Black Magic PocketHD and 4K production camera

You said it: you compare 35 to S35. They are not the same.

To start with Super 35 was created for 3-sprocket size cameras, which run longer than traditional 35mm cameras. They are more efficient in film use than 4-sprocket 35mm cameras, because 1/4 of the frame is not thrown away in the lab to get to 1.85 ratio.

But during full film processing times they had to be optically lab processed to print back onto 4-sprocket projection copies. With present video processing that is no longer done.

The S35 video frame, which I'm not sure if it corresponds exactly with the film S35 frame, is a different matter.

Remember what I said that for regular shooting, to get the same height in 1.85 that you got with 1.33 you had to use a 40mm lens. But that lens perspective is not the same: it's slightly wide angle.

The perspective for a 50mm in cropped-35 or S35 should be the same as a 25mm in 16 and S16. But to get same figure size in cropped-35/S35 you will have to get back a bit. Perspective will be the same, not height/distance ratio.
 
Samuel H said:
Ok, then. My conclusion: you oldies were doing some weird stuff back in the celluloid days... :)
(because 50mm on S35 or 25mm on S16 is more telephoto than what I would consider "normal"; 50mm on APS-C, which is basically just like 50mm on S35, is my main portrait setup)
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Thats because 50 is not really a portrait lens in the 35 world. That starts around a 65/75...much like an 85-105 for full frame 35 still photography.

Dont forget S35 was still 1.33 while shooting (Prior to the latter 3-perf/2-perf shooting.) It was the DP/Directors' choice as whether they did a center frame or a common top for their ground glass/extraction
 
carlmart said:
But to get same figure size in cropped-35/S35 you will have to get back a bit. Perspective will be the same, not height/distance ratio.
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If you back up, that is what will change perspective. Perspective is a property of the distance of the lens to the subject, not a property of the lens focal length.
 
AFAIK perspective does not change: it belongs in the lens, as it belongs in our sight. We can not change our perspective, we can get closer or further, and adjust focus both in the eye and in the brain.

If space is no problem, you could shoot a film with just one lens. It was a legend, which I never confirmed, that Kurosawa shot everything with just one lens: a normal.

What will change, when you go further, is DOF.

I am from the time when zooms were not that good, and you used prime lenses only if you wanted image quality. If you were shooting indoors you could never used a zoom. And in such cases you can't really change your perspective too much.
 
The Sarlacc said:
Thats because 50 is not really a portrait lens in the 35 world. That starts around a 65/75...much like an 85-105 for full frame 35 still photography.
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Yes, a portrait lens should start in 75mm, and IMH0 may go up to 105. In the Nikkor range, the 85 was a superb portrait lens.

Dont forget S35 was still 1.33 while shooting (Prior to the latter 3-perf/2-perf shooting.) It was the DP/Directors' choice as whether they did a center frame or a common top for their ground glass/extraction
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Certainly so. The S35 lenses values were the same as those used in 1.33 35mm. In the end it's a question on telling a story with framing.
 
Perspective is all subjective...no one is really trying to match perspective...trying to match frame sizes while shooting singles...different story...and its easy to cheat if you know the math between lenses and distance. Hell, pCam will do it for you these days.

In the last 7 years a 65mm has become a very popular prime for portrait use in cinema. And Nikons 85mm is one of their best pieces of glass. I own one :)
 
Barry_Green said:
Perspective changes when you change distance.

When you change lenses, you are changing magnification, not perspective.
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Sorry to disagree on that. Or maybe we have different points of view. What I'm talking about is a geometric concept, which I think is called "vanishing point" in English, and it's what perspective is all about.

Every optical lens has its own VP, and when you change lenses you change VP, not magnification.

The lens that resembles the human VP is called "normal lens", and it's a different focal length for every sensor or film frame window size.

When you change distance you change magnification, not perspective. The VP is still the same, as it's inherent to the lens.

I don't think is necessary to talk further on what is VP, as it's more geometry than anything else, and it may not add anything to this discussion about the Pocket camera.
 
My memory from my days as an (admittedly terrible) 3d engine programmer is getting fuzzy, but I believe that Barry is referring to perspective distorion, and is essentially correct here. It sounds like you may be saying "perspective" to refer to "field of view."

The farther from the camera (real or virtual, in the case of CGI) an object is, the "flatter" it will appear, as the perspective changes. Farther objects appear more like an orthographic projection than closer ones, where the z value in 3d space becomes less of a factor in the projection of 3d to 2d.

As an example, let's say that you are standing 20 feet from a subject and snap a picture of it with a lens giving a field-of-view of 30 degrees (we'll call it picture A). You then change the lens (or zoom, doesn't matter) to give you a field-of-view of 15 degrees (picture B). If you take picture A and crop it down to match the framing of picture B, you'll notice that the subject looks identical (we'll ignore resolution for this example). There's no change in the perspective distortion.

However, if you move closer, the subject's perspective distortion does change, as the dimensions of the subject in 3d space become more significant, relative to the camera's distance to the subject. If you take a third picture at 10 feet, no amount of cropping or other manipulation will make the subject look like it did in either Picture A or Picture B. The perspective has changed. If you get closer still, the subject may get so large that you have to switch lenses to widen your field-of-view to fit the whole subject in the frame. That wider lens doesn't actually change the perspective, but it does allow you to see more of the subject, which means that the perspective distorion is more obvious. That's why close-up, wide-angle shots of faces can look a little "off."

Sorry if that was a little tech-y. That's the best way I know how to explain it.

Wikipedia has a good, writeup: http://en.wikipedia.org/wiki/Perspective_distortion_(photography)
 
What Barry said

And going into more detail:
* distance determines perspective
* sensor size and focal length determine field of view
* distance, sensor size, focal length and aperture determine depth of field

Not that it is that important, in any case: shoot how you like!
 
And just to hammer this down with nails... What Barry and Samuel said is true:

* distance determines perspective
* sensor size and focal length determine field of view
* distance, sensor size, focal length and aperture determine depth of field

Simple example of perspective change, stand in front of a window, walk slowly towards the window, see how you can see more of what is beyond that window as you get closer. The same applies if you walk towards a large pole, and in principal dolly up from a table or what ever. Yes, of course the item you move towards gets larger, but I think perspective is more interesting.

Which is also why a zoom can never substitute a dolly... it simply not the same thing.
 
I'm not sure this discussion is relevant to this camera matter, but let me try to explain better what I mean. As I see it there seem to be some conceptual differences, and I will point out what I think is related to our thread.

Perspective is something we discussed and made tests for in my film school days, and it's related to geometry and painting, and so to photography and film.

Let's consider two planes: a foreground and a background. Now we take two points on the foreground (A - B) and one on the background (C), then draw a triangle joining those three points.

Perspective is the value in degrees of the background angle C, and sets what is called a vanishing point. Distance between planes being always the same, we may have a long perspective if the angle is small, or a short perspective if the angle is large.

If we do not move the planes, a prime lens will always have a fixed perspective, only one, determined by its focal length. In 35mm photography, a normal lens (50mm) would have a perspective or VP that resembles that of the human eye; a wide angle (e.g. 28mm) would widen the distance between points A- B, enlarging the viewing angle, so the background angle C would be greater; a longer tele lens (e.g. 105mm) would shorten the distance between points A - B, and the angle C would be smaller.

Of course that in film this is all dynamic if we move the camera, changing the distance between background and foreground, or if we use a zoom, changing the focal lengths. And even more when we do both.

Sometimes, if there is no background reference or if it is out of focus, we may have some difficulty in separating one lens from the other. Let's say we are framing a face: the lens length will determine the form of the head, from almost flat (tele) to "rugby ball" shaped (fish-eye). Of course, everything should be in focus in those, only the shape being affected.

There is some sort of explanation here:

http://www.cambridgeincolour.com/tutorials/tilt-shift-lenses1.htm

In any case, what is important is for us here to be talking the same language and mean the same when we comment on something.
 
Igelkott Film said:
Nice reel with the already out BMCC
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THis is silly.

The only Blackmagic stuff in that reel are shots released by other people, test footage.

This guy...

If you want to see what a Pocket Cam frame might look like, here:

https://vimeo.com/63949090

This is MFT BV1 (Blackmagic Version 1) composed with the approximate Pocket Cam dimensions via a TVLogic Matte, Zeiss Super 16s on a Hot Rod PL mount and SLR Magic 12/1.6, 25/0.95

Read the rest of the vimeo.

I did this to give the Blackmagic community an idea of what it MIGHT look like so take it with a grain of salt if you must. I do know that there will be Pocket Cam footage posted any day now.
 
This obsession with the fear of rolling shutter for 2D production is simply annoying... : ) I wonder myself what will come next when there will have no more reasons to complain or concern about :P
 
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