05-25-2017, 10:38 AM
Yes, "high" refers to the numerical value, which is actually a smaller physical opening. A good way to think about aperture is high = deep depth of field, low = shallow DoF.
A low aperture gives you a very shallow depth of field so only your subject is in focus, everything in the foreground and background will be blurry. The other main reason to use a low aperture is because you can take in more light in less time, so that's why pretty much everyone buys a lens with a sub<2.0 aperture.
Indoor lighting at night is only juuuuuust bright enough for my f3.5 to get a decent exposure. I have to crank ISO up to 2000 or 4000, and I can still only manage a 1/60th shutter speed. If I had an f1.8, I could increase my shutter speed so I don't have to worry about shakey hands, and reduce the ISO which will give a sharper image all the way around.
A high aperture does the opposite, it allows you to get more (or all) of the image in focus. It also requires a longer shutter speed to get the same exposure vs a lower aperture setting in the same conditions, so for those nice race car shots with a blurry background you'd want to increase the aperture setting and decrease the shutter speed.
Here's a good simple example:
![[Image: deep%20vs%20shallow%20DOFchess%20pieces.JPG]](http://teachers.sduhsd.net/delliott/Files-Photo/Lessons%20&%20Related%20Photos/deep%20vs%20shallow%20DOFchess%20pieces.JPG)
I don't want to speak for Garrett but I don't think his shutter speed math is broadly applicable. The distance between you and the subject is a big factor, as well as whatever apeture settings you're using. A shutter of 1/8s to get a shot of the guy on the bicycle would be almost impossible to get it crisp, just of the top of my head I think a 1/40-1/60s in that situation would still allow you to get the cool blurry background, assuming the 16mph bike is much closer to you than the 100mph race cars.
A low aperture gives you a very shallow depth of field so only your subject is in focus, everything in the foreground and background will be blurry. The other main reason to use a low aperture is because you can take in more light in less time, so that's why pretty much everyone buys a lens with a sub<2.0 aperture.
Indoor lighting at night is only juuuuuust bright enough for my f3.5 to get a decent exposure. I have to crank ISO up to 2000 or 4000, and I can still only manage a 1/60th shutter speed. If I had an f1.8, I could increase my shutter speed so I don't have to worry about shakey hands, and reduce the ISO which will give a sharper image all the way around.
A high aperture does the opposite, it allows you to get more (or all) of the image in focus. It also requires a longer shutter speed to get the same exposure vs a lower aperture setting in the same conditions, so for those nice race car shots with a blurry background you'd want to increase the aperture setting and decrease the shutter speed.
Here's a good simple example:
I don't want to speak for Garrett but I don't think his shutter speed math is broadly applicable. The distance between you and the subject is a big factor, as well as whatever apeture settings you're using. A shutter of 1/8s to get a shot of the guy on the bicycle would be almost impossible to get it crisp, just of the top of my head I think a 1/40-1/60s in that situation would still allow you to get the cool blurry background, assuming the 16mph bike is much closer to you than the 100mph race cars.
Now: 07 Porsche Cayman S | 18 VW Tiguan
Then: 18 VW GTI Autobahn | 95 BMW M3 | 15 VW GTI SE | 12 Kia Optima SX | 2009 VW GTI | 00 BMW 540i Sport | 90 Mazda Miata | 94 Yamaha FZR600R | 1993 Suzuki GS500E | 2003 BMW 325i | 95 Saab 900S