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I'm doing a research project involving machine vision, and would ideally like to find a lens with a shallow DoF (perhaps about 2m or so in-focus) that can be attached to a smartphone. Something that would be able to focus reasonably from a couple meters in front of the camera up to 20m away or more (I understand my DoF will get deeper as I focus further, something with 'minimal' change to DoF would be great). Can anyone suggest a lens that would fulfill my criteria?

(I currently have an S9+, but any smartphone lens is acceptable)

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The problem with the request, shallow DoF with a smart phone, is that they are, by design, using a very wide angle and aperture large enough to effectively put everything in focus. Just about every attachment that I've seen relies on this principle. I've experienced a decent amount of additional bokeh when using Moment's macro - but here the focus becomes fixed. The Tele adds just a touch as well, but still doesn't allow one to change the focus...If you want full control, you may want to look at Beastgrip's DoF Adapter or similar.

  • Thanks! I checked out the link and that might be exactly what I need! – chasedj Feb 11 at 22:46
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You can use a Depth of Field Adapter. It basically projects an image of the scene onto ground glass that you can record with your cellphone. It is used to "convert" the depth of field and field of view of one format into another. Disadvantages include reduced light transmission and the potential to capture the texture of the focusing screen.

There are adapters that blur the texture of the focusing screen by moving it with a motor. You can also experiment with not using a focusing screen, but results will be inconsistent.

DOF Adapter

  • Beat me to the punch by 120 seconds >_< – Hueco Feb 11 at 22:36
  • Thanks for the info! Hadn't heard of this before and might just do the trick! – chasedj Feb 11 at 22:45

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