Mathew Collins Posted June 18, 2017 Share Posted June 18, 2017 (edited) Hi, Is there any relationship between Sensor/Film size and depth of field? The following video says, Sensor size has an effect on the depth of field. -Mathew Collins. Edited June 18, 2017 by Mathew Collins Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 18, 2017 Author Share Posted June 18, 2017 (edited) Adding to the above question, a document "Sensor Size and Field of View of the Primo 70 Series of Lenses" in the following link says, http://panalab.panavision.com/panalab-reference-library?page=4&title=&field_document_tags_tid[0]=228 Sensor size has no effect on the depth of field. A 21mm at T2.8 will always be a 21mm at T2.8, whether it’s on a 70mm camera, a Red Dragon, or a Super 35 camera. However a 27 mm on a Red Dragon will give you the same Field of View as a 21 mm on Super 35, and using a longer lens gives you less depth of field. So at the same camera position and with the same framing, a filmmaker will get less depth of field on a Red Dragon than on Super35, but only because he has to use a longer lens. Please provide your views. Edited June 18, 2017 by Mathew Collins Link to comment Share on other sites More sharing options...
Dan Hasson Posted June 18, 2017 Share Posted June 18, 2017 While sensor size/film gauge affects your DoF, there are of course other factors to what affects it - distance from the subject, t or f stop, focal length, light & composition. But then your t or f stop is affected by you cameras/film ISO. But the wikipedia page can help explain it a lot about DoF for you: https://en.wikipedia.org/wiki/Depth_of_field Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 18, 2017 Author Share Posted June 18, 2017 While sensor size/film gauge affects your DoF, there are of course other factors to what affects it - distance from the subject, t or f stop, focal length, light & composition. But then your t or f stop is affected by you cameras/film ISO. But the wikipedia page can help explain it a lot about DoF for you: https://en.wikipedia.org/wiki/Depth_of_field Thank you Dan. I am aware of the factors distance from the subject, t or f stop, focal length, light & composition. Link to comment Share on other sites More sharing options...
Robin R Probyn Posted June 18, 2017 Share Posted June 18, 2017 Man.. that dedo video is one of the weirdest Ive ever seen.. that voice !!.. and all the rubbish info.. ? its like a piss take xmas video.. Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted June 18, 2017 Premium Member Share Posted June 18, 2017 Not just focal length, f-stop and distance focused affect depth of field, but also the Circle of Confusion figure used. A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure. However in general larger formats have less depth of field when you match field of view, f-stop, distance focused to a smaller format because you have to use a longer focal length on the larger format to achieve the same field of view as the smaller format. 1 Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 19, 2017 Author Share Posted June 19, 2017 Not just focal length, f-stop and distance focused affect depth of field, but also the Circle of Confusion figure used. A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure. However in general larger formats have less depth of field when you match field of view, f-stop, distance focused to a smaller format because you have to use a longer focal length on the larger format to achieve the same field of view as the smaller format. > A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure. Not able to understand the this part. Link to comment Share on other sites More sharing options...
Premium Member Mark Kenfield Posted June 19, 2017 Premium Member Share Posted June 19, 2017 Imagine that you're framing up the EXACT same image with two separate formats, the first version is with a 50mm on a S35mm sensor at T/2.8, and the second is with a 25mm on a S16mm sensor at T/2.8. The composition of your images is identical, but the S16mm image has a deeper depth of field because (in order to achieve the equivalent field of view) you're using a wider lens. Link to comment Share on other sites More sharing options...
Gregg MacPherson Posted June 19, 2017 Share Posted June 19, 2017 (edited) Mathew, I think getting a feeling for the field of view relative to the frame size is the key to being intuitively comfortable with this issue. EDIT: I was was going to quote David to pose that..... Edited June 19, 2017 by Gregg MacPherson Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 20, 2017 Author Share Posted June 20, 2017 Imagine that you're framing up the EXACT same image with two separate formats, the first version is with a 50mm on a S35mm sensor at T/2.8, and the second is with a 25mm on a S16mm sensor at T/2.8. The composition of your images is identical, but the S16mm image has a deeper depth of field because (in order to achieve the equivalent field of view) you're using a wider lens. Thank you Mark. What is the meaning of "so you have to use a more critical Circle of Confusion figure"? Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted June 20, 2017 Premium Member Share Posted June 20, 2017 https://en.m.wikipedia.org/wiki/Circle_of_confusion https://www.cookeoptics.com/techdoc/9D03B7A06B44885385257BB40054DA06/Depth%20of%20Field%20Explained-F&DTimes%20June%202006.pdf https://books.google.com/books?id=uyMYMbjheqgC&pg=PA275&lpg=PA275&dq=circle+of+confusion+for+16mm&source=bl&ots=UOmOYhYlgo&sig=TMvMf81zGXcRAilywYtB84VKJe4&hl=en&sa=X&ved=0ahUKEwiIoYWjj8zUAhVKcj4KHT4gDX8Q6AEINjAF#v=onepage&q=circle%20of%20confusion%20for%2016mm&f=false http://www.dofmaster.com/cinematography.html Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 20, 2017 Author Share Posted June 20, 2017 https://en.m.wikipedia.org/wiki/Circle_of_confusion https://www.cookeoptics.com/techdoc/9D03B7A06B44885385257BB40054DA06/Depth%20of%20Field%20Explained-F&DTimes%20June%202006.pdf https://books.google.com/books?id=uyMYMbjheqgC&pg=PA275&lpg=PA275&dq=circle+of+confusion+for+16mm&source=bl&ots=UOmOYhYlgo&sig=TMvMf81zGXcRAilywYtB84VKJe4&hl=en&sa=X&ved=0ahUKEwiIoYWjj8zUAhVKcj4KHT4gDX8Q6AEINjAF#v=onepage&q=circle%20of%20confusion%20for%2016mm&f=false http://www.dofmaster.com/cinematography.html Thank you David. My question is not 'What is circle of confusion?' but 'more critical Circle of Confusion figure' Link to comment Share on other sites More sharing options...
Mark Dunn Posted June 20, 2017 Share Posted June 20, 2017 Thank you David. My question is not 'What is circle of confusion?' but 'more critical Circle of Confusion figure' "Critical" is a common English word. Here it means smaller. Link to comment Share on other sites More sharing options...
Robin R Probyn Posted June 20, 2017 Share Posted June 20, 2017 When my wife uses it.. it means small and alot more.. Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 20, 2017 Author Share Posted June 20, 2017 "Critical" is a common English word. Here it means smaller. Does that mean 'small Circle of Confusion figure'? But my understanding was 'critical=urgent'. Link to comment Share on other sites More sharing options...
Brian Drysdale Posted June 20, 2017 Share Posted June 20, 2017 (edited) Here are the meanings of "Critical" 1.saying that someone or something is bad or wrong: 2.of the greatest importance to the way things might happen: 3.giving opinions or judgments on books, plays, films, etc.: 4.extremely serious or dangerous: In this case I suspect, the meaning is the the second, in referring to the image in the smaller format appearing sharp requires the use of a smaller tcircle of confusion because of the greater magnification.. Edited June 20, 2017 by Brian Drysdale Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted June 20, 2017 Premium Member Share Posted June 20, 2017 Yes. Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 26, 2017 Author Share Posted June 26, 2017 (edited) Thank you David and Brian. I am trying to understand it. Edited June 26, 2017 by Mathew Collins Link to comment Share on other sites More sharing options...
Premium Member Adam Frisch FSF Posted June 26, 2017 Premium Member Share Posted June 26, 2017 Depth of field remains the same regardless of focal length as long as the aperture and image size stay the same. Longer lenses do not shorten it, it just appears so because the background gets more magnified. Link to comment Share on other sites More sharing options...
Kyryll Sobolev Posted June 26, 2017 Share Posted June 26, 2017 (edited) matthew think of it this way. theoretically (for lack of better term) sensor size has no effect on dof practically, however, it very much does say you have a lens on a 16mm camera then mount that lens to a 8x10 camera, or project it onto a 111'x32' plane what happens to dof in those cases? nothing happens. it remains the same but, practically speaking, there is no sense using a 16mm lens on larger formats, you will just get vignetting. so you use a longer lens, or one that covers the larger format, and as a result, you end up with less dof. Edited June 26, 2017 by Kyryll Sobolev Link to comment Share on other sites More sharing options...
Mathew Collins Posted June 27, 2017 Author Share Posted June 27, 2017 matthew think of it this way. theoretically (for lack of better term) sensor size has no effect on dof practically, however, it very much does say you have a lens on a 16mm camera then mount that lens to a 8x10 camera, or project it onto a 111'x32' plane what happens to dof in those cases? nothing happens. it remains the same but, practically speaking, there is no sense using a 16mm lens on larger formats, you will just get vignetting. so you use a longer lens, or one that covers the larger format, and as a result, you end up with less dof. Just comparing this with David Mullen quoted on Jun 18th, "A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure." Can i put it in this way? If i am planning to project an image which is shot in 16mm onto 70mm format, image being enlarged so we would use use small circle of confusion while shooting in 16mm. Link to comment Share on other sites More sharing options...
Brian Drysdale Posted June 27, 2017 Share Posted June 27, 2017 The small circle of confusion remains a requirement on 16mm, regardless of going onto a 70mm release. You may even become more demanding, by only selecting the sharpest lenses, if it's being shown on larger screen. Link to comment Share on other sites More sharing options...
Kyryll Sobolev Posted June 30, 2017 Share Posted June 30, 2017 Can i put it in this way? If i am planning to project an image which is shot in 16mm onto 70mm format, image being enlarged so we would use use small circle of confusion while shooting in 16mm. whatever format you are shooting on, use the known CoC values for that format (or plug in your own ones) to calculate dof while you are on set what happens to the shot material after is a different story - you can project it to youtube or imax screen if you like Link to comment Share on other sites More sharing options...
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