Angle of view

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rick.lang

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Angle of view

PostFri May 03, 2013 12:58 am

There has been discussion from the experienced cinematographers that recommend planning lenses for a camera based on the angle of view (in degrees) or field of view desired. The AbelCiné FOV calculator was as I recall a good way to compare the field of view of different lenses' focal lengths but, unless my memory has failed me, there has been a change and now it only compares some large sensors including the BMCC and some tiny sensors. The sensor size as well for S16 seems incorrect. And no mention of micro four thirds at all! Nearly useless for us. To find an alternative, look at this information which I have also posted in another forum"

"I found an iPhone App, called Angle of View, which does a great job in comparing angles of view for up to five sensors. The beauty is you can enter your own custom sensors and compare to predefined common formats. I also created custom formats for full frame and Super 35 by using a common 16:9 aspect ratio to normalize all comparisons to the HD aspect ratios used by the BMD cameras. So that takes a bit of work as well as $1.99 to Apple, but I am very happy with the results.

I display results for FF, S35, BMPC4K, BMCC, and BMPCC on the same screen as buttons. Clicking any of those five buttons shows the comparison to all others. Also shows crop factor comparisons in relation to the button clicked so you can quickly see the crop factors related to S35 or FF or MFT as you prefer. As you all know (I think) the AOV for a normal 50mm lens on a full frame sensor is 39.6 degrees. You can easily then adjust sliders or drop downs to find out how to get that or any desired angle on the BMPCC for example. Of course you know the answer to that is a 17mm lens. But I find it helpful since so many experienced cinematographers are saying you need to pay attention to the angle of view and not the crop factor.

Is my thinking correct on this or have I missed some salient point? Thanks for any reply."


Rick Lang
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popcornflix

Re: Angle of view

PostFri May 03, 2013 6:14 am

Yes, working from Angel Of View is better, because it's absolute. Crop Factor is a relative measure depending on which sensor/film you use as a factor of 1.0.

Angle Of View is what you can see when you shoot through the lens.

FWIW, "normal" AOV for motion pictures is generally accepted as 45º. Here's a chart made some time ago by Barry Green over at DVXUser.com:

Image

If you learn what AOVs you like for normal, wide & Tele, you can get consistent results no matter what camera you have on hand.

You can get additional accurate, detailed information from the American Cinematographer's Manual

Hope that helps.
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Joseph Ciccarella

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Re: Angle of view

PostFri May 03, 2013 7:42 am

This is great! Thank you both for the info and resources.

I'd like to ask a sincere question as i'd love to clear something up for myself.

This question is specific to the intention and what i see as the practical usage of the BMCC, both EF and MFT, not pocket or 4K versions.

It would seem that when the EF version of the BMCC was announced, its main purpose was to use the opportunities made possible by the growing number of DSLR shooters and give them a camera that they could then use with the lenses they already had in their kit, making it an easy migration and in turn giving the user more bang for their buck. Even in most of the advertising for the EF BMCC we see pictures of EF lenses mounted on it, especially Canon L series and Zeiss compact primes.

So, although learning angle of view as a long term skill is great for cinematographers whom will operate many different types of cameras and formats, is it the best thing for hobbyists and lower budget filmmakers who are buying a $3K camera?
Of course any aspiring DoP would be foolish not to learn these skills and could only find themselves bettered by doing so. But, are we elevating this particular product and situation a bit?

Would the beginner and hobbyist gain from a more attainable set of guidelines and something closer to that which they are more familiar with, namely the cameras and formats this camera is replacing to make that transition easier?

I know some on this forum have a hard time with this, but isn't it easier to just make that factor of 1.0 be the full frame 35mm. Therefore taking a number most people (especially those coming from the dslr world) are already familiar with and working from there?

Now, i know easy can be a sin and hard work builds character and will eventually lead to success. But, i wonder, how many people buying this camera will ever become the professional cinematographers these guidelines were meant for?

I am by no means a professional, but is this a professional camera? It can be in the right hands.

I appreciate all the real professionals on this forum. Having you here definitely brings the conversation to a higher plain and I learn more everyday. But for those of you just starting out, is this helpful or does it make sense to learn something more akin to the DSLR like crop factors?

Once again I am sincerely curious what people think and not attempting to antagonize anybody.

Thank You.
Joseph Ciccarella
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Pete Proniewicz-Brooks

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Re: Angle of view

PostFri May 03, 2013 8:46 am

Joseph Ciccarella wrote:Snip


The issue is that everyone comes from different experiences an sensor sizes. Mines all over the place, and though I have shot with DSLRs none have been FF35 sensor-ed cameras (indeed potential job next week on a 7D I believe). I'd wager a fair portion of the DSLR people have been using non FF35 cameras too, the Panasonic GH's are smaller for a start.

All this means that crop factors are based off a standard size from Stills photography not motion photography, and it's one that even those coming from such DSLR shooting backgrounds may not have touched.

Crop factors would make slightly more sense based around S35, not only is this a motion standard (for cinema at least the most common) but also lines up nicely with the Nikon DX format cropped sensors (and reasonably well with the canon crop as well). But still I feel they often add a level of fog and confusion to a conversation.

The way they are used terminology wise is often incorrect and this leads to a lot of the misunderstandings. A common misconception stemming from this is around the focal length, and the impression bad crop factor use that its a relieve concept. A 50mm lens is always a 50mm lens whether it was designed for DX, super 16 or FF35, it may not cover all the sensor sizes, and give different FoVs but its focal length is unchanged.

The best method to gauge it right is to experiment and build up things that way, they way most people probably learned their lens choices originally. This stops you having to do the maths (and therefore risking getting it wrong, wanting lenses in odd focal lengths etc) on set and just allows you to reach for the right lens. Remember it may well be 2 sums if you are used to a cropped sensor DSLR or a super 35 camera, but moving to a BMCC using FF35 crops... If you have a little chart on set/in your camera kit you might as well have the one pasted above or similar.
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Re: Angle of view

PostFri May 03, 2013 9:00 am

I 'm with Joseph on this. Every video camera I've ever had stated the zoom factor in specs in terms of what a full frame 35mm camera would be. With my BMCC Ef I have ben using a multiplier of 2.6 To determine where the angle of view of a particular lens would be. So the wide end of my 18-55mm zoom would equate to approximately a 47mm on a full frame. Thats close enough to "normal" for most anyone's purposes.
I also know that if I add my 0.43 x adapter to the lens, I will get len angle back pretty. close to the equivalent of the 18mm or so in full frame. Its not like it has to be an exact match of the field of view.
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rick.lang

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Re: Angle of view

PostFri May 03, 2013 12:30 pm

popcornflix wrote:Yes, working from Angel Of View is better, because it's absolute. Crop Factor is a relative measure depending on which sensor/film you use as a factor of 1.0.

Angle Of View is what you can see when you shoot through the lens.

FWIW, "normal" AOV for motion pictures is generally accepted as 45º. Here's a chart made some time ago by Barry Green over at DVXUser.com:

Image


Thanks for the chart which shows one view using the cinema 35mm as the standard. The appeal of using an app like Angle of View is you can touch any button to immediately change your frame of reference as it suits your purposes.

The chart has all sensor sizes adjusted to a 16:9 aspect ratio to compare apples to apples so kudos to Barry Green for that.

This chart does show why BMD reps at NAB2013 consistently said the BMPC4K used a 35mm sensor. Their sensor is extremely close in size to the sensor ascribed to 35mm cinema film in the chart! And that is smaller than Super35 as shown in the chart. Mystery explained so thanks for that!

The 45 degree angle for normal is shown in the chart to be achieved by a 50mm lens on a full frame stills camera. I can only conclude then the angles of view in the chart refer to the angle of the diagonal of the sensor. The Angle of View app uses the diagonal angle which is about 45 degrees, the horizontal angle which is about 40 degrees, and the vertical angle which is about 23 degrees but when all angles refer to sensors in the same aspect ratio of 16:9, they are making the same lens recommendations based on using either a consistent diagonal angle or a horizontal angle. Apologies if I wasn't clear enough in my original post that my reference to 39.6 degrees was the horizontal angle and the diagonal angle used by cinematographers is 45 degrees.

To those coming from a primarily DSLR background like me, I found the angle of view concepts awkward until I started playing with the Angle of View app and then it all makes sense and is very easy to use and determine which lenses you will want to use on a variety of sensor sizes. The app compares five sensor sizes and instantly determines the exact lens focal lengths for those sensors that provide the same angle. Of course when it tells you to use a 17.3mm lens on the BMPCC as your normal lens, you are likely to actually select a 17-18mm lens in practice but I like seeing the precise comparisons.

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Re: Angle of view

PostFri May 03, 2013 12:35 pm

ChrisBarcellos wrote:...I also know that if I add my 0.43 x adapter to the lens, I will get len angle back pretty. close to the equivalent of the 18mm or so in full frame. Its not like it has to be an exact match of the field of view.


Good point that these charts and the Angle of View app I recommended don't account for use of wide angle adapters or Metabones Speed Boosters. Maybe one day, but not today.

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Re: Angle of view

PostFri May 03, 2013 2:13 pm

Thanks Rick, I've been checking out the app and I can see the potential. What always gets me with AoV is when you start adding in Distance from Subject. Luckily I've had the same lens kit (FD's) for about 10 yrs and know pretty well what they'll do on my camera body (which these days is a 7D, used to be an AE-1, back in the day).
AoV also limits a common language I can use with the sometimes completely uninitiated, like Directors, who in my small experience, can barely speak in mm. ("Sometimes")
But, I definitely see the value in learning things this way and am gonna start referring to that chart and see if I can work this app into my routine. It's always best to be on the side of more knowledge than less, for sure.
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Re: Angle of view

PostFri May 03, 2013 2:53 pm

rick.lang wrote:
ChrisBarcellos wrote:...I also know that if I add my 0.43 x adapter to the lens, I will get len angle back pretty. close to the equivalent of the 18mm or so in full frame. Its not like it has to be an exact match of the field of view.


Good point that these charts and the Angle of View app I recommended don't account for use of wide angle adapters or Metabones Speed Boosters. Maybe one day, but not today.

Rick Lang
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That application looks like a useful reference. Once you get to know your lenses, it's pretty straightforward to get used to using them on a camera with a different sensor simply by using them. A tool like this will help with that part; once you're used to your combination of camera and lenses, you won't need the app much until you change something up. It's also useful for when you add lenses or change camera formats, to help you visualize the difference before you purchase your new stuff.

There's going to be quite a bit of confusion when people starting to use cameras like this start to realize that what still photographers refer to as "full frame" is one thing, while everyone else either calls 35mm something different like 35mm to be clear that they're not talking about, say, 645, and that in cinema 35mm isn't the same format.
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Re: Angle of view

PostFri May 03, 2013 6:21 pm

As I was perusing the internets today I came across an interesting tab on red.com. It's a set of tools to determine crop factor. You can put in a lens and it will show you the crop. What I found most interesting is that they use a 35mm still camera as their standard. Do you think that's because red is a stills as well as motion camera? You can find this on red.com under learning and then tools. I'm not going to link to it as I think that's against the rules of this forum but...
Here is their description: "Estimate Crop Factors With RED Cameras
Use this tool to preview how a given focal length will appear depending on resolution setting and sensor type. Illustration depicts viewable area relative to a traditional 35 mm stills photography sensor. The relative size difference between two sensors is typically expressed as a “crop factor.” A higher crop factor means a given lens will appear as if it were a longer focal length, and at the same subject magnification, that lens will also have more depth of field. The crop factor of a RED Mysterium-X[TRADE MARK SIGN] sensor is similar to the familiar Super 35 mm film format (with motion) and APS-H digital sensor (with stills). Then, as the resolution is decreased from the maximum setting, the crop factor increases. At 2K resolution, the Mysterium-X[TRADE MARK SIGN] crop factor approaches Super 16 mm film."
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Rakesh Malik

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Re: Angle of view

PostFri May 03, 2013 6:40 pm

Joseph Ciccarella wrote:As I was perusing the internets today I came across an interesting tab on red.com. It's a set of tools to determine crop factor. You can put in a lens and it will show you the crop. What I found most interesting is that they use a 35mm still camera as their standard. Do you think that's because red is a stills as well as motion camera?


It's more likely the chart that's aimed at still photographers, because people with a background in cinema will be more accustomed to the angles of view of super 35 to begin with.


A higher crop factor means a given lens will appear as if it were a longer focal length, and at the same subject magnification, that lens will also have more depth of field.



That's not actually correct, the magnification doesn't change with a smaller sensor, unless they're referring to post-capture magnification. The same is true for depth of field; it's the same, until you magnify the image to the same presentation size, because you end up magnifying the smaller capture to a larger degree.

An easy example is 4x5 vs 8x10 (easy because it happens to have even, round numbers that are easy to visualize). I can shoot in image with both formats, using the same lens and framing. One big neg, one small. I don't actually have to change anything in between shots - let's for simplicity assume that the subject is in the center, maybe it's a portrait or macro, or just a crappy composition suitable only for experiments like this. :)

Now print them to fill an 8x10 picture frame. The magnification in the 8x10 print: unity. No change. The magnification in the 4x5? 2x. A significant change.

I suspect that Red is pushing the Epic and Scarlet families for fashion photography in order to expand its market. With the Mysterium-X sensor, it's not that much better than a crazy expensive SLR if you're using it for stills photography, but with the Dragon that's no longer the case. With the Dragon the Reds are getting close to level of 35mm film in terms of resolution, but with higher dynamic range to go with their much higher price tags.

For stills photography you DO need more resolution in the high end markets, because high end photographers are shooting for printing, for which you need more resolution than for motion pictures.

A lot of the high end fashion photographers are still shooting with medium format though, which is anywhere from 20 to something around 80 megapixels now, and with 12+ bit color. I'm not certain, but I think some of the higher end medium format backs can actually capture 16 bit color rather than just capturing 12-bit and padding it to 16 to fit the file format. Of course, they don't have to do this at 24+ frame per second without melting down ;)
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popcornflix

Re: Angle of view

PostFri May 03, 2013 9:25 pm

Angle Of View is most useful as a common communication standard. When you talk to other people about the lenses you need for a shoot, tell them the Angle Of View, and the focal length for your favorite sensor size. (45º AOV, like a 30mm on an ARRI.)

Angle of View is an absolute measurement.

Crop Factor is a relative measurement, depending on which sensor you define as 1.0. Stills photogs and folks who started on 5Ds will calculate crop factor from a 135 FF. Movie people who have shot film will calculate from 35mmAA or S35. So three different shooters will cite three different crop factors for the same lens.

But if they included AOV in their communications, they will get the lens they need.
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Re: Angle of view

PostFri May 03, 2013 10:42 pm

Joseph Ciccarella wrote:As I was perusing the internets today I came across an interesting tab on red.com. It's a set of tools to determine crop factor. You can put in a lens and it will show you the crop. What I found most interesting is that they use a 35mm still camera as their standard. Do you think that's because red is a stills as well as motion camera? You can find this on red.com under learning and then tools.


Yes I have bookmarked that. Off topic: I just finished reading Phil Holland's NAB Journal where full-frame lenses received a fair amount of coverage. I'm not sure but I think the full-frame coverage may be needed for at least some wide focal lengths on the new Dragon 6K sensor.

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Re: Angle of view

PostFri May 03, 2013 10:59 pm

Tamerlin wrote:
rick.lang wrote:
ChrisBarcellos wrote:...I also know that if I add my 0.43 x adapter to the lens, I will get len angle back pretty. close to the equivalent of the 18mm or so in full frame. Its not like it has to be an exact match of the field of view.


Good point that these charts and the Angle of View app I recommended don't account for use of wide angle adapters or Metabones Speed Boosters. Maybe one day, but not today.

Rick Lang
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That application looks like a useful reference. Once you get to know your lenses, it's pretty straightforward to get used to using them on a camera with a different sensor simply by using them. A tool like this will help with that part; once you're used to your combination of camera and lenses, you won't need the app much until you change something up. It's also useful for when you add lenses or change camera formats, to help you visualize the difference before you purchase your new stuff.

There's going to be quite a bit of confusion when people starting to use cameras like this start to realize that what still photographers refer to as "full frame" is one thing, while everyone else either calls 35mm something different like 35mm to be clear that they're not talking about, say, 645, and that in cinema 35mm isn't the same format.


Completely agree. I'm using the app to compare lens' behaviour simultaneously across all three BMD cameras before making a purchase e decision. Finding which lenses will work best on each sensor and which lenses can be practical to share first between BMPC4K and BMCC EF and then which lenses can be shared between BMCC MFT and BMPCC. After discovering that the sensor size of the BMPC4K is almost exactly the size of Academy cinema 35mm, I feel good about that camera's potential but there is the problem of what to put in front of it. It is a lot easier picking wonderful lenses for the BMCC MFT and BMPCC.

Now if only I could afford a useful quality ciné lens for it! No problem when I'm dead but I guess that's not much help now. I wonder what Canon's 14.5-60mm will rent for.

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Rakesh Malik

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Re: Angle of view

PostFri May 03, 2013 11:08 pm

rick.lang wrote:Now if only I could afford a useful quality ciné lens for it! No problem when I'm dead but I guess that's not much help now. I wonder what Canon's 14.5-60mm will rent for.

Rick Lang
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Same here! However, if I could afford the cinema lenses I'd be using a Red and not waiting indefinitely for a Black Magic. :)

Hopefully there will be more lenses from companies like SLR Magic that are of good quality yet affordable. They may only be stepping stones to "real" cinema glass, but they might also end up being good enough to last through several generations of cameras. I have an SLR Magic lens, but I haven't been able to shoot anything with it yet. Aargh.
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Re: Angle of view

PostFri May 03, 2013 11:10 pm

Joseph Ciccarella wrote:I've been checking out the app and I can see the potential. What always gets me with AoV is when you start adding in Distance from Subject.


I didn't mention that so thanks for pointing it out. Yes, your iPhone in your pocket means you are a click and a touch away from knowing where your camera needs to be to ensure your image frame includes what you are framing in your scene. Of course you can get their quick enough without it, but it might help planning your blocking when you can very quickly calculate this before the scene is set. Nice to have is spelled out for you that at a planned distance for example your frame in focus will be eight feet wide and four and a half feet tall when you really need it to be six feet tall.

I agree if you are using the lenses you are most familiar with, this isn't needed compared to lenses that are new to you or lenses you are considering.

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