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-   -   What is the mm equivalent of the GoPro Hero 3 in the narrowest FOV setting? (http://www.goproforums.com/15-gopro-hd-hero-3/1268-what-mm-equivalent-gopro-hero-3-narrowest-fov-setting.html)

daviesgeek 01-08-2013 02:20 PM

What is the mm equivalent of the GoPro Hero 3 in the narrowest FOV setting?
 
As I've said in a previous post, I'm looking to get a GoPro Hero 3 for live event shooting. I mainly shoot with DSLRs. I'm wondering what the mm equivalent of the Hero 3 (on the narrowest FOV setting) would be. I've read that the Hero 2 has an equivalent 15mm lens for a 35mm camera. Is this the same with the "Narrow" setting on the Hero 3?

Sticky 01-09-2013 12:29 PM

daviesgeek wrote:As I've said
 
Quote:

Originally Posted by daviesgeek
As I've said in a previous post, I'm looking to get a GoPro Hero 3 for live event shooting. I mainly shoot with DSLRs. I'm wondering what the mm equivalent of the Hero 3 (on the narrowest FOV setting) would be. I've read that the Hero 2 has an equivalent 15mm lens for a 35mm camera. Is this the same with the "Narrow" setting on the Hero 3?

Here's some not very helpful info right from GoPro:
http://gopro.com/support/faq-hd-hero/
"The GoPro cameras do not have zoom, however you can vary the field of view by changing the resolution settings. At 1080p you will have a 127 degree field of view, while at the other settings you will have a 170 degree field of view."

They make no mention of which camera they are talking about here. Nor do they tell us if this is horizontal, vertical, or diagonal field of view. Meh... whatever.... let's press on.

Here's a groovy lens calculator: http://www.tawbaware.com/maxlyons/calc.htm
I'm sure this was munged together by some college student overdosing on Cheetos and Mountain Dew at 3 a.m. I'm certain it's accurate. Those numbers above are really (really really really) wide. Let's assume it's diagonal FOV.
127 degree FOV translates to about a 12.5 mm lens in 35mm (technically 135mm) speak.
170 degree FOV translates to about a 1.7 mm lens.

This is very impressive. So impressive in fact that it's blatantly incorrect. Dang. Except it's not wrong......... wait. WUT?

So to achieve a 180 degree field of view, you need a 0.0 mm lens. Think about that for a moment. In fact, if you had a film plane and no lens, the film would receive light from a 180 degree FOV. However, Nikon and some other camera makers actually have a 180 FOV lens and they are rated as 5-10 mm fisheye lenses.

So when we get this wide the math starts to break down and there isn't a very good comparison. My experience is that the GoPro is really really wide. Like 14mm or 16mm wide.

Remember that the FOV of a H3 changes depending on the resolution setting.

This reply was no help at all... so there.

daviesgeek 01-09-2013 05:27 PM

On the contrary! Your reply
 
On the contrary! Your reply was helpful though it didn't give me a definite answer :) That's okay, because it helps me to understand it.
I have a question though...you mentioned the FOV settings. My apologies, since I have never used a GoPro (yet). My understanding (from watching various videos), was that the resolution and FOV were set independently. Am I understanding you correctly that the FOV setting is dependent on the resolution? I saw this video and it seems to say otherwise...

Sticky 01-09-2013 09:21 PM

daviesgeek wrote: Am I
 
Quote:

Originally Posted by daviesgeek
Am I understanding you correctly that the FOV setting is dependent on the resolution?

Short Answer: Yes

Overly complicated and vague answer:
Different Video resolutions will work at different FOV. GoPro details this as "Narrow", "Medium", and "Ultra Wide". Or at least that's what's written in my manual. Check out page 22 of the H3 Black manual:
http://d3m6eq123hajy2.cloudfront.net...2-000_RevC.pdf

This has been an interesting research project for me and TIL two things:
1. 1080p60fps is "Ultra Wide" while 1080p30fps is "Narrow" Wait............ WUT? So the same resolution but different frame rates give you different FOV?!?! Oh snap. I'm glad I figured that out.
2. The Hero 3 white, silver, and black have different sensor chips. Yea, sure. Each sensor is a different size. It's safe to assume they all use the same body and lens so you can just assume that they all provide a slightly different FOV even at the exact same settings. I wonder which one is widest? Well... probably the silver edition which has the biggest sensor.

daviesgeek 01-09-2013 10:19 PM

On the contrary! It was
 
<deleted> (accidental double post :) )

daviesgeek 01-09-2013 11:48 PM

Sticky wrote:daviesgeek
 
Quote:

Originally Posted by Sticky
Quote:

Originally Posted by daviesgeek
Am I understanding you correctly that the FOV setting is dependent on the resolution?

Short Answer: Yes

Overly complicated and vague answer:
Different Video resolutions will work at different FOV. GoPro details this as "Narrow", "Medium", and "Ultra Wide". Or at least that's what's written in my manual. Check out page 22 of the H3 Black manual:
http://d3m6eq123hajy2.cloudfront.net...2-000_RevC.pdf

This has been an interesting research project for me and TIL two things:
1. 1080p60fps is "Ultra Wide" while 1080p30fps is "Narrow" Wait............ WUT? So the same resolution but different frame rates give you different FOV?!?! Oh snap. I'm glad I figured that out.
2. The Hero 3 white, silver, and black have different sensor chips. Yea, sure. Each sensor is a different size. It's safe to assume they all use the same body and lens so you can just assume that they all provide a slightly different FOV even at the exact same settings. I wonder which one is widest? Well... probably the silver edition which has the biggest sensor.

Okay, thanks! That helps. Do you have the Black edition? If possible, I really would like to see the different FOVs. I'm looking to use this in more film-centric work. Live events, weddings, etc., so I need to know how much distortion I am going to get.

michael_vorhis 07-26-2013 02:32 PM

FOV for GoPro cameras
 
I think it's far easier to compare FOV angle than to try to compare focal lengths, since the focal length yields a different angle depending on the dimensions of the surface on which it's projecting (i.e., the digital sensor array or the film area rectangle.).

> Let's assume it's diagonal FOV.

That's correct, confirmed to me by GoPro some time back. [I find the publishing of a diagonal spec (and not saying it's diagonal) a little disingenuous, since almost no one can make use of a diagonal dimension. I had bought a Hero2 after doing the math and confirming that 170 degrees in the horizontal would yield me 90+ degrees in the vertical, but it wasn't horizontal (it was diagonal) so I didn't get the 90 degrees I needed (and now have to figure out how to cobble together some kind of strap-on adapter and probably accept major vignetting, to get the 90+ degrees I need for the in-flight hang gliding footage I shoot).]

Anyway, back to the angle. For 35mm full-frame (or film) cameras, you get about 100 degrees horizontal with about an 18mm focal length. For half-frame you need to be down around 12mm to get the same angle. Full-frame and half frame are both about a 3:2 aspect ratio, so if your digital SLR gets 100 degrees horizontal with whatever focal length you're using to get that, you'll get about 67 degrees in the vertical.

Now for GoPro: I can speak about the 960p setting, since I've measured it. I find that I can get around ~80 degrees in the vertical, maybe 85, if I shoot that taller aspect ratio (the 960p setting, being 9601280, has a 4:3 aspect ratio). The diagonal angle is 170 degrees in this mode, so horizontal will be maybe around 110 based on my measurements. Again the vertical angle is in the low 80's if memory serves. (Hence my need to make some makeshift optical adapter...if anyone knows of a wide-angle filter-mount adapter for any kind of camera, let me know because I might be able to strap something like that on the front of the GoPro. Done it before with other video cameras and it works, although the ones I have are small and the vignetting would be terrible...so I'm looking for something with a little larger diameter.)

- Mike Vorhis
Author of ARCHANGEL 5-star suspense thriller
Author of OPEN DISTANCE 5-star deep sea action thriller


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