The F stop number on lenses tell you a lot about each lens!
Yesterday we went over the power numbers on lenses, and how you can tell what kind of power you have with your lens, or how much wide angle you could get.
Today we are going to talk about the other number on the lens, the aperture number:
We went over the “focal range” of lenses. For further information in case you missed it, is yesterday’s blog. Just go to that page for more info.
Today, we will cover the rest of these numbers on the lens.
The first one that you see on the diagram above is an indication of what filter size, or lens cap size this lens takes. On the lens above you will see that it says: 58mm, which means, that it takes a 58mm filter or lens cap. That indication on the lens is with a circle, and a line through it, and then the number.
The next set of numbers is what I really want to get into. That is the “MAXIMUM APERTURE” of this lens. All lenses have this number. Now, in order to understand maximum aperture, let’s go to this diagram:
If a lens has a marking that says it is 3.5 lens, then it only goes to 3.5 maximum aperture. Can you see if you had the exact same lens and it goes to 2.0, can you see that this lens let’s in more light, that the one that only goes to 3.5? Yes, they make lenses this way. And the more glass you have in a lens, the more money they are too!
Here is a great example:
Canon 24mm F2.8 lens:
It is selling on the Canon Website at $599.00. And really, a wide angle lens like this with an F2.8 maximum aperture is a sweet lens.
Shown here now, is another lens from Canon. It is also a 24mm lens. But, it’s maximum aperture is 1.4 ! If you follow the chart above and the maximum apertures lenses go, to go from F2.8 to F2, the lens will actually let in twice as much light as the F2.8. So, if we go one more step: 24mm f1.4, you will let in twice as much light as the F2 lens, and 4 times the light as the F2.8 lens. The price for this lens: $1599.00.
Are lenses worth that $1599 price tag? Yes, if you do extreme low light photography, that may be worth every penny. Because it lets in so much more light than the standard lens with F2.8 maximum aperture.
What is the depth of field like with an F1.4 lens vs. the F2.8?
Well, I would say the F1.4 lens has a very shallow depth of field. Much more shallow than the lens with F2.8. But, again, if you are shooting low light, you will just figure out how to get around that. Probably the person who owns the F1.4 lens is not shooting a lot of close-ups, so he won’t have to worry about depth of field so much. But, they may be the best Real Estate photographer.
All camera manufactures make lenses like this. I want everyone to know that I wasn’t picking on Canon. Canon makes excellent lenses, and so does Nikon, Olympus, Sony, etc, and they have lenses comparably priced to the Canon lenses I just went through.
I hope that helps you to understand it. If you have further questions, I have an email that will help you. Go to: question.123photogo.com And I will personally answer for you.