Daniel Klockenkemper

Several years ago I was looking for more information about why Zeiss might use a triangular aperture (technically a Reuleaux triangle) and came across a white paper I wish I'd saved about the effect of aperture shape on laser optics. What I recall from it is that a perfectly round aperture produces concentric rings of diffraction, radiating outward evenly in all directions; while a triangular aperture has lines of diffraction that radiate away parallel to each pair of corners, kind of like a 6-point star filter, with areas in between the lines unaffected by diffraction. So my guess is that Zeiss was trying to delay the onset of diffraction-related softness at small f-stops, to keep the image acceptably sharp for a wider range of apertures. It certainly seem characteristic for Zeiss at that time to care more about the sharpness of the in-focus parts of the image than they would about the softness of the out-of-focus areas.

This is a fairly easy query to look up - there were short sequences shot as stills with the Canon 1D Mark III, which has a burst mode capable of 10fps. The different gamma from the 24fps footage is also a minor tell. https://shotonwhat.com/cameras/canon-eos-1d-mark-iii-camera This article gets the frame rate slightly wrong: https://www.reuters.com/article/uk-mumbai/slumdog-crew-took-to-the-streets-of-mumbai-idUKTRE49T37T20081030

Without having data for the bulbs spectrum*, my best guess is possibly a little bit, but probably not very much. The strongest UV filter I've personally seen - a Tiffen UV-2A - has a perceptible light yellow tint, which means that it does slightly filter some blue wavelengths in the visible spectrum. If the filter appears clear/neutral to the eye, then it follows that it shouldn't affect the brightness of the bulbs' output in the human-visible spectra. To be sure, I'd recommend visiting the location with the UV filter you plan to use, and metering the bulbs through the filter. A C800 color meter might also be informative if you can get your hands on one. Of course, the only way to be really sure is to shoot a film test, but I know that's a luxury these days. The original article I remembered about UV filter transmission is here: https://www.lenstip.com/113.1-article-UV_filters_test_Introduction.html There's also this more recent one from Lensrentals: https://www.lensrentals.com/blog/2017/09/looking-at-clear-and-uv-filter-spectrograms/ * I searched a little bit for this, but the few spectral transmission graphs I could find for tanning bulbs only show the UV portion, and omit the visible light wavelengths.

While I don't have any experience with tanning beds - neither from filming nor otherwise - I do know that the major filter manufacturers have and do make UV filters in 4x5.65" sizes. Tiffen has a few strengths, with older filters labeled UV haze 1 or 2, and newer filters named UV-15, UV-16, and UV-17; higher numbers filter more UV. Schneider offers a UV-410 filter that claims to cut most UV wavelengths. I haven't personally tested any of the above UV filters... I am aware of a test of stills filters, which found that B+W (owned by Schneider) was by far the most effective at actually filtering UV, while the lone review on B&H of the Schneider UV-410 filter claims that the filter added significant flare/glare. It's possible that the B&H reviewer is correct, but it's also possible that they made some mistake, like not bothering to clean the filter, or didn't mitigate it by tilting the filter... A polarizer can help with UV exposure in landscape scenarios, but this might not be applicable in your situation, with the camera aiming directly at the UV source. I'm sorry I can't help with anything more than hearsay! But at worst the UV would cause a loss of contrast, for which you might be able to compensate somewhat in the grade. Flicker would be my biggest concern, and it seems like you're already prepared for that. Your test with the Cine Check will be the most informative. In the absence of a test, I would film with a 144 degree shutter, assuming a 60Hz line frequency.

While I get the point you're trying to make, your point would be better made if you didn't make demonstrably false statements in the same breath. (Nevermind not even trying to answer Chantel's question in a constructive way...) Super 16mm isn't "1mm added," it's 2 and a quarter millimeters wider. By itself, that's a 20% increase in area; but if normal 16mm has black bars added (i.e., if the image is cropped) to make the same aspect ratio as Super 16, S16 has 49% more image area on the negative. And because film resolution is determined by the size of the image area, having ~50% more area is a compelling and perfectly understandable reason to prefer Super 16. Yes, plenty of us have gotten away with mixing the two formats, myself included; and standard caveats about aspect ratio / extraction areas apply - there obviously would be no difference whatsoever if one intended to deliver 4:3 or 1:1. But if you have some weird axe to grind about the difference between formats, you might consider getting your facts straight in the first place - especially facts that are so trivial to look up.

Thank you! I think technical reasons are the original purpose for all strengths of diopter, and the extra artefacts of the higher strengths are probably an unintended side effect. But using technical flaws in unexpected creative ways is part of the innovation and fun of cinematography. In your case, anamorphic lenses are a special scenario - especially classic/traditional lens designs - because they're known for having different behavior depending on the focus distance. I think they might behave differently, I wish I could try that! Thinking about all this reminds me of a tilt-shift style diopter holder I saw at the last Cine Gear Expo before the pandemic: https://www.vocas.com/vocas-5-axis-diopter-holder.html I can imagine a lot of creative ways to use something like that, especially with split or selective diopters. Neither would I, and I hope I didn't come across as dismissive in my previous post. If people want to believe a little bit of magic is real, why spoil the fun?

I also decided to do a test to get to the bottom of this. I actually have the same lens as the one in the original post, a Zeiss Contax 50mm (not rehoused, but the glass is what matters), and combined it with a "full-frame" camera and some Lindsey Optics diopters. The first test was set up to replicate the interior conditions mentioned above - the slate was 4.5 feet away, and the background 15 feet away. The lens was set to f/2. Focus was sharp on the slate for each take. I only used the +1/4 and +1/2 filters on this test, because the farthest focus with a +1 diopter is 1 meter. Diopters always went into the same tray in the matte box. I had read or been told at some point that putting a diopter in the wrong way can increase aberrations, so I tested that, too: https://vimeo.com/522484255/02c168ba97 As Stuart already demonstrated, I don't think there's a meaningful difference. Feel free to download the original files, pixel peep, and come to your own conclusion. I also wanted to see if the diopters were introducing any field curvature, which would affect focus on the background. I set the focus to the surface of the coin for each take. Skip to the second half if you want to see the differences made obvious: https://vimeo.com/522487048/887642358c Without the filter, the Zeiss 50mm has a very flat plane of focus (which is why Zeiss called it a 'Planar' lens after all). There is some mild field curvature added by the +1/4 and +1/2, but not enough to notice if you aren't looking for it. The +1 does noticeably distort the field of focus away from the background, especially when turned the 'wrong' way. But given that a +1 filter is confined to 1m or closer distances, its utility in normal photography is limited. My final thought is that it's basically a magic trick for the people at the monitor. The focus on the lens is set for the background; "Now watch as I put in the special filter for the talent's close up!" Everyone watches the background suddenly go out of focus before their eyes as the filter slides into place.

Thanks, and likewise! I think you've got the right idea. I'd say there's three categories - "this looks good," "this might look iffy on the monitor but I know I can deal with it in post," and "I need to do something about this before we do a take." Watch enough movies and you'll see that even the greatest cinematographers occasionally have a shot here and there, where they got into a little trouble with the exposure... but it's only something that a real nerd like me would notice. This interview with Gordon Willis about The Godfather Part II is great, and I think one of his statements applies just as well to the plethora of choices in digital cameras we have today: "There’s a great deal of latitude in the Eastman color negative. A lot — an incredible amount. But you have to know where it is you’re going to put it."

Hi Robert. I'll give it a try, and probably explain a few things you already know along the way. 🙂 I think it helps to start with how it works for film, because it's easier to visualize. If you look at the pictures in this post on another forum - https://www.minilabhelp.com/forums/topic/25897-control-strip-issues-v30-ra-kodak-chem-lorr/?tab=comments#comment-62349 - they're Kodak control strips, with calibrated pre-exposed steps. The lightest, most see-through parts have no exposure; and the more exposure the negative received, the more "dense" (i.e. opaque) the negative is. Consider what it means that the straight-line portion is "linear" - that a measured amount of exposure will have a predictable and proportional change in how opaque the negative is. The amount of change stays constant: if you photography a grey card first without a filter, and then make a second exposure with an ND 0.3 filter in front of the lens, there will be a change of 0.3 optical density between the two exposures when you measure the negatives with a densitometer, as long as the two exposures are within the straight-line portion. The toe and shoulder are where the change in exposure is not equal to the change in recording. That's "tonal compression." If you have details that were exposed in the non-linear parts, and try to bring them back into the straight-line range, they probably won't look how we expect they would look. For example, if an actor's skin is overexposed enough to be in the shoulder, there's little chance their skin tones will look right if you bring the levels down in post. Digital sensors are fundamentally a bit different from film, and digital "density" is really "sensor voltage interpreted as a level of brightness." (That sentence glosses over a lot of complex math and engineering.) Hypothetical digital characteristic curves are still interpreted as logarithmic graphs that simulate an optical density-like response, partly because it's how it was done in the past and we're used to working that way, and mostly because a log curve is easier for us to wrap our heads around than a linear representation. Looking at a log curve can be a handy way to see at a glance how a camera or film stock might respond to exposure. The curve only tells part of the story, though, especially for digital sensors. A camera's sensor might clip long before the log curve would indicate - the manufacturer might have given the curve a longer shoulder so they can still use the same curve with better sensors in the future, or to prevent issues if raw footage is post-processed far differently than it was exposed. And for both film and digital, each color layer (for film) or color channel (for digital) has its own curve, with potentially different toes and shoulders for each color - meaning one color might clip or show noise before the others. Intentionally exposing in the toe or shoulder is pretty rare - you have examples like Gordon Willis deliberately pushing and underexposing The Godfather so that the image couldn't be brightened at all in printing, locking in his exposure choices. On the 2007 film Sunshine, to convey the intensity of the sun up close, Alwin Küchler intentionally overexposed the negative by up to 10 stops in certain scenes so that details were actually "burned out." It would seem much more common to make small exposure changes to avoid going too far into the toe or shoulder, like underexposing slightly to retain highlight detail, or overexposing a greenscreen shot slightly to get a better key. Generally, I think the idea is to know where the toe and shoulder start, and how that will translate into the final image via post, so that you can know on set when your exposure is in trouble, and do something about it before it's too late! If you want to do a deeper dive into this, the first few chapters of David Stump's Digital Cinematography book go into much more detail. It's not the easiest read, but it at least has more pictures than the wall of text I just wrote. But I hope it helps!

The aperture works exactly the same; depth of field, exposure, etc. will behave as they normally would. You can think of it as extracting the central 1/3 of a 135 stills frame. To tell you how I learned the hard way: I once borrowed a Nikkor 55mm f/1.2 for a shoot, hoping it'd be a bit more similar to the Kowa 16mm primes in terms of the coatings and the stop. While passable wide open for full-frame stills, on 16mm the chromatic aberrations were proportionally larger since the area of the negative being used is smaller. I went back to my Contax lenses after that - the Zeiss 50mm/1.7 was usable wide open, so it wasn't worth keeping the Nikkor if it'd need to be stopped down anyway. It almost sounds like circular logic - the better your lenses are, the better they'll look on smaller film formats.

This is no problem at all. I used a c-mount to Contax adapter all the time when I had an Eclair. Coverage is not an issue, since the 135 stills format is much larger than 16mm. The only minor caveat is that, because the diagonal measurement of 16mm is almost 3 times smaller than 135, the image from the lens is effectively magnified 3x. So if the lens has some aberrations, they will be much more apparent than what you might be used to from stills or video from larger formats. I'm sure you're aware that c-mount lenses can become unscrewed if the lens is torqued; this shouldn't be a problem if your lenses are properly lubricated and the focus turns smoothly. On the other side of the adapter, the lens can shift in the mount of a stills bayonet mount since they are not positive locking. If your adapter and lenses are in good shape, you shouldn't have to worry about this either. Other than that, enjoy having lots of longer focal lengths to work with.

While 'personal shooting quirk' satisfies Occam's razor, it's definitely interesting to speculate what the reasoning behind the decision is. For the most part, lenses designed before the 1990s had their best performance when focused at infinity - aberrations, especially away from the center of the frame, increased at the closer distances where filming normally takes place. (Optimal performance at closer distances was a big selling point of the Ultra Primes.) So perhaps the idea was to use the lenses closer to their 'sweet spot,' ignoring the effect that adding a diopter has on lens performance? Of course, the minor side effects of adding an extra, presumably uncoated, lens to the optical path could be the entire point, too. This is the other possibility I can think of. Like many older lens designs, most of the Zeiss Contax lenses focus by moving the entire lens away from the focal plane; and the closer you need to focus, the further the lens has to be moved (which is why the closer distances are spaced further apart on the ring). So when the diopter is added, perhaps the optics don't need to move as far to change focus, which could reduce breathing.

From the pictures on this site, it looks like the c mount is attached to the back of the lens, and you're missing that piece: http://www.bigeye.url.tw/big5/d_ange17_68_22.htm

If you're looking for a modern style of head with adjustable counterbalance, there's unfortunately a large gulf between the affordable heads and the heads that can handle a higher payload. You're right to look on the used market. Something like an old OConnor 30 doesn't have an adjustable counterbalance, but it's from the same era as the NPR and would probably work rather well. When I owned an ACL, I used a higher-end Libec head - they're often overlooked because most Libec gear is aimed either at the low end or towards broadcast studios. A used H70, H80, H85, or even H100 could likely be found at a much cheaper price than an equivalent head from another manufacturer. Since you're in the UK, you might be able to more readily find a Vinten Vision 22SD - it's a substantially larger head, but would easily handle the weight of the NPR. Though like any used, older head, spare parts are going to be difficult if not impossible to find should anything need repair. For any head, be mindful of the stated weight capacity - it's usually quoted for a low center of gravity, while film cameras' C.G.s are much higher, meaning the maximum payload is much lower.

CVP has an excellent web app to check illumination circles for various combinations of cameras and lenses: https://cvp.com/tools/cameralens The Fujinon MK lenses aren't listed in the tool, but from what I recall they only cover the 4k S35 crop mode on the FX9, and vignette on 5k. As for FS7 vs FX9 4k - it's 2012 vs 2020 sensor technology. Even without oversampling I'd expect the FX9 to have better overall performance.