Dud copy of 17-40mm F4L??

Hi Guys,

Sorry I haven't posted to the thread for a while! I still haven't had a chance to get outside to do some high shutter speed testing yet (darn winter!), but I did do some more in door stuff using slightly better lighting and this time, the 17-40mm performed better that before (probably equal to or in some shots ever so slightly better than, the kit lens). I will try and post the samples of these shots as soon as I can (probably this afternoon sometime). I might even get a chance to do some outdoor testing this afternoon if the weather holds, which I will also post here.

Vixeh, sorry to hear your disappointed with your lens! I guess the only encouragement I can offer is that from the above advice, there do seem to be a lot of variables that can throw up poor results that may not necessarily be the lens. It sounds like you've taken many more shots that I have so far though.

Lester Wareham My shots above were at 17/18mm respectively. Also the crops above are centre crops. Interesting about the MTF data. I didn't realise wide open, the lenses would have similar performance (particularly in the centre). Definitely more testing is required here. Fingers crossed I can get out this afternoon and finally confirm one way or another if this lens is doing what it should be. Hopefully I can produce a shot that rivals the sharpness of Bluedog's shot above, which is just outstanding for clarity!

I wouldn't be very happy with those results either If the kit lens can do it, then so should your new 17-40 L.

Well unfortunately it's snowing here, so doing outside tests isn't going to be possible today, however here is another test attempt and this time, if anything, I think the 17-40 has the edge on the kit lens:

17-40mm F4L (@ 17mm, 1/19th, F4, AWB, Shot as JPEG, 100% centre crop, self-timer +mirror lockup):

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**sigh**

Have I missed something?

Glad you are happier Gcams. If you are looking for more chances to increase you blood pressure you can put some crops up for other focal length and for corner and stopped down.

Me I would love some snow to take shots off. No sign here in Hampshire yet though.

Thanks Lester Wareham, I'm hoping to do some more testing over the weekend, weather depending! I'm seriously hoping the further testing will improve rather than increase my blood pressure!

Unfortunately I was stuck at work for the best part of the snow here. By the time I left it had turned mainly to sleet and rain. Now the place is a big mushy mess but it sure was pretty when it was fresh!

I think I've finally got this lens problem narrowed down now.

Wide open, the F4L does continue to appear a little soft against the kit lens, particularly noticeable in the centre. This seems pretty consistent across all the tests I did. However stopping down both lenses a bit (e.g. at F6.3), the F4L kicks the kit lens' proverbial:

F4L @ F6.3, 17mm, 1/100sec, 200 ISO, Mirror Lockup/Timer enabled:

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Those do look better and should but I like you would want better performance wide open too. Is the Lens new? If so maybe swap it out. If not maybe send it in to Canon.

I've read similar comparisons on the 17-40 f/4L wide open as yours. I guess myself should be lucky as I'm totally pleased with my copy and the 70-200 f/4L both wide open.

The Kit Lens gets a bad wrap sometimes but for what it is you'll be hard pressed to beat it for the price. I had a copy that was sharp but when taking the proverbial landscape photo with tree limbs against the sky > CA showed up <.

Well after much testing, the results are too consistent to deny that this 17-40mm F4L just isn't performing as well as it should. I would at least expect it to match my kit lens but the consistency of the performance gap between the two, particularly wide open, leaves too many questions about the performance of this copy of the 17-40mm.

I've just e-mailed the supplier to arrange to return the lens. Hopefully "take two" will be better! Thanks everybody for your input, help and thoughts. I'll update this thread with the results.

If you have to look as hard as I have had to, to those last test images to see a difference between a "kit" lens and an "L" lens, then that should make you think twice before spending $500.00 for the 17-40L.

Actually these tests confirm what I have said all along....
My 18-55mm "kit" lens ROCKS!!!!!

The results here dont tell us about a bad 17-40L.
They tell us about the the very good quality of the 18-55.

I bought the 17-40L about 4 months ago and have to admit that my 18-55mm is very close to the same (if not equal) in quality.
I think most people don't want to admit that they just spent $500.00 on a "L" lens and it isn't any sharper than the kit lens.

Tom

Hi Tom,

Well in my case, I can't even get the F4L to perform equally to the kit lens at f4!! As you know, I have to stop the lenses down until they start to look comparable. That, at least in my mind, is not right for any L lens. As several posters have commented previously, at F4, the F4L should definitely produce better (at the very least, equal) images to that of the kit lens.

I purchased the 17-40 F4L for a number of reasons, including improved CA, build quality and of course performance. However if I'm going to get sub-kit lens performance from this new lens, then it has clearly failed to meet at least one of the 3 criteria above.

I would happily keep the lens if I was getting equal centre-image performance, as the edge performance of the F4L will beat that of the kit lens as others have testified above.

I'm sending the lens back for replacement, not for a refund. I still believe in the 17-40mm F4L as a good lens, I just think I've got a bad copy. I'm actually starting to wonder if the success of this lens is it's downfall. Could it be it's now being produced in such large numbers, that has resulted in more bad copies are hitting the shelves than say when the lens was only out for a few months and demand was perhaps lower?

Had the same problem. Sent for repair, they lost it. Waiting for the cheque.

Like I say the centre MTFs are very close wide open.

Also having compared photodo mtf measurements against canon mtf (simulations) it looks like L zooms and short primes vary from the mtf chart by about +0.1 to -0.2 depending on location and direction, longer primes match more closly.

So what you seeing could be typical process variation.

Hi gcams and all

You are having the same problems I had with the 24-70 F2.8L. I returned 2 copies because the did not compare with an old 28-70mm 3.5, or indeed the (much maligned in this forum) 18-55mm kit lens. I found the kit lens - apart from lacking that desirable F4 aperture - to be as good as - in most respects -the 24-70 F4L considering bang for your buck, as our friends the other side of the pond might say. I took similar images of my bookcase and also outside where I had images to compare.

Fortunately the 24-105 F4L came along - the 24-105 F4L really is the sort of lens to keep on the camera most of the time. It really feels comfortable to handle. Pity about it being only F4 though.

I use the kit lens when I need a bit of a wide angle - it performs really well.

We ain't 'ad no snow down in Kent yet - but I am waiting.

Regards