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35mm format lens used in Super16 format


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#1 Erkan Umut

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Posted 05 January 2008 - 06:52 PM

We learned that F/50mm is the normal lens for 35mm format and F/25mm for 16mm format.
So, in theory, F/25mm will be a wide angle lens for 35mm format and F/50mm will be tele lens for 16mm format.

Recently, for my project shot in Super16, the rental house recommend me to use F/12mm lens made for 35mm format instead of F/6mm lens made for SUPER16 format.
Because of above theory, I accepted it. But I surprised when I saw that F/12mm didn't give me the result of F/6mm of Super16 lens...
What is the reason?

Thank you for your explanations... :)
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#2 David Mullen ASC

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Posted 05 January 2008 - 11:47 PM

We learned that F/50mm is the normal lens for 35mm format and F/25mm for 16mm format.
So, in theory, F/25mm will be a wide angle lens for 35mm format and F/50mm will be tele lens for 16mm format.

Recently, for my project shot in Super16, the rental house recommend me to use F/12mm lens made for 35mm format instead of F/6mm lens made for SUPER16 format.
Because of above theory, I accepted it. But I surprised when I saw that F/12mm didn't give me the result of F/6mm of Super16 lens...
What is the reason?

Thank you for your explanations... :)


I'm not sure what "F/50mm" means, I think you just mean a 50mm lens.

Your rental house was wrong. 12mm and 6mm are different focal lengths. If you want a 6mm view on a Super-16 camera, you use a 6mm lens. If you put on a 12mm lens, you get a 12mm view. It doesn't matter whether it is a Super-16 or 35mm lens -- that only affects lens coverage, i.e. a Super-16 lens image will vignette on 35mm. The focal length is the focal length, only the view changes depending on the format.

So if you want the view of a 12mm lens on a 35mm camera, you'd use a 6mm lens on a 16mm camera. The only difference between a 12mm lens made for 35mm work and a 12mm lens made for 16mm work is not the field of view, it's that the image from the lens made for 16mm might vignette on 35mm because it's not large enough.

Maybe the rental house misunderstood what you were trying to achieve.
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#3 Tim O'Connor

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Posted 06 January 2008 - 03:17 AM

I'm not sure what "F/50mm" means, I think you just mean a 50mm lens.

Your rental house was wrong. 12mm and 6mm are different focal lengths. If you want a 6mm view on a Super-16 camera, you use a 6mm lens. If you put on a 12mm lens, you get a 12mm view. It doesn't matter whether it is a Super-16 or 35mm lens -- that only affects lens coverage, i.e. a Super-16 lens image will vignette on 35mm. The focal length is the focal length, only the view changes depending on the format.

So if you want the view of a 12mm lens on a 35mm camera, you'd use a 6mm lens on a 16mm camera. The only difference between a 12mm lens made for 35mm work and a 12mm lens made for 16mm work is not the field of view, it's that the image from the lens made for 16mm might vignette on 35mm because it's not large enough.

Maybe the rental house misunderstood what you were trying to achieve.


I've heard the focal length is the focal length in many different threads and I get things sorted out
and then sometimes confused again.

If he wants the view on his Super 16mm image, that is produced on 35mm by a 12mm lens,
and he's using 35mm lenses, then does he use a 6mm lens made for 35mm use?

Here are the widest 35mm lenses available in my area for rental: 8mm Nikon, 9.8mm Tegea,
10mm Zeiss, 12mm Zeiss.

Also, I haven't shot much 35mm but doesn't anything much wider than
8mm or so get into fisheye territory?

It makes sense that a lens, a wider one anyway, designed for a 16mm image is going to vignette
when used for a 35mm format. Conversely, would a 35mm (format) lens, provide more image than can be
captured by the Super 16mm space?


When you say "if you want the view of a 12mm lens on a 35mm camera, you'd use a 6mm lens on a 16mm
camera." how do you translate this if you're using 35mm lenses for Super 16mm images? Taking it a
step further, if you're using a P+S Mini 35 adaptor on an HVX-200 with 1/3" CCDs, how do you
calculate what 35mm format lens package to get based on say your understanding of focal lengths in 16mm,
Super 16mm, or something else?

I'm sure that this is simple and I'm asking humbly because I am confused about this even though
I feel uncool in saying that.

I like the line in the movie "Serendipity", when Jeremy Piven's character says "The Roman philosopher
Picticus said that if you want to improve, you must be content to be thought stupid." (Hope I got the
name right.)

Thanks.
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#4 David Mullen ASC

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Posted 06 January 2008 - 04:24 AM

Repeat to yourself over and over again: "A 50mm lens is a 50mm lens is a 50mm lens..." The focal length is the focal length. It is a physical thing, what the lens is. That never changes.

A 12mm lens moved from a 35mm camera to a 16mm camera is still a 12mm lens. It doesn't matter if the lens was made for 35mm or 16mm cameras. It is still a 12mm lens. It will always be a 12mm lens. It will be a 12mm lens on a Super-8 camera and it will be a 12mm lens on an IMAX camera -- because it is a 12mm lens. It will be more wide angle in view on a larger format and it will be narrower in view on a small format. But it is still a 12mm lens.

(Now I suppose in real life, you reach a point where you can't "see" any more of the lens image even as you put it on a larger and larger format camera because all you get is a circular image that gets smaller and smaller on the film as the negative gets bigger and bigger. But it's best not to confuse yourself thinking about that...)

What changes is field of view. The focal length is whatever it is.

When you say "if you want the view of a 12mm lens on a 35mm camera, you'd use a 6mm lens on a 16mm camera." how do you translate this if you're using 35mm lenses for Super 16mm images? Taking it a step further, if you're using a P+S Mini 35 adaptor on an HVX-200 with 1/3" CCDs, how do you calculate what 35mm format lens package to get based on say your understanding of focal lengths in 16mm, Super 16mm, or something else?


It's not exactly that you'd use a 6mm lens on a 16mm camera when you'd use a 12mm on a 35mm camera -- because half of 35 is 17.5, not 16.

It's simple math but you have to know the exact dimensions of the film aperture to calculate the exact equivalency -- not that it matters because unless you use a zoom, they don't make prime lenses in exactly the focal length that the calculation tells you to use. What if the math told you that you needed a 15.643mm lens? Or a 22.36mm lens?

For example, let's say that your 35mm format is using an aperture that is 24mm wide. And you like the view that a 50mm lens gives on that. Well, use an aperture that is exactly 12mm wide and you've cut the horizontal view of the 50mm lens in half, so now the field of view is narrower, as if you had doubled the focal length if you were still shooting with an aperture that was 24mm wide. So having cut the view in half by cutting the gate down from 24mm wide to 12mm wide, you have to use a focal length that was half the length to restore the wider view, so you'd use a 25mm lens.

Well, in real life, the 35mm sound aperture is 22mm wide and the Super-35 aperture is 24mm wide. And the regular 16mm aperture is 10.26mm wide and the Super-16 aperture is 12.52mm. So you can do the exact math if you want, or you can just figure that half is close enough, or you can look it up on a chart.

So if you want to compare 35mm sound (22mm) to Super-16 (12.52mm) that means you'd divide the 35mm focal length by 1.757 to get the equivalent view in Super-16. So if you like a 25mm lens on regular 35mm, you'd use a 14.228799mm lens in Super-16 for the same horizontal field of view (remember that aspect ratios will affect view both horizontally and vertically so you have to decide which direction you are matching to if the two formats have different aspect ratios, are you matching up and down or side to side?) If you like the view of a 50mm lens on a 35mm sound aperture, you'd use a 28.457598mm lens on a Super-16 camera.

The P&S Technik adaptor, and other similar devices, project the lens image onto a 35mm-sized groundglass and the video camera then takes a picture of that groundglass image -- so the field of view and depth of field characteristics are the same as if the lens was on a 35mm camera. Now whether these groundglasses are the size of the 35mm Academy frame or Super-35 frame or 8-perf 35mm still camera frame, it depends. I think most are the size of the 35mm "cine" frame, but I don't know if that is 22mm or 24mm wide.
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#5 Erkan Umut

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Posted 06 January 2008 - 08:14 AM

I'm not sure what "F/50mm" means, I think you just mean a 50mm lens.

So if you want the view of a 12mm lens on a 35mm camera, you'd use a 6mm lens on a 16mm camera. The only difference between a 12mm lens made for 35mm work and a 12mm lens made for 16mm work is not the field of view, it's that the image from the lens made for 16mm might vignette on 35mm because it's not large enough.


Yes! F/50mm means 50mm focal length like T/4 stop.

I've got the exact reply I want to hear... Thank you David! You're an invaluable contibutor... :D
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#6 Tim O'Connor

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Posted 06 January 2008 - 12:09 PM

Repeat to yourself over and over again: "A 50mm lens is a 50mm lens is a 50mm lens..." The focal length is the focal length. It is a physical thing, what the lens is. That never changes.


What changes is field of view. The focal length is whatever it is.





It's simple math but you have to know the exact dimensions of the film aperture to calculate the exact equivalency --



Wow, David! That really helps. I think your note that "you have to know the exact dimensions of the film
aperture to calculate the exact equivalency" is what finally helped me get it. I'm going to print this out and
keep rereading it until I don't have that experience where I feel like I understand and then three days later
I'm driving along thinking and I get confused.

I think that I'm pretty good understanding most stuff but this one hasn't always been firmly in my
grasp even though I know that it's basic and rather essential that the guy with the camera know it!

If I did get to shoot a Super 16 film with 35mm format lenses, and I did call for a 14.228799mm lens,
most experienced A.C.s would be okay with that though, right? (Kidding.)

Seriously, you wrote an essay. Thank you.
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#7 Adam Frisch FSF

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Posted 06 January 2008 - 02:56 PM

Repeat to yourself over and over again: "A 50mm lens is a 50mm lens is a 50mm lens..." The focal length is the focal length. It is a physical thing, what the lens is. That never changes.


But the confusion arises (rightly so) because the focal length has become a measure of field of view. This is the problem. Therefore, for a layman, "the 50mm is a 50mm is a 50mm" is in practical terms misguiding. In fact, it's such a problem that not even people who supposedly understands this gets it right. Focal length should be measured in angles of view, not mm.

How many times have I ordered this for a 16mm production -

16-series Zeiss: 9,5mm, 12mm, 16mm
35-series: 16mm, 21mm, 24mm, 28mm etc, etc

- only to hear back from rental houses "why do you need two 16mm lenses?".

Another thing that drives me crazy is that the circle of coverage isn't a part of a lens's data. That is crucial information, because if you see an old lens advertised on Ebay, let's say an old Cooke 20-100mm T3.1 or an Angenieux 17,5-70mm - how do you know if this is a lens made for 16mm, S-16mm or 35mm or if it covers S-35 without resorting to empirical data?

We screwed up this lens classification business a 150 years ago and now we're stuck with the confusion.
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#8 David Mullen ASC

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Posted 06 January 2008 - 02:59 PM

Well, Todd-AO lenses were originally labelled in degrees of horizontal view, not focal length.

Trouble with that is degree of view is format dependent, and the same lens may be used on a Regular 35mm or Super-35 or a Super-16 production, let's say.
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#9 David Sweetman

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Posted 06 January 2008 - 08:23 PM

(Now I suppose in real life, you reach a point where you can't "see" any more of the lens image even as you put it on a larger and larger format camera because all you get is a circular image that gets smaller and smaller on the film as the negative gets bigger and bigger. But it's best not to confuse yourself thinking about that...)

This actually doesn't serve to confuse at all, it makes it crystal-clear. The circle is the image projected by the lens, and the square "cut out" by the frame is the varying format size, which, when put this way, would obviously be narrower or wider with the same lens. That's a great visual way to explain it, I'm gonna remember it so I can draw pictures for people.
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#10 Tim O'Connor

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Posted 06 January 2008 - 10:58 PM

This actually doesn't serve to confuse at all, it makes it crystal-clear. The circle is the image projected by the lens, and the square "cut out" by the frame is the varying format size, which, when put this way, would obviously be narrower or wider with the same lens. That's a great visual way to explain it, I'm gonna remember it so I can draw pictures for people.


Hey David, you were on "24" last year. Do you know what's happening with that? Is there even going to
be a show this year with the strike?

Maybe if they have some scripts already done they could at least do "7" or "12" or something!

"Jack Bauer's back...and he's not staying up all night this time!"
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#11 Chris Keth

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Posted 06 January 2008 - 11:30 PM

It's really not that difficult a concept. If you ever confuse this issue, just look at a field of view chart, like is available in the back of the american cinematographer manual.

You generally choose a lens for the field of view you get with it. That affects how wide or long a lens looks. It may also allow you to move further from the subject, which gives the flattened perspective flattering for many close-ups. A field of view chart will clearly show that to get a look (field of view) similar to X lens on 35mm film, you need to use Y lens on 16mm film (or whatever formats you need to compare).
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#12 David Mullen ASC

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Posted 06 January 2008 - 11:52 PM

I wasn't on "24" ever -- I was on HBO's "Big Love" last year.
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#13 Tim O'Connor

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Posted 07 January 2008 - 01:35 AM

I wasn't on "24" ever -- I was on HBO's "Big Love" last year.



No, I meant that David Sweetman actually was on "24" in that he was an extra. He posted about how
they shot a scene in a subway which was cool because I saw that episode a month or so later.


I've been getting into "Big Love". It's a funky show. I haven't seen any of your episodes yet though
but I'm catching up.
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#14 Matt Pacini

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Posted 07 January 2008 - 07:43 PM

I know this wasn't the focus (bad pun !) of the question, but I feel the need to correct this statement that is constantly repeated, incorrectly:
50mm is NOT NORMAL looking in cinematography, it's normal IN 35MM STILL PHOTOGRAPHY, where the frame size is more than twice what a it is in cinematography.

Also, the way to look at this focal length business that made it clear (at least to me), is that a 25mm lens in 16mm filming, will LOOK LIKE what a 50mm lens LOOKS LIKE in 35mm filming.

Yes, a 50mm is a 50mm is a 50mm... but saying this doesn't lead to less head scratching for these guys, because they then wonder why it looks differently, and it sounds like you're telling them it's exactly the same IN EVERY WAY.
Technically correct, obviously, but it doesn't clarify the problem to them.

MP
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#15 David Mullen ASC

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Posted 07 January 2008 - 09:32 PM

But the first step is to stop thinking the focal length changes when you put the lens on a different camera format. If you can't get past that, you're always going to be confused. If saying "a 50mm is a 50mm" is confusing, saying "a 50mm is a 25mm" is even more confusing!

The focal length is just a number, a length measurement (hence why it is in millimeters.)

It's only because of practice or tradition that we associate any field of view with that focal length number. If you shoot mostly 35mm motion pictures, what effect a 50mm gives you is more familiar to you than what it gives on a 35mm still camera. If you shoot mostly 16mm, then you have a different idea of what view a 50mm gives you.

As I said about Todd-AO lenses, you could mark lenses by field of horizontal view in degrees instead, but then that figure only works with a specific horizontal dimension of a camera aperture.

What I don't get is why so many people are confused -- I got past that before I even went to film school. It's just a mental discipline thing. People spend way too much time trying to transpose everything in their head. You may have to do that once or twice when ordering a package for a shoot, but once you start working everyday, you just get used to the view that your lenses are giving you.

I went from shooting anamorphic to Super-35, but it's not a big deal to figure out that a 40mm anamorphic lens has a similar horizontal view to a 20mm spherical lens in Super-35.

I mean, you put the lens on the camera and say "that looks too wide" or whatever. The numbers mean less than what it looks like through the viewfinder when you are shooting the scene. It's the same reason why the concept of what a "normal" lens is pretty unimportant to me -- I can see with my own eyes which lenses distort perspective or view more than others. The mathematical calculation for what is "normal" does really matter much to me.

We're not dummies here -- surely we all can agree that a 50mm lens sees a different view on a Super-8 camera, a 16mm camera, a 35mm camera, etc.??? Surely most of us have shot more than one format in our lives? Most of us have used a 35mm SLR, a Super-8 or DV camera, maybe a 16mm, a 2/3" video, or a 35mm movie camera -- maybe we don't know the exact views that a certain focal length gives us on those different formats, but we all know that the view is different for each format, right?

If you don't even know that the 4-perf 35mm movie frame is a different physical size than the 8-perf 35mm still camera format, then you're really at the beginning of learning this stuff.
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#16 Hal Smith

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Posted 07 January 2008 - 10:07 PM

If you don't even know that the 4-perf 35mm movie frame is a different physical size than the 8-perf 35mm still camera format, then you're really at the beginning of learning this stuff.

Particularly since there are good books, like yours, with photos and diagrams showing the visual impact of different focal length lenses for a given film format. A book and some time spent with a video camera and a zoom lens with focal length markings should be all that's needed to start to understand focal length visually.
Once someone gets that, then the idea of the image circle projected by a given lens and the different format "rectangles" that can be drawn within it should be second nature. But maybe some people never get off first?
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#17 Tim O'Connor

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Posted 08 January 2008 - 12:49 AM

I do agree that there seems to be a bit of obsessing about this. I would say in my case that yes I think
more in terms of this looks right or that looks right rather than what number is right. However, I've been
thinking about understanding the numbers, or seeing if I understand the numbers more clearly, because
lately I've been more involved in talking about lens rentals. I'm familiar with lenses for 16mm cameras and
how they look because of my experiences in saying hmm, this looks like this and getting used to correlating
that to the numbers for those lenses. With 35mm, I don't get to work everyday shooting that and what I have
shot has been second unit so the camera packages were already there and I didn't really worry about the
numbers then, I was able to start with lenses that I knew would be close and change if necessary for
what looked right for the assignment and for whatever discretion I was allowed.
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#18 Leo Anthony Vale

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Posted 08 January 2008 - 03:32 PM

50mm is NOT NORMAL looking in cinematography, it's normal IN 35MM STILL PHOTOGRAPHY, where the frame size is more than twice what a it is in cinematography.


To add to the confusion, 50mm has always been considered normal lens for 35mm cine and 25mm for 16mm cine.

Apparently there seems to be be different definitions for a normal lens in cine and still photography.

Why is it called a normal lens? And what do non normal lenses distort?

Could it be the perspective when the image is viewed from a specific position?

& perhaps the recommended veiwing positions are different in cine and still?

Might one be based on the screen height and the other on the prints diagonal?

All I know is that I've always sat close to the screen in a theatre. Fourth row is my current preference.
From that position wide angle seem normal and very pleasing, while long lenses seem to push me back and feel quite oppressive.

One shouldn't underestimate the importance of perspective when veiwing pictures.
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#19 Matt Kelly

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Posted 08 January 2008 - 05:41 PM

I was always under the impression that 50mm was a "normal" lens because in most SLR's it's the focal length that would match the field of view of your left eye (if you have both open at once).  Really your eye's field of view is crazy wide, but the size of objects in each eye would be about the same.  I'm not sure why this has carried over to motion picture stuff...especially since the ground glass varies in size (from the eyepieces POV) from camera to camera.
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#20 Paul Bruening

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Posted 08 January 2008 - 10:04 PM

I recall the "normal lens" topic coming up here a couple times before. There didn't seem to be an absolute resolve to the issue. Film class taught me that a one inch (25mm) lens for 16mm cine format and two inch lens (50mm) for 35mm cine format were normal. But that was a rule of thumb. More of a common knowledge than an absolute. Lens design alters those rules. A 50mm lens designed for 16mm format is going to look different from a 50mm made for 35mm cine just as a 50mm made for 35mm still framing.

Some here feel a lens closer to the 35mm-40mm focal length range is normal for a 35mm cine format. Some here prefer a 50mm focal length. All have their own reasons for the preference. So, what am I saying? This is a great topic for argument.

As I understand it, "normal" means that the image most replicates the optical-lensing characteristics of the human eye. No lens does that perfectly, so it is up to the lens designers to decide which characteristics are most important to achieve that, "normal". I find that 35mm lenses stretch subjects away from one another on the z-axis too much to seem normal. A 50mm juxtaposes objects in the z-axis closer to the eye but the angle of view can be restrictive in common, location rooms. Here, that 35mm comes in slightly more useful, and can become, practically speaking, your "normal" lens.
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