeh is the same (here in the eample at 14:28) as a result of same or very similar depht of field please tell me if I am wrong thanks

[@FilmmakerIQ]

No you're right, FF80mm f3.2 is the equivalent of APS-C 50mm f2.0. Changing the aperture to 3.2 is how we get those DoF to match

[@Japhgar]

+Filmmaker IQ Thank you! Example given a picture taken with 1/3"sensor 4mm f2.2 iso100 would be equivalent to a FF 29mm f16 iso5184?

[@FilmmakerIQ]

+Jakob Friedrich 1/3" is a crop of 7.2 so your numbers look right. You even got the iso(crop^2) right which I stated incorrectly in the video

[@Japhgar]

+Filmmaker IQ Thank you!! with your help I am understanding photography much easier and better!!

[@CED3]

Loving that Overlook Hotel carpet!

[@hoosier.daddy5000]

This single video could create peace on Earth if all photographers watched it. 😁

[@funking5404]

Nice work!!! The experiments are super interesting and show perfectly what you want to tell!!

[@xolracke]

The part of the f-stop in crop sensor to match full frame i did not get

[@yukwarit6082]

so at 15:46, full-frame and aps-c are identical if we just adjust the shooting distance?

[@FilmmakerIQ]

Not quite... The distance changes the perspective... The ratio of close and far objects.

[@jonathanfurtado6880]

Do you have a link to the equipment you used in this so we can purchase some to make our own lesson plans with?

[@FilmmakerIQ]

Hiya! We're working on a total revamp of our site Filmmaker IQ.com which will have lots of stuff for folks like yourself to make lesson plans including quizzes. It's coming really soon. But specifically I saw you asking on this video and another optics video. We're using a basic optics bench kit which you can get from any science teaching supply store. Make sure you experiment with the lenses first because some aren't very optically sound and will give you very weird results. So that's why I use that third hand magnifying glass. Outside of the optics bench kit and third had magnifying glass - everything else is pretty much gerry-rigged.

[@Kirmo13]

This is great! I've been seeking this kind of photography content.

[@venvatpictures]

What is distance to object and distance to image mean? If the bulb is the object then what's the image? And where do we measure them both from?

[@FilmmakerIQ]

The image is the image of the bulb on an imaging plane. In this basic thin lens set up, the distances are from the center of the lens. For a thick lens, they would be the distance from a principal point

[@LazyZeus]

Thanks, John. Brilliant videos.

[@PauliJuppi]

Excellent again! Familiar stuff, but great demonstrations! Thank you

[@christophergrove4876]

🇨🇦/🇺🇸... Thanks... when I frustratingly try to describe Circle of Confusion to others, I'll just point them to this, excellent video! NOW... if only I had a video describing sensor pixel pitch in relation to the number of megapixels, tripod vibration damping (as opposed to stiffness) and the diffusion of lens glass!!! 🤔

[@WhisperingChocoTaco]

I don't understand why the aps-c is converted if it is more similar to the Super35 size? If you took a photo from a film camera from the same position with the same lens wouldn't it be 'cropped' assuming it was Super35. This whole 'crop' thing got me thinking that the aps-c sensor was both smaller and in a different position than film making the image wonky with normal size lenses and you need to buy special crop lenses. Nevermind, you answered my question in your video on camera lens properties.

[@lakshmanprasad2798]

Excellent presentation. A quick query. I take it that the crop factors need to be applied only if we using the same lens on both full frame and APS-C sensors. If we are using custom lenses designed for APS-C or Micro four thirds, do we still need to apply the crop factors? In other words if it is a custom lens 50mm f 2.8 for a Micro four thirds, it is just that and no crop factors become applicable?

[@FilmmakerIQ]

Crop factors need only be applied when _comparing_ lens on different formats. If you're not using different formats you should not be using crop factor at all. On your second question, lens designed for the format still require the crop factor unless there lens says "equivalent" (super rare). But again you only use the crop factor if you are comparing formats. If you are only working with one format you should not be speaking about equivalents.

[@lakshmanprasad2798]

@@FilmmakerIQ Many thanks for your prompt response. Much appreciated. Please refer to the link to the Wikipedia page on Nikon1 Nikkor lenses. There is a table provided at the end. The second column notes 35mm equivalents to native bespoke Nikon 1 camera lenses( much smaller format). Appreciate if you could please help me understand it more clearly. en.wikipedia.org/wiki/Nikon_1_series The reason I am asking this question is that it has an impact on the depth of field. If I use a native bespoke 50mm f2.8 lens for an APS-C or micro four thirds, does the f-stop remain at f2.8 or does it have to be multiplied by the respective crop factor 1.6 or 2.0 resulting in an f-stop of 4.5 or 5.6. This means that at f4.5 or f5.6 the depth of field will be much larger than for f2.8 claimed on the lens. Thanks again for your help.

[@FilmmakerIQ]

@@lakshmanprasad2798 if you are looking for the equivalent then you must multiply the crop factor into the f/ratio as well. You should review the video again because we covered that part in the video. This is why they say smaller sensors have deeper depth of field even though technically speaking the smaller sensor actually has a shallower depth of field.

[@lakshmanprasad2798]

@@FilmmakerIQ Thanks again. Difficult concepts are slow to sink in. Your explanations are the best I have ever come across. Keep it coming! It is a joy to watch and learn from your videos.

[@roopjm]

I always wanted to go to Film School, and this is the best option I can find! Thanks for the great videos! Have you ever thought about, (or done and I just missed it) a video on how they clean up footage? That process seems fascinating!

[@FilmmakerIQ]

+Jon Roop If you're asking about Color Grading - we do have a introduction to color in the digital realm: kzbin.info/www/bejne/rGiwlYOApqqCi5Y

[@roopjm]

+Filmmaker IQ I mean more of cleaning up dirty film and making it look so crisp and clear

[@FilmmakerIQ]

Jon Roop Oh like Restoration? Yeah that's something we'd definitely to look at one of these days :)

[@roopjm]

+Filmmaker IQ Restoration maybe? I'm talking about dirty film that you sometimes see in Unused Footage / Deleted Scenes where there are the imperfections in the film, dirt, etc. It maybe covered in Color Grading, I'm watching that one again today :)

[@omarquintana3481]

Is there a difference of DOF between a f/ and T? Is The compensation of the transmission of light done by adjusting the entrance pupil’s size resulting in the dof is slightly smaller because a larger aperture ?

[@FilmmakerIQ]

Yes there is a small difference between f stops and t stops. T-stops have the glass transmission factored in. The entrance pupil isn't adjusted - the scale is just reassigned. So on the lens itself, it might be marked a t/8 but in f-stops it would be an f/7.9. It wouldn't be enough to really notice unless your precisely matching something for a technical purpose. Not enough to matter for anything artistic.

[@brentdrafts2290]

About the circles of confusion. Is this why older digital censors have moray (for give spelling) affects. Due to light bleed between sensors?

[@FilmmakerIQ]

+Brent Drafts I haven't thought about the relationship between circle of confusion and moire (sometimes spelled with the accent on the e) but I think you are on to something ;) I have to research it further but I would guess that if the regular repeating pattern which cannot be described as a *whole* number circle of confusion widths would result in some sort of moire. I may be off on the math... so don't quote me. With pixels it's really basic to understand - but I see moire in every day objects like mosquito screens. :)

[@franklinmichael671]

So smaller sensors have a shallower depth of field than larger sensors *if they have the same resolution*, right? So this means that the sony a7siii has deeper depth of field than the a7riv for example? Since both are full frame cameras but one has 12megapixels crammed into the sensor and the other has 61 megapixels crammed into that sensor? I have a question, if a 50mm f2 on a camera with a x1.5 crop factor is equivalent to a 75mm f3, and you have a full frame camera and a crop factor camera with the same resolutions, then each pixel on the crop factor camera will be smaller and therefore will have less photons hitting it in the same amount of time, right? Then will an APS-C camera be as noisy at ISO 1000 as a full frame camera would be at ISO 1500? *Assuming they are both the same resolution and use the same lens*

[@FilmmakerIQ]

Nope, resolution relatively unimportant (it puts an limit on the depth of field but that's at the extreme end) Given the SAME focal length lens and f/stop - the smaller sensor will have shallower depth of field. You actually prove this every time you punch in to check your focus.

[@matthewwilkes6065]

if i could like this twice i would. brilliant demo, keep up the fantastic work john.

[@tomronstone]

Why, at 09:00 does our depth of field start becoming shallower at our 'far' measurement than at our 'near'?

[@FilmmakerIQ]

Tom Ron TV your question doesn't make sense. The near and far are the limits of what we could consider acceptably sharp

[@tomronstone]

I get that bit, and I understand that it is somewhat subjective because it is just what we consider acceptable, but I was surprised to see the 'near' measurement become further from the focal plane than the 'far' measurement is from the focal plane in your final 2 tests. I got the timecode a little wrong in my original message (should be 9:34), but here is a summary of what I mean: ‘Far’(F) - ‘Optimum’(O) - ‘Near’(N) measurements | their respective distances from the focal plane | and F relational to N: 3:14 : F=23, O=20, N=17 | Far=3, Near=3 | F=N EQUAL 3:56 : F=30, O=20, N=16 | Far=10, Near=4 | F>N GREATER 4:35 : F=16, O=12, N=10 | Far=4, Near=2 | F>N GREATER 4:47 : F=25, O=19, N=16 | Far=6, Near=3 | F>N GREATER 9:12 : F=30, O=18, N=11 | Far=12, Near=7 | F>N GREATER 9:34 : F=21, O=18, N=13 | Far=3, Near=5 | F

[@FilmmakerIQ]

Okay I see your question now. Good point - I probably should not have even notated that the focus was at 18 inches because that may not have actually been true - it may have shifted as we changed cards. The errors you see here are a matter of not having precise tools to measure these distances and measure exactly when things hit the edge of the pixel... So I wouldn't put too much stock in precision there. But the ratio between near and far is going to go from about 1:1 ratio when really close to the camera to 1/2 the focal distance all the way out to infinity when you hit the hyperfocal point.

[@tomronstone]

Filmmaker IQ OK, thanks

[@themustang181]

This is the first video I've seen of yours and it was so interesting! I know it's a little older at this point but very relevant as I just bought the Panasonic GH5. I'd love to see a video (maybe just a quick one) about how using lens adapters like the metabones affects the image, and how to calculate equivalency. (which I know you said not to worry about as much, but it helps when purchasing new gear and you're used to a different size sensor) I think you'd do a good job explaining it :)

[@FilmmakerIQ]

It's really simple with the telecompressors like the metabones. You just multiply the compression factor into the crop factor. So a 0.64 Metabones Speed booster would make your GH5 have a crop factor of 1.28 instead of 2.

[@themustang181]

Filmmaker IQ gotcha. One more question, for native MFT lenses, you double the aperture to find the full frame equivalent. When using say a canon EF lens and the adapter, does the same rule apply? That's more what I was getting at. Should have specified. Thanks for the reply though!

[@FilmmakerIQ]

+Tyler Penrod: the crop factor math applies regardless of what type of lens. A 50mm EF lens has the same magnifying power as a 50mm MFT lens. The only difference is how much sensor they are designed to cover. When using a telecompressor like the metabones, you would no longer double it but multiply it by 1.2 or 1.4 depending on which speed booster you get. You may also want to check out this video for more basics on lenses kzbin.info/www/bejne/eXiqhot3gtGcp68

[@michael29913]

I love your videos. How do you use the focus chart?

[@hubertvermeersch3049]

indeed a wonderful teacher, respect

[@SamLovesMovies25]

Hey you know what I think would be really neat to see on the show is a lesson about the history of animation. Maybe you'd consider doing that if you would be interested? :) I love all your lessons though, they really do help me gain a better understanding of how film/cinema works.

[@DawRoStudio]

excellent examples and explanations! Congratulations for your work!

[@IndieFrames]

Fantastic video! However, I've got one question: How would the DOF of APS-C compare to FF when using an APS-C 50mm lens (EF-S, Super 35)? Would it be shallower than the one used on the full frame? Same aperture settings of course, since there's no crop factor...

[@FilmmakerIQ]

+Independent Frames The only difference between an APS-C lens and a Full Frame lens is the light circle it puts down - if you put the APS lens on the FF, you will get vignetting because the light from the lens only covers the smaller sensor. Other than that the focal length measurement and all the stuff we talked about behaves exactly the same as a FF lens.

[@IndieFrames]

+Filmmaker IQ Ah alright, thanks. Now I get it. So the bokeh would look pretty much the same like the FF.

[@FilmmakerIQ]

+Independent Frames If you took an APS-C camera - put on a 50mm Full Frame Lens and then swapped out with a 50mm APS-C sized Lens - they should give you identical pictures.