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This weekly course covers the most common questions videographers encounter when shooting and editing with DSLR cameras, from choosing a frame size and frame rate to understanding moiré. Authors Rich Harrington and Robbie Carman will also help you understand the impacts of compression and the difference between cropped (or micro 4/3rds) and full-sized sensors in cameras, and much more. This continual FAQ guide is a handy way to find the answers to the questions that plague you the most.
Rich Harrington: Okay. So, we took a look at prime lenses. Great option. For a lot of people starting out in DSLR video, they want zoom. Zooms are very popular because they let you change lenses less often. Robert Carman: Absolutely. I mean, you know, why have three or four lenses when you can have one? Rich Harrington: Well, there are certain aesthetic benefits. Robert Carman: Of course, of course, of course. Rich Harrington: Yeah. Robert Carman: But I'm saying for, I'm saying that for ease of use, sometimes, of course, it's, it's nice to have that zoom lens so you're not swapping out as often. Rich Harrington: Well, and this is my favorite zoom lens when I'm on vacation. This is my tourist lens. 28mm to 300mm.
Great range of coverage, but very hard to rack focus on. Because as I zoom in on this lens, the F-stop is going from 3.5 to 5.6. So if I'm zoomed all the way in to 300 mm, I might not be able to rack focus, because I have too great of a depth of field. Robert Carman: Right, and that sort of variable depth of field that's going on, we talked about it previously, is that sort of subtle change of attention, if you will, by the viewer. And it's often sort of amplified by a nice, soft background blur that you get with a fast lens.
And as you pointed out, one of the problems with a variable aperture zoom lens, is that that background blur quality can possibly change as you're zooming in and out, making your rack look a little, kind of, weird. Rich Harrington: Yeah. So let's take a look at that, here. I've got a constant lens hooked up that uses a 70 to 200 millimeter, 2.8 all the way through. Robert Carman: Yep. Rich Harrington: And right now, I'm at F 4.5. Robert Carman: Okay. Rich Harrington: So notice our subjects there, they're about a foot and a half apart. Robert Carman: Yep. Rich Harrington: At 4.5, I could easily control focus here right? Like this would be the difference between the person's nose in focus, and the back of their head being out of focus.
Robert Carman: Sure. Rich Harrington: Now, as I'm dealing with this, I know that that subject's in focus. I've placed my target over it, and I'm using the auto focus on the camera to check. It racks, locks in. I've nailed it. I could push the magnify button a lot of times and zoom in to really check, you know, and, again, you're blowing up the image there a bit, but you can rack that yourself. Robert Carman: Yup. Rich Harrington: So it feels pretty good. Now, I've looked at the lens itself here and I see that that's reading as basically 6 feet, Robert Carman: Okay. Rich Harrington: Well that other thing? Robert Carman: It's maybe about 6 and a quarter, 6 and a half.
Rich Harrington: That's probably closer to 7. Robert Carman: Yeah. Rich Harrington: That's probably about a foot distance. Now, I'm just going to pull back out. And so as I'm looking at that there, our second subject is about a foot away. If I look at the lens, I can actually see numbers on it. And so, I can go from six feet to seven feet. Robert Carman: And look at that, it's actually in focus. Rich Harrington: Now, you may have to practice. Robert Carman: Right. Rich Harrington: And that's a very small movement here. That's hard to do fluidly. Lay off the caffeine. Robert Carman: Hm. Rich Harrington: Make sure you get some sleep. You know, it's hard to get that movement fluid.
Robert Carman: Right. Rich Harrington: But that's really what that's designed for. Now, let's go ahead and change the F-stop on the camera, and we'll see that that distance changes even further. Robert Carman: Okay. Rich Harrington: So as I start to modify here, now, sometimes on these cameras, if you're in live view mode, changing the F-stop doesn't actually change the F-stop until you get in and out. Robert Carman: Okay. Rich Harrington: So I'm just going to flip that off for a second. Robert Carman: Yep. Rich Harrington: Pop out of live view. Pop back in. Robert Carman: Right. And then you can have your updated F-stop. Yep. Rich Harrington: Yeah. So now we're at 2.8 and you notice that the second monkey is blurrier.
Robert Carman: Of course, because you opened up the lens and increased your background blur area. Rich Harrington: Yeah. Now, it's not uncommon when doing that to have to adjust the ISO, because more light was coming into the camera. Robert Carman: Of course. Rich Harrington: Now as I make that change there, again the F-stop and the ISO may not live-update on the camera, so you might have to, again, pop in and out. Robert Carman: And of course this is just a camera-specific thing on this particular Nikon we're shooting with that's the case, other cameras it might not be. Rich Harrington: So let's just pop out of that, and we'll go back in. It looks good. Now this is one of the benefits that I like on some of these older-style prime lenses Look at that, I could see the F-stop with a real dial.
Robert Carman: Of course, what a novel idea. Rich Harrington: A novel idea. But again, it's not great for shooting stills. So I've got that same idea and I'm just going to look through the viewfinder here. And this makes it a bit easier. And I could use that as I rack. So I'll find the first position. It feels about right. And I'll turn to the second one. I just overshot it, so that's where this whole practicing comes in. Robert Carman: Yup. Rich Harrington: All right, that's in focus. Slow turn, and I'm moving between. Robert Carman: There you go. Now, I should point out though, the nice thing about this, because you're on a fixed aperture lens, a 2.8.
Rich Harrington: Yeah. Robert Carman: It doesn't matter if you were to zoom in more, or zoom in, or zoom in less. That background quality, and that background blur, would remain the same and, sort of, the repeatability of that rack. Rich Harrington: Yeah. Robert Carman: Would also remain the same, because it's a fixed aperture lens. Rich Harrington: Yeah, as I adjust that, the F-stop did not change. Notice it still reads as 2.8 throughout that. Robert Carman: Yep. Rich Harrington: So I pushed in a little further. I'm all the way at 200 millimeters now. And, using my eyepiece so I can really see what's happening, I've hit focus for the front and the back. Robert Carman: Yeah.
And so, you know, in many ways Rich, shooting with a fixed aperture zoom lens for purposes of rack focusing is kind of the same thing as shooting with a prime lens, with the added benefit that you have variable amount of reach. Rich Harrington: Yeah. Robert Carman: Now, again, when you go with, sort of, a variable aperture lens, you get the reach. But then you have the addition problem of, sort of, the background and blur quality changing based on the aperture change. Rich Harrington: So it's really matter of personal preference, though, because the cost of that constant aperture lens. Robert Carman: Uh-hm. Rich Harrington: Would have been about the same as the cost of four or five used prime lenses for the old ones.
Robert Carman: Totally. Rich Harrington: Even three new prime lens. So there are aesthetic benefits and technical benefits to both. It's really a matter of personal preference. If you're going to be picking up a zoom, though, for shooting video, you're probably going to have to graduate from the really fast auto focus, you know, tourist style, mom and pop lenses and go to a more professional lens, higher quality series that has that constant aperture. Robert Carman: So,, Rich, one of the things I've just gotta point out is that when you were futzing with the focus control there, and you were kind of trying to go between six feet and seven feet, and whatever, repeatability of that is challenging, and you did mention it takes a little practice, which I agree with.
Rich Harrington: Yeah. Robert Carman: And coming up in a little bit, we'll talk about using a device called follow focus to help us with this rack focusing, but there's one little small technique that I want to share. Rich Harrington: Yeah. Robert Carman: And we discussed this previously before we started recording today, and that's just using a small little piece of tape in a similar way that you would use markings on say, a follow focus unit. And that is just to put it right around the focus ring. Just like that. Rich Harrington: Yep. Robert Carman: And the problem is, is that these numbers are pretty hard to see on the end of the lens in sort of the, the distance window there. So what you can do is find your first focus point.
And then on the piece of tape just kind of make a mark there because the distance window here has a little mark on itself. So if you can get those two marks to kind line up you can easily and repeatedly make that focus happen. Rich Harrington: Well, and I could cheat too. Like if I want to make this easier to see, I could put my own piece of tape right up there... Robert Carman: Yep. Rich Harrington: with a line to just give me my own target. Robert Carman: Yep. Rich Harrington: And so I've got that. I've zoomed in here. If you take a look at the camera's feed, I've magnified it up, and I've really punched in very large.
But I could use that, or even the auto focus on the camera. Robert Carman: Yep. Rich Harrington: So it looks in. And I'll say, all right, great, let's just put a tick mark there. And that lines up. Robert Carman: So, Rich, I think I know where you're going with this. So you, you got focused. Rich Harrington: Yep. Robert Carman: You marked, you marked the first point. Rich Harrington: Yep. Robert Carman: Now why don't you move over to the second little monkey guy there on the table? Rich Harrington: Yep. Robert Carman: All right there. You maybe just pan up a little bit with a little D-pad on the back of the camera. And now physically move the focus ring, and find that new, that new focus point. There you go. That looks right. Rich Harrington: Yeah, I'll just punch in there to make sure.
Robert Carman: Okay. Rich Harrington: I was close. Robert Carman: That's perfect like that. Now you're just making another little mark on your piece of tape there. And now, in a much easier way than looking at the actual distance window on the lens itself, you got these nice markings and guess what? You can simply just take the piece of tape off... Rich Harrington: Yeah. Robert Carman: ...when you're done with it. No harm, no foul. Rich Harrington: So if we're here and I can now rack between those two values and use those marks as a guide, and that's a lot easier, cause you might be able to just catch that out of the corner of your eye. Robert Carman: Yep. Rich Harrington: So that's a good tip.
Works really, really well. Now, this is the budget oriented solution. Robert Carman: Yeah. Rich Harrington: The tape, the pen, but, hey, that's okay, a lot of people doing DSLR film making are on a budget. Robert Carman: Hold on. This technique will apply to exactly what we're going to talk about next, right? It's the non-budget solution of the dedicated follow focus. Which, it's main purpose, besides letting you follow focus, which we've talked about in previous episodes, help you do repeatable rack focusing as well. Rich Harrington: Yeah, so we're going to take a look at that on this Panasonic AF100 which is a type of camera that a lot of folks doing cinema-style shooting or graduating from DSLR are using the follow focus on the side there.
It's going to make it very easy to mark out our different focus positions. And on top of it, instead of having this really tiny little mark that we have to hit, you know, very, very small movement, it's going to basically use a system of gears to step that, so you can have a finer range of control, and you're not trying to go Robert Carman: Exactly. Rich Harrington: So we'll be right back.
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