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Apefos Scoperama Anamorphic Adapter Development Topic
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  • No oval bokeh in the 1.33x Bokeh is round.

  • The afocal system does not change the focus on the camera lens. I could use the Nikon 50mm 1.4 AIS no problem.

  • What I can do now is to chose the best combination between the positive cylindrical diopter and the negative cylindrical squeeze to build the 1.33x adapter. Using the available glass this adapter will allow the use of lenses from 35mm to 50mm. In GH2 it will be equivalent to 70mm to 100mm in full frame terms. Maybe it can allow 85mm lenses also, need to test IQ.

    The chromatic aberration is low, but it is there. I will try to cancel it using a flint glass as diopter, but I cannot improve the optical system to cancel all the corner softness because my knowledge and resources are not enough, so will try my best using the design I can do to minimize softness.

    I quit developing the anamorphic adapter using acrylic because if I use a big front negative acrylic to do squeeze to allow using more wide camera lens, the corners will be more soft. The bigger the width used in the lens the bigger the softness is. I believe this kind of adapter needs aspherical lenses or a more complex design using more spherical elements and this is beyond my resources. The aspherical lenses cannot be grind, they are built molten / constructed fused.

    I did the design to do a black plastic body and if I get a good IQ after the final test with the flint diopter using the best squeeze/diopter combination, I will hire my plastic partner to do it. Also I will do multicoating in the lenses.

  • Ok, two new design working in progress:

    Design A: use a flat surface in front of squeeze element to allow a smaller negative curve on it to try to improve corner softness. Use a flint glass as diopter to remove chromatic aberration

    Design B: use an achromat doublet in squeeze element to improve corner softness and remove chromatic aberration keeping the same crown glass as diopter

  • I am not worried about this adapter become a product anymore. Now I am doing this just for fun. There are chances to get a better quality with the two new designs I said in previous post. So after these two final tests I will assemble one multicoated unit in black plastic body, and, if i realise it is good enough, I can build some units to sell (showing its features and also its limitations).

  • It seems both the 1.25x and 1.50x tests you did earlier looked better that the 1.33x in the corners (I would have though the other way around). Is it your goal to have more of a 1.33x solution or 1.5x?

  • Hi @Ian_T let me clarify something. It is important to not confuse "out of focus" with "softness". In the 1.5x image, the bottle and the tree is in better focus. But if you zoom out the images in your browser and look at them from corner to corner you will realise the wall and the grass is sharper in the middle and start to become soft at the edges of frame. This is more pronounced in the 1.5x, and this behavior increases when the squeeze increases because the lens curves are stronger to get more squeeze. I could use weaker curves to do the same squeeze but the front lens distance would increase so much and vignette would be a problem. So the 1.25x will always be better than 1.33x and 1.33x will always be better than 1.5x considering the edges IQ in the designs I can build. Also if you zoom in and magnify the images you can see the chromatic aberration is bigger in the 1.5x squeeze also due to more strong curves in glass.

    Sometimes the prototype assembling with adesive tape does not allow precise focus because it is difficult to put the lenses in very precise distance from each other, but it allows to understand what I can get from the final product.

    What i am trying to do now with the two new designs is to improve the quality and minimize softness and chromatic aberrration in the 1.33x squeeze using different curves, flint glass and achromatic doublet. It seems these two new tests are the last ones to do, because anything further than this will be beyond my optical knowledge and manufacturing resources.

  • If you want to expand your knowledge, this might be a good place to start.

    http://www.optenso.com/links/links.html

  • @Ralph_B What a nice website! There are moments in my life I feel sorry for having changed the option from course of physics at college to video production.

  • I am already very impressed by your results! I would love to buy it when its done! :)

  • It's no worse looking than a Century Optics imo.

  • @fatpig @johnnym thanks, i believe one design can become a product, lets wait the results from new tests next week. The optical lab is grinding lenses, now it will be 4 different optical designs to try, 2 main designs with two variants in each, the final tests.

    Got the 52mm thread and shim pieces today. shim pieces are in 1mm step increase distance to pursue focus, and the 52mm thread will allow better alignment. New lenses will be ready probably next tuesday.

    I am developing some draft drawing for a focus mechanism to get best possible cilindrical and distance focus in the final black plastic body. Once focus is done and locked there is no need to refocus again.

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  • @apefos Just wanted to say that I am glad you are still working on it.

  • Ok, got the new lenses today, will start new tests to try finding the best optical design.

  • Set of cylindrical lenses to test the four new optical designs. two designs are 3 elements and two designs are 2 elements.

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  • I hope it works, very glad you are working on it. One thing I would recommend to you is to look for topics about anamorphic lenses.

  • The guy who had some experience in film was saying that:

    First Choice would be "rear mounted" Anamorphic elements. These are elements that can be added to the rear of the prime lens. The advantage is they don't vignette and you don't have to focus them separately. These were made for PL and Arri B mounts. They usually sell for about $2,500.00 but they will work well on zoom lenses.

    Would it not be better/easier/cheaper to do a rear anamorphic adapter that would fit nikon or Canon lens with the flange distance we have with micro 4/3.

  • @danyyyel Thanks for the tips.

    I am waiting to finish experimentations and see the results before talk in other forums.

    I have a FD/M43 adapter here and the internal distance to fit the lenses is small, I did a measure and there is 8.4mm room to fit the lenses. so maybe it would not be enough to get the 1.33x squeeze. the lenses power need to be increased, and if it works, probably the IQ in corners would not be good, also the optical construction and lens fit need to be very precise to get good focus, because it cant have a focus mechanism. And I dont know if it will have horizontal flares. It is more difficult to do and I will not start developing it now.

    About the focus in the front adapter: if the adapter become a product it will be shipped with preset focus, and dont need to do focus again. Its optical design is afocal, it does not change the camera lens focus. The focus mechanism is to help me to calibrate and lock the focus between the front cylindrical squeeze and the rear cylindrical diopter.

  • I did some calculations using the magnification optical formula and the room distance in the fd/m43 adapter is not enough to get the 1.33x squeeze.

    If the rear anamorphic adapter inside the FD/m43 or inside the Nikon/M43 use all the room, it will be 15mm room distance in the FD/M43 and 19,5mm room in the Nikon/M43.

    Using the magnification optical formula M = -f2 / f1 the lenses power would be so strong to get the 1.33x squeeze and I believe the IQ in corners would be very very bad, also the lenses curves would be very pronounced and maybe the room inside the adapters would be small to fit them.

    It seems like to try to put New York inside Asheville.

  • First reports from the new tests with new set of cylindrical lenses:

    The anamorphic adapter cannot be focus preset. Each time the object distance changes it needs to refocus the anamorphic adapter. So to use it there will be two focus to do, focus in camera lens and focus in anamorphic adapter. The distance from the front squeeze cylindrical lens to the back diopter cylindrical lens needs to change when the object distance changes.

  • The flint diopter helps minimize chromatic aberration in the two element design.

  • Tests are finished, squeeze is 1.33x. The focus is not perfect yet because the prototype does not allow precise distance between lenses, but it is good enough to see the improved corner quality, minimized chromatic aberration and the average image focus.

    Here are the results from the best optical system: Two Images showing flares (there is no multicoating yet) and three images showing the Image Quality in three different camera lens aperture: f4, f5.6, f16 (no corrections in images). These shoots was done with nikon 35mm 1.4 AIS lens.

    Please manifest your opinions: is it useful?

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  • It's dfifficult to judge the quality of the lens by the subject matter you've chosen. It would be more helpful if you shoot a detailed street scene with everything in focus. Also, you should shoot the same scene without the anamorphic adapter for comparison.

  • @apefos I think it looks pretty good. It would be nice to see some other subjects like Ralph_B said, and to see what happens if you shoot with a more open aperture; portrait f.i. (blurry background).. shots w/o the adapter for reference would also be nice to see.

    If you´ve got some other lenses to try out I would be very interested to see that as well.

    There seems to be something funny going on @f16, where there is a slight streak of blur a little bit from the edges of the picture.