If you want to go beyond even 1:1, you can get larger than life-size by adding magnifiers called diopters—but beware the pitfalls.
- [Deke] In this chapter, we'll discuss a few special techniques that fall into the category of advanced underwater photography. Or, if you prefer, things to try once you become comfortable with macro. And, we're going to start off with the macro of macro, which is super macro, in which we capture images that are larger than life size. There's the idea. And so, you may wonder what exactly is super macro. If macro describes images that are reproduced on the sensor at actual life size, one to one in other words, then super macro reproduces the image at greater than life size.
So, it could be two to one, three to one, what have you. Super macro images are most commonly achieved by adding magnifying close-up lenses, which are commonly known to underwater photographers simply as diopters. And, that's how you'll hear us refer to them as well. And finally, because it relies on multiple lens elements, super macro photography may require you to consider additional optical issues, and we'll review what that means in just a moment. - [Instructor] So, let's take a closer look at these diopters that Deke just mentioned.
So, some diopters can actually attach to the lens inside the housing, and those are less common, because you don't have the flexibility of removing that underwater. More often, they're what we like to call wet-mate lenses, which means you can attach and remove them underwater. And, you can see examples of those here on the right. So, some of these wet-mate diopters can also turn a non-macro lens into a macro lens. So, here we have an image of a nudibranch, and this was taken with a non-macro lens. And, that's probably why I have to tell you that this is an image of a nudibranch, because you wouldn't be able to tell.
So again, this was taken with a non-macro lens without a diopter, whereas here on the right, I think you have a much better chance of figuring out that this is a nudibranch without me telling you. So, this was taken with the exact same lens, but in this case, we've applied a diopter to the front which again is going to allow that lens to focus closer, and thereby turn it into a macro lens. So, now let's talk about when we're using a dedicated macro lens what's going to happen when we apply a diopter. So, here again, we have a little flatworm, and this is taken at one to one.
So, this is the maximum magnification possible on this lens without any sort of modifier. So, here on the right, we have the exact same animal, except this time we've put one of those diopters, so one of those magnifiers, in front of the lens. So, the lens is still set on its maximum magnification setting, but now we've placed this diopter in front, and you can see we've gotten a huge boost in magnification. So again, when you combine with a dedicated macro lens a diopter, it magnifies the image before it hits the lens, and that's going to allow for greater than life size reproduction.
- [Deke] So, for those of you who are absolutely crazy about macro photography, diopters offer you a whole new level of magnification. But, I was telling you we do have some optical issues. Namely, the diffraction dilemma. So, diopters necessarily reduce the depth of field, so you have to increase the aperture value to compensate. Problem is, light rays passing through a small aperture, which is what you get at a high aperture value, interfere with each other, which is known as diffraction.
And so, I've gone ahead and drawn up a diagram that gives you a sense for how those light rays are jostling up against each other when they hit the image sensor. And so, as a result, diffraction ends up causing minor loss of sharpness, or at least so the story goes. - [Instructor] And, I'm here to tell you about what I call the diffraction myth. So, meanwhile, you're shooting through a medium, water, that's almost 800 times more dense than air. So, that means all that light is passing through something that's 800 times more dense.
Also, sitting in front of that lens, part of the housing, we have that macro port. So, we've got one more piece of glass or possibly plastic in between that lens and the subject that any of that light is going to have to pass through. - [Deke] And, that port can be of variable optical quality, and also it might've gotten bumped against things, it could be scratched. And so, it's a lot more of an unknown issue than a diopter lens. - [Instructor] So, I'm pretty sure that all of this is causing way more softening than diffraction. So, I would say go ahead, feel good about setting that camera on f/32.
So, when you're shooting something like this basket star shrimp over here, who's really really small, you really want to maximize that depth of field. So, don't even bother thinking about the diffraction, just go ahead and get that aperture as high as you can to maximize your depth of field. And, I'm going to get back on my soapbox here for another second. We're going to talk about being aware of over-accessorizing. So, diopters are great. They're easy to add on, so it's tempting to go a bit nuts and just try to get as much magnification as you possibly can. And, sometimes you're going to end up with what we like to call the Frankenrig, where you've put every accessory you can possibly get your hands on, and you're trying to use them all at the same time.
Well, to be honest, each additional diopter that you put on is going to cause a slight loss in sharpness and depth of field. So, eventually you're going to reach that point of diminishing returns where to be honest you're better off just cropping in post. You can get cameras nowadays that have 50, 60 megapixels, and the cover of a magazine is only 12 megapixels, so you could honestly crop a fifth of your image and still have a perfectly viable, printable image that's going to have much more sharpness, much better depth of field than you did by just putting four or five diopters on there.
- [Deke] So, for those of you who are just crazy about macro, that is our introduction to the world of super macro and diopters.
- What is macro?
- Macro etiquette
- In-camera histograms
- Lighting your underwater scenes
- Working with shadowless lighting
- Using snoots, backlighting, or lighting from below
- Controlling your depth of field
- Capturing details
- Setting up your Lightroom workspaces
- Advanced post processing