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Variable a Focus Lens Sourcing

Started Sep 21, 2018 | Discussions thread
petrochemist Veteran Member • Posts: 3,619
Re: Variable a Focus Lens Sourcing

SmoothOperator wrote:

petrochemist wrote:

SmoothOperator wrote:

Does anyone know where I can source a variable focus lens to play with. The ml-20-35, by optotune seems really interesting. Edmund optics carries the electrical versions. M12(s-mount) to c-mount to nex are readily available, but I can't seem to find anyone carrying the manual lens.

https://www.optotune.com/products/focus-tunable-lenses/manual-lens-ml-20-35

I think it would be interesting to play with because it seems to approximate human vision. I'm really curious what happens when the focal length of a lens is changed without changing the distance.

Interesting but the last bit is pretty easy to predict. as you increase the focal length the bit thats focused will move away. The simple lens formula 1/F= 1/i + 1/s should apply

F = focal length, i = image distance (your keeping this fixed) s= subject distance ( the bit thats focused)

That is the simple part, but what about image size, depth of field and such. I suppose I could get some intuition by swapping in and out my 50mm macro and my 105mm enlarging lens. My intuition from practicing with my eyes focusing on a finger close to my face, then far away is that the field of view doesn't really change.

DOF and FOV will both be identical to a normal lens of the same focal length & the same degree of focus...

Things get more interesting when you pair one of these with another lens, to make a zoom, that can be retrofocus or telphoto...

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