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Brian Caldwell

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Brian Caldwell last won the day on September 18 2016

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About Brian Caldwell

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  1. The Ultra uses a significantly better optical design, with very high MTF and insignificant corner falloff. As a result, the Ultra will sharpen up any lens that is attached to it, including the Zeiss Otus series. Below is a very detailed MTF comparison of the original M43 Speed Booster, the Ultra, and the XL. The XL is also very sharp, but is a little more specialized than the Ultra.
  2. Large marginal ray obliquity darkens the edges of bokeh circles. Large chief ray obliquity in image space darkens the corners of the image. Two very different but related effects.
  3. Oblique rays strike the center of the image as well as the corners. These are aperture dependent and are called marginal rays. The relationship between f-number and the marginal ray angle is given by f/# = sin(theta), where theta is the marginal ray angle. So, at f/1 the marginal ray angle is 30 degrees, and so on. The obliquity of the marginal ray does cause a form of pixel vignetting that perhaps should be called pixel apodization. The effect is that the edges of bokeh blurs - where the marginal ray obliquity is highest - is darkened relative to the center. The good news is that this is the definition of "good bokeh". I think Andrew's two sample images reveal this effect. I would guess that the bottom image was shot with the faster lens.
  4. I haven't carefully read every post in this thread, but everyone keeps incorrectly referring to the document in the first post as a "patent", when it is in fact only a published patent application. Patent applications aren't officially issued patents, and normally haven't even been reviewed by an examiner when they are published.
  5. I'm assembling and adjusting the first 100mm prime right now. Samples of the 100mm and 32mm should be ready by the time Cine Gear rolls around. Another two (50mm and 150mm) hopefully by the end of the year. The "in-betweens", 40mm, 60mm, and 75mm will likely not appear until next year. I'm not sure about the adapter schedule yet.
  6. That's what I'm thinking, although GH5s in anamorphic 4k mode and GH5 in anamorphic 6k mode to be more exact? Thanks Andrew!
  7. I've built prototypes of an iscorama-style single-focus adapter, but its really only suitable for shorter focal lengths in the 35mm to 75mm range. Also, its a bit large, and the front element moves during focusing, which may cause some issues with matte boxes. I'm also building a second type better suited for longer focal lengths in the 75 to 200mm range. I'm still debating whether to modify these for internal focusing, which would be good for heavy-duty cine use, but would make the adapters larger, heavier, and more expensive. To be honest, I've put the adapter project on hold until I get a few focal lengths in my anamorphic prime series completed.
  8. I'm trying to find out whether the Panasonic GH5s has an anamorphic movie mode that uses the full 17.3 x 13.0mm m43 format (21.6mm diagonal). Does anybody know? The actual format size for anamorphic shooting is critical to me. Thanks!
  9. Brian, I'm a big fan of your Speedboosters. I understand you are working on anamorphic primes that will uniquely take 4:3 to 2:39? What price range are you aiming for with those?

    1. Brian Caldwell

      Brian Caldwell

      Hi Sage:

      For anamorphic I'm doing what I can to keep costs under control.  However, I'm using a Panavision-style focusing system which requires a pair of counter-rotating cylindrical astigmatizers precisely linked to the rear focusing lens.  Tolerances on the rotation mechanism are just a few arc-minutes, so the mechanical complexity is similar to a clock!  As a result, these can't be low budget items, but they certainly will be vastly cheaper (and better!) than, say, Hawk.

    2. Sage


      I expect no less from you! That's exciting. IWhen do you estimate the first lens will be ready?

      I always felt the 2x convention needed a shake up; I suppose the desqueeze camera feature will have to be updated..

  10. Forgive me if this question has already been answered. Does the GH5s have a full-frame 4:3 anamorphic mode - i.e., with a full 21.6mm image diagonal? I know that 6k anamorphic is gone, but the maximum anamorphic image size is critical to me. Thanks.
  11. I'm curious if you are using a cropped mode on the GH5, because a quick test shows you get severe vignetting with the Lens Turbo II on full-sized m43 format when paired with the Sigma 18-35 at shorter focal length settings. This despite the fact that the Lens Turbo II has less reduction (0.726) than the Speed Booster (0.71) Even though the 18-35 has sufficient image circle diameter at 18mm to handle 0.71x focal reduction, the lesser 0.726x factor of the Lens Turbo II does not mean you are "inside safe margin". The issue here is that image circle diameter is only part of the story. Equally important is the exit pupil distance of the lens, and how well the focal reducer handles longer exit pupil distances. This is where the Lens Turbo II completely falls apart, because the 18-35 is nearly telecentric at the wide end, with an exit pupil distance of 150mm. My simple test above shows what happens: the vignetting with the Lens Turbo II is clearly caused by the focal reducer, and not the Sigma 18-35.
  12. Agreed about the de-squeeze options. If I were writing the monitor firmware I'd allow a continuous variation between 1.00x and 2.00x (at least to 0.01x resolution), and then show the resulting output rectangle ranging from 4:3 to 2.66:1. "Special" values like 1.33x, 1.5x, 1.79x, and 2x could be made available in a separate dumbed-down menu I suppose. I think the problem is that anamorphic is confusing to many people, and Panasonic has made some lowest common denominator assumptions about their customer base.
  13. The problem is that focal reducers naturally want to shrink the optical path, which is why a boosted lens is shorter than the same lens with a plain adapter. To do an anamorphic focal reducer you need to overcome this tendency, which is much easier said than done. Even if you succeeded and were able to produce an anamorphic focal reducer I don't think that people would go nuts over it. The reason is that it would be a rear anamorphic adapter, and therefore would not produce the horizontal flares, oval bokeh, and differential depth of field that are the main reasons why anamorphic is used nowadays. No doubt there would be a flurry of interest in the market, but then people would be spitting mad when they discovered that their newly created rear anamorphic lenses just do not look anamorphic. And then the mob with pitchforks and torches shows up at my house. No thanks!
  14. The "why" seems pretty obvious. 16x9 is enormously important, and to get there from 4:3 without wasting sensor space you need (16/9)x(3/4)=1.33x. Whether or not 1.33x is "crap" or not depends entirely on the lens design.
  15. The base design is for Arri Alexa open gate, with a PL mount. I've intentionally made the BFL very long so that all lenses will be compatible with PL-EF adapters ( https://c7adapters.com/en/product/pl_lens_-_ef_mount/35 ). Due to the positive lock feature these adapters are completely rock steady and don't introduce any play that would be noticeable during focus pulls. So you basically have a choice of PL or EF by use of the adapter. With EF you can use COTS Speed Boosters to go down to M43 at very high speed. Alternatively, I may offer "native" M43 mount if the demand warrants it. Similarly I'll be able to produce "FF" and 65/70mm versions using the same base optics plus different rear optical groups. Either way, focus will be one-ring.
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