Ignorant 16x9 Question?

[Graham Bernard]

Eh?

Isn't a 1/3 receptor a surface area spec? The same as 1/3 of a square inch. And 1/4 is one quarter of a square inch. 2/3 is two thirds of a square inch area. None of this describes the shape, purely surface area. We need convention ratio to then define the shape. Here that would be 4:3 or 16:9 .

So a 4/3 is four thirds of a square inch area, which I could say was one square inch PLUS another third of a square inch?

Right or wrong?

Grazie

[R Geoff Baker]

Well, wrong.

The convention is to describe a diagonal corner to corner length, so a 1/3 inch chip is one third of an inch, diagonally. A 4/3 is four thirds on an inch, corner to corner. You can see that this means the dimensions in real terms are different for every aspect ratio -- which is why I again refer you to Panasonic's diagrammatic example. It is clearly demonstrated, with pictures, how it works.

In no case is format size using 'area' -- in video the standard is diagonal width. So in fact, as demonstrated in the picture and stated here -- the format describes a circle. The aspect ratio is a 'slice' from that circle, and each aspect ratio uses a slightly different slice ...

Please look at the diagram I have linked repeatedly, and ask questions in reference to that so we can speak the same language ...

Cheers,
GB

[Brian Drysdale]

Yes, it's not the standard 35mm cine frame.

In practise, since this seems to be what everyone is getting excited about you should be able to achieve a DOF pretty similar to most 35mm productions by opening your lens an extra stop over to that used on most 35mm motion pictures. So if you use a stop on the AF100 of between f1.4 and f2.4 you should be in a quite common DOF zone.

[Mark David Williams]

You're right Grazie.. Heh heh But then in old money 2/6 might mean something else. The / can be a way to join something as a part of and in relation to. Sorry just my interpretation.

4:3 aspect ratio (4/3 = 1.33, medium shape)

I'm happy to agree to disagree Some may see clearly that 4/3 or 16/9 has no relation to 4:3 or 16:9 Indeed the former makes sense to me I have many times though seen the aspect ratio written as 16/9 Specifly in TV shops a few years back. However experiences may differ.

As regards the the GH2

QUOTE
As for 'using the whole chip' I can't see how this is important or significant. The size of a 4/3 imaging chip at 16:9 is an 'absolute' -- if the designers choose to derive it from something larger, that seems neither here nor there, so long as they get it right.

That statement could be confusing to those of us who stupidly and ignorantly confuse 4/3 with 4:3 and was the interpretation I wanted to help be understood by some not up to speed by saying it might be best to call it four thirds.
QUOTE
As for the proximity to Cine 35 in size, there does indeed seem to be some hyperbole here. The real numbers are these:
4/3 is 17.8mm x 10mm in 16:9 mode;

Numbers are aproximate my guess is its 17.3 x 13 and cropped.

[Mark David Williams]

Originally Posted by Brian Drysdale

Yes, it's not the standard 35mm cine frame.

In practise, since this seems to be what everyone is getting excited about you should be able to achieve a DOF pretty similar to most 35mm productions by opening your lens an extra stop over to that used on most 35mm motion pictures. So if you use a stop on the AF100 of between f1.4 and f2.4 you should be in a quite common DOF zone.

You'd have to stand further back to get the same field of view if using equivilent lenses though.

[Graham Bernard]

Ok, this is helpful:Image sensor format

Grazie

[Brian Drysdale]

Yes, the field of view at a particular focal length will be narrower than standard 35mm. It's really no big deal in the longer term, this can also happen when you go between different 2/3" cameras (some of which are nearly Super16), you do get used to it.

Perhaps it's more of an issue at the wider end, but that would depend on the lenses you have available, although there are a number of possibilities .

[Olof Ekbergh]

OK I hope this does not complicate things more.

In the drawing below, on the left is a 24mm x 36mm full 35mm frame, just for reference.

On the right are measurements (in mm except where shown in ").

You will notice that a 4/3 standard chip is not 4/3" in diameter. It is .804" in diameter, in this case (using measurements from the AF100 manual). This is because chip size is an old standard from the Tube days when tubes were measured to the outside of the tube, not the imaging area.

The outer circle shows the actual 4/3" or 1.33333" diameter.

It is confusing to look at and think about, but those are the standards, they are shown in the table in the second image (source Image sensor format - Wikipedia, the free encyclopedia).

[R Geoff Baker]

Agreed, close to Cine 35 but not quite there -- Sony's APSC choice for some of their cameras is in fact closer.

What is significant I think is that it is 4/3 standard -- the same lens on any 4/3 camera using 16:9 would deliver the same result.

Cheers,
GB

[Mark David Williams]

Originally Posted by Brian Drysdale

Yes, the field of view at a particular focal length will be narrower than standard 35mm. It's really no big deal in the longer term, this can also happen when you go between different 2/3" cameras (some of which are nearly Super16), you do get used to it.

Perhaps it's more of an issue at the wider end, but that would depend on the lenses you have available, although there are a number of possibilities .

The problem is your not getting the same angles either. Say you shoot an OTS you have to stand back a lot further to get the same dof. This might be a problem in a small room for example and is a compromise and not the idea that's being sold. It's not the same similar or close to S35. But none the less will give you something in between 16mm and 35mm and that will match many more 16mm lenses and turbo charge what they can do in terms of dof.

[R Geoff Baker]

Originally Posted by Olof Ekbergh

It is confusing to look at and think about, but those are the standards, they are shown in the table in the second image (source Image sensor format - Wikipedia, the free encyclopedia).

Note that the chart is not standardized to 16:9, so the numeric values are 'off' as they seem to assume 4:3 -- again, I suggest readers look at the Panasonic pictures I have linked in this thread as they include examples and values for 16:9

Cheers,
GB

[Mark David Williams]

I'd also like to know if the camera line skips.

[Brian Drysdale]

Most film productions aren't shot on Super 35, although it's becoming the size for digital sensors rather than the old standard 35mm.

I think you can only regard a format for what it actaully is and quite few people were asking for this particular format in the early RED days, so I suspect there's a demand for it.

Personally, I tend to work by angles of view, it tends makes more sense in story terms. rather than obsess over working to a very shallow DOF for a shot. I'd worry more over this if the character(s) feel isolated and alienated, which can to be the effect in story terms of a very shallow DOF. Certainly the AF100 does allow a useful DOF option range, which people can creatively use.

In the wide shots, framing, composition and action are usually more important.

[Mark David Williams]

I "think" the sensor size is perfect for me if as I suspect my 16mm superspeeds will work with this.

However most will need to buy dedicated lenses as ordinary still 35mm lenses will have a 2x zoom making wides difficult.

My problem is possible line skipping and 8 bit out make it all a little questionable for me. I really need more info on this.

[Mark David Williams]

Originally Posted by Brian Drysdale

Personally, I tend to work by angles of view, it tends makes more sense in story terms. rather than obsess over working to a very shallow DOF for a shot. I'd worry more over this if the character(s) feel isolated and alienated, which can to be the effect in story terms of a very shallow DOF. Certainly the AF100 does allow a useful DOF option range, which people can creatively use.

In the wide shots, framing, composition and action are usually more important.

Agree.

For me shallow dof is useful to create a pretty C/U (Ooops did I just use the /) ... and to separate the background and define the intent and focus the eye on the target. I was watching the news last night and far more interested in what some kids were doing in the clean background rather than the presenter! Anyway it's just a tool but it's the tool that up till now has separated Pro's from consumers. and many consumers in their long long wait are over compensating. But a Camera is only a small part of making a film and a good DP can use a camera without shallow dof and still make a masterpiece.