24-105mm Canon L lens, darker when zooming in?
- Thread starter Solstice
- Start date
No, you are mistaken.
On a canon lens a F-stop range means that your maximum aperture changes while zooming in.
I have a 18-200mm with a F3.5-6.5 range. This means I can't have an aperture of 3.5 while the lens is set to 200mm.
However I can set the lens till F22 if I want.
The same goes with the 50mm 1.8 lens. 1.8 is the widest possible aperture, but I can change it up to F22.
What you see on your Sigma lens is that your maximum aperture become smaller when you zoom in.
Set your lens at the widest. Set aperture to 1.8. Now zoom in with your lens and watch what happens with the aperture.
PS.
Use the Manual settings, so the F-stop is displayed on screen.
Here are photos of how F stops are indicted on the Lens from my SLR collection.
The first set of numbers away from the body of the camera are the zoom range of the lens. The second set of numbers closer to the body of the camera are the F stop settings.
The Canon lens has only one set of numbers. And, they are for the zoom and focus range. You can see other manufacturers such as Nikon and Pentax follow the same format of labeling their lens. The Sigma lens follows this same standard format.
The first set of numbers away from the body of the camera are the zoom range of the lens. The second set of numbers closer to the body of the camera are the F stop settings.
The Canon lens has only one set of numbers. And, they are for the zoom and focus range. You can see other manufacturers such as Nikon and Pentax follow the same format of labeling their lens. The Sigma lens follows this same standard format.
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That are some nice old school lenses where you probably had to adjust aperture manually.
Nevertheless, this is still nonsense:
And you can find out the way described before.
The canon lenses just tell you the maximum aperture with the numbers, because that is the difference between lenses. The fact you can't rotate an aperture ring doesn't mean the aperture can not be changed.
Read your 60D manual on changing aperture and see it happen on your 'fixed aperture' Canon lenses.
Believe me: I own a 60D and a Canon 50mm F1.8 and I do that all the time.
Just like I own a 18-200mm F3.5-F6.5 lens that behaves the way I described.
Are you sure your wide telephoto lens can't close down the aperture beyond F5.6?
With modern lenses that would be unthinkable, because the ability to close down to F22 gives a lot more possibilities.
Nevertheless, this is still nonsense:
And you can find out the way described before.
The canon lenses just tell you the maximum aperture with the numbers, because that is the difference between lenses. The fact you can't rotate an aperture ring doesn't mean the aperture can not be changed.
Read your 60D manual on changing aperture and see it happen on your 'fixed aperture' Canon lenses.
Believe me: I own a 60D and a Canon 50mm F1.8 and I do that all the time.
Just like I own a 18-200mm F3.5-F6.5 lens that behaves the way I described.
Are you sure your wide telephoto lens can't close down the aperture beyond F5.6?
With modern lenses that would be unthinkable, because the ability to close down to F22 gives a lot more possibilities.
Just looked at the photos. It looks pretty normal to me and I can't pinpoint exactly why one image is slightly darker. Could be:
1: The slight vignetting as mentioned by Stef.
2. Lenses are not perfect. Slight aberrations can occur.
3. Try shooting in a controlled lighting environment instead of outdoors.
Lenses used to have manual aperture rings to adjust the aperture. Nowadays the aperture is controlled electronically through the camera body.
All lenses can have tiny apertures like f/22 or f/36 so manufacturers do not bother writing that number down on the box or lens. We are more interested in how much light a particular lens can give us so they write that number down.
Simply go into your Av (or A) mode or in your M mode and rotate the different dials on the camera body. You'll see the aperture value change on your LCD and in the viewfinder.
I saw your post earlier and couldn't figure it out.
It appears you are a bit confused. Because f stop is affected by focal length in addition to the size of the aperture, its far cheaper to sell a variable fstop lens, as the actual front element doesn't have to be larger.
What you were told above is correct.
The lenses you showed have a manual aperture ring. All of my lenses (and I have a lot) have a minimum aperture from 16 to 48 or so. And the 16 is a 1.4 wide open. But all the modern standard canon lenses have the aperture electronically controlled, so you will never have an aperture ring except on the cinema lenses.
Guys, thanks for the clarification. That's why I posted the picture of the lens as a visual of what I was trying to talk about.
