Grim Fandango

You both have mega cool portraits! That's my only excuse and I'm sticking to it!

Nah, I got the pair of you confused as one person! I combined your disagreement with me with zaks blog post etc... don't worry about it, the post above I feel is good information for people or easy enough to ignore

My apologies then, you were correct! In truth, my first contact with you was in the piracy thread, where you were needlessly rude and caustic and I really only skim through your posts giving them minimal attention because, quite frankly, I don't like you.

It's like if I told you I was shooting my lens wide open and you all jumped on me telling me that if I used screwdrivers on my lenses then my warrenty would be void. It's obvious that despite the words I used, I just used shorthand to refer to how I had set my iris. And likewise, to me the idea that you would buy a lens without understanding the picture it will give you on your cameras compared to your other lenses, well, lets just say, my jaw has hit the floor and it won't be being picked up for quite a long time. I literally didn't think that this needed to be explicitly stated.

Yes, well I'm new here and I honestly thought this stuff was basics 101 and you would all understand what I meant. Clearly, I misjudged! Of course nothing stops you from speedboosting the sigma onto a m4/3, but the conversation was talking about emount sonys.

No, if you stick that sigma on a crop frame camera and open it up to 1.8, you will get the precise same image at f2.88 on the canon with the speed booster on that camera for any given focal length. That gives you a 0.8 twist on the aperture dial of extra speed that is not avaliable to the sigma. Not a life changing amount I grant you, but mathmatically there.

Bokeh - a term used to subjectively describe the way a lens renders an out of focus area. Is not measured by aperture size or focal distance, but in rather more fanciful ways, such as "jittery", "creamy", "lively" Circle of Confusion - The flattened spherical area rendered acceptably sharp by a lens to be described as in focus. Determined by a complicated function unique to each lens, commonly able to be moved and resized/shaped by a user using the aperture and focus controls on a camera Background Blur - Any part of the image that is in the background of an image and outside of the circle of confusion Depth of field - a laymans description of a linear line through the circle of confusion Fixed that for you

We are not talking about leaving a lens in place and putting a crop sensor behind it, we are talking about putting a different lens that throws a smaller circle. But regardless, lets talk through your scenario, step by step. You put a lens on a tripod. It creates an image in a circle, lets say 44mm behind the lens. You place a sensor behind that lens. It is a 1m by 1m sensor. Luckily, it's a really large format lens. You measure the number of photons striking the sensor and ignoring the quantum problem of changing the energy by measuring it, you find that exactly 1,000,000 photons strike the sensor every second. Each photon carries 1 unit of energy, you you have 1,000,000 energies of light striking your sensor, energy that activates it. Interestingly, if you isolate a 1cm square area, you would find that as there are 10,000 square cm in 1m square, there are 10,000 times less photons striking that small isolated area, no matter where you measure that cm squared. Great! Now you remove that sensor, and put one there that is only 1cm by 1cm. You could place 10,000 of them on the big sensor to cover it exactly. So naturally, it is being hit by 10,000 less photons every second, that is 100 every second. So the energy being recieved by the smaller sensor is, drum roll, 100 energy units, 10,000 less. Thats a lot less light striking your sensor. Fortunately, you are a good engineer, so you don't lug that gigantic lens around to cover that tiny sensor, you designed a much smaller, lighter lens for that camera, that still lets 100 photons strike it every second. But because it's only got to cover a 1cm area, it is so tiny, it only lets 100 photons in every second, being a great designer, they are all passed through straight to the sensor. But the big lens is letting 1,000,000 photons in every second. To provide the same level of illumination on the sensor. The big lens is letting in a lot more light. It's so simple. The big sensor has a lot more light to work with. Why is this even worth worrying about. You're making a film, you're halfway through a piece of dialogue. You're filming at 100mm on a full frame sensor, open at 2.8. Your camera just stops working. You've got actors, crew etc all standing around, not doing anything. You reach for your spare, and guess what, it's a m4/3 camera. You know you need this to match as closely as possible or it's going to be really jarring, and difficult to edit. You get your 50mm lens because like a trooper, you are aware that the crop sensor needs a wider lens. Then comes the sticky question, what f stop do you set this new lens to? .... .... If you said f2.8 of course, (BUZZZZZZZ) Wrong, you notice that the background which was a beautiful creamy blur, is now clearly showing cars in your victorian costume drama. So what gives! It let's the same amount of light through, you incorrectly bemoan to all and sundry around you. Suddenly, I pop up, I'm your ruggedly handsome lead. In my deep, inspiring voice, I declare my truth. "Good Director of Photography, please, allow me. I know a thing or two about these matters. You chose this lens very wisely, for it has an apeture which opens much wider than your setting here of f2.8. It's a m4/3, a 2 times crop. If you apply that factor to the aperture and open it all the way up to f1.4, you will make a picture the equal of your ruined kit" "Nonsense" you hiss "This cannot be so! Get back to your place, sullen curr, and approach me not again!" Eventually, after much wailing and decrying of the gods, men and sheep, you, in a temper grasp the lens and make to hurl it from your visage. But, whats this, your fingers knock the aperture dial to 1.4, and in front of you, the beauty of my face, creamy, carless bokeh behind. It is the picture you longed so desperately for all along. It's overexposed now, but no matter, you have an ISO control in your picturebox. "To your places!" you shout rumbuctiously "Put down those nachos and clean the cheese from your chin. We resume shooting!" . . . Again, if you really think I am wrong on this, then do post two identical pictures, from different sized sensors demonstrating that the relationship between the differing f stops you used was not directly related to the differences in the sensor sizes.

Then you will have literally no problem proving that! Get two cameras with different size sensors, stick two lenses on the front of them set to the same f-stop number, and try to take identical photographs with them. When you give up because the bokeh in one is far more out of focus than the other for the same frame, apply my formula and then take those same photos. Or just watch the video I posted above where they perform that precise test.

The F-Stop number is a ratio, between the focal length and the aperture, so if you have a 100mm lens with an aperture opening of 50mm, it is set to f2.0. But a 100mm lens that covers a full frame sensor and a 100mm lens that covers a m4/3 sensor are very, very different to each other, despite sharing those two common measurements. The difference in designs manifest in the size of the image projected by the lens. The aperture blocking certain angles of light reaching the sensor is the same, thus the out of focus areas will be the same amount out of focus, but your 100mm lens on a m4/3 lens will show a much narrower DOF - as you so correctly point out. So to achieve the same frame as the full frame, you actually need to mount a 200mm lens on the full frame. What happens, the DOF changes because to maintain f2, your aperture is now 100mm wide, blocking far less of that light coming in. Therefore, you cannot achieve the same picture. In order to do that, you will need your 100mm to open up more, in this case, also to 100mm diameter - f1. So you see, for any particular picture, you cannot recreate it by matching the lens numbers and plopping it on any old sensor (we all understand this) not can you only multiply the focal length crop factor (becuase the out of focus character is different) but if you want to achieve the same look, you have to also apply your crop factor to the f number, your lens needs to be faster for the crop sensor to achieve the same shot. Thus when comparing two lenses for the same sensor, one a lens designed for that crop frame sensor, and one a full frame lens with a speed booster, not only is that speed booster concentrating the light, increasing it's brightness on the smaller lens (F2.8 becomes an F2), but you are bringing the full frame characteristics of the lens to that crop sensor efectively making that sensor a full frame. Therefore to achieve the same look that the full frame lens brings, you need to use that crop factor on the aperture too for the crop lens (which remember is not going through a speed booster).

This explains things better than I can:

My apologies, in my rush, I had confused you with DPStewart

And don't forget that while it has the DOF of a 1.8, in light terms, it is illuminating like a 2.8 on a crop frame sensor - making the speed boosted 70-200 faster

And here is my evidence: https://ec.europa.eu/jrc/en/publication/eur-scientific-and-technical-research-reports/online-copyright-enforcement-consumer-behavior-and-market-structure Taken at face value, our ndings indicate that digital music piracy does not displace legal musicpurchases in digital format. This means that although there is trespassing of private propertyrights (copyrights), there is unlikely to be much harm done on digital music revenues. http://www.lse.ac.uk/media@lse/documents/MPP/LSE-MPP-Policy-Brief-9-Copyright-and-Creation.pdf The creative industries are innovating to adapt to a changing digital culture and evidence does not support claims about overall patterns of revenue reduction due to individual copyright infringement. http://www.ew.com/article/2013/03/31/hbo-thrones-piracy And it certainly didn’t negatively impact the DVD sales. http://www.nber.org/chapters/c12454.pdf In spite of this, the supply of recorded music appears not to have fallen off much since Napster, and there is at least suggestive evidence that independent music labels, which operate with lower break-even thresholds, are play-ing an increased role in bringing new works to market. http://crem.univ-rennes1.fr/Documents/Docs_workshops_2013/2013-10-24_Digital_Piracy/2013-10-24_3_PeukertClaussenKretschmer.pdf Our main finding is that smaller and larger movies were differentially aected by Megaupload's shutdown: while only very large movies benefitted from the shutdown, revenue formost smaller and medium-sized movies decreased with the shutdown. https://www.vg247.com/2012/05/19/cd-projekt-pirated-games-are-not-lost-sales-drm-is-a-lot-for-legitimate-users-to-put-up-with/ “It really puzzles me how serious software companies can consider each pirated copy to be a lost sale,” said Iwinski. “Maybe it looks nice in an official report to say how threatening pirates are, but it is extremely far from the truth. https://stephenfollows.com/has-piracy-harmed-the-uk-film-industry/ I can see why the community pirated as they did – our core audience were teenage boys, who are also the keenest pirates. They were faced with a choice of either paying money (via credit card, which they may not have) to wait a week for a physical copy to arrive which could be scratched or lost; or they could instantly get a copy for free, which could also be backed-up and shared with friends. This stuff backs up and supports everything that I have been saying - 1) Piracy happens and you can't stop it. 2) Piracy can't be quantified in economic terms as you cannot "minority report" a downloaders intentions. 3) Piracy is a service problem, not an unwillingness to pay problem. Do with that as you will, there is tonnes more evidence out there, but I only have a half an hour to compile this for you. I'm not here on the side of the pirates, I genuinely want you to suffer less for it - but I don't have the answers, only a good sense for codswallop, and when I see inflammitory, clickbait posts like the OP, when I see pie in the sky numbers being hurled around with free abandon, I call it out because belief in something that isn't true does not help you in the short or the long term. I've already seen two people talking about "locking your work down". For gods sake, please, before you do anything that could actually ruin your career, please research what happened to large companies like gametrailers - http://www.thejimquisition.com/2016/02/gametrailers-was-a-victim-of-itself/ - the takeaway is what audiences do when they have to deal with a "locked down" media player. They go somewhere else. This is hardly evidence, but it's an interesting read nontheless http://www.cato.org/blog/how-copyright-industries-con-congress

OK, Here: BTW, before I start, I'm a new user and posting a list of links probably isn't going to go well for me. So I'll do it in the next post, so you at least will know why I've gone silent Incidently, while I'm at it, why don't you post your evidence to support the claimed 10% you wrote about in that blog post. To save you an hour or two googling, the best figure you will find is the widely derided 6-7%, rightly ignored because it was based on "industry predictive models", i.e. someone thought that sounded about right. You'll also find a student paper which talks about the shutdown of megaupload and the 18 week increase globally in sales. If you use this figure, please look at the graph showing the period not affected by normal increase in sales and rentals as a result of the christmas period - it shows a change of between +4% and -4%, i.e. a statistically insignificant amount. Of course if you also include the weeks affected by christmas increase in sales, then we get to 6%-10%, and if you do want to use that figure, and I'm sure you do, then please apply the differential results to your own specific scenario, the one that shows only the biggest movies benefited from megauploads shutdown in increased sales, while medium and small productions suffered a loss of sales in the same period. In case my link doesn't come up for this, crucially important study, google "Piracy and Movie Revinues: Evidence from Megaupload A tale of the long tail by Peukert, Claussen and Kretschmer of LMU Munich, Copenhagen Business School and Institute of Economic Research, Munich respectively"