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How much MEGAPIXEL does one really need ?

The first thing that people like to find out about a digital camera is it’s megapixels. Megapixels is not the bottomline of digital photography. Unless of course you’re planning to print giant billboards… 

Photographers who shoot professional photos and want their pictures to be able to retain a lot of detail even when cropping will shoot with 24 megapixels or even 36 megapixel camera.

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Viewing distance & print size

There is some relationship between print sizes and the megapixels. Look at a billboard from a distance. It looks sharp??? Its been printed at about 72 DPI (dots per inch!) Remember how we use to look at news papers in the good old days and realize that the picture is nothing but many man many dots really close by!!! The further u go from the image the lesser dots or pixels you will notice… Thats the concept of dots per inch. Anyway  the minimum distance at which a billboard is seen is always more than 20 feet. At that distance it is impossible to notice the pixels. A magazine is normally printed at a resolution of 300 dpi.

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Relation between dpi and megapixels

So then, what is the perfect megapixels count that can give you that 300 dpi resolution? The first thing you need to know is what are the dimensions you will be printing?

 

Let’s say you need a print out of 8 x 12 at 300 dpi. 

Multiply 300 x 8 that gives us 2400 pixels and multiply 12 x 300 that gives us 3600. So 2400 x 3600 pixels is the exact pixel size of the image that you need in order to print an image with 300 dpi.

If you have a 16 megapixel digital camera & the maximum image size it offers at 4608 x 3456 pixels settings. Means, it is perfect for a print size of 15.36” x 11.52” at 300 dpi resolution.  If you want to print a billboard at 72 dpi, the same image size will be good enough for a 64” x 48” print. Photo labs recommend at least 250 dpi input for normal prints.

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Megapixels vs. Print Size Chart

So it will be correct to conclude that:

280 dpi & up = Excellent. Average person won’t see “dots” at a few inches away
180 – 287 dpi = Good quality.Will not show visible pixels at normal viewing distances
179 dpi or less = Poor quality.Will show visible pixels at normal viewing distances (the distance you normally read the magazine at) 


Image quality vs print size

Apart from megapixels here are few other factors may influence your printing capability. Using good optics, low ISO setting, correct exposure, proper depth of field, keeping camera shake free and proper post processing is critical to get quality print out. Of course starting with high megapixels will always give you a good start.


Image sensor vs print quality

Size does matter... For example, a 8 megapixel mobile camera sensor won’t be able to produce same image quality as a 8 megapixel DSLR does. Here sensor size & pixel density are important factor. In general, bigger sensors produce better image quality. Because, their pixels or light sensor are bigger and can gather more information than the smaller one. Which results cleaner and better images. 

Thoughts on lensing

In my journey of cinematography so far. I have understood that every script/story has a mood. Lighting, lensing and camera movement are the tools a cinematographer/ DOP uses to create the mood. I am often left wondering if lenses are doing something more than just capturing an image in a particular way? How much of a role do lenses play in making the viewer feel a certain way?  

 

If we talk about composition… Lets assume we are shooting on a 35mm format, we can compose a mid shot with a 50mm by placing the camera approximately 12 feet away from a character. We can put an 18mm, move the camera closer and create a mid shot or we put on a 100 mm and move the camera away. Theoretically, all of them would be mid shots. But each would look different from the other.

 

So are different lenses making the viewer feel differently? Is it possible for lenses to manipulate the viewers? … how should we decide to lens a particular scene to get the maximum juice?

 

A scene has multiple shots, with various permutations and combinations of camera positions, movement and lenses… Is there a way to know what works best or is it just instinct and experience that will guide us?

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Below is a compilation of shots from 3 sequences. I remember the lensing so they make good examples. They have been divided as:

 

  1. Scene shot using tele/ long lenses

  2. Scene shot using wide lenses

  3. Scene shot using only 1 lens

 

Each sequence looks starkly different because of the way they have been lensed… When I am DP-ing a scene I ask myself. Should I choose to shoot on the zoom Or should I shoot on block lenses? The compression achieved on a zoom is starkly different from a shot taken on a block lens, even if the angle of view (mm) is the same.

Optimo 24 -290, & Cooke S4i: 65mm & 100 mm.

 

The entire scene is lensed tele. Only the first shot is on the 65mm block, everything else is on the optimo and I was always tighter than 65mm on the zoom. 

 

Scene:

 

Day Ext: Crowded market place.

 

Two characters are on a motorcycle. One of them is on the phone.

 

 A man comes and starts honking next to them. The character on the phone, whacks the guy honking, abuses him and gets back on the call.

 

___________________________

 

We had 18 extras/ back ground artists to recreate a crowded market place… so I decided to shoot tele in-order to compress the image and make it appear more crowded than it actually was.

This scene was shot on a mix of wide lenses.

 

The shots of the table are 25mm

 

Establishing shots / wide shots of the room are on a 16mm

 

The dirty shots are on the 25mm

 

The inserts are on a 32mm

 

Scene:

 

Day Int: Police commissioner’s office

 

The commissioner has called a special officer and is giving him an order to take over, as the violence in the city is going out of control.

 

__________________________

 

The room where we were shooting was small I think it was 12Ft by 10ft.

 

We were on the 2nd floor of a building, there were 3 windows in the room. The scene is lit with four 6Kw Pars (filter 3) + ½ grid from outside the windows. Keying in from the right of camera and negative fill on the left side of the camera. The 3rd window can’t be seen, it was on the right side of the table and was working as the fill.

This entire scene was shot on a 21mm.

 

In the effort to salvage a boring scene, I shot the entire sequence on a single wide lens because I had never done it. 

 

I had one Arri M90, three 4K pars and two 2ft 4Bank kino flows… I put No. 5 on the 4k pars and a ½ grid cloth on a 12X12 and let the 4Ks come through that. The M90 was left naked and placed really far away and it created the patch of hard light. I controlled it with nets and used it for the shot with lens flare.

24 fps vs 23.976 fps explained.

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Where did 23.976 fps come from??? This is a question often asked by people who come from shooting on physical film that was always shot on true 24 fps. Or PAL countries. 

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When, how and why did 24fps become 23.976 ??? 

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A little bit of history: 

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During the silent era films were shot at 12 to 16 fps... Charlie Chaplin, Buster Keaton anyone ? Then came sound. And sound could be synced to the moving image at 24fps. Thats why films were shot and projected at 24fps. The term 24fps comes from the world of film, celluloid, from the times when there was no video. You just had physical film to shoot on.

 

 As technology advanced we had video & television sets. Television originated in the US. Television used house power to run. Electricity in the US runs at a frequency of 60Hz. Initially, there was only live TV (video recording came later). The TV cameras in studios and TV sets at home needed to run in sync. The only way to achieve that was by syncing the cameras to the main electrical system. 60 Hz corresponded to the camera shooting 60i (interlaced lines). With technological advancements today 60 interlaced lines have become has become 30p (progressive) that is 30fps. NTSC. All of North & South America is NTSC i.e 30 progressive frames therefore 30fps.

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Meanwhile, in the PAL world (Europe, Asia & rest of the world) TV began as 25fps since electrical mains in those countries was at 50 Hz. So, PAL countries adopted 25 fps for TV.

 

When colour TV came about, a small adjustment had to be made to transmit the colour reference signal. This needed the frame rate for colour TV (in the US) to be set to 29.976 fps. Which is why NTSC is 29.976 fps. And there’s no such thing as 30 fps any more. So on video each time you read 30 fps or 60i you know its actually 29.97 fps.

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The Telecine:

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Before the invention of the Arri Alexa. Almost all commercials were shot on either 35mm or 16mm film. Why ? Because the video cameras didn't have the resolution or the dynamic range to give a good looking image. In short the output quality was just really bad. And so anything of standard was shot on celluloid in the old days. 

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Say you shot a commercial for American Airlines. You shot on film but it needed to be aired on the TV screens as well. In such a case you did something called a telecine. ‘Telecine’ converted film to Television. In NTSC countries, this was done by repeating 6 frames every second so 24 fps became 30 fps in the Black & White TV days. For colour TV (NTSC - 29.976 fps), film was run at 23.976 fps and 6 frames repeated every second to get 29.97 fps.

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In PAL countries, while shooting a commercial the film camera was either run at 25 fps (4% faster) to get a 25 fps to match the TV signal, or one frame was repeated every second to get 25 fps from 24 fps. So, in PAL countries film was 24 fps in a cinema and 25 fps on TV. No in-betweens like 23.98 fps.

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The short answer is that 24 fps video does not play on 29.976 fps TV sets or TV monitors. But 23.976 fps can be made to play on 29.976 fps monitors. But the NTSC countries have 29.97 fps TV monitors. That’s why people from NTSC countries don't get the concept of 24 fps video. They only understand 23.98 fps video. And people from PAL 25 fps countries dont get 23.98 fps. They only understand 24 and 25 fps

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North Vancouver, BC

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