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@jcs wrote that article? I missed it! Could you please provide a link to that article, and please quote the passage in which he addresses how the equivalence principle and DOF calculation applies to the dramatic difference in focus roll-off between 135mm apodization lens and other non-apodizatioin 135mm lenses? Thanks!

Are you forgetting once again that I (and others) have stated I am not referring to the sensor/film size? My (and others') contention is that there are properties generally inherent in the optics designed for a certain sensor/film size. I thought that I made that clear. However, with this comment, you seem to have inadvertently admitted that there is a variable that affects DOF and focus roll-off that is not considered in the equivalence principle and in the DOF calculation. Is that true? Agreed, as I have stated before... except maybe for the consideration that a lens is designed for a specific sensor/film size. Funny, I was thinking of asking the same of you. It's not sensor size... Instead of suggesting that someone do an experiment, perhaps it would be more expedient if you would simply respond directly to the points made in this forum. For instance, please explain how the equivalence principle and DOF calculation applies to the dramatic difference in focus roll-off between the two Fujinon 56mm lenses shot at identical f-stops. I do, and I have. In fact, my footage/images that I have posted in this forum were part of lens/camera/adapter tests. I predict that you will not directly address how the equivalence principle and DOF calculation applies to the dramatic difference in focus roll-off between the two Fujinon 56mm lenses shot at identical f-stops.

Are you saying that the difference is minor between the Fujinon APD and other lenses of similar focal lengths? The difference looks fairly dramatic to me. They're really not even close in the posted comparison.

The two Fujinon 56mm lenses are mounted to the same camera (suddenly camera/format makes a difference?) and have the exact same optical elements, except for the apodization filter. Wait a second. Mr. Caldwell stated that, "The combination of a 0.7x focal reducer and an 80mm lens is a 56mm lens. Period. Put that 56mm lens on a 24x36mm format camera and it will behave just like any other 56mm lens attached to that camera, the only caveats being related to aberrations and other flaws in the lens and focal reducer." So, as long as there are no significant aberrations nor flaws, the "design" of a lens has little bearing on it's look, as all lenses of the same focal length should behave the same ("period"). Do you disagree with Mr. Caldwell's assertion? How many of those lenses will be as different as the Fujinon APD? Don't you think that there could be something else to focus roll-off, other than the simple DOF calculation. Well, above, you seem to be contradicting Mr. Caldwell.

It seems that you and @jcs cannot resist bringing Mr. Caldwell into the middle of this discussion. I believe that I already addressed this argument. Essentially, my point is that the testers should address all differences, regardless of whether or not they think those differences are "reasonable/unreasonable." Again, some of us immediately spotted the differences without the "blink comparator," and the blinking GIF was employed merely to reveal the differences to those who couldn't discern them with the side-by-side comparison. Furthermore, I am fairly sure that everyone in the discussion was focused on the first Brightland Studios test when Mr. Caldwell made this post. The second test (with in-camera sharpening eliminated) reveals more dramatic differences. Again, the Brightland Studios tests were all shot with the same zoom lens, so the differences would be much more subtle than those encountered with two prime lenses of different focal lengths and designed for two different formats. Ahh, so this is the line in which Mr. Caldwell validates @jcs's equivalence test. Nevertheless, I strongly disagree with Mr. Caldwell's notion that all aspects of a lens designed for one format can be reproduced with a lens that is designed for another format. Again, I strongly disagree here. Merely demonstrate a S16 lens/camera combo that can come close to matching the look of a large format lens/camera, and I will give you US$100. The assertion that a 0.7x focal reducer and an 80mm lens will behave like any other 56mm lens is logically (and demonstrably) false, because lenses of the same focal length can exhibit a dramatic difference in behavior, even when designed for the same format by the same manufacturer. Lo and behold, Fuji makes two 56mm lenses in their X-mount line: the XF56mmF1.2 R; and the XF56mmF1.2 R APD. These two lenses are identical, except for the fact that the APD version contains a apodization filter near the aperture. Here is a comparison of the two lenses mounted to the same camera and set to the same f-stop: Notice any difference in the focus roll-off? You can see an enlarged version of the comparison with a few mouse clicks. If you can't see a dramatic difference between these two images, then it is futile to continue this discussion. On the other hand, if you do see the dramatic difference between these two images, then you must logically conclude that Mr. Caldwell's statement is false, regarding a 0.7x focal reducer and an 80mm lens behaving like any other 56mm lens. The 80mm lens with a 0.7x focal reducer could behave like one of the 56mm Fujinons or like the other -- but it cannot behave like both. Thus, the 80mm lens with a 0.7x focal reducer does not "behave like any other 56mm lens." Furthermore (and most important to this discussion), how can this dramatic difference in focus roll-off be reconciled with the notion that the equivalence principle is absolute? The focal length of the lenses are identical, and the f-stops are identical, so these images should have the exact same DOF/focus roll-off -- but they obviously don't have the same focus-roll-off. In addition, if you look closely at the enlarged images, you will see that the technical DOF of these images does not match. Again, there were no differences in aberrations nor "flaws" between these two lenses -- they are identical except that one of the lenses includes an apodization filter. On the other hand, there are other lenses with intentional aberrations that also challenge the notion of absolute equivalence, such as soft focus lenses and the Fujian 35mm f1.7 (the aberration became "intentional" after folks used it). So, do you think that there might be more to the look of a lens besides the equivalence/DOF formula? I'll call him "doctor" when he reconciles the notion of all lenses of the same focal length behave identically and when he explains how the focus differences in the BG bush/car in the "beer bottle" test proves "equivalence."

Although I respect Mr. Caldwell for his optical engineering prowess and for his high-quality products, his "calling your tests valid" (please provide a link to this statement) certainly "isn't proof of anything." In addition, Mr. Caldwell might not desire your dragging his name into this discussion. In regards to my "referring to bad tests done by others" as not being proof, note that not only did I criticize the setups of the tests but that I also analyzed the results of the tests. Those results show a difference in DOF/focus between optics made for different formats, a point which you still have yet to address. Perhaps you (or Mr. Caldwell) could explain why the "beer bottle" equivalence test shows the BG bush/car to be conspicuously sharper in the Iphone image than in the FF Nikon image. Perhaps we should first thoroughly analyze the results of the tests done so far, instead of glossing over the information and dismissing discrepancies out-of-hand. Why would one do a comparison test and not focus on the differences in the results? My guess is that such a tester does not want to contend with results that he/she is biased against. Again, dismissal out-of-hand... Mr. Ezcurra is clearly referring to how the Cyclops works and to the making of the Cyclops in the passage you quoted. He is not commenting about the results of the Cyclops. There are several videos on Mr. Ezcurra's Vimeo channel that show the unique look of both the "full" and "mini" Cyclops versions. Again, if you (or anyone else) can duplicate this look with just a S16 camera and S16 lens, I will give US$100.

No. It's not. As I just said, the fact is that all of the equivalence tests so far show a difference in DOF/focus between lenses made for different formats. I would be happy to point out those differences to you once again. So, given the DOF/focus differences inherent in all of the equivalence comparisons up until now, the "burden of proof" is on those who deny those results. I said that I would not bother to do a test unless it involved two extremely different formats, so that the differences are undeniable. The differences are already clearly visible in all of the equivalence tests so far, but biased testers and equivalence followers deny the results. Your two tests were flawed in almost every way, so they are hardly worth considering, even though the results showed differences in DOF/focus between different focal lengths. In the first place, you used the same lens for every single test image. How do you expect to get a valid result if you use the same lens (made for a single format) in every test? And that lens is a zoom lens to boot, which means that its internal convergent/focal point doesn't necessarily move to different positions to match the positions of focal/convergent points of prime lenses with different focal lengths. Using two different focal lengths on the same zoom lens is like using the same prime lens with and without a focal reducer -- there will be almost no difference in DOF/look between the two focal lengths. To properly test equivalence, one must use two prime lenses with differing focal lengths and with each lens designed for a different format. Secondly, you did not include any middle-ground in the frame that could reveal the character of DOF/focus fall-off. This mistake seems common amongst those making tests biased toward equivalence. Having only air between the foreground and a distant background renders useless any test of DOF range/falloff. Thirdly, you misinterpreted/ignored/dismissed your results. When you first posted your two tests long ago, I and others stated that we could see differences in the DOF/focus, but you and other equivalence supporters failed to address those points. In a more recent thread, I used flashing GIF images with colored circles which pinpointed these differences. You and the other equivalence folks dismissed these differences as slight imperfection inherent in testing equivalence that only becomes apparent in flashing GIF images, even though these differences are quite clear to me and others without the flashing GIFs. Furthermore, in your second test, you eliminated the variable of in-camera sharpening -- lo and behold, the differences in DOF/focus became more dramatic. However, you and other equivalence supporters glossed over these more conspicuous non-equivalent second test results and only "focused" on the first test in all of the discussions. Such examples have already been linked several times on this forum. You almost never respond to such links/points. Notable examples would be the PhotographyLife "beer bottle" equivalence test (note the obvious differences in focus of the BG bush/car to the left of the bottle) and footage from Gonzalo Ezcurras extreme large format Cyclops cameras (if you can show a lens made for S16 that has this same, exquisite DOF roll-off/look, I'll give you US$100). First, why don't you explain one-by-one each of the DOF/focus differences that I pointed out in your tests (especially the DOF differences in your second test). Also, please explain the huge, conspicuous DOF/focus differences in the "beer bottle" test linked above, which compared an Iphone camera lens to a full frame camera lens. Here is the first post covering my points on both of your tests and on the "beer bottle" test, and here is a further breakdown of your first test. There are a lot of specific focus/DOF differences both in the BG and FG in the tests that you (and others) have already done which you have not yet reconciled. Even the bokeh is substantially different in size and edge sharpness (both tell-tale signs of DOF differences). As I stated before, I will do an equivalence comparison if I can obtain a S16 camera/lens and a large format camera/lens, but you or some other equivalence supporter must be present to oversee the camera settings. In regards to the optical properties that might differ between various sized formats, once again, these have been posted several times in this forum.

Nope. With all the equivalence tests that have been done, none have been conclusive. In fact, all of those equivalence tests show a difference in DOF between lenses made for different formats, and some comparisons actually show a dramatic difference in DOF.

Black paint and clean, sharp edges.

Looks like the fittings might be die cast. They could fatigue early.

Thanks for the validation. I have never used the Kupo combo stand, but I have seen them at NAB and CineGear. I have used Kupo contract stands (the ones that they make for other manufacturers), and they were good. On the other hand, there is not much to a combo stand. I can't recall ever having a huge problem with any particular brand.

A combo stand is much sturdier than a baby stand. Essentially, a combo stand is a junior stand that includes a smaller, pop-up baby pin. I think Kupo is based in Korea, but I am fairly sure that they have worldwide dealers. Their starting list price seems very competitive. Not sure if Arri is considered a "well known brand" in regards to grip equipment. I have never seen an Arri combo stand on set.

Never tried those stands, but Kupo is a decent, established brand from Asia, and they have pretty good prices on their combo stands.

Loosen the lowermost knob (where the light's stand fitting meets the light stand) and pan, then re-tighten that knob. Or, loosen one of the stand's stem knobs WHILE FIRMLY HOLDING THE STEM ABOVE THAT KNOB. Then, re-tighten that knob.

This is great news! It appears that they have picked a better default sensor than their original choice (CMOSIS 12000), which was the same sensor in BM's 4k cameras. I would guess that this Kodak sensor avoids the FPN problems inherent in the CMOSIS sensor. Apertus has been making raw, open source cameras for around a decade. If anyone can do it, the Apertus people can. However, I don't think that it can work that simply -- there has to be electronics/processing specific to each sensor. So, at minimum, it would be a swappable sensor/electronics module (which would essentially be the entire camera, minus the recorder). Too bad the BM ASP-C/Super35 cameras lack an MFT mount. The MFT mount on the ASP-C Axiom makes it very versatile.

There are several companies who make fabric egg crates. Some fabric egg crates include "pop-out" frames. Light-Tools will probably be the most expensive brand. Don't know if anyone will have your exact size (120x100cm) "off-the-shelf," but the manufacturer in the link (The Rag Place) can make custom sizes. Years ago, grip manufacturers offered black, aluminum, honeycomb grid sheets, but I haven't seen those in awhile.

The Nila Arina appears to be one stop brighter, and it is doubtful that the Arina has the highest output of all LED filmmaking lights. Nila was one of the very first high-power LED brands, so they have years of experience in designing for the film industry. There are weatherproof versions of the Nila fixtures. I would also check out Mole and other major brands.

We'll probably need a macro lens for that.

Possible straggler.

Manufacturers in the USA have been putting protective screens over the front of their open-face halogen fixtures since the early 1990s. This practice was mandated by a few local fire depts. (mostly SoCal) in their push for testing lab approval (ETL, UL, etc.) for filmmaking fixtures. These protective screens are basically scrims that block 25%-or-less of the light. To avoid liability, some lighting manufacturers (the smart ones) provide these protective screens for free, even if one has a used, out-of-warranty fixture. Always use a protective screen (or some other barrier) in front of an open face halogen source. In regards to the lighting needed for OP's shoot, OP needs to first determine what the client means by "hard light" (as @TheRenaissanceMan suggested in an earlier post. A lot of folks confuse "spot lighting" with "hard" light, and those two lighting conditions are not necessarily the same. (In fact, the "spot" setting on most focusable fixtures is actually softer than the "flood" setting.) Also, many confuse "contrasty" lighting with "hard" lighting. It would probably best to get the client to link an example of what he/she wants.

If you frequently will be shooting outdoors, you might consider using rags that breathe, as ripstop nylon and sail cloth can turn your "6-by" (2mx2m frame) into a powerful sail/kite. When I used to build frames out of PVC, I would mostly use cheap, white bed sheets as a silk. Also, it might be good to use "grommets and ties" to attach the rags to the frame, as they are secure and easy to use, and they can be readily adapted to fly the rags in other ways, without the frame.

You might consider something like the Lowel Tota-Tilter: There is no locking mechanism for the tilt -- it just provides constant tension. The pan would require loosening the black knob. You would also need a stud/baby-pin to mount it.

Perhaps a flex-arm solution could work. Such a set-up would allow you to hold the camera in one hand and adjust the monitor with the other hand. Here's the Manfrotto flex-arm: Here is some other gooseneck for a tablet: Here is the Lowel Flexi-Shaft (modular system): Here is a Matthews flex-arm: Here is some audio gooseneck selling at B&H:

I do not dispute this assertion. Right -- it becomes a 56mm FF lens, with the properties of an 80mm lens on MF. Well, adding a condensing stage as part of a unified lens design merely to achieve a certain focal length (no boost in brightness nor look needed) might seem like a roundabout and expensive way to achieve that focal length. Why not just design a simpler lens with the desired focal length -- without any focal reduction stage? LMFTFY: The only reason that it will look different from any other lens will be due to lens/reducer aberrations and other variables. No. The subject of equivalence will not be resolved until a proper test is conducted.

Or, perhaps you are making an incorrect assumption about why I referenced that simulation and about who I was addressing. Not sure of the relevance of the fact that the simulation was not created for me nor of the relevance of Mattias' denial of Timotheus' writing. I was merely responding to another poster who presented that simulation as evidence/proof of the equivalence principle. Maybe you didn't read (that part of) the thread. Just guessing, but did Mr. "Northup" make yet another equivalence test with a foreground and distant background... but with no middle ground? Are you asking me?