Daniela Lopez Posted February 20 Posted February 20 Hello everyone! I'm working on a cinematography research project which entails testing the limits of depth of field, on camera and/or in post, but with my limited resources, in particular with telephoto lenses where "deep focus" would typically be very difficult to achieve. One of the various ideas I thought of is using some sort of stereo lens or set up, two get two almost identical images but with different focus distances, and then find a way to combine them in post. I have seen that these 3D beamsplitter stereo rigs exist, not intended for what I want, but I think they would theoretically work for it? My questions for you are - 1. Have you ever used one of these rigs? Are they very expensive to rent for a day? 2. Has anyone built a DIY version of these, maybe to use with smaller cameras, or with two iPhones or something like that? Thank you so much 🙂
Joerg Polzfusz Posted February 20 Posted February 20 Hi! Are you trying to achieve this effect in the same camera and hence are looking for a lens like this? https://www.amazon.de/Loreo-Lens-Cap-Macro-Pentax/dp/B003O3BSJC/ Maybe you could also try a „split diopter“? https://www.amazon.de/7artisans-Dioptrien-Objektivfilter-Spezialeffekte-Fotografie-Vordergrund/dp/B0BX68RZ6J/ https://www.amazon.de/JONGSUN-Spezialeffektfilter-Widescreen-Anamorphotische-Fotografie/dp/B09NN4XWBT/ When testing with two cameras, then the cheapest way to mount two small and lightweight cameras onto the same tripod would be a metal bar like this: https://www.amazon.de/WANGCL-Bracket-Tripod-Camera-Extension/dp/B0B1MN23TT/ (Of course, making them 100% pointing into the same direction would be cumbersome.) Good luck! 1
Daniela Lopez Posted February 20 Author Posted February 20 12 minutes ago, Joerg Polzfusz said: Hi! Are you trying to achieve this effect in the same camera and hence are looking for a lens like this? https://www.amazon.de/Loreo-Lens-Cap-Macro-Pentax/dp/B003O3BSJC/ Maybe you could also try a „split diopter“? https://www.amazon.de/7artisans-Dioptrien-Objektivfilter-Spezialeffekte-Fotografie-Vordergrund/dp/B0BX68RZ6J/ https://www.amazon.de/JONGSUN-Spezialeffektfilter-Widescreen-Anamorphotische-Fotografie/dp/B09NN4XWBT/ When testing with two cameras, then the cheapest way to mount two small and lightweight cameras onto the same tripod would be a metal bar like this: https://www.amazon.de/WANGCL-Bracket-Tripod-Camera-Extension/dp/B0B1MN23TT/ (Of course, making them 100% pointing into the same direction would be cumbersome.) Good luck! Hey Joerg! Thank you so much for your reply! Yes, I've thought about all those ideas and will test them out to see what I get, but the reason why I was interested in the beamsplitter rig is because, in theory, it would make the compositing part much easier because the two images would pretty much be identical (other than the out of focus areas), as opposed as with the stereo lens or the two cameras on a tripod 🙂 So that's why I was curious if there was any not super expensive way that I could test the beamsplitter setup or something similar. But thanks again, I'll check your links, I might find something interesting.
Karim D. Ghantous Posted February 22 Posted February 22 So basically focus bracketing - not an easy thing to do with only two focusing distances. However, if you could split the light into three, that could work. And you would have the sensors at different distances from the image plane. Beam splitters for stereo rigs are slightly offset so each camera has a slightly different perspective. If you use one, make sure there is no offset. One idea is to use the smallest possible format (Micro 4/3?) and stop down as much as you need. Yeah there's diffraction but who cares? The bigger the sensor, the more you'll have to stop down, so diffraction ends up being the same. Maybe try Micro 4/3 as well as VistaVision and even medium format (GFX). Try them all, comparing the image at the same DOF for each system. But you will have a problem with telephoto lenses, as you say. So maybe a smaller sensor again is necessary. Sub-1" maybe.
Daniela Lopez Posted February 25 Author Posted February 25 On 2/21/2026 at 6:37 PM, Karim D. Ghantous said: So basically focus bracketing - not an easy thing to do with only two focusing distances. However, if you could split the light into three, that could work. And you would have the sensors at different distances from the image plane. Beam splitters for stereo rigs are slightly offset so each camera has a slightly different perspective. If you use one, make sure there is no offset. One idea is to use the smallest possible format (Micro 4/3?) and stop down as much as you need. Yeah there's diffraction but who cares? The bigger the sensor, the more you'll have to stop down, so diffraction ends up being the same. Maybe try Micro 4/3 as well as VistaVision and even medium format (GFX). Try them all, comparing the image at the same DOF for each system. But you will have a problem with telephoto lenses, as you say. So maybe a smaller sensor again is necessary. Sub-1" maybe. Thank you so much for your thoughts. I'll look into a few things you mentioned. Diffraction does worry me but I've assumed I'll have to live with it. I'm not as technically knowledgeable as I'd like (and my studies/professors aren't either, so I'm a bit on my own here) so the idea of splitting the light into three rather than two feels even more out of my possibilities 😂 But it sounds very interesting. I would like to test different systems/sensors; just need to get ahold of them for one of two days without having to sell a kidney, we shall see. And yes, telephoto lenses are the main issue here. The "ideal" type of image that I would like to achieve is a very "visually compressed" one, where you can see, let's say, half of the face of a person filling up half of the frame, and a mountain in the background (or part of the mountain), both subjects being far from each other but the perspective still looking very flat and almost "collage" like. With everything as sharp as possible. So that's the type of look I'm trying to get, if that makes any sense. Similar to what has been done with a split diopter, but more extreme when it comes to distances and a flattened perspective. Plus, I'd like for movement of the camera or subjects to be possible, or for another subject to be in between the foreground and background. So my goal is purely aesthetic but I'm having to get into technical territory that is very new for me. Sorry, I don't know why I'm writing this much, I should go to sleep, I'm just rambling. Thanks again! D.D
Karim D. Ghantous Posted February 26 Posted February 26 17 hours ago, Daniela Lopez said: Sorry, I don't know why I'm writing this much, I should go to sleep, I'm just rambling. Thanks again! D.D Well, we really do need to do a lot of talking to find a solution. 😉 It's like shooting a million feet of film for a 90 minute feature! I think this also depends on what kind of telephoto lens you want. 4x? 6x? 8x? Once you know the maximum magnification you want, it becomes much easier to start. You might even be able to tilt the lens, depending on the shots you want. This will work very well as long as one edge of the frame has no subject.
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