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I have shot some video footage using two iPhones from two different vantage points for doing motion capture of a human figure. In order for this to work I need to do camera-matching in my 3D software. In order to do the camera-matching I'm searching for the following specs:

Note that the iPhone 7 in question is not a Plus (so it has just one camera). Note also that this is for video footage, and that while shooting video the iPhone crops the frame slightly to compensate for stabilization. My understanding is that this results in a longer focal length. I've read that on iPhone 5 the result is a 4.1mm focal length instead of 4mm (or 4.027777~ to be precise... I think). Not sure if this is the same for iPhone 7.

So, I have the following specs for the iPhone 5, in case that helps determine those of the 7:

  • iPhone 5's focal length: 4.1mm (after cropping for stabilization)
  • iPhone 5's sensor: 4.54 x 3.42 mm

Thanks in advance for any help.

P.S. If you can explain how you found the answer that will be even more helpful than specs alone.

  • Comments are not for extended discussion; this conversation has been moved to chat. – bmike Jul 29 '17 at 22:10
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On the iPhone 6, I have found the video crop with stabilization activated to be 1.1x tighter than a still photo with stabilizer deactivated. The field of view goes from 63.9° to 58.1°, diagonally. The effective focal length changes from 4.2mm (29.3mm on full frame DSLR) to 4.6mm (32.3mm on full frame DSLR).

If you overlay a still image from the video footage and align it to a photo from the same position, you can see this crop in action.

iPhone 6 video stabilized crop vs. still picture

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The full specs of the iPhone 7 camera are:

Primary camera

  • 12 MP
  • f/1.8
  • 28mm
  • phase detection autofocus
  • OIS
  • quad-LED (dual tone) flash
  • 1/3" sensor size
  • geo-tagging
  • simultaneous 4K video and 8MP image recording
  • touch focus
  • face/smile detection
  • HDR (photo/panorama)
  • Video: 2160p@30fps or 1080p@30/60/120fps or 720p@240fps

Secondary camera

  • 7 MP
  • f/2.2
  • 32mm
  • face detection
  • HDR
  • panorama
  • Video: 1080p@30fps or 720p@240fps

Let me know if you need more info.

  • Thanks. Those specs are correct, but I need them in a different format. It seems the 28mm listed is the "35mm equivalent" according to this page. If I run that through this Lens Multiplication Factor Calculator I get a factor of 7.2. So I think next I'm supposed to divide 28mm by 7.2, which gives 3.888888~mm. But then the Apple-specific question is: how to compensate for the stabilization cropping? Also, I still don't know what the sensor width and height values would be. – Mentalist Jan 7 '17 at 7:42
  • Update: After finding this question on Photography Stack Exchange and following its link to this Table of Sensor Formats and Sizes, I now understand where the iPhone 5's values came from, and therefor understand that for the iPhone 7 it should be 4.80 x 3.60 mm (assuming the iPhone 7 is the same as the 6, and it should be since both have a 1/3" sensor size). Only question left is how to compensate for the cropping. – Mentalist Jan 7 '17 at 8:10
  • Firstly, thanks for sharing the update - I'm sure others will find the info helpful as well. Now, I don't claim to be any sort of photography expert, but I thought that Optical Image Stabilisation (OIS) doesn't crop the frame? Or am I misunderstanding that part of your question (i.e. About compensating for cropping)? – Monomeeth Jan 7 '17 at 8:50
  • Thanks, I don't know much about how image stabilization works either, but I read that the iPhone's video is cropped slightly to make it possible. (I think it's like when you rotate an image in an image editor, you either get white space or a cropped image.) When you switch from photo mode to video mode on an iPhone the zoom level increases noticeably, and this may be the reason. I'm hoping the Apple SE community here can shed some light on this. – Mentalist Jan 7 '17 at 9:32
  • @Monomeeth Is there an option in Settings to change the normal video to 1080p120, or is that only possible in the slo-mo video mode? – Skeleton Bow Jul 29 '17 at 20:29
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I just found this page which seems to completely answer our focal length questions: http://www.anandtech.com/show/10685/the-iphone-7-and-iphone-7-plus-review/6

That webpage says for Apple iPhone 7 (I LEFT OUT THE iPHONE 7 PLUS INFO):

FRONT CAMERA
Resolution: 7MP
Sensor: Sony Exmor RS (1.0 µm, 1/?")
Focal Length: 2.87mm (32mm eff)
Max Aperture: F/2.2

REAR CAMERA
Resolution: 12MP
Sensor: Sony Exmor RS (1.22 µm, 1/3")
Focal Length: 4mm (28mm eff) 8mm (56mm eff)
Max Aperture: F/1.8

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protected by bmike Jul 29 '17 at 22:08

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