L Lens not sharp

[eas01010]

Hi guys. I got hold of a 2nd hand L lens but I find it not as sharp as I expected.

Pictures I tested was on tripod and the handshake factor was removed. Other lens tested on my 400D body achieved sharp results.

Need some advice here from ClubSnappers here. Would sending the lens for re-calibration help?

[zj2000]

Which lens do you have? It could be focusing error.

[eas01010]

It's a 17-40L.

How to correct focusing error?

[ilihz]

Originally Posted by eas01010 Hi guys. I got hold of a 2nd hand L lens but I find it not as sharp as I expected. Pictures I tested was on tripod and the handshake factor was removed. Other lens tested on my 400D body achieved sharp results. Need some advice here from ClubSnappers here. Would sending the lens for re-calibration help?

What lens are you comparing 17-40 with? Keep in mind that 17-40 is not the sharpest lens out there.

Test using manual focus and post pics.

[estel]

post a photo without any resizing / post processing so we can have a look before comment. "not sharp" is not a quantifiable term. It may be possible that what you expected was not what the lens actually delivers. Even with L lenses, especially 17-40, 100% crops aren't always sharp.

[coffee3in1]

I'm so interested to learn abt sharpness of L lens, coz i'm gearing up for 85L. Does one equal sharpness to AF accuracy?

Or shud i setup the camera on tripod & using liveview MF to the sharpest image and take a picture? Then compare against different version of the same lens. (Apologies to TS for abit of OT).

[m3lv1nh0]

I also just got a used 85L and I feel it's not as sharp as other claims to be. Might be that's why the previous owner wants to sell it fast. My 35L is much much sharper at the same aperture. Think I have to setup a tripod to test tonight.

[thinkvision]

85L version I sharper than version II, but just lit bit slower in AF speed.

[Kit]

Originally Posted by eas01010 Hi guys. I got hold of a 2nd hand L lens but I find it not as sharp as I expected. Pictures I tested was on tripod and the handshake factor was removed. Other lens tested on my 400D body achieved sharp results. Need some advice here from ClubSnappers here. Would sending the lens for re-calibration help?

Were all your lenses tested in the exact same condition? Take note that there are a lot of factors that can affect your results other than the lens performance.

[coffee3in1]

Keep me posted on ur findings.

Originally Posted by m3lv1nh0 I also just got a used 85L and I feel it's not as sharp as other claims to be. Might be that's why the previous owner wants to sell it fast. My 35L is much much sharper at the same aperture. Think I have to setup a tripod to test tonight.

[SamPaul]

Can I also ask if there's any diff. when using some lens but diff. body like 400D & 5D?

[LeaderXXX]

Send in canon cs with the body.

[eas01010]

I can't really compare like for like between my 17-40L and the other L lens I got, which is a 70-200 f4 L as their focal length do not overlap.

But what I'm trying to say is that in shooting the same object at the same time, the image quality I got from the 70-200 was much better in terms of sharpness and color contrast when compared with 17-40.

Also if you purchase an L lens you would expect a certain degree of sharpness to justify the L premium.

I will try to post pictures.

[adamadam]

Bring to CSC.

[hammie]

*waiting for picture*

As a fact, different body even with the same lens will varies the degree of sharpness by a few minute

[Kit]

Wide angle zooms traditionally loose out in sharpness. This is especially so for Canon.

[megaweb]

Try this test

http://photo.net/learn/focustest/

[calebk]

Originally Posted by eas01010 I can't really compare like for like between my 17-40L and the other L lens I got, which is a 70-200 f4 L as their focal length do not overlap. But what I'm trying to say is that in shooting the same object at the same time, the image quality I got from the 70-200 was much better in terms of sharpness and color contrast when compared with 17-40. Also if you purchase an L lens you would expect a certain degree of sharpness to justify the L premium. I will try to post pictures.

Is this a case of perceived sharpness? Because you can see the clear boundaries of the shallow depth of field rendered by your 70-200 f/4L, you perceive it to be sharper than the 17-40L because it is a wider lens, and depth of field fall off is not so pronounced, hence the in-focus area is also not so pronounced.

Secondly, how are you performing your tests? You haven't given us a clear breakdown as to how you are testing both lenses.

[Snoweagle]

Originally Posted by SamPaul Can I also ask if there's any diff. when using some lens but diff. body like 400D & 5D?

To me there's not much difference except sensor size, DOF control and colour rendition. But u're comparing a FF to a cropped body. If u're comparing cropped bodies but different year makes, there are differences too.

[twnll]

I have a 17-40L. Don't expect corner sharpness once you go pass 24mm. Centre sharpness is great even at 17mm. The 16-35L, from what I gather, isn't any better. Wide Zooms have their limitations when it has to gather so wide an angle. Its a characteristic, not a weakness.