17-40L - any easy way to check focusing?

Raider

Raider

Raider

Soldato
Joined
18 Oct 2002
Posts
4,576
Location
Leamington Spa / Oxford
I received my 17-40L last week, but so far i've been disapointed with the sharpness. My 70-200mm F4 L seems to have it beat hands down.

I may be wrong, but the focusing seems to be a little off. Despite good light at the weekend, I haven't taken a photo with the lens that makes me say "Wow!"
I try to use the lens at F5.0 rather than wide open, but still I'm thinking that I haven't got much for my £450. :(

I'm guessing I should try and take a few photos of a single object with both the 17-40L and 70-200L, and compare them. If this lens can't perform then it'll have to go :(
 
Remember that wide angle lenses are not as sharp as telephoto lenses.
If you really have to test them side-by-side then post some 100% crops for us to judge :)
 
SDK^ said:
Remember that wide angle lenses are not as sharp as telephoto lenses.
Click to expand...

Why's that then? I'd have thought it would be the other way round? Genuinely interested to hear. I've also heard that 'Canon's wide angle lenses aren't the best' and that was from an established photographer who has Canon kit.

I've heard other people moaning about the 17-40L lens on other forums but there are several users on this forum who have this lens and love it (Fstop11 springs to mind).
 
Wide angle lenses distort the path of the light more than telephoto lenses which will impact sharpness because of the different distances the light travels from the object to the focal plane. I guess asymetric elements will help, but there's always going to be some variation in focus across the image.

I guess we also expect more depth of field from wide angle shots, which stretches the abilities of the lens, especially at larger apertures.

I've got a 17-40 myself, and although it's not perfect, it's just about the best sub-20mm lens I've seen.
 
Ok so maybe I shouldn't expect so much from the 17-40L?
Stopping down to F5.6 or F8 will sharpen it up nicely, but that gives a huge DOF, which isn't always useful for an all-rounder lens.

How does the 24-70L compare in terms of sharpness wide open (F2.8)?
If it was a big step up, then i'd consider ditching the 17-40L in favour of the 24-70L in order to get a nice DOF, and sharper images.
 
The 24-70 is the sharpest zoom canon make (as far as I've seen).

You'll get reduced depth of field and better sharpness, but then you'd expect that from a longer lens at ~£300 more.

So I guess it depends on the camera. Full frame, then the 24-70 is your best bet. For a 10D/20D etc, the 17-40 is probably the better all-rounder.
 
Maybe I should keep my Sigma 10-20mm, and go with the 24-70L.

Will have to swap lenses for wide work (quite rare), but it'll be useful having the extra 40-70mm range on the same lens! :p
 
What you say matches up with what a few other people say about the lens. The first thing to think about is that generally, the focal length doesn't produce that wow factor unless the scene you're photographing includes a great deal of contrast or colour - that's when the characteristics of the lens comes into it's own.

I own the 70-200, and it does produce far apparently 'sharper images' than my wide angle because normally because I am taking full frame images of objects and the depth of field characteristics of telephoto lenses tends to give it that extra kick.
 
Mohain said:
Why's that then? I'd have thought it would be the other way round? Genuinely interested to hear.
Click to expand...
Pretty much what arcamalpha said
Wide zooms are very difficult to manufacture. Light at the edges has to travel further and has more distortions etc. Ensuring it hits the sensor at the same point isn’t easy.

Below are the MTF charts for the 17-40L and 24-70L

17-40L F4

mtf-17-40L.jpg




24-70L F2.8

mtf-24-70L.jpg




Info
The black lines are measurements taken with the lens wide open.
Blue lines are with the lens at F8.

The thick lines refer to the contrast reproduction capability of the lens.
The thin lines refer to the resolving power and thus subjective sharpness of the lens

The higher up the chart a line is, the higher the contrast/sharpness
The 0 to 20 across the bottom scale represents the center of the lens to the edge.
Ignore the dotted lines.
 
Last edited:
I recently got a 17-40 L. I've only used it in the garden so far to take snap shots... just to make sure it works etc. Here are three full size cropped images.

Canon 10D

f/6.7, 29mm, 1/50, ISO100
http://www.v12digital.com/17-40/test001.jpg

f/11, 38mm, 1/60, ISO100
http://www.v12digital.com/17-40/test002.jpg

f/11, 40mm, 1/180, ISO100
http://www.v12digital.com/17-40/test003.jpg


I find the wide angle to be disapointing, but I've only taken a handful of photos with the lens so far. I'd say the lens is generally on par with my 28-135 IS for sharpness.
 
From what I have seen from the above and from other photos, I can't see much difference between it and my kit lens for my 300D. (albeit with some unsharp mask processing in photoshop!)

I don't think I could justify £400-500 or whatever the cost is for the apparantly small increase in picture quality from the camera.

Has anyone done a comparison of pictures from a 17-40L and the canon 17-55 kit lens?
 
my 17-40 seems pretty sharp to me, a lot better than the kit lens . But not only is it sharper, the colours and contrast seem a lot nicer
 
nomore said:
I'd say the lens is generally on par with my 28-135 IS for sharpness.
Click to expand...
Pffft, the 17-40L blows the 28-135IS away, especially at the wider focal lengths.


AndyBorzi said:
Has anyone done a comparison of pictures from a 17-40L and the canon 17-55 kit lens?
Click to expand...
Assuming you mean the 18-55 kit lens ;)

A couple of links to comparisons
http://www.fountainphoto.com/2004/05/10/canon-ef-17-40l-vs-ef-s-18-55
http://foro.meteored.com/index.php/topic,29903.0.html



So many bad things being said about the 17-40 here !!! It's a superb lens and certainly the best all round wide angle lens you can buy today.
 
So many bad things being said about the 17-40 here !!! It's a superb lens and certainly the best all round wide angle lens you can buy today.
Click to expand...

Perhaps quality wise, but I think there are better value for money offerings personally.
 
nomore said:
Pffft, the 17-40L blows the 28-135IS away, especially at the wider focal lengths.
Click to expand...
At longer focal lengths 100mm+ it's okay but it's worse than the kit lens when used 28mm-40mm, especially wide open.
 
Have you thought about the 17-55 2.8 IS USM ? From tests all over the net it is as sharp as the 24-70 L and has L glass inside it sans L lens build and wetaher sealing. for £750 it also can't be beat by *** looks of it.
 
mrk said:
Have you thought about the 17-55 2.8 IS USM ? From tests all over the net it is as sharp as the 24-70 L and has L glass inside it sans L lens build and wetaher sealing. for £750 it also can't be beat by *** looks of it.
Click to expand...
£750 is approaching twice the cost of the 17-40L and whilst the 17-55 is sharp the build quality is very poor. Factor in the restriction to EF-S cameras, limiting camera upgrade options and it's a lens not many would go for.
 
You must log in or register to reply here.
Back
Top Bottom