Wider Red

[Martin Drew]

I would like to go wider than the 18mm end of the Red Zoom. The cheapest way to do this seems to be 14mm Nikon stills lens, but that would mean changing the lens mount whenever I needed to get a wider shot. Is there an easier way that isn't big bucks and that will still give an acceptable quality level (I appreciate that is a subjective question, I can accept some compromise, I just want the image to be good enough to intercut without looking obviously crap).

I have used adapters with SD cameras before never with HD. Has anyone had any experience of using lens adapters or converters on s16 or 35mm cameras? If so what sort of results did you get? certainly a 0.8x or 0.7x adapter on the front of the Red zoom will give an acceptable FOV but would one be even usable, they require macro focusing, will Red zoom have macro?

Martin

[PaulClements]

Why not look at using Primes, you can pick up 2nd hand Zeiss Primes for a fairly decent price or look at cheaper manufacturers if budget is a large constraint (As it is for many of us!). Some of the best Nikons brand new can be similar prices to 2nd hand Primes. Quality is an issue of course but you ought to be able to find PL mount Primes alot easier which means not needing to change the lens mount. Also if you were looking to hire yourself with the camera or the camera with accessories they'd be more responsive to having Primes they know than Nikon Stills - The value of renting with a decent prime would be alot more as well.

However if you are looking purely at personal use and do not consider it an issue then Nikons are a great way to go. Overcome the inherent issues with still lenses and you will enjoy similar images to the primes.

[Akcelik]

i've been looking into this myself and did not find anything wider with manual aperture ring control.

from another thread i read, its possible to use lens with no aperture ring, adjusting the setting from dslr.
hyperfocal that with ie' a sigma 10-20mm (equivalent 15-30) would make it the most affordable, inconvenient, widest option.

i will probably end up with the sigma 15-30 (equivalent 22.5-45) thats a nice wide & normal in1, with aperture ring control & its affordable.

[Martin Drew]

As always budget is the issue a 14mm PL mount prime would be ideal and ultimately a set would be great (a bit out of my range at the moment though). I have been keeping my eye out but I haven't seen much around second hand at this kind of focal length without paying a lot of money.

Martin

[Zakaree Sandberg]

im still confussed on why nikons wouldnt be a good choice for a commercial production. As i understand they can definatly cover a super 35mm frame...is it just the focusing thats an issue? not as smooth as a zeiss prime? whats up!

[Jaime Vallés]

I believe that focusing is harder (but a good follow focus unit can help a lot), and they breathe more (which can't really be helped).

The actual quality and sharpness should be spectacular, though. I'm most definitely going to start with Nikon lenses, and for big productions I'll rent PL lenses.

[Zack Birlew]

Yeah, that's been what I was thinking of doing. The Nikons though, from all the 35mm adapter footage and some of RED test footage, don't seem to be anything to worry about when it comes to image quality. :cool:

[Martin Drew]

Broadly speaking there is no problem with the image quality of still lenses, obviously there are good still lenses and not so good still lenses but there are a number of operational issues with even the finest quality still lenses which make a compromise for cine use.

Breathing: When you focus a lens the elements move and that can add a zooming effect. This isn't a problem for still cameras because you only take the picture when you have finished focussing. It is a problem if you are racking focus mid shot on a cine camera. Cine lenses are designed to reduce breathing

Pulling focus: When shooting motion any focussing on shot must be smooth and precise, for this reason cine lenses have an expanded focus ring range compared to still lenses. In contrast modern still lenses are designed for autofocus so often the focus ring only turns a small way to cover the whole focus range.

Image centreing: With still zooms the image centre may not remain constant while zooming. Cine zooms are adjusted to so that the elements are aligned to avoid this.

Consistancy: Cine primes within a set are matched, so that if you swap lenses the image doesn't subtly change colour.

There is no reason why you can't use a still lens but it is limiting for these reasons. Having said that a 14mm Ultra Prime T1.9 is about $15000, in contrast the Nikon 14mm f/2.8 can be had for about $1350. So budget sometimes decrees that these operational compromises are acceptable.

Martin

[Ben Feuer]

OTOH -
How often do you see yourself using 14mm over 18mm? If the answer is "once in a long while", why not rent the Zeiss for individual days/shots? Maybe the answer to the Red Lens dilemma is to own the most basic stuff, rent the rest, and upgrade as budget permits?

[Greg Lowry]

Don't forget that a 14mm Nikon for the still format will not be wider than 18mm designed for cine format. Also, extreme wide angle lenses for still format will tend to have greater curvilinear distortion.

[Martin Drew]

Maybe you are getting that the wrong way around Greg. You could say that a 14mm lens used for a 35mm cine format will give you the same field of view as a 22mm lens used on a 35mm stills film camera, was that your point? But 14mm is 14mm whatever format it is used with. A 14mm stills lens on RedOne will still be 14mm and will give a wider FOV than 18mm.

Martin

[Greg Lowry]

Maybe you are getting that the wrong way around Greg. You could say that a 14mm lens used for a 35mm cine format will give you the same field of view as a 22mm lens used on a 35mm stills film camera, was that your point? But 14mm is 14mm whatever format it is used with. A 14mm stills lens on RedOne will still be 14mm and will give a wider FOV than 18mm.

Martin

Sorry, Martin, but that is not true. A 14mm Nikon still lens (for the 36x24mm format) will NOT provide a wider FOV than an 18mm cine lens when used on RED ONE (sensor size 24.4x13.7mm). In fact, they're roughly equivalent in terms of FOV. If you're talking about a Nikon mount lens for the APS-C format, that's different, but I don't think you were.

Yes, a 14mm lens is always a 14mm lens, but the FOV is different for different formats.

[Jarred Land]

remember the Mysterium sensor is the same size roughly as an APS-C sensor.

We have a Tamron 14mm lens at Red with manual overide aperture (nikon mount) that I put on to test a few weeks ago when i did the other Nikon test and it worked fine.

[Anders Holck]

A 18mm gives a 64˚ Horizontal FOV, a 14mm 75˚ in N35mm gate (Red at 4k)

A 14mm still lens will have the same FOV as a 14mm Cine lens when exposing the same gate size.

The image circle of the still lens will cover a larger format, but that doesnt matter as the crop is defined by size of the gate.

[Anders Holck]

For example on a Nikon DX body (Close to Red at 4.5k), the Nikkor 17-35mm f2.8D and the Nikkor 17-55mm f/2.8G DX both have a 79˚ FOV at 17mm, even thpugh the latter is a scaled down lens with a smaller image circle.

[Greg Lowry]

A 14mm still lens will have the same FOV as a 14mm Cine lens when exposing the same gate size.

Sorry to disagree, Anders.

Let's be specific here. The RED sensor is 24.4x13.7mm. One would need about a 9mm still camera lens (designed for the 36x24mm format) to be roughly equivalent to the FOV of a 14mm cine lens on the RED ONE.

A 14mm still camera lens is roughly equivalent to a 20mm cine lens in terms of FOV on the RED ONE.

[Nick Shaw]

I'm with Anders (and Martin) on this Greg. People talk about the 'conversion factor' for 35mm full frame stills lenses when used on an APC-C DSLR, so a 14mm still lens on a Red may be 'equivalent' to a 20mm lens on a full frame 35mm camera, but it's still the same FOV as any other 14mm lens, ciné or otherwise.

Nick

[Graeme Nattress]

Yup. 14mm = 14mm = 14mm. You can use a crop factor to think about how the lens might look on a camera with a different size sensor, but, mm always gives the FOV of the lens.

Graeme

[Shawn Bannon]

Is it just me or are some people repeating the same things back to each other but with different wording?

Is everybody talking about Field of View or are some of you actually talking about Depth of Field?

Field of View represents the degrees a film format or sensor is seeing.

Anybody remember Dimension 150? An 18mm lens which gave a 150 degree field of view for the 70mm format.

[Anders Holck]

Yes it's Field Of View.

The misconception is that there is somehow a multiplier included in the given focal lenght of a lens based on the gate size. Which not true.
The focal length of a lens is not dependent on the gate size but strictly on the distance from the secondary principal point of a given lens to the imaging plane.

The FOV of the lens is dependent on both the focal lenght and the gate size. The formula for H FOV at infinity focus is 2 * arctan (Sensor width/(focal length * 2))

[Greg Lowry]

Yes it's Field Of View.

The misconception is that there is somehow a multiplier included in the given focal lenght of a lens based on the gate size. Which not true.
The focal length of a lens is not dependent on the gate size but strictly on the distance from the secondary principal point of a given lens to the imaging plane.

The FOV of the lens is dependent on both the focal lenght and the gate size. The formula for H FOV at infinity focus is 2 * arctan (Sensor width/(focal length * 2))

I have never disputed that the focal length remains the same no matter the format. in fact, you'll find dozens of posts on the old forum where I reinforced this fact.

However, the EFFECTIVE FOV (perhaps the word "effective" is necessary here for clarity) of a 14mm (35mm stills format 36x24mm) still camera lens when used on the RED ONE is not the same as a cine format purpose-built 14mm lens. I stand by my statement that the 14mm 35mm still format lens is about the equivalent of a 20mm cine lens in terms of FOV when used on the RED ONE.

Indeed, FOV is dependent on focal length and "gate size" as you call it.

Are we disagreeing or miscommunicating?

[Greg Lowry]

Yup. 14mm = 14mm = 14mm. You can use a crop factor to think about how the lens might look on a camera with a different size sensor, but, mm always gives the FOV of the lens.

Graeme

Yes, 14mm = 14mm = 14mm. But, for example, the RED 300 when used on the S16 format provides a FOV equivalent to between a 400mm and 500mm if recall correctly (I made the computation months ago and would have to look up the exact number). When using lenses designed for a different format it is simply not true that the "mm always gives the FOV of the lens". This is always focal length and format dependent.

A more extreme example: Does a 150mm camera lens designed to cover the 6cmx6cm medium format (e.g. Hasselblad) provide the same FOV or image magnification when mounted on a 35mm still camera? No, it doesn't.

[Martin Drew]

I think a lot of the confusion comes from the the talk of equivalent focal length, which sort of implies the focal length changes when a lens is used for a different format. The only big difference between a lens designed for a larger format and a lens designed for a smaller format will be that the larger format lens has to project a larger image.

Martin

[Martin Drew]

A cine 14mm lens is designed to cover a smaller format so it will not need to project as large an image as a still camera 14mm lens, but they will both have the same magnification. If we use both lenses on the same sized sensor the image they project will be the same. If you used a S16 14mm lens it will project the same magnification image on the sensor too but because it is designed for a smaller format it will vignette.

Martin

[Martin Drew]

A more extreme example: Does a 150mm camera lens designed to cover the 6cmx6cm Medium still camera format provide the same FOV or image magnification on a 35mm still camera? No, it doesn't.

It provides the same image magnification but because the sensor is smaller that image is cropped hence FOV is reduced, it is all down to the size of the sensor. If you mounted a 150mm medium format lens on a 35mm camera it would give you the same FOV as a 150mm 35mm still format lens on that same camera.

Martin

[Greg Lowry]

A cine 14mm lens is designed to cover a smaller format so it will not need to project as large an image as a still camera 14mm lens, but they will both have the same magnification. If we use both lenses on the same sized sensor the image they project will be the same.
Martin

This is fundamentally incorrect.

If you use both lenses on the same size sensor, the image circles for each of the lenses are obviously different -- one is larger than the other. The fact that you are cropping an image area from the large image circle effectively alters the FOV of that lens relative to the format for which it was designed.

[Greg Lowry]

It provides the same image magnification but because the sensor is smaller that image is cropped hence FOV is reduced, it is all down to the size of the sensor. If you mounted a 150mm medium format lens on a 35mm camera it would give you the same FOV as a 150mm 35mm still format lens on that same camera.

Martin

These are contradictory statements.

Wow. We couldn't disagree more. But rather than burn up more bandwith, I'll defer further discussion on this subject to others and will contribute further if I feel I can be useful.

It's an important discussion.

[Anders Holck]

Greg,
The 18 mm Zeiss Masterprime has a horisontal FOV of 68.6° in DIN S35 (24mm x 18mm)

The Nikon 18mm 2.8D Prime has a horisontal FOV of 69.2 ° on a Nikon DX DSLR (23.7 x 15.7)

Thats pretty close both in imaging format and FOV.

So a 18mm purpose built cine lens should be pretty damn close to a 18 mm still model.

[Anders Holck]

If you use both lenses on the same size sensor, the image circles for each of the lenses are obviously different -- one is larger than the other. The fact that you are cropping an image area from the large image circle effectively alters the FOV of that lens relative to the format for which it was designed.

The image circle has nothing to do with magnification or FOV. It only affects the net area that the lens is projecting at the sensor plane.

A 100mm lens that covers a radius of 12mm, has the exact same magnification as a100mm lens that covers a radius of 24mm.

In a 20x20mm gate size both lenses would project the same FOV. In 40x40mm the FOV would also be identical, but the first lens would vignette horrobly (project a round image)

[Greg Lowry]

The image circle has nothing to do with magnification or FOV. It only affects the net area that the lens is projecting at the sensor plane.

A 100mm lens that covers a radius of 12mm, has the exact same magnification as a100mm lens that covers a radius of 24mm.

In a 20x20mm gate size both lenses would project the same FOV. In 40x40mm the FOV would also be identical, but the first lens would vignette horrobly (project a round image)

You focused of an incidental part of my post.

Let me use another illustration:

A 18mm Zeiss Master Prime covering the S35 format (24.9mmx18.7mm) has a horizontal angle of view of 77 degrees.

The same 18mm Zeiss Master Prime covering the Normal 35mm format (22x16) has a horizontal angle of view of 70.2 degrees.

Unfortunately, ARRI doesn't specify the vertical angles of view and I'm not inclined to compute them myself right now, but just from these differences in horizontal angle of view one can infer that the field of view between these two formats, using exactly the same focal length lens, will be different. How could it not be?

[Chris Kenny]

A 18mm Zeiss Master Prime covering the S35 format (24.9mmx18.7mm) has a horizontal angle of view of 77 degrees.

The same 18mm Zeiss Master Prime covering the Normal 35mm format (22x16) has a horizontal angle of view of 70.2 degrees.

Unfortunately, ARRI doesn't specify the vertical angles of view and I'm not inclined to compute them myself right now, but just from these differences in horizontal angle of view one can infer that the field of view between these two formats, using exactly the same focal length lens, will be different. How could it not be?


FOV will be different when using lenses of the same focal length on different formats, yes. But what's under discussion here is whether FOV will be different when using two lenses of the same focal length (14mm) on the same format, just because one lens is designed to produce a larger image than the other.

It won't; it'll be exactly the same.

[Anders Holck]

Yes, we agree on that of course.

What I'm disagreeing with was the comments like:
"I stand by my statement that the 14mm 35mm still format lens is about the equivalent of a 20mm cine lens in terms of FOV when used on the RED ONE"
I still dont get that one :-)

I argue that a 18mm still format lens is about the equivalent of a 18mm cine lens in terms of FOV when used on the RED ONE

or as I wrote based on specs from the two manufacturers:

The 18 mm Zeiss Masterprime has a horisontal FOV of 68.6° in DIN S35 (24mm x 18mm)

The Nikon 18mm 2.8D Prime has a horisontal FOV of 69.2 ° on a Nikon DX DSLR (23.7 x 15.7)

Almost the exact same FOV, One is a CINE lens the other is a 24x36 still model.

[Greg Lowry]

Yes, we agree on that of course.

What I'm disagreeing with was the comments like:
"I stand by my statement that the 14mm 35mm still format lens is about the equivalent of a 20mm cine lens in terms of FOV when used on the RED ONE"
I still dont get that one :-)

I argue that a 18mm still format lens is about the equivalent of a 18mm cine lens in terms of FOV when used on the RED ONE

or as I wrote based on specs from the two manufacturers:

The 18 mm Zeiss Masterprime has a horisontal FOV of 68.6° in DIN S35 (24mm x 18mm)

The Nikon 18mm 2.8D Prime has a horisontal FOV of 69.2 ° on a Nikon DX DSLR (23.7 x 15.7)

Almost the exact same FOV, One is a CINE lens the other is a 24x36 still model.

The Nikon DX DLSR (23.7 x 15.7) is NOT a "24x36mm" still camera. The Nikon DX sensor is 23.7mm wide x 15.7mm high. The standard 35mm still format is 36mm wide x 24mm high. As far as I'm aware, the discussion about using Nikon lenses on the RED ONE is about use the manual F mount lenses. Those lenses are designed to cover the 36x24mm format.

I was always careful to specify that i was referring to the 36x24 still camera format, NOT a smaller APS-C sensor size such as that on the Nikon DX. Of course if the sensors sizes are about the same, the same lens focal lengths will have roughly the same FOV.

Has there been some development that will allow auto Nikon lenses to be used in manual mode? Otherwise, you'll need to use manual F mount lenses designed for the 36x24mm still format and they will not provide the same relative FOV on RED ONE.

Perhaps we can now agree on the points I made?

[Martin Drew]

Not contradictory at all. I presume you are talking about the maximum FOV the lens can image, I am talking about the FOV of the image taken from the sensor, that is the only significant FOV. Sure the medium format lens will have a larger maximum FOV, but we won't be using it, we will just be using the FOV defined by the area of the sensor, in this case a frame of 35mm film. It would be exactly the same size image as if we used the 150mm lens on a 6x6 camera then took the 6x6 trannie and with a scalpel cut it down to 36mm x 24mm

Any lens will have a maximum FOV beyond which it will vignette, that is defined by the magnification of the lens (determined by the focal length) and by the format the lens is designed for. That FOV, the lens maximum FOV, is only relevant in deciding whether a lens will vignette or not. If a lens is used to create an image on a sensor, assuming the lens doesn't vignette, the FOV of the sensor will be determined purely by the magnification of the lens and the size of the sensor.

Martin

[Anders Holck]

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 :-)

[Greg Lowry]

Not contradictory at all. I presume you are talking about the maximum FOV the lens can image, I am talking about the FOV of the image taken from the sensor, that is the only significant FOV. Sure the medium format lens will have a larger maximum FOV, but we won't be using it, we will just be using the FOV defined by the area of the sensor, in this case a frame of 35mm film. It would be exactly the same size image as if we used the 150mm lens on a 6x6 camera then took the 6x6 trannie and with a scalpel cut it down to 36mm x 24mm

Any lens will have a maximum FOV beyond which it will vignette, that is defined by the magnification of the lens (determined by the focal length) and by the format the lens is designed for. That FOV, the lens maximum FOV, is only relevant in deciding whether a lens will vignette or not. If a lens is used to create an image on a sensor, assuming the lens doesn't vignette, the FOV of the sensor will be determined purely by the magnification of the lens and the size of the sensor.

Martin

Martin, you're a formidable opponent in a debate, with or without the facts, but I must respectfully say that you're knowledge of this subject is fuzzy. I guess we'll have to agree to disagree.

[Greg Lowry]

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.
a 14mm 24x36 lens on a 35mm still camera will have an even larger FOV.

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

OK, Martin. Someone else will no doubt pick up where we left off. I rarely disagree so completely with anyone on a technical matter, but in this case I do. I believe the opposite of what you say above is true. But no hard feelings indeed. It's just tech talk.

[Martin Drew]

OK, Martin. Someone else will no doubt pick up where we left off. I rarely disagree so completely with anyone on a technical matter, but in this case I do. I believe the opposite of what you say above is true. But no hard feelings indeed. It's just tech talk.

Just for reference that was Anders post

[Martin Drew]

Martin, you're a formidable opponent in a debate, with or without the facts, but I must respectfully say that you're knowledge of this subject is fuzzy. I guess we'll have to agree to disagree.

Greg

It is pleasant to have such a good humoured argument even if we do totally disagree. I am not going to give up on this one because I have the advantage of knowing I am right :) (don't we all). I will give a little thought to how I can convince you, I am sure there is a way. Hopefully someone who's opinion you value will chime in and you will see it.

I am sure it won't carry a huge amount of weight but I would point out that so far no one who has contributed to this topic agrees with you, of course that doesn't mean anything in itself but surely it must give you pause for thought.

Got to go to bed now, but I shall return.

Martin

[Greg Lowry]

Just for reference that was Anders post

Whoops, sorry!

[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? :confused:

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:confused:

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:confused: 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 (http://en.wikipedia.org/wiki/Focal_length) 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 (http://www.panavision.co.nz/main/kbase/reference/calcFOVform.asp) 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.

[Greg Lowry]

Yes, the thread went on way, way, WAY too long and got twisted and turned by various interpretations of the original question. And part of that is my fault because I wasn't always paying close enough attention to the individual posters who were sometimes asking different questions or expressing different points of view not related to the original matter. Mea culpa.

The FOV of any two 14mm lenses on the same format will be the same.

A 14mm still lenses for 36x24mm still format used on the RED ONE will have a decreased FOV and doesn't offer a viable increase in wide angle FOV relative to the 18mm on the 18-85 zoom.

Can we leave it at that?

[Jaime Vallés]

You're all pretty, and you can all go to the prom.

[Chris Kenny]

Yes, the thread went on way, way, WAY too long and got twisted and turned by various interpretations of the original question. And part of that is my fault.

The FOV of any two 14mm lenses on the same format will be the same.

A 14mm still lenses for 35x24mm used on the RED ONE will have a decreased FOV and doesn't offer a viable increase in wide angle FOV relative to the 18mm on the 18-85 zoom.

Can we leave it at that?

Um. I hate to be the bad guy and drag this out, but... your two statements appear to directly conflict with each other.

If the FOV of any two 14mm lenses on the same format will be the same, then it follows that a 14mm photo lens (which is a member of the category "any 14mm lens") will offer wider FOV than the 18mm on Red's zoom, when both are used on the same format.

Yes, a 14mm lens on Red will offer less FOV than a 14mm lens on the 35x24mm photo format, but this is a separate issue (about which there has been no disagreement in this thread).

[Greg Lowry]

I've reviewed the entire stream and I now see where it came off the rails. My original post was, I believe, misinterpreted and I responded without correcting the misinterpretation or clarifying my meaning. Disagreement resulted because the misinterpreted premise was compounded by oher posts, including mine, that threw other issues into the mix. I'm not sure we can untangle it now. And I'm too tired to try tonight. I'd hate to be somebody trying to decipher this thread. Perhaps nuking is in order.

[Jarred Land]

Well at your request Mr. Lowry... i offer you the first locked thread of Reduser :)

I shoulda locked it after Jaime's great words of wisdom, so I will repost then and close it down.




You're all pretty, and you can all go to the prom.

.