Wider Red

[Ace]

The Nikon 18mm 2.8D is a stll 24x36 prime with the larger image circle.
Fitting it on the red would still produce the same FOV on the RED as the 18 mm Master Prime.

What you stated earlier was that a 14mm 24x36 still lens when mounted on the RED would not be wider than a 18 mm Cine lens on the RED, which is wrong. The 14mm still lens will be as wide as a 14mm cine lens.
The 14mm 24x36 lens, when mounted on a 35mm still camera will have an even larger FOV, of cause, so would the Cine lens if the image circle was larger end the rear element would clear out from the mirror.

Greg, I will exit this discussion, as it seem to lead nowhere.
No hard feelings here, just tried to help out. Peace

Anders, some of your statements are true, but you might be using the wrong terminology as to why im confused. Im with greg on this. The RED sensor would crop a significant portion of a 24x36mm lens out, hence producing a longer focal length. The RED sensor would only "see" a portion of the middle of the projected image.

 

[Mike the beginner]

A beginners uptake on this. I think you guys are getting mixed up somewhere?

Lets try sort it out! otherwise i will go off my head. The red zoom at 18mm-85mm is I presume designed for a S35mm lens format and matched sensor right.

Ok we shoot 4k and we get whatever image we get. We then window the sensor and shoot 2k s16mm format. No vignetting because we have windowed the sensor and the lens is designed for a larger format (the full sized sensor). But the magnification is now increased (stronger) so the zoom takes on the magnification equivalent of roughly 36mm-170mm lens. How can the FOV with that magnification be the same as a 18mm-85mm lens?

Some of you guys are saying it does not make any difference but in a smaller format surely it does, simply because the magnification is altered and because of that the FOV is also altered. How can it not alter. The angle of a 170mm is much narrower than an 85mm lens all things equal. I just dont get it?

Anyway i am with Greg on this unless someone can explain in simple terms.

Maybe you really are all saying the same thing only different

Someone really should get to grips with this as i thought that was all sorted.

Michael

 

[Chris Kenny]

The RED sensor would crop a significant portion of a 24x36mm lens out, hence producing a longer focal length.

No, the Red sensor would crop a significant portion of the image, thus producing an image with a smaller FOV than you would get on the photo camera. In order to produce an image with a similar FOV on the larger format camera, you would have to use a lens with a longer focal length; this is where the notion of "focal length equivalents" comes from. But don't let this trick you into thinking the actual focal length of a lens changes depending on what format it's used with. Focal length is solely a property of the lens itself; the format doesn't factor into it.

In fact, this is what makes the notion of "focal length equivalents" necessary in the first place. You wouldn't need to say that a 14mm lens in 35mm cine format is (roughly) the equivalent of a 28mm lens in 16mm cine format if the format differences were already factored into the focal length numbers.

Or, to address this from another angle...

The argument here is whether a 14mm photo lens will appear wider on a Red than a 14mm cine lens. Now, it might be intuitive to think that this would be true, because the photo lens produces a larger image... therefore it must be focusing light less strongly, right? But this isn't the case. Focal length is a direct measurement of how strongly a lens focuses (or diverges) light. A 14mm lens is a 14mm lens, regardless of how large an image it produces.

In the most simple case, imagine two 14mm lenses, one having twice the diameter of the other. They both focus light with exactly the same power, but one produces an image twice as large. This larger image has a larger total FOV, but only because the image is physically larger. If you crop an identically sized rectangle out of the circles produced by both lenses, the FOV within the cropped areas will be identical.

Thus, a 14mm photo lens on Red produces exactly the same FOV as a 14mm cine lens. If you put both these lenses on a 35mm photo camera, they will produce a wider image than they will on a Red, but both lenses will still produce the same FOV. (Though the cine lens will show bad vignetting.)

 

[Chris Kenny]

Ok we shoot 4k and we get whatever image we get. We then window the sensor and shoot 2k s16mm format. No vignetting because we have windowed the sensor and the lens is designed for a larger format (the full sized sensor). But the magnification is now increased (stronger) so the zoom takes on the magnification equivalent of roughly 36mm-170mm lens. How can the FOV with that magnification be the same as a 18mm-85mm lens?

The argument here is not over whether a lens of focal length A will produce a different FOV depending on whether it's used with format X or format Y. It will; everyone agrees on this.

The argument is whether a lens of focal length A designed for format X will produce the same FOV as different lens of focal length A that's designed for format Y, when both are used with format Y. Greg says it won't, most other people say it will.

 

[Mike the beginner]

The argument here is not over whether a lens of focal length A will produce a different FOV depending on whether it's used with format X or format Y. It will; everyone agrees on this.

The argument is whether a lens of focal length A designed for format X will produce the same FOV as different lens of focal length A that's designed for format Y, when both are used with format Y. Greg says it won't, most other people say it will.
__________________
RED #404, Zoom #211

A 14mm photo lens from what i understood has a certain amount of magnification to produce a specific FOV in that particular format that it was designed to be used with. When you alter/change the format do you not also change the magnification coc etc and the same sized lens gives a narrower FOV when used with a smaller sensor. That is what my reading on this subject infered If your argument stood up Chris why is there smaller sized lenses in the s16mm format. A 14mm photo lens would not give the same FOV on a s16mm format to get that you would have to use roughly 9mm or something similar.

Maybe you are all saying the same thing but saying it eh....differently

The easiest solution will be for red to test the various lenses and inform us. I believe that has been their intentions anyway. I hope so.

Its late for me and time for bed zzzzzzzzzz

Michael

 

[SF Geek]

Chris, the answer is that it will. A 14mm from a still camera would produce the same field of view as 14mm cine lens on the red camera regardless if you're shooting 2k windowed 4k or 4.5K. I think if you just clear your mind and think about it simply you'll see that Graeme and Anders are right. This whole thread is completely convoluted and confuses the whole thing. I don't know who you have to hear it from to believe it, considering you wont trust Graeme, but I'm sorry Greg and Chris, you're wrong. Wasn't there a link to a visual representation of this somewhere on the old site? This is how it works.

Use this as an example:
With the full-sensor, 4.5K frame your lenses will have the widest FOV possible with the red, but a cine 14mm will have the same FOV as any other 14mm be it Nikon or Canon or Pentax even.

In 4k mode you'll get less FOV, effectively lengthening your lens but a 14mm or any other focal length lens will act the same as any other brand lens at the same focal length; ie a 14mm cine = a 14mm still

At 2k you'll effectively double your focal length compared to 4k but once again a 14mm lens will equal a 14mm lens whether it be meant for 35mm still or cine, or even if it is meant for 16mm.

That's it!

The only other issue that can be discussed is that you can't use a lens meant for a smaller format than what you're shooting; ie you can't use a 16mm lens for 35 formats and you can't use a cine lens for still 35 formats. That's where you get vignetting.

 

[Chris Kenny]

A 14mm photo lens from what i understood has a certain amount of magnification to produce a specific FOV in that particular format that it was designed to be used with. When you alter/change the format do you not also change the magnification coc etc and the same sized lens gives a narrower FOV when used with a smaller sensor.

Yes. This is what I described as what everyone agrees on, above.

If your argument stood up Chris why is there smaller sized lenses in the s16mm format. A 14mm photo lens would not give the same FOV on a s16mm format to get that you would have to use roughly 9mm or something similar.

Right, exactly (well, less than 9mm I think, but the point is valid). And the reason you need a lens with a different focal length is because 14mm is 14mm is 14mm. That's what I keep saying. Greg's argument is that 14mm lenses nominally designed for two different formats will produce different results when used with the same format.

If this were true, if format size were factored into focal length numbers, you would expect a 14mm lens designed for the 16mm format to produce the same FOV as a 14mm lens designed for the 35mm format, when each lens is used with its intended format. But as you point out above, that's not the case, creating a need for shorter focal lengths in 16mm format.

Format size isn't factored into focal length numbers. Look at the equations for calculating focal length; there isn't even anywhere to plug it in. Thus, when two lenses have their focal length given as 14mm, it means the same thing in both cases, even if the lenses are designed for different formats. And therefore, a 14mm photo lens on Red, while it will produce a narrower FOV than it does on a photo camera, will produce exactly the same FOV as a 14mm cine lens used on Red.

 

[Chris Kenny]

Chris, the answer is that it will. A 14mm from a still camera would produce the same field of view as 14mm cine lens on the red camera regardless if you're shooting 2k windowed 4k or 4.5K. I think if you just clear your mind and think about it simply you'll see that Graeme and Anders are right. This whole thread is completely convoluted and confuses the whole thing. I don't know who you have to hear it from to believe it, considering you wont trust Graeme, but I'm sorry Greg and Chris, you're wrong.

Uh... you seem to be confused about which side of this debate I'm arguing on. I've been arguing for exactly what you're saying.

 

[Jarred Land]

you guys are all nuts

just think about it as zoom compensation and you can all go back to playing nice

 

[Greg Lowry]

The factors used to calculate field of view are:

1. The dimensions of the format (frame, aperture or sensor -- the recording surface);
2. The focal length of the lens creating the image;

Format dimensions are defined by the dimensions of the recording surface, i.e.:

a) horizontal
b) diagonal
c) vertical

The format dimensions completely define the angle of view/FOV for any given lens focal length.

Because this is a trigonometric function, the angle of view does not vary linearly with the focal length. That is why a small change in the focal length of wide angle lenses produces a greater change in the angle of view than the same change would produce in a telephoto lens.

Any change to format dimensions or lens focal length changes the field of view.

 

[Chris Kenny]

The factors used to calculate field of view are:

1. The dimensions of the format (frame, aperture or sensor -- the recording surface);
2. The focal length of the lens creating the image;

[...]

If any of these factors change, so does the field of view.

This argument started when you said that "a 14mm Nikon for the still format will not be wider than 18mm designed for cine format." From the context (someone talking about buying a 14mm Nikon lens rather than a 14mm PL lens to save money) it seemed clear that you were talking about both of these lenses being used on Red.

But if you have a 14mm photo lens on a Red, and a 14mm cine lens on a Red, none of the factors you mention above are different. As per what you say above, which is exactly correct... same focal length, same format dimensions. You'll get the same field of view with either lens.

 

[Greg Lowry]

This argument started when you said that "a 14mm Nikon for the still format will not be wider than 18mm designed for cine format." From the context (someone talking about buying a 14mm Nikon lens rather than a 14mm PL lens to save money) it seemed clear that you were talking about both of these lenses being used on Red.

But if you have a 14mm photo lens on a Red, and a 14mm cine lens on a Red, none of the factors you mention above are different. As per what you say above, which is exactly correct... same focal length, same format dimensions. You'll get the same field of view with either lens.

The factor that's different is that the 14mm Nikon designed for the 36x24 format is used on the smaller RED ONE format. That's a format change and will result in a change to the FOV relative to its originally intended format.

The 14mm Nikon is designed to create a specific FOV for the 36x24 format. Change the format, the FOV naturally changes too.

I was involved in the development of the ARRI 765 (65mm) camera. Remounted Zeiss/Hasselblad lenses were used for the camera lenses. These lenses were originally designed and built for the Hasselblad 6cmx6cm format, all of which had a specified FOV when used for that format. When remounted for the widesceen 65mm 5-perf film format, the lens' focal lengths remained the same of course, but the field of view was dramatically different because they were being used on a different format, one that is about half as high of the original format size intended for those lenses. Think about this: how can an 80mm Hasselblad lens designed to cover a square format have the same FOV as the same lens used on a movie camera with a 2.21:1 widescreen aspect ratio? It can't and doesn't.

I don't know how much more I can say on the subject, but it's very important that this concept is understood.

 

[Chris Kenny]

The factor that's different is that the 14mm Nikon designed for the 36x24 format is used on the smaller RED ONE format. That's a format change.

That just means the 14mm photo lens will have less FOV on Red than it will on a 36x24 camera. It doesn't mean it'll have less FOV than a 14mm cine lens when both are used on Red.

Just to be a little more clear... as you noted above, the format (that you are actually using) and the focal length of the lens are the relevant factors. The format the lens was designed for is not a relevant factor. (Well, it is if you're worried about vignetting, but it has no impact on the FOV a lens will produce when used with a given format.)

 

[Greg Lowry]

That just means the 14mm photo lens will have less FOV on Red than it will on a 36x24 camera. It doesn't mean it'll have less FOV than a 14mm cine lens when both are used on Red.

Your first statement is right. The second is not.

Just to be a little more clear... as you noted above, the format (that you are actually using) and the focal length of the lens are the relevant factors. The format the lens was designed for is not a relevant factor. (Well, it is if you're worried about vignetting, but it has no impact on the FOV a lens will produce when used with a given format.)

The format for which the lens was designed IS a crucial factor because its FOV was determined by its intended format use. See the example above.

 

[Greg Lowry]

you guys are all nuts

just think about it as zoom compensation and you can all go back to playing nice

I would never dispute the suggestion that I'm nuts, but you'll have to explain your zoom compensation analogy a bit more completely, please.

BTW, I think we ARE playing nicely. We don't agree, but we're not throwing sand in each other's eyes. Yet.

 

[Chris Kenny]

The format for which the lens was designed is a crucial factor. See the example above.

The example above demonstrates that a lens of a given focal length will produce different FOV when used with different formats. As I've stated explicitly several times, nobody is disagreeing with this!

The point of contention is whether two lenses with the same focal length will produce different FOV when used with the same format simply because the lenses are nominally designed to cover different formats. I say they won't. You seem to be saying they will.

 

[Greg Lowry]

My original post in response to Martin's first post was to point out that a 14mm Nikon lens (for the 36x24 still format) would not offer a wide angle FOV greater than the 18mm on the 18-85mm zoom used on the RED ONE. Does anyone disagree with that?

 

[Chris Kenny]

Yes, that's what I'm saying.

OK.

One implication of what you're saying (that focal length numbers are based on FOV at a given format size) is that a 14mm lens designed for s35 should produce the same FOV when used with s35 as a 14mm lens designed for s16 produces when used with s16.

But this is clearly not the case! An s35 14mm lens is much wider on s35 than an s16 14mm lens on s16. This is what necessitates s16 lenses with very low focal lengths. Go find a FOV calculator and try it. Panavision's tells me that for s35mm 16:9, horizontal angle of view for a 14mm lens is 81.2º. For s16mm 16:9, it's 46.2º.

Note also that the calculator doesn't ask you what format the lens is designed for. Because it doesn't matter.

Once again, focal length is not a measure of FOV at a given format size. It's a measure of the ability of a lens to converge or diverge light. Format size doesn't enter into the equation. (Literally, if you look at the equation for calculating focal length.)

My original post was to point out that a 14mm Nikon lens (for the 36x24 still format) would not offer a wide angle FOV greater than the 18mm on the 18-85mm zoom used on the RED ONE. Does anyone disagree with that?

Yes. When used with a given format, any 14mm lens will produce the same field of view. The only time the format size that the lens is nominally designed for becomes relevant is when one is concerned about vignetting.

 

[SF Geek]

Please tell me that this post hasn't gone on all of this time and the original debate was you stating that the FOV of an 18mm lens on the red camera was wider than a 14mm lens on a standard 35mm still camera. Please tell me it wasn't. As far as that goes, you could be correct. I don't know the specs well enough to say if that's true or not, but I don't think anybody was disputing that with you. This post has gone on too long. I don't know how I got sucked into it.

 

[Chris Kenny]

Please tell me that this post hasn't gone on all of this time and the original debate was you stating that the FOV of an 18mm lens on the red camera was wider than a 14mm lens on a standard 35mm still camera.

I've tried to clarify that point several times, and as far as I can tell, Greg is really saying that a 14mm cine lens will produce wider FOV when used on a Red than a 14mm photo lens will produce when used on a Red. But maybe my attempts at clarification have been misunderstood as well.