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Lens Quality

Lesson 13 from: FAST CLASS: Fundamentals of Photography

John Greengo

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Lesson Info

13. Lens Quality

Next Lesson: Light Meter Basics


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Photographic Characteristics


Camera Types


Shutter System


Shutter Speed Basics


Camera Settings Overview


Camera Settings - Details


Sensor Size: Basics


Focal Length


Lesson Info

Lens Quality

all right, final little section here on lens quality. And so we talked about the angle of view. We talked about the aperture, but there's also a few things that impact the image quality that you're gonna get from any particular lens. So first off, we want to talk about some of these optical challenges and making lenses, and we want to have lenses with the highest resolution possible. And there is no rating on this as faras a number when you buy your lens. But lenses tend to be getting sharper because we have higher resolution cameras now. And so there are some older lenses, which are quite nice, but on newer cameras with higher megapixels, they don't stand stand up a swell as they used to back in the days of film and lower resolution sensors. And so that's one of the things that we're getting just inherently. In the newer lenses. Some lenses deal with flair better than other lenses, and so when light strikes the front of the lens, it causes ghosting and light hitting different parts of...

the sensor. And so this is why you want to use the lens hood and why some lenses are better corrected for lens flare than others. I talked about diffraction when we stop our aperture down. And so what happens is that when we stop our aperture down the light hitting those aperture blades gets refracted, sent in slightly different directions, which causes just a little bit of blurriness. So stopping down to F 22 32 is not recommended unless you really need it because it's gonna cause a loss of sharpness on any particular image. Chromatic aberration, chromatic color, aberration, ghostie color ghosting will occur when you were shooting a solid object that has light behind it. And so is the light comes around the solid object. The light kind of gets a little misdirected and it doesn't land in the right spot on the sensor. And you get this color ghostie. Now, this could be corrected. Sometimes in camera, you can turn on chromatic aberration, correction, or you could do it in post production in a program like adobe light room. Hit the check box and it knows what lens you have, how bad that problem is and can automatically fix it. Or you can even go in and manually fix it. Where it looks for edge lines of a certain color and corrects it and d saturates it basically. And so it's something that will happen. Even with the best of lenses in bad conditions, you might say distortion is something we talked a little bit about before. Barrel distortion is more common on wide angle lenses and pin cushion distortion is a little bit more common on telephoto lenses, and all lenses should be perfectly corrected. But the reality is, is that all lenses have a little bit of distortion. And to fix this, programs like Adobe Light Room will have a little check box or they'll have a slider where you can fix this up later. In most images, you're not going to notice. This is a problem, but if you have buildings and straight lines, you might see that, and you might want to correct for that. If you have a lens that has a bit of an issue with ease. Vignette ing is something we talked about earlier. It's a darkening of the corners, and sometimes we like it, and sometimes we don't like it. It depends on what type of photograph it is and what you want from the photograph. This is a problem of fast lenses, wide angle lenses and cheap lenses. In the early days, some of you might remember we had TV's that had rounded corners, and that's because the image was really dark and blurry in the corners because the lenses weren't very good at getting sharp edges. So they just said, Well, let's just make it like this. And there were some TV's that were round because they had really bad lenses. I think at the time that they couldn't get anything sharp from the corners of them. The bow okay, the quality of the out of focus area. And you know, you're getting picky about lenses when you're worried about the bouquet of this, and I'm not even gonna get into the How do you pronounce it thing? There's a whole thing on the Internet about it. I call it okay, it's my class. That's the way I like to call it. Eso a good Bow K is gonna have a smooth and creamy out of focus area. The bad. Okay, you might be able to see an outline of the aperture, and it's a little bit more jittery and less smooth. And so this is something that some people will grade and qualify. There is no number on this. It's just more of a feeling. It looks more smooth than it does over here. On the right hand side, it's not very good at kind of goes bright and dark very, very quickly there. And so some lenses are a little bit better than other lenses. Construction of lands. This is really important. Me. I like working with a lens that feels good in the hand That's comfortable. That focuses smoothly, has nice click stops on the apertures, things like that. And so metal lens mounts because I tend to change lenses a lot. The less expensive lenses will use plastic lens mounts. I like a real focusing ring with the rubber grip on it so that I have a good area to to grab on to distance scales. And there's other factors in here. We'll talk more about as we talk about lenses, but there are some pretty big differences between the lowest end and the highest end lenses, and so it's not just optical quality. It's the entire quality of that entire product that you're going to be looking at. And so when it comes to the optical hierarchy of what are the best lenses and what are the worst lenses? It generally falls into this category of professional prime lenses. And so a prime, like a 200 millimeter lands is gonna be a really high quality lands. Next up is going to be a prime, Linds, just, you know, your standard 50 or 35 millimeter lens. They're not necessarily quote unquote pro lenses. There just prime lenses. They're going to be very, very sharp. Next up are your professional zooms your 24 70 72 202.8, kind of next down on the list of you know, sharpest, they're gonna be your standard zooms now the difference between the 18 to 55 the noticeable, but not huge. You could shoot a cover of next month's National Geographic or whatever magazine you want to think of with any of these would be my guess if it's a rig, if it's a good subject, But when you get into the pixel peeping, you will notice greater sharpness with those primes and especially those high end primes, the lowest on the list are the super zooms, the ones that zoom a really large rains. You know, the jack of all trades, Master of none philosophy. If you design a lens to try to do everything, sharpness is going to suffer a little bit. And what I have found is that Tele Converters will take any lands and lowered by one step on this list. And so what you probably don't want to do is put a tele converter on in to 200 Super Zoom. Lins kind of falls off the chart then, but if you use it on a high quality lands, you'll be getting decent results still, but it it's gonna lower it just a little bit from its original native abilities. Without using tele converters, we'll talk more about tele converters in the gadget section in this class.

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