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Yes. Low contrast filters. Lee, Tiffen and Hitech all manufacture them. Varying densities available in round and rectangular products. Some in stock at BH others special order. Your local camera store should be able to get for you as well.


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For so-called unit focusing lenses (many but not all prime lenses are), moving it closer to the sensor is what will make it focus to infinity, and that is what the lens mechanics are actually DOING to focus. Lens designs that focus only by moving the front element or group closer to the rest of the lens can usually (if these are simple designs like tessars) ...


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If the lens can focus on closer objects, but not achieve infinity focus, the lens needs to be brought closer to the sensor or film plane. This often happens with adapted lenses that move the lens too far from the imaging plane. This also happens when you insert focusing bellows or extension tubes between a camera and its lens — you trade infinity focus for ...


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Because your plan is to mount a supplemental close-up lens, in direct contact with the surface of your camera phone, you believe this added lens must have a very short back focus. This is incorrect thinking. In fact, you can procure most any hand-held magnifier and place it in direct contact with the phone. The air-space between the phone and lens will not ...


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Most magnifying lenses will reduce the focus distance therefore increasing the magnification. You really need a lens designer, which you might find on physics SE, but since they won't know what is inside the phone, they may not be able to help. Your best bet is trial and error. iPhone8 Only: iPhone8 with expensive 8X Loupe iPhone8 with cheap magnifier. ...


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It would appear that a thick, planar optical glass window is also capable of lengthening back focus - and would probably introduce less new problems. Why is this not done in practice? Because it won't work. It won't lengthen the back focus enough. That is, a flat optical element shifts the focus by an amount less than the thickness of that flat element....


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Sometimes, the absence of more elements than absolutely needed, and of modern coatings that can give multicoloured ghosts. Steinheil Cassarit f/2.8 45mm at f/4 or f/5.6 on Sony APS-C, scaled but otherwise as shot, daylight balance, "clear" creative style. This is a simple triplet (with its disadvantages - see corners) with first gen coating. Example has: ...


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Because in many cases the flat glass needed to lengthen the back focus by the needed amount would need to be thicker than the entire registration distance. The effect of flat glass is so miniscule that it would take glass thicker than the space available to get the desired additional back focus distance for most applications. Flat glass would also ...


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Camera lenses are converging lenses, meaning they have positive power. A simple convex lens will do this job, however, the image is flawed. I am talking chromatic aberration whereby each color will come to a focus at a different distance downstream of the lens. Now a negative lens diverges and a positive lens converges. Additionally they display opposite ...


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As pointed out in the comments, your illustration shows the image in the wrong place. The image is formed behind the lens. Moreover, the image is doubly inverted with regard to the actual object: If you put the pinhole at the origin (0, 0, 0), things are quite simple: no calculations are necessary, just a reflection about the origin. Suppose the film/sensor ...


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