Focusing on Depth of Field and Lens Equivalents
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- Опубликовано: 7 сен 2024
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How much space in front of the lens will be in focus? That question defines Depth of Field - but this simple concept has lead to a staggering amount of confusion in today’s multi-format camera environment. Through some fundamental scientific demonstrations, we will clarify concepts like circle of confusion and lens equivalency.
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ERRATA
The ISO in regards to Lens Equivalents should be multiplied by ISO^2 because we're dealing with two dimensions not just one. Multiplying by just the ISO will result in slightly darker image (as see in the demo)
Some people have jumped to the conclusion that the Circle of Confusion is the Pixel Size. The CoC is LIMITED by the Pixel Size in that it cannot be smaller than the pixel size, but in most cameras the pixel size is much smaller than the CoC (or at least by a standard CoC that calculators use for determining depth of field). This explains why a Full Frame 12MP camera will have the same DoF as a 50MP camera. But if you enlarge the photo enough, eventually you will be able to see more detail in the 50MP image which less of what looked in focus in the 12MP image will actually be in focus.
Some people have commented that the video is a bit soft... when I'm large in the shot, it does indeed look soft - when I'm shrunk down, the video looks sharp. The lens has not changed - only the magnification of the image. This is a very real analog to what's happening in smaller sensors - when a small sensor crops in you can see better detail and it looks soft, when captured by a full frame, the image looks sharp. Therefor smaller sensors (given all other factors equal) have a shallower depth of field.
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 :)
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.
This is so true. I've been studying film production for 3 years now and nobody ever explained to me this so didactically.
Photoshop Tutorials | Photo effects impactguru.com/s/uxZ0zQ support us donate
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
yikes
This is one of those videos i regularly come back to watch...
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.
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 :)
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).
It's a straight multiplication, not taking in consideration of stops. So 2*f/4 is f/8
mr john: i really really appreciate your fast answer. So the four cases ( focal, focus, aperture and iso^2] are straight multiplication
Focus does not change. Remember these are equivalents... What would be the equivalent on a full frame sensor.
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!!!!
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
Yes it is... it is an apples to apples comparison. it's just different which apples you want to compare.
@@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?
RUclips 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
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.
Thank you! After all these years... I never realized that crop factor effects *everything*, not just "equivalent" focal length.
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.
Brilliant! Kubrick would be proud. He was obsessed with tack sharp images.
As usual, fantastic stuff. Personally, I love the in-depth coverage - sent many a person over here when they have questions. Thank you.
Kevin - The Basic Filmmaker impactguru.com/s/uxZ0zQ support us donate
Finally somebody who knows and explains the subject very well not is not from the manufacturer side(who wants to market us).
This is seriously the best video on DOF and sensor size in the world.
"I can see clearly now" ...... Thank you Mr Hess for this sweet video! I love the work done on this channel!
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 :)
+victorbart Not sure what the other way is, but this is the right way :P
+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).
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.
+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.
+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.
Your videos are amazing and every photographer should watch them!! Wonderful explanation!! :)
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.
All your content is superb, but you went to even greater heights with this one.
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!
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.
Your last point is the best summary. It is not about the sensor size, it is how you shoot.
I'm so happy every time you upload a video that I thumbs up it within the first couple of seconds.
I'm not even involved in filmmaking. I just watch this channel because the videos are extremely well made and entertaining
NIce Shining reference on the sample photo.
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.
+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!!
+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.
+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
+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.
+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.
Your method of teaching is insanely solid John! I think im going to use your stuff to start off some ACs!
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.
Watch our forced perspective video for more on perspective distortion ruclips.net/video/pl4ah_HvWkg/видео.html
Perfect explanation! :)
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!!!!!
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
This is great! The visuals are a big help (cameraman banging his head on the keyboard was hilarious) Thanks!
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.
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
I won't go to film school. I just watch all your videos :)
Ironically this is the first tutorial you've ever made which is out of focus. ;-)
+Symon Says TV I noticed that too, glad to know it wasn't just me. I wholeheartedly believe he did it on purpose.
same here, hope this was on purpose.
its the nature of the subject material...circle of confusion
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
Have just watched 10 seconds and already know it's gonna be something great! ;)
I know im like 5 years late to the party, but I love how you used the Stephen King theme while explaining.
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!!
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!!!
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. :)
+DAVIDSDIEGO He's always been the caretaker..
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)
somebody give this man a tv show
great info. best channel on YT. j.
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.
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.
🇨🇦/🇺🇸... 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!!! 🤔
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.
I wish I had stumpled upon this video (and channel) in 2016. Thank you sir! Very plain language, beautiful demonstrations 😊
Just fantastic video, explaining this whole concept with good examples.
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.
You are magnificent, I've been so confused about focus vs depth of field for so long
Best explanation for this subject ever!!!👍👍👍
Thank you for these videos! They made me see the process of 'taking a picture' in a whole different perspective. Keep doing these videos! :)
Thank you so much again. Best on RUclips truly.
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!
+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.
+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. :/
+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.
+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
+Fyodor Chernych Are Nolan, Abrams & Tarantino hipsters cause they shoot on film?
Finally I came somewhat close to understanding this topic.
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.
Yup, three years late! But this has just provided an easy to understand explanation for me about how number of pixels and sensor size affects DOF. Thanks! BobUK.
Careful, it's not really number of pixels...
Your practical examples with the magnifying glass are just insane! Thanks a lot for the video, helped my life out, hahahaha
Another great video! This one had to take a while to make! Thanks!
Great explanation
This was super, thanks John.
Can't wait for your paid photo and video courses. This is too good, to be free!
Loving that Overlook Hotel carpet!
I don't understand yet. I don't have a DSLR just a phone but I guess this is a good start before sinking my hard earned cash on expensive gear. I like the math, the explaination and examples in this tutorial. Thank you!
This single video could create peace on Earth if all photographers watched it. 😁
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.
I've started to shoot 4x5 and it's so fun but intimidating
@@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.
if i could like this twice i would. brilliant demo, keep up the fantastic work john.
Excellent again! Familiar stuff, but great demonstrations! Thank you
Great content!! Tnks for all the support for the photography community!!
Love this video. But love that carpet from the Shining the Monkey is sitting on.
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!
+Jon Roop If you're asking about Color Grading - we do have a introduction to color in the digital realm:
ruclips.net/video/v7MdPJqEOU4/видео.html
+Filmmaker IQ I mean more of cleaning up dirty film and making it look so crisp and clear
Jon Roop Oh like Restoration? Yeah that's something we'd definitely to look at one of these days :)
+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 :)
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 :)
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.
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!
+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 ruclips.net/video/CGGUXAMliqM/видео.html
John Hess, thank you for an awesome demonstration.
So tired of hearing and reading made up stuff about sensor size.
Yes, they are DIFFERENT and that's all. Matisse's brush strokes are indeed different from Sargent's - which makes neither better.
I still prefer my full size sensor. But that's only because I know my lenses so well from when I was shooting stills with my film camera in the late 90's. I do have a T3i with the APS-C sensor so I have both. Speaking of the APS sensor. It took me awhile to figure out. That the sensor is 24mm. the same as the film from the Advantex photo system from the late 90's. Hence the name APS. I had a point and shoot APS camera to try it out in the late 90's. It was overrated.
You can get pretty similar results from a FF Camera as you can get from a MFT but not the other way around. Just stop down the aperture 2 stops and raise the ISO by a factor of 4. One is a limited version of the other. When you want additional options like low light performance and bokeh bigger is better, or at least has more capabilities. It is for you to decide if the drawbacks of a large sensor regarding cost and portability of the gear offset the flaws of a small sensor. If you are shooting handheld at f/5.6-f/11 (FF) all the time and do not intend to print big then MFT is the better choice for you.
kirkelicious This really is the key. What is demonstrated here to create an equivalent image between the two cameras is to modify the aperture and ISO of the full frame camera - effectively trying to match the standard of the APS-C image. But now let's try to do it the other way around: take the APC-S image and modify the aperture and ISO to match the full frame image. Oh wait, your f-stop is already as wide open as it can go and you can't reduce the ISO below its base setting? You're screwed. And that's why simply relying on physics - while useful in helping others understand the process behind the numbers - isn't very applicable in the real world.
Essentially, what this video is really saying is that smaller sensors are no worse than larger ones - as long as you can shoot at f/0.4 and can set your camera's ISO to 25. Or, like you've said, only if you ever shoot at f/8.0 with your full frame camera. Sure, physically that's true. Too bad nobody shoots like that.
There are a lot of people who shoot f/8 on a full frame. When I got over fetishising bokeh like an amateur I was amazed by what shooting stills at f/8 opened up. For motion I tend to stick around f/4 but then I'm using an APS-C sensor.
Filmmaker IQ When you say things like "when I stopped over-fetishizing bokeh like an amateur," you're speaking from a place of feeling as opposed to fact and you lose all of your credibility. The aesthetic characteristics of bokeh are admittedly subjective (and I conceded that in a different reply), but to take the other extreme and dismiss the preference for shallow depth of field as amateur is ridiculous. It's a completely valid storytelling tool used to draw a viewer's focus to the part of the frame where the filmmaker wants our attention. Having everything in focus all the time makes for a vastly more busy and scattered image - and again, one may consider this a style - but the greatest motion picture artists on earth have been harnessing shallow depth of field to incredible effect since the medium has existed. They do this even today, where technology has advanced to a point where increased sensor sensitivity and high-output, lower-powered lightning has greatly reduced the necessity for extremely fast lenses. You don't have to agree with my feelings about bokeh, but to dismiss shallow depth of field as "amateur" is beyond nonsense.
In the world of still photography things are slightly different, but your channel is called Filmmaker IQ, not Still Photography IQ, so that's what we're focusing on here.
You also conveniently ignored my point that larger-frame sensors can always be stopped down if you are trying to widen the total depth of field, but smaller sensors can't open up any more than the lenses will physically allow to reduce it. In other words, regardless of if you prefer wider or more restrictive depth of field in a shot, it is easier to accommodate either with a larger sensor. That makes it objectively better. Furthermore, in a small space, simply "moving back" is not always an option.
I appreciate your efforts to help educate others on different aspects of cameras and production, but don't start name-calling or getting on a soapbox and pretending that you're some expert in the field. You're just another dude on RUclips with an opinion. In fact, compared to the professional filmmakers actually applying these techniques on a daily basis - the ones who create the stories which move us, make us feel, and change people's perceptions about the world... the ones who win awards for world-class image capture and craftsmanship - I believe you are what is known as an "amateur." Good day, sir.
Thank so much, this is the best explanation about lens !
One more time you do it!!! Teach in a comprehensive way without made the class too basic.
I'm more a photography than a videography guy, but your vídeos aways have lots of knowledge to stills.
Thank You, Sir,,, I would say This is one of The most informative and well-presented videos
I have seen...
Thank you. I'm giving up on the idea of going to film school. Thank you so much.
Great explanations of very complex subjects. Very well done!
Really excellent video and explanation of equivalency and its implications.
I understand that the convention of identifying lens properties for a full-frame camera (as per the old 35mm format) is standard, however it is important that a purchaser understands equivalency when buying a lens. One place where knowledge of equivalency is useful is when someone is seeking a specific lens range for, say, a wide angle application. They might want a 10-20mm lens and they go and get one with those numbers marked on the barrel of the lens and the packaging. However, they have and APS_C camera so in fact they have purchased a lens with a FoV that is going to be equivalent to a 16-32mm lens - a very different animal. Again for someone seeking a fast lens with a low f-value, not realizing how equivalence impacts on a potential purchase for a crop camera could be frustrating.
In cases were lenses are produced specifically for a crop sensor, it would be more accurate to give them an equivalency value instead of the FF one. My thought is that there should be a measure like an "e-value" for focal length and f-value based on the equivalency principle.
I'm not a fan of printing "lens equivalences" on the side of lenses. The millimeter numbers the lenses are *not a property of format size* - they are are objective numbers of the property of the lens itself and DO NOT change whether you put them on a FF or crop or even a medium or large format camera. So that's the most accurate definition of the lens.
If I purchase a 50mm lens, it ought to be just a 50mm lens. Then I can figure out what that will look like on whatever format I end up shooting. Even if the lens is _designed_ for APS-C - I can still use it on a micro-four thirds. If you printed the REAL focal length of 50mm then it's just a simple operation of multiplying the crop factor to determine the "equivalent" - if you printed a "equivalent" say a *50mm equivalent* on APS-C, then I would have to learn a new crop factor if converting to MFT. I could do the reverse math and find out its really a 31.25mm lens and then apply the 2.0x crop factor for MFT, or learn the new crop factor of 1.25 to go between APS-C... You can see how this is going to devolve into an absolute mess really quickly.
No, just print the real focal length on the lens. If you want to put the equivalent in the manual or on the box - that's fine (so long as you carry out the equivalent f stop as well). A better "newbie friendly" measure might be a chart of angle of view with the lens with different formats (say 60 degrees for MFT and 120 for FF). But on the barrel itself should only be the real focal length numbers.
absolutely agree that the lens itself does not change it's physical properties in any way. But how it behaves changes with the crop factor. I have had so many discussions with people who took the numbers on the lens as read and were unhappy when their crop sensor camera didn't deliver what it said on the box. That is why I will be recommending your video! {:-)
Well it delivered exactly what it said on the box ;) They just don't understand how to read that number - there just needs to be more understanding of what crop factor means. If you're sophisticated enough to know that a 16mm is wide on FF, you ought to also know that a 16mm is going to be a medium-wide on a MFT.
Which is why did make this video - thanks for pointing them this way :) :)
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.
+paristo Very thorough comment - thanks!
I am still circling in confusion here although i do appreciate the time you took to explain this. Thanks a lot and will rewatch to try make it stick
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
Spot on facts, simply explained - You, Are, GREAT!!
Great information..!! But there is one way to get same depth of field on smaller sensors. That is by using Speed Boosters.
This is great! I've been seeking this kind of photography content.
Nice and funny Shining reference! :)
Nice work!!! The experiments are super interesting and show perfectly what you want to tell!!
That's some deep stuff guys, I hope the AF on my D3300 knows how to do all the maths and keep my out of these.
+Stavros VI your AF just finds the focal distance. All the math just describes the boundaries of the psychological effect of "depth of field"
Thanks, John. Brilliant videos.
Holy shit , this channel rocks. Great video. The multiplying/dividing the 1.4 to get the next stop or light was #GameChanger
excellent examples and explanations! Congratulations for your work!
I really enjoy your videos, you do a great job explaining things in simple terms and the historical anecdotes are great.
The depth of field explanation seems to be talking more about image matching between sensor standards rather than what actually affects depth of field.
You've explained very well the answer to the question, "How do I get the same depth of field between two different sensor standards?"
However, if the question is, "What elements of a camera affect depth of field?" does sensor size still really matter?
Thanks for the video.
+Christopher Lozano The first 10 minutes are dedicated to answering what elements affect depth of field - mainly aperture, distance, and circle of confusion ;)
Does sensor size matter? Yes: 10:20
:)
Sensor size does not affect focal length. The focal length and aperture does not change when you change the sensor... We talk about equivalents, but that does not mean the lens focal length changes only that it's equivalent to a different lens on something else ;)
The factors of depth of field are aperture, distance to the object, the focal length and the circle of confusion which is largely set by the size of the sensor.
Your videos are top notch. You should post your own work on here too.
Very informative video. I have just one small gripe: You're saying that you increase the distance to match the field of view, which is incorrect as the fov doesn't change. What you're matching is the magnification of the subject (monkey) in the frame. The foreground and background will look different from the full frame image because you're changing perspective as can be seen by how much is visible of the chair.
+AManWhoWasntThere That is correct - good point :)
John, you are awesome man!!! Thanks very so much for these lectures!
Thank you so much for making these videos mate. They are incredibly insightful and they make me better at my job ;)
Bloody awesome series, I hope you're getting some rep out of all this hard work
Awesome knowledge! Really helped me a lot.
Thank you for the very helpful video. Great explanation, and it surely helps me to put my mind to ease about my aps-c. I am always mad about the results I get, and looking for a full frame - but every website and blog announces the next best camera to come out soon, so I didn't made a decision yet. Seems like I dont have to.. or do I? here's the thing. I think that full frame is better, because of the wider field of view. let me explain and start with a practical problem. shooting indors sets a boundary to how distant I can get to the object. sometimes there is just a wall, and your 50mm is not wide enough, but you can't step back any further. The other way around - wider lens let's me get much closer to the object. and here is why I think this is important: the closer I can get to the subject, the better the resolution will be, thus the better image quality achieved. My assumption is derived from my eyes. you know, there are situations when you start reading shampoo bottles. to get that little text, you grab em and hold them closer to your face, because the eyes can't resolve details in the far. so is this true or not? does 50 on ff have the same resolution as 80 on crop? I can't test it, because I don't have both lenses or both types of sensors. And that's what most people deal with. We - the aps-c people, buy the same lenses as ff users, because there is no real equivalent gear out there, and because all the youtubers test and review them. So please enlighten me on this one: does the same lense perform better on one sensor, and second question, will give different, but equivalent lenses(settings), the same quality?
So the answer to your question is "no" - you don't get better resolution with distance to the object. You hold the fine print close to your eyes to so the fine print covers a wider angle of view - not because it resolves better.
My main work now occurs 100% on an APC Super 35mm sensor with a 18-80 F/4 cinema lens.
Regarding your question on does the same lens perform better on one sensor or another - no - a lens is a lens. Smaller sensors will need more precision in the lens design so a smaller sensor might be less forgiving..
@@FilmmakerIQ Thank you very much for such a quick reply. I'll let that sink in, and try to get my head around this topic. Awesome channel by the way, already watched two more videos in the meantime, and planning to go on all night. super fascinating and great teaching.
Both camps are correct. It just depends on which side you're on. Russians believe russian media, Americans believe american media. If you're a full frame user, if you want to replicate what the aps-c has taken using the very same lens, you simply crop the picture and it would have the same depth of field. ON THE OTHER HAND, If you're an aps-c user and you want to replicate what full frame (say 50mm 1.8) has captured, you cannot simply crop, you need to use a lens with a wider field of view, and that would be 35mm to account for the crop factor. And since it's a no brainer that 50/1.8 would have different bokeh to 35/1.8, you have have to use the crop factor and use 35/1.2 to get the same bokeh.
Thank you so much for this great video!
Excellent explanation.