I am a graduate student of mathematics and the only thing I understood from this mathematical video is, to blur the background - 'subject near, background very far'!
I liked the other video about long exposure but this one is like the worst. I'm an engineering student, and didn't understand anything. You talk way too fast and don't explain how you get to your numbers... Also the music is very annoying.
he's telling you that it's more of a guesstimate thing and not exact, if you have a focal length of 100 mm then you'll have 2/3rds of that behind the focal point in sharp focus
+Shane Irving if he is using guessitmate how did he come to give measurements like 30.07m DoF( refer 5:14) . This tells us that he is resolving to the nearest 100th of a meter= 7cm ! over 30 meters..that's not a guesstimate ...
+Saranporn Panruksah because it changes for every lens..... DOF calculator and shit like that dont work... they're made for particular lenses and all lenses are different...
+Saranporn Panruksah Good question and acctually DOF calculator works, it takes a bit of time and patience to figure out what is it all about but it works :)))))
Wow Matt thanks so much for your videos, very easy to understand. I am very new to photography, in fact I just got my first DSLR yesterday. Nikon D7000 with a 18-105mm f3.5/5.6G and a 50mm f1.8d (they came with the kit) and a tripod. Very excited to unleash my creative side of me and your videos are going to be a big help. Thanks
I like your video..but I think it's tooooo fast... everyone scratch their head to understands how you get those numbers. Is there any computing trick that you get them so fast like that? Please share. Thanks.
There's an awesome iPhone app with a DOF calculator built-in called Photo Pills. It also has a ton of other useful features for photographers. Definitely worth checking out.
gud vid This is the problem with many they dont realize the math and figures in using the equipment.When you go through a lens manual they can sometimes be more pages than the camera manual itself.Focal length is one of the biggest people dont understand.Once you master you see the difference.The problem is consumers make cameras entry level and compact cameras to just point and shoot.There are reasons professionals are in the game and yes charge £$£ there is work load edits and earning a living
As much as I love your videos (being a complete newb to this), this was way to fast for me. I could not follow how you were determine the total DOF, or what the math was behind it.
This is a great information Matt. Isn't it true that that farther we go away from the subject, the lesser the details will be? Any simple formula to get this DOF on the spot?
It would be interesting to see a practical demonstration of this. I get the theory, but I still find it a lot quicker to take three different shots at different focal distances. I mean: how do you focus 10m into something where there is nothing to focus on (like between the river and the mountain in your drawing)?
That is not an answer, sorry. What is the calculated relation between the aperture, focus lenght, and focus distance? I do not get it, the focus distances are falling out of the sky?
Nice video, but you really should have left out all those precise numbers and calculations you were using. It made it seem like there was a basic formula that was being used when clearly there isn't. Don't know why you did that really - just confused everyone.
"Yes, thank you, Data!" Jeesh... talk about information overload! lol All great info and very useful, but I think I'm going to have to return to this video over and over to let the info sink in. I'm not a young man any more, and I'm not sure I could even have taken all of this in, with a single viewing, when I was... But, I really appreciate and recognise the value of this video! Thanks, and see you again (many times over) soon! :)
How do you focus somewhere into your river if there is nothing but water(or is it wawda) . Is it a good technique to focus on the near edge of the river and walk a few meters forward, stopping just BEFORE the near edge of the river is out of focus, so that your focus point is somewhere in the river?
Thank you very much Matt. This was fantastic, super easy explenation ;) Now I can say: I can handle DOF in any situation :) Keep going, You're doing great job. BTW. Any chance for your workshops in the UK?
Thanks for the video. You could be a little slower so that everyone could follow you! - You are way too fast to follow the figures you are writing and I had very little time to think how you calculated those values...
Unbelievable how many people could not follow your math. They are so closed minded, they missed the process. Everyone should just chill, the math is correct. Follow the process, Matt explains exactly what he is doing. If you miss the 1/3 and 2/3 concept, you will not understand any of the rest of his explanation. The more you shoot, the more natural this method will become. The math is only an explanation of the process and it would be good to travel down that road a few times to see the actual relationship. Slow the video down and stop it when you need time to absorb what Matt is explaining. Great Job Matt. This is not for everyone, but it does make DOF and aperture easier to understand. Some just need to open their minds long enough to let the light hit the sensor.
@squamishscepter great stuff - congratulations! And welcome tot he channel. Check out the playlists - there are lots of videos that may be helpful. I'd love to see some of your work on our flickr and facebook groups too.
@mssissyphancypants your's is the best advice yet! Yes - so many what everything handed to them - there is certainly great value in discovering or 'getting' something on your own, rather than being spoon fed it and never putting it into practice. I hope everyone is out there playing, practicing and advancing their skills.
I think we were all expecting some sort of equation. The only one we got was, 85mm + 3m = 10.3cm I'm pretty sure that isn't correct. maybe there's a variable missing? then again, I live in america and we're on that retarded Imperial unit of measurement, so it may just be me...
It really is simple. It's just a matter of not over thinking it. If my son for example is standing in front of me, and there is a mountain way behind him and I'm using a small aperture, the mountain will be blurry. However, take that same aperture and focus on the mountain...different effect. Try this in your houses. Stand in a doorway and focus on a door jam and look into a room, blurry. Now, just change your focus (not the focal length/zoom or the aperture, just the focus) to the back wall.
I have a question that No one I ask seems to know.... If the opening on the f-stop(aperture) is smaller then the sensor, How does the image fill the sensor? Is the image magnified once it passes through the aperture opening to fill the sensors larger size? Does the image not fill the sensor size physically?
ZibZab I found this a bit puzzling as well.. As far as I know there is another convex lens behind the aperture mechanism that bends the light to fill the sensor.
+ZibZab I'm not sure I understood your question properly but I'm gonna try to answer to what I think you asked. The light doesn't enter straight in the lens. By saying that I mean that when you take a picture of someone, the head area (top of the picture) goes diagonally in the lens and hit the bottom of the sensor. So the image has to go through the center of the lens no matter what. And that obviously apply for the entire picture. So the bottom goes through the middle of the lens and hit the top of the sensor, left goes to right, right goes to left etc etc... Like the human eye. So lets say that the iris goes tighter than what it is suppose to (which I dont think can happen) then you would start to see the blades of the diaphragm in the frame. This is why the blades in a lens are close to the mount. You probably noticed that long focal length lenses have larger f-stops than regular lenses, and this because the longer your focal length is, the less light can enter in with an angle (logic, it has to enter from the front element of the lens, which is for example 77mm wide and 20, 30 or 40 cm away from the sensor. So your diagonal lines still have to cross each other right in the middle of the aperture whole, but are just straighter, which allows the diaphragm to close smaller without getting in the way of those lines. And so, the size of the diaphragm doesn't affect the size of your image. I hope I was clear, and I hope this is the correct explanation.
so, shooting landscape with f2.8 (esp at night) is ok, as long as I place the focus point 1/3 into the area of interest? Wouldn't the edges be blurry at lower aperture? need to play with mah camera moar to figure that one out. :D
Thank you for the effort done in this video but in fact I didn't get anything concerning the math upon which you calculate what's in focus or not in relation to the lens focal lens. I understand that rule of 1 third: 2/3thirds though. I wish you could clarify that. To be more clear, does the lens mm size affect DOF? What's the rule to calculate that? Thanks again
DOF is calculated based on 3 variables: 1.Aperture, 2. Focal Length, 3. Camera to Subject Distance. There is also a 4th, sensor size due to Circle of Confusion, but this has very small influence so it can be left alone. The reason you were able to shoo the 4 row portrait at 2.8 was the focal length. Same distance, same aperture at 200mm will have only the bride in focus and 3rd row really blurred. Aperture is LEAST important when thinking DOF. Focal length and camera distance ...
I think the point of this isn't to understand the math behind it, but rather that close subjects will have a shallower dof, compared with focusing on something far away will give you a much larger dof. Thanks, Matt.
Hello, 1st VERY INFORMATIVE tutorial. can u please make another one explaining with DRAWINGS, how the angle of the camera affects DOF, or if you move the camera to right or left, keeping the same object in focus... PLEASE! Practical examples would be very appreciated :'(. 99% of tutorials about DOF tell "short f. short DOF, long f. long..." and that's it, nothin'about distance, focal length, AND until nowNONE about the position of the camera, how this affects the DOF. U've made me 50% happier!
Far bettter video than just comparing different lenses ... I do sometime enjoy those too but thus is far better Thanks.... I would suggest adding a small demo of how hyper distance scale on the lens explains this.... i love my old zoom lens which has good scale of DOF with aperture .... It helped me too much.. Thanks for this video .. good stuff... cheers..
Great video very valuable information however, if you could please be a little more clearer on the values for example at 3:33 min of your vidoes where you exlained about the group picture.. I would like to know how did you derive the value of 3.19 M and 50.15m. could please simplify the value conversion, thanks a lot
Many people ask for a formula...well, apart from the fact that the formula is rather complicated to be calculated on the spot, there are many ios and android (some free, some paid) applications which calculate this very fast. Just do a search on app store for "dof calculator".
The math is half wrong. If camera's focal point is 6 meters from subject, the nearest depth of field is 3 meters (you are correct). However, the farthest depth of field is twice that distance or (3 meters x 2 = 6 meters + 6 meters = farthest DOF) 12 meters from camera and not 50 meters. So total depth of field is 3 meters near plus 6 meters far for total depth of 9 meters ( not 47 meters).
Your comments made sense about the 1/3 before focus point and 2/3 after - but your numeric workings out confused me - and im good at maths! Can you explain how you are working these out either in the video or in the text thanks
Hi Matt. Thanks for you videos! I have question for you about DOF. DOF calculator shows that on: Focal: 50mm Distance : 1m DOF: 0.05 m I use have crop sensor 1.6 50mm -> 80mm Which focal distance should I use to calculate DOF? Thanks!!!
f2.8 on landscapes : ouch ... wide open most lenses display their weak side f50 on macros : ouch ... f50 creates massive diffraction sorry, but those recommendations are not really helpful for beginners.
@001hoekie There's an app for that. Check App Store/Android Market/Marketplace and you will find several alternatives. That way you always have it with you, if you have a smartphone that is...
Hey Matt. Can you take us through a quick way to do the maths in our head for DOF. If I am taking a portrait and need say a 20cm DOF. I am 1m away then what should my focal length be?
I have downloaded an app that calculates the depth of field. In this app you also have to give the camera body that is used. What influence does the camera body have on the DOF distance?
Oh my God Turn off this stupid music. It's like I am trying to learn something against the clock. Instead of me understanding what you are saying, I am worried about how long it's taking to listen. it is not conducive to understanding.
Absolutely nothing explained here. The 'gives you this value point...' is never explained how OR why as you present that. The George Jetson music does not help at all... Thank you for the attempt, but, try again mate...
How are you calculating DOF ? Seems like you're just pulling the DOF numbers out of thin air. Are you using a lookup table that provides the DOF or are you using some equation ??
Who are you, who are so wise in the ways of science? Excellent explanation, the math isn't that difficult at all, but the only way I know to get an accurate measure of the distance to a far object is perhaps to use a rangefinder. Is guesstimating good enough in this case for something far like a waterfall or a distant building?
I know it was like my college physics professor stating Maxwell equations were simple. That was only true if you if you were fairly strong with derivation, had a solid grasp of line integrals, partial derivatives, and were comfortable with Ampere, Gaussian, Faraday, Ohms and the constitutive relations. Sheesh no wonder I dropped the class after my 2nd c- on the second pre midterm quiz. ha ha. I am sure this presentation was very clear and simple to you but not us optics novices.
I've got to admit that for the first time you've got me totally confused. It's not the first time I've been confused, but it's the first time one of your tutorials have left me that way. I understand that the further away an object is the deeper your depth of field will be a round that object, but you seemed to suddenly use random numbers, how do we figure how much we have to work with?
Thats very interesting Matt, but what I would like to ask is where can I get those info to be able to figure out the math myself, as you do in the clip? I guess a chart or something similar Sorry if already answered but on phone not read previous comments
1:36 That 1/3 2/3 rule is an approximation for typical distances. In reality if can vary from infinitely close to 1:1 to infinity beyond the focal point. The only exact rule is that there never is more in the front.
I really don't understand the relationship between distance and deep depth of field using a telephoto vs a wide angle lens. Shouldn't the wide angle lens with an open aperture give a shallow dof? I see it when I do it myself, but I don't understand what is at work making it happen.
The best explanation I’ve seen to date, love this guy, he’s like your best mate and boy does he know his stuff! Art should never be just about the numbers and Matt really gets that.
This is bang on. I have a DOF app, which I used to follow Matt's calculations and they're spot on. The important thing is to know the distance from the camera's focal plane to the subject. I use a tape measure and the rest just falls into place. I also use a light meter and shoot to the right too. If you want to be a photographer you should learn the craft otherwise you're a snapper who hopes the camera will work everything out for you.
As a murrican guy i usually relate to distance in other measures like yards or feet or miles. Meters and centimeters might as well be Greek. Guess I'm gonna have to take a crash course in metrics.
