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Camera Sensor


Sushanta Barman
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Based on what you said, I suppose you are referring to super 35 sensors. To that, I don't think s35 is the best anymore. Back in the film days, s35 film were used because it's a good balance between price and image. However, in digital, VV and 65mm cameras are becoming much more common. I used be loyal to s35 myself few years back, but after watching few pictures shot on larger format, I totally changed my mind. Alexa 65 or even LF shots is just at another level.

But to answer your question, the only reason I could think of to choose s35 is for lens compatibility, as most older (pre 2010) lens are designed to fit s35, so if you want to shoot on certain older lenses, you need to go s35. But even then, a lot of older lenses do cover LF or even 65mm even if spec sheet says otherwise. I remember thinking larger formats has no place when they were first released, because the lack of good lenses, but now days, some of the best lenses cover larger formats.

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35mm has been the standard "sensor-size" for over 100 years. Other film formats have been introduced, but the bulk of movie production has been on 35mm film stock.

So when transitioning over to digital from film, 35mm becomes a logical choice because its a size people are used to and there already exist hundreds of thousands of lenses designed to cover the format. 

The main desire at the induction of digital was to "match" 35mm, matching sensor size is one way to do this. 

We are seeing a movement to larger sensors (RED Monstro, Alexa 65, LF, Venice, FX9 et al) these sensors do provide better images then super 35, but require large format lenses (and right now there is less choice/availability).  Also LF needed faster sensors to allow for DOPs to stop down a bit more - T1.3 on a full frame sensor is less practical to shoot compared to a S35.

It seems that greater quality/resolution gains occur when you make the sensor bigger vs cramming more pixels into a S35 sensor - so I think full frame sensors are going to become pretty standard at the high end over the next few years.

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I just researched a piece about this and it is fascinating, and it's not even that obvious why it ended up being 35mm wide with a roughly inch-wide picture. Edison (or possibly his associate William Dickson) picked it for his Kinetoscope machines in the 1890s and it essentially stuck until the present day. It's not clear why they chose this geometry, but there's some suggestion that they were splitting 40mm film down to get to 1-3/8" (34.925mm) film, so they must have had a reason.

1890s Kinetoscope films were substantially similar to silent aperture 4-perf 35mm and that is fundamentally the film width we use today.

The height of the frame comes from the mid-century rush for wider frames to compete with television. I couldn't find where they got 1.85:1 from, but it was one of several that were tried at the same time. It stuck. 16:9 is four-squared by three-squared and extremely close to the arithmetic mean of 4:3 and 2.35:1 so might have been seen as a good general purpose format.

In short there is nothing special about these numbers. They all come from times when a lot of different things were being tried. What we got are the ones that stuck through commercial success or wide standardisation.

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Oh my dear friend, you cannot be more wrong.... 

 

There is no such a thing as best camera, best lens or best sensor size. 

 

Yes, The super 35 sensor are becoming pretty much the standard. But actually sometimes using a camera with a different sensor size is more suitable for you. For example Epics like "Avengers: End Game" or "The King" are shot in 70mm and 65mm because these sensors sizes give you more field of view. "1917" was shot by an ALEXA Mini LF that has a full frame sensor instead of ALEXA Mini that has a super 35 sensor because a larger sensor gives more depth of field. But  the TV series "Biggest and Baddest" was shot by using  cropped sensor cameras for the purpose of getting less depth of field. 

 

So yeah, your choice of sensor size depends on what you are about to shoot, and the 35mm sensors are not always your best choice.

 

 

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9 minutes ago, Abdul Rahman Jamous said:

Oh my dear friend, you cannot be more wrong.... 

 

There is no such a thing as best camera, best lens or best sensor size. 

 

Yes, The super 35 sensor are becoming pretty much the standard. But actually sometimes using a camera with a different sensor size is more suitable for you. For example Epics like "Avengers: End Game" or "The King" are shot in 70mm and 65mm because these sensors sizes give you more field of view. "1917" was shot by an ALEXA Mini LF that has a full frame sensor instead of ALEXA Mini that has a super 35 sensor because a larger sensor gives more depth of field. But  the TV series "Biggest and Baddest" was shot by using  cropped sensor cameras for the purpose of getting less depth of field. 

 

So yeah, your choice of sensor size depends on what you are about to shoot, and the 35mm sensors are not always your best choice.

 

 

Dear Friend .. you cannot be more wrong .. 😉 

Edited by Robin R Probyn
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Larger sensor gives you more field of view for the same focal length but all you have to do is pick a different focal length to match the  two formats' field of view.  If you shoot regular Super 35 and want a larger field of view, you just pick a shorter focal length, there's no problem getting a wide field of view in any format.

And depth of field on average is shallower for larger formats, not deeper.  Because the focal lengths are longer on larger formats if matching the field of view of smaller formats.  Feeling of three dimensional depth might be greater on the shallower focus image however.

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The field of view / depth of field differences between formats are over-hyped these days, but particularly between an Alexa Mini shooting Open Gate 3.4K and an Alexa LF shooting Open Gate 4.5K.  It's like a 1.3X crop factor, a 1.3-stop difference in depth of field.  Certainly there are plenty of short focal length lenses for Super 35 (just look at a Terrence Malick movie) but the FF35 size does make it a bit easier getting both a shallow focus and a wide-angle look if you don't have access to f/1.3 Master Primes or something. Bigger difference in look between Super 35 and 65mm sensors.

What larger sensors give you is both more pixel resolution without resorting to smaller photoreceptors that allows you to downsample with cleaner results, giving you more dynamic range at least in the shadows because the noise is less visible.

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22 minutes ago, David Mullen ASC said:

Larger sensor gives you more field of view for the same focal length but all you have to do is pick a different focal length to match the  two formats' field of view.  If you shoot regular Super 35 and want a larger field of view, you just pick a shorter focal length, there's no problem getting a wide field of view in any format.

Yes using a shorter focal length will give you a larger field of view. But it comes with the cost of changing the "characteristics" of your image.  

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30 minutes ago, Abdul Rahman Jamous said:

Sorry, larger sensor gives less depth of field. that was a typo. Thank you 

Hi Abdul..  I edited my first comment as I thought it might be seen as a bit condescending ... I now realize my edited comment could be seen as a bit rude .. even with the smiley face .. its a joke and not meant to be taking the piss..

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1 minute ago, Robin R Probyn said:

Hi Abdul..  I edited my first comment as I thought it might be seen as a bit condescending ... I now realize my edited comment could be seen as a bit rude .. even with the smiley face .. its a joke and not meant to be taking the piss..

I did write a wrong information and you corrected me.

 

No worries, love you! 

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1 minute ago, Robin R Probyn said:

Hi Abdul..  I edited my first comment as I thought it might be seen as a bit condescending ... I now realize my edited comment could be seen as a bit rude .. even with the smiley face .. its a joke and not meant to be taking the piss..

I did write a wrong information and you corrected me.

 

No worries, love you! 

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I mean let's go back a ways, 4 perf 35mm (18.6 x 21.95) was the theatrical projection format from the moment sound on film started in the late 20's, to the date film projection died 90 years later. We've been stuck to that frame size with digital cameras because the vast majority of lenses on the market cover Super 35mm (slightly wider frame). So for digital cinema camera makers, it only made sense to make an imager (that are sometimes much smaller) that worked with those lenses. 

Because the higher-end still cameras continued to use full frame imagers on the film and digital size, there was a push to make more and more lenses that cover full frame. Thus, there has been a new market of full-frame and large format imagers on the market because now they can be supported with the various lenses. 

So the answer isn't that 35mm imagers are the best, it's that up until very recently, there haven't been lenses to use the other imager types, so nobody bothered. Now that there are lenses, we're seeing more and more people shift to FF and it's wonderful. The movie "Joker" is a great example of how the FF imagers can help add more depth by using longer lenses for similar field of view of 35mm. I think in the next year or two, FF will become the new 35mm standard because there is no reason to use 35mm sized imagers anymore. 

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49 minutes ago, Abdul Rahman Jamous said:

Yes using a shorter focal length will give you a larger field of view. But it comes with the cost of changing the "characteristics" of your image.  

Not really.  You put a 50mm on a FF35 camera at f/4 and a 35mm on a Super-35 at f/2.0-2.8 split and it would be very hard to see a difference in anything -- field of view, depth of field, distortion, perspective, compression, anything.

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58 minutes ago, Tyler Purcell said:

I mean let's go back a ways, 4 perf 35mm (18.6 x 21.95) was the theatrical projection format from the moment sound on film started in the late 20's, to the date film projection died 90 years later. We've been stuck to that frame size with digital cameras because the vast majority of lenses on the market cover Super 35mm (slightly wider frame). So for digital cinema camera makers, it only made sense to make an imager (that are sometimes much smaller) that worked with those lenses. 

Because the higher-end still cameras continued to use full frame imagers on the film and digital size, there was a push to make more and more lenses that cover full frame. Thus, there has been a new market of full-frame and large format imagers on the market because now they can be supported with the various lenses. 

So the answer isn't that 35mm imagers are the best, it's that up until very recently, there haven't been lenses to use the other imager types, so nobody bothered. Now that there are lenses, we're seeing more and more people shift to FF and it's wonderful. The movie "Joker" is a great example of how the FF imagers can help add more depth by using longer lenses for similar field of view of 35mm. I think in the next year or two, FF will become the new 35mm standard because there is no reason to use 35mm sized imagers anymore. 

But wouldn't the longer lenses needed for FF, for the same frame size .. same distance to object .. result in a shallower depth of field .. rather than "more depth"..  or I just wasted my money buying a FF camera 🙂 

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"More depth" is a pretty vague term. I think it's because a wider-angle but shallow-focus image has a more 3D effect because the subject feels close to the lens (because it is) but pops out of the background because of the fall-off in focus.  So even though there is less depth of field, some people call that "more depth".

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4 minutes ago, David Mullen ASC said:

"More depth" is a pretty vague term. I think it's because a wider-angle but shallow-focus image has a more 3D effect because the subject feels close to the lens (because it is) but pops out of the background because of the fall-off in focus.  So even though there is less depth of field, some people call that "more depth".

Ok thanks ..got it .. Ive never heard the term depth used in this way re lenses  .. have say I would still call it a shallow depth of field look...   I hope this inverse usage of the word never makes it to the fields of air traffic control or surgery 🙂 

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2 hours ago, David Mullen ASC said:

"More depth" is a pretty vague term. I think it's because a wider-angle but shallow-focus image has a more 3D effect because the subject feels close to the lens (because it is) but pops out of the background because of the fall-off in focus.  So even though there is less depth of field, some people call that "more depth".

Ah yes, that's better terminology. 

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If I'm understanding things correctly, depth of field or more importantly blur circle size is based on the opening size of the iris, the distance the subject is from the lens, and the distance of the out of focus objects from the lens.  Higher focal lengths will have larger pupil openings for the same f stop.  100mm at f4 has a 25mm iris hole, 50mm at f4 has a 12.5mm pupil.  But if you open the 50mm to f2 it will have a 25mm pupil and will be the same blur circle sizes as the 100mm with the focus set at the same distance.  It seems like the notion of bigger sensor means thinner depth of field is the wrong emphasis.  There are pros and cons for any focal length on any sensor size, it just seems more important to know how the variables influence one another to get the right pairing for the project.  I think its a great time now, because with larger sensors on most modern cameras you can crop in and use difference sensor sizes for different situations and still retain enough quality.  More recently I've been experimenting with shooting super35 for wides and mediums with the 25mm 35mm, then cropping the sensor to micro 4/3 for close ups and cutaways and staying on the 35mm instead of switching to the 50mm.  Since the 50 will have thinner depth of field at the same f-stop, the close up might require stopping down to get the subject completely in focus, then the lighting has to change or ND has to be used for the wides, either way the set needs to be lit for an extra stop.  But if I just crop the sensor, the 35mm will have the field of view of a 50mm, but the depth of field of lets say a f2.8 on m 4/3 will equal a f4 on super 35mm with the same exposure.  So the wider depth of field of the sensor lens pairing saves the gaffer a stop of light for the scene.  Just trying to show an example where bigger is not necessarily better, smaller sensors can produce the same depth of field with less light.  That might come in handy.  Big sensors have thinner depth of field for the same f stop, that might come in handy too.    Also for shooting wider lenses on a smaller format, barrel distortion can be corrected.  Longer lenses will have pin-cushion distortion on larger formats, which can be corrected as well.

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My reason for buying a FF camera was to get a down sampled 4K image from a 6K sensor .. and for interviews in confined spaces.. it makes it easier to get a blurred background .. as I don't have the space to move back and go on a longer APS-C sensor lens to achieve the same effect.. and I can always crop into s35.. (changing scan mode).. if I need to.. the down side is increased possibility of rolling shutter as slower read out time ..and reduced high frame rates in FF scan.. ..  but there is, I think, a tangible different in the image between 4K after debayer from a 4K sensor .. and the down sampled 4K from a 6K sensor .. and for good or bad FF will become "the thing" to some extent ,it already has really in feature films ..and we see it trickle down to corps and docs.. 

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The only thing that determines perspective is the front of the lens's position relative to the subject and environment. The combination of focal length and sensor size determine the angle of view (AoV), which simply controls what "slice" of that perspective is captured.

Here's a great article addressing some fallacies about large formats, by Steve Yedlin, ASC, that goes into more detail:

http://www.yedlin.net/191106.html

And here, he's matched the AoV and DoF of IMAX film to the Alexa:

170504_005.jpg

170504_006.jpg

It can be argued that, if you want a razor-thin depth of field for some reason, instead of renting an f/0.7 lens, just use a larger format for that shot. But I think this is more of use for special purposes.

The primary advantage of a larger sensor, then, is really its larger resolution for the same pixel pitch. However, this is also less useful than you might think:

http://yedlin.net/ResDemo/index.html

He's also created a demo that shows just how little camera resolution influences the final image. The second part in particular is very eye-opening.

I believe he shot Knives Out (2019) almost entirely on the Alexa Mini, except for a few VFX shots on the Alexa 65 for the extra resolution. But don't quote me on that.

Interestingly, this is similar to how, before digital, many films were shot entirely on 35mm except for a few VFX shots on 65mm or VistaVision.

I believe a more rigorous way to create different "perspective" looks is simply taking a better look at how you place the camera and choose lenses. Simply choosing a 50mm further away instead of a 24mm closer to the subject might provide the same framing but a different actual perspective.

 

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