Canon® Lens Composition
So beyond kind of the standard glass cannon developed ultra low dispersion glass and so dispersion is when light hits a lands and it disperses it goes off somewhere else and we don't like that because we're losing that light source okay so they designed ud glass to correct for this chromatic aberration of light hitting glass and kind of taking off doing its own thing and so there's a full list of lenses and for those of you by the class and get the pdf you don't have to write all these numbers down you go back and you can just look at this slide number and you can pull up the whole list of these air lenses that have ud glass and one of the things I really want to make sure is getting this list right current and up to date of which ones have all this in here so this is a significant improvement over normal glass because image quality less chromatic aberration less dispersion of the glass as we shooting images improved contrast improve sharpness because of this type of glass that is in t...
here and there's a type of class we're going to talk about next called fluoride and this is a much cheaper glass to use in that so it's a relatively affordable way of improving the quality of the glass of our lenses now this is originally called you d and they have since made subsequent improvements to it and they now call it super ud glass, and so if you see super ut that's this higher in type glass, but then along came fluoride. All right, so fluoride is a rare earth element, and it isn't any fairly elite collection of lenses that you'll see listed here on the left of your screen and fluoride is a rather interesting element is that you're going to get pretty much no chromatic aberration at all. If you use it, excellent let's put in and all of our lenses. One fluoride element has the power of to you, d elements. Awesome. We just saved money and wait. By reducing the number of elements in our lands. 00:02:00.32 --> 00:02:02. We're gonna make our lands smaller now, because we're 00:02:02.12 --> 00:02:05. using these fluoride elements. This is great news, 00:02:05.11 --> 00:02:06. love to hear about this new technology. Very low refractive index so refract ok what is refract reflect and we all know what reflect is we see our reflection in a mere light bounces off of a surface okay when you react to something what happens along something happens okay react to that all right so when light hits glass dispersion refraction it takes off and into a different direction very low refractive index which means the light is going where it's supposed to go very low dispersion this is all sounding really good here's a problem natural fluoride is too small for photographic lenses so when you find natural fluoride I don't know what exactly looks like but it's too small to just grind it and put it in a lance it'll work out for certain types of small microscopes but it's not big enough toe work put in a regular lands so kanan grows their own synthetic flow right crystals that they put in their lenses so in case you're wondering why is this two hundred to four hundred lands costs ten thousand dollars because they're growing gloria class crystals to put in your leads how long does that take? I don't know but it can take quite some time I know there are certain lenses that take more than eighteen months from the beginning of the lens curing process and so sometimes they're working on these lens elements and therein bats and heating up and cooling down going through cycles for weeks at a time. And it takes four times longer to grind a flow right element than it does a u, d or a standard glass element. They're very fragile, and they could be broken. And so they have to be able to be mounted in very strong lenses so that they don't get moved in the wrong way. 00:04:02.44 --> 00:04:06. And so imagine if you're breaking four times the amount 00:04:06.19 --> 00:04:07. of glass every time you're trying to grind it, that's 00:04:07.93 --> 00:04:10. going increase. The cost of that lends quite a bit. 00:04:10.63 --> 00:04:13. And so the lenses, as I say, this is a pretty lofty 00:04:13.87 --> 00:04:17. line of lenses that are using these fluoride elements. 00:04:17.47 --> 00:04:20. But you'll see it listed as one of the elements that 00:04:20.04 --> 00:04:21. is part of that lens design.