Probably a stupid question I know.

I am just getting started in photography and have posted a few questions here and read a ton of others. One thing I notice in peoples post, and someone just put this in an answer to my question, is the talk about "stepping down" What does this mean. I know this is probably photography 101 but I never took classes or anything. Just a hobby. For an example my question was about a lens. And the person that answered me told me that a particular lens takes great pictures if you "stop down from wide open" What does that mean. Thank you so much for any help

Stopping down on a lens means moving from a large aperture, for example f2.8, to a smaller aperture, such as f4.0. If you move from a smaller aperture to a larger aperture, f11 to f8.0 for instance, that's called "opening up."

Mark

I get everything confused and the terminology is all weird when it comes to aperture. Open wide means a small number. But the question really is, if you open the lens wide, does the focus get worse?

The only stupid question is the one you don't ask.

Stopping down your lens means going to a larger "f" number, say from 2.8 to 5.6. This gives you more depth of field (more of the subject in focus). Most lenses are sharpest at f8 though depth of field will increase as you stop down.

If the focus mechanism isn't accurate, yes, shooting wide open will reveal the issue. Stopped down a bit, the problem is less prevelent. This is the exact reason I chose the 50 f/1.4 over the 50 f/1.8. It's also the reason I haven't gotten a Sigma 20 f/1.8. My primary usage will be wide open, or nearly so, therefore accurate focus is a prerequisite. Still looking for a good Sigma 20 .

With the lens wide open (low f numbers) the depth of field is shallower. At higher numbers (say, f5.6) the area in focus will be deeper. You can test this by shooting the same subject (using the same focus point in each shot) and taking shots wide open and stopped down. You'll notice that in the stopped down shots more of the subject is in sharp focus.

Take the 50 1.4, it's great. So sharp. But if you want more than just your one subject in complete focus and everything else blurry, you have to step down and set a larger aperture. That way if you are shooting a group of people, everyone in the same plain will be in focus. But if you buy a lens with a higher f number, less light comes in, so the lens won't produce as bright pictures as a lens with a smaller f number.

Not exactly. The "slower" lens will require a much longer shutterspeed to get a proper exposure, hens the terms "fast" and "slow" when describing a lens.

Ah, but there are also arguments about how bright a lens is, letting in more light to produce a sharper picture. The 50 1.8 is a lot slower than the 50 1.4, and some people get confused about that.

Sure it will, it will just require a longer exposure to produce the same "bright picture".

The larger aperture will allow more light into the viewfinder, true. And yes the 1.8 is slower than the 1.4. But a brighter lens as you put it won't give you a sharper image. Sharpness is not a function of a large aperture. Just look at the reviews of Canon's 50 f/1.0. Faster than both current 50s, but sharpness isn't its strong suite.

Suzie, I think you are confusing the "lens speed" with "focus speed." The 50 f/1.8 is 2/3-stop slower than a 50 f/1.4. That isn't much. My 17-40 f/4 is 3 stops slower than the 50 f/1.4 and it's sharper. Sharpness is not directly linked to max aperture size. I can make the same exposure with all three lenses using different shutterspeeds.

That's right, but that's where people like me got confused about the 3 factors of proper exposure. Manuals just don't explain what the lens can do, how to set it. Before getting an SLR, the camera does everything and if you get a great shot, that was a good camera. When I got my first DSLR, I was using AUTO all the time. I wish Canon would explain their lenses' capabilities in their manuals. When I got my 24-70L manual, it didn't say more than just how to mount it on the camera and go for it! I thankfully, had some Canon guides (not written by Canon) that described the capabilities of the lens. That really helped me. When I first started buying lenses, cost meant more to me than quality. I didn't know primes were so good and sharp. Asked a few more questions and got the answers that helped me figure things out so I don't want to go on AUTO anymore. I can control the exposure. How fun it is now, but learning takes time. And I couldn't take a photography class and didn't have any money.

Suzy, if you are still confused about the three factors of exposure then I would suggest one of Bryan Peterson's books, either Understanding Exposure or Understanding Digital Photography. I have the latter and found it invaluable when starting out. I had no idea what any of this aperture business meant.

The thing is, most lens meet our favor through purely subjective impressions. All the specs are right there on the Canon site. It's like buying a car. You may be able to compare the performance of a Chevy, a Toyota, a Honda, and and a VW, but anything that describes the experience of driving any of these cars would be marketing hype. After a while, you'll understand immediately that even though f/6.3 doesn't sound that fast, it actually is if you're looking at a 500mm lens, and that you'll have no problem "throwing a background out of focus" with it. You'll also realize that even though f/2.8 is incredibly fast for a wide angle zoom, it isn't that steller for wide prime.