I'm confused - DPChallenge Forums

Canon EF 24-105mm f/4.0L IS

05/15/2006 01:47:41 PM · #1

There's a thread where someone's talking about focus issues with a Canon 50mm f/1.8. I thought he (she?)'s just specifying what lens he (she?) is using? There's post upon post in hardware about what an awesomely sharp lens the Canon 50mm f/1.8 is, and what a great portrait lens it makes. I was planning on ordering it from B&H tomorrow.

But, now a bunch of people are saying that f 1.8 is shallow. One person even said they're moving away from it. So, are they saying that f 1.8 is the only aperature setting that lens is capable of? When a lens says f/ 1.8 or f/2.5-5.6 exacty what does it mean? I know it has something to do with the speed of the lens, but is it also saying that's the only aperature range that lens is capable of?

I'm confused? Should I still order the 50 mm? I'd like to have something a little better than my kit lens for senior portraits.

scalvert

Canon EOS-5D Mark III

05/15/2006 01:51:09 PM · #2

Originally posted by ragamuffingirl:

...is it also saying that's the only aperature range that lens is capable of?

No, that's simply the widest aperture the lens is capable of. The 50mm ranges from f/1.8 to f/22 (I think), and f/1.8 is a very shallow depth of field. Go for it. That lens is the best Canon bargain you can buy.

Refwhett

Nikon D300

Nikon AF-S DX NIKKOR 18-200mm f/3.5-5.6G ED VR II

05/15/2006 01:54:02 PM · #3

On prime lenses ther will be on ly one aperture value but on zoom lense you will have two. They are both the widest aperture the lens is capable of but in the extremes of its range the first at the widest angle and the second for max zoom.

05/15/2006 01:56:22 PM · #4

I like my 50mm f1.8 lens, which does stop down to f22.
When a range is given it's for a zoom lens which will vary on its widest aperature depending on what length you have it zoomed to.

f1.8 has a shallow depth of field on any lens. To get a better feel for DOF, try this site: Bob Atkins DOF Calculator or search for "depth of field calculator" until you find one that makes the most sense to you.

05/15/2006 02:17:27 PM · #5

So, why is a lens that has a value of f/1.8 considered to be faster than one that is f/3.5?

05/15/2006 02:20:24 PM · #6

Originally posted by ragamuffingirl:

So, why is a lens that has a value of f/1.8 considered to be faster than one that is f/3.5?

Because the wider the lens is open the more light it lets in allowing you to set a faster shutter speed given the same lighting conditions.
LINK to an entry on this in a rather cool online dictionary of photo terminology.

Message edited by author 2006-05-15 14:22:17.

w24x192

Canon PowerShot S50

05/15/2006 02:23:10 PM · #7

Originally posted by KaDi:

Originally posted by ragamuffingirl:
So, why is a lens that has a value of f/1.8 considered to be faster than one that is f/3.5?

Because the wider the lens is open the more light it lets in allowing you to set a faster shutter speed given the same lighting conditions.

Right, and the smaller the number, the larger the aperture, since f/1.8 is a fraction (here it would be 50mm/1.8 = 27.8 mm)

05/15/2006 02:57:12 PM · #8

Never mind.

Message edited by author 2006-05-15 14:58:20.

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

05/15/2006 03:48:00 PM · #9

Originally posted by ragamuffingirl:

Never mind.

Awww, c'mon! Ask us another! I was doin' good here!

thegrandwazoo

Nikon D750

05/15/2006 03:51:24 PM · #10

Originally posted by ragamuffingirl:

Never mind.

Smaller the number the bigger the hole. The bigger the hole more light will be let in to hit the sensor thus the faster shutter speed.

1.8 = Big hole more light
5.6 = Smaller hole less light

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

05/15/2006 04:09:39 PM · #11

Originally posted by thegrandwazoo:

Originally posted by ragamuffingirl:
Never mind.

Smaller the number the bigger the hole. The bigger the hole more light will be let in to hit the sensor thus the faster shutter speed.

1.8 = Big hole more light
5.6 = Smaller hole less light

F/22 = 1/22 of the focal length is the aperture size
F/2 = 1/2 of the focal length is the aperture size

1/2 is bigger than 1/22, so F/2 is a larger aperture, on a given lens, than F/22...

R.

w24x192

Canon PowerShot S50

05/15/2006 04:17:53 PM · #12

Originally posted by Bear_Music:

Originally posted by thegrandwazoo:

Originally posted by ragamuffingirl:
Never mind.

Smaller the number the bigger the hole. The bigger the hole more light will be let in to hit the sensor thus the faster shutter speed.

1.8 = Big hole more light
5.6 = Smaller hole less light

F/22 = 1/22 of the focal length is the aperture size
F/2 = 1/2 of the focal length is the aperture size

1/2 is bigger than 1/22, so F/2 is a larger aperture, on a given lens, than F/22...

R.

Right.

05/15/2006 04:28:21 PM · #13

Originally posted by w24x192:

Originally posted by Bear_Music:

R.

Right.

Are you attempting to kill this thread?