How to get / test a good copy of a L lens?

[Marsu42]

Thanks for the link! However, it basically says that you cannot check for overall sharpness

I don't think it says that at all.  You certainly can test a lens for overall sharpness, and several suggestions have been offered for doing so.

I didn't make myself clear on this, sorry: The article "How To Test a Lens" says what you just wrote: You can test for overall sharpness, but not for a "good copy" with just one lens to test.

However, on reflection I don't think this is entirely true (see my suggestion: compare the differences between two lenses you own (of which one has to be a good copy for the baseline) to the differences between the same lenses from the digital picture)

Having said all of that, there is a test you absolutely should perform, and one that will make a whole lot more difference than finding the sharpest copy of a lens.  Test the AF performance of your new lens. [...] Still, I've heard of people who send every lens they buy into Canon service, and some report the lenses are adjusted and come back sharper.

That's interesting, because the guy who sold my macro lens said just that - he had it adjusted by CPS, and it indeed is extremely good.

You don't seem to have first-hand experience, but maybe someone else can comment on this - what is Canon service actually able to do?

* AF adjustment (Do I have to turn in my non-afma body with my lens)?
* sharpness / ca-improvments?
* Do they do it for free on warranty / how bad does a problem have to be to make them do it for free?

[unfocused]

Maybe I'm missing something, but is all this agonizing really necessary?

If you buy a Canon lens with an in-country warranty and it turns out to have a problem, just send it back to Canon for repair/adjustment under warranty.

Are we talking about buying a lens and then not knowing if it is sharp or not? If you can't tell, then what's the issue? Are you interested in taking pictures or just owning a lens that meets some idealized standard for sharpness? I'm just not getting the point of this.

If your pictures are sharp, they are sharp. If they aren't, and after a few months of shooting you are convinced there is a problem with the lens, then send it in for repair. As long as you aren't buying grey market or used, what's the problem?

[Marsu42]

Maybe I'm missing something, but is all this agonizing really necessary?If you buy a Canon lens with an in-country warranty and it turns out to have a problem, just send it back to Canon for repair/adjustment under warranty.

Well, that's the point, isn't it? How do I know it turns out to have a problem - because it bursts into flames while shooting? Of course you could say "If I don't have a problem, there is no problem", but I'd rather adopt this stance with my mobile phone camera and not a 1k€+ lens. And I never wrote I have to have the sharpest lens on the block (cite me if I'm wrong), but I want to get around a bad copy.

If your pictures are sharp, they are sharp.

Maybe I'm a bit macro-lens infected, but either a hair is a line or a blur. If I find out after shooting 50k pictures that these blurs would have been hairs with a properly adjusted lens, it would be somewhat frustrating to me.

If they aren't, and after a few months of shooting you are convinced there is a problem with the lens, then send it in for repair. As long as you aren't buying grey market or used, what's the problem?

And how would you know the support doesn't just return the lens stating that to them, it seems to be well inside the qa specs? These guys don't work for free, after all, and have evaluate the possibility to get around a repair.

And most important: I'd rather return it right away if possible, the last time I had a lens repaired it nearly took three (3) weeks - which was exactly the period in which I'd needed it most. If you just grab another lens out of your stack, congratulations - but I am not able to do this.

[unfocused]

Well, I still don't get it. I guess it's just a difference in perspective. Not saying your wrong. It's your money and if this is really important to you, then by all means, go for it. You might as well get your money's worth out of something, before it all gets spent propping up the rest of Europe.

[Stu_bert]

Well, I still don't get it. I guess it's just a difference in perspective. Not saying your wrong. It's your money and if this is really important to you, then by all means, go for it. You might as well get your money's worth out of something, before it all gets spent propping up the rest of Europe.

Having bought a 100-400mm L as my "joint 1st" L lens for my canon and it being a "lemon" then I well sympathize with the OP wanting to ensure he gets a good copy. Back then, I was completely ignorant about differences between lenses, the chance of a poor copy etc, and only through research on various websites and forums did I start to learn there's a lot more to consider. But the bottom line for me, if you are paying for quality, you expect quality (within tolerances). I've had "that" lens in with Canon 3 times, always with the body I shoot it on, and frankly it's still soft as hell but it's so far out of warranty that it's basically not much better than a doorstop.

Point number 2, and this also goes back to my earliest dSLRs, but I remember comparing my 16-35mm to a friends 17-40mm and being disappointed at how his picture (same body) was sharper than mine. Yes, up to that point, I was happy. Then I found there was better. Granted it was a different lens, but if you don't know what "best" is and I would guess most people on here aren't involved in lens manufacturer or testing & therefore wouldn't, then it's not unreasonable to seek guidance on forums like this.

Finally, returning any lens under warranty is just a right pain in the butt, and costly for insurance, especially if you send back you body as well. In fact, I would have to arrange a special courier as returning just a single body & L lens exceeds most standard insurance. I'm just lucky to be an hours' drive from Canon CPS.

Marsu42 - would be interested on how you get on...

[ejenner]

I think this is what I would do:

1. If I don't have a suitable lens to lest against, buy 2 copies on credit, compare and return one.  You might even tell the retailer what you are going to do.  This assumes that you/they haven't got a defective 'batch'.
2. Test against a suitable lens you have or can borrow.  For instance if you have a lens with a FL of 50-100mm, decide how sharp is should be compared to that lens for you to be satisfied, then test.  Maybe it will be a good copy, but still not be what you were expecting?

I totally agree that it's hard to say whether a lens is 'sharp' without direct comparison, although with some experience you should be able to ascertain whether it is sharp enough for you.  But again it's too easy to be mislead without a direct comparison IMO.

Bad copies, however, will look obviously unsharp compared with something comparable, even if the FL is not quite the same.  Or they will have obvious sharpness variations across the frame (don't pixel-peep the corners at large apertures though - there will likely be some small variations).

I must admit though, for the first time ever I recently bought a second copy of  a lens (TS-E 17mm) because I was seeing some effects that I couldn't explain, nor find any info about.  Turned out to be exactly the same with the second lens, but hearing all these horror stories does make one a little nervous.

I also had an obvious with my 17-40 when I moved to FF which I never noticed on a crop soft on one side) and after spending $200 and sending it to the shop twice I would say it is 'acceptable', but not great. 

But I also now have enough lenses to test anything I'm going to get so see if it meets my expectations.

[JerryBruck]

Marsu42 asked,

...-what is Canon service actually able to do?
* AF adjustment (Do I have to turn in my non-afma body with my lens)?
* sharpness / ca-improvments?
* Do they do it for free on warranty / how bad does a problem have to be to make them do it for free?

I've wondered about that also -- since they took the trouble to remove afma from our 60Ds, can and will they correct a mismatch, and at what cost, post-warranty?

[tom_webster]

For me there are two ways of looking at these issues. The first is that if a lens seems sharp and produces nice pictures then it is ok, nothing more to worry about. The second is that if you are spending a lot of money on purchasing expensive Canon L glass then you should expect it to perform as well as it should and that sample variation should be minimal to the point of being irrelevant.

Half the issue these days I suspect is the fact that it is so easy to pixel-peep and there are also so many internet forums which allow people to rave about the sharpness of their copies or to warn about issues that they have experienced, this then leads you to doubt the quality of the lenses that you have or possibly to expect too much.

I have just been through this process myself. I have a Canon 35L and had a 100L macro on my 5D2. Both performed flawlessly in my opinion and produce images a sharp as I would ever have expected.  I then traded by 100L for a new 135L as I though this would be more use to me.

The 135 is great but its sharpness doesn't blow me away in the same way as the 100L did and the 35L still does. I have micro-adjusted it by +8 and this helps but though it still produces great/good images I didn't feel that it lives up to the 'sharpest lens ever', 'truely wonderful' comments that I read so much before purchasing.

Granted I am comparing it to a macro lens known for sharpness and the 35L which is also very highly rated but something still doesn't sit quite right when I have spend many hundreds of Pounds on the lens.

End result, the lens has been sent in under warranty for calibration (to my camera body which has previously been checked calibrated by Canon) so I am hoping that it comes back working better. If it does not then I hope I shall rest happy knowing that it is at least as good as Canon think it should be.

For me then I guess the question is whether when buying L glass you should almost by default send the lens in for checking/ calibration. This seems ridiculous but without doing so I don't really see how you can know whether the lens is working as well as it should. It may work great but could it work better?

If you spend as much as these lenses cost then I would expect it to work as well as possible. For me, and most others I suspect, I have no practical way of comparing my 135L against other copies on my camera body or against the same or other copies on different bodies. You therefore either accept it as it is or have it tested by the experts.

[Marsu42]

Marsu42 - would be interested on how you get on...

I've written about my test and experience with the lens here http://www.canonrumors.com/forum/index.php/topic,3359.60.html at page 5

[drmikeinpdx]

I've spent way too much time testing lenses and sending them in for adjustment.  It is the autofocus system that causes most of the problems, but poor assembly of lens elements seems to occur occasionally.  The unreliable performance of the current autofocus system (both lens and camera functions) is a real problem for serious photographers.

I don't know of an easy and practical way to determine the inherent sharpness of a particular lens, other than shooting lots of photos under good conditions (tripod, etc...)  and pixel peeping.

I have developed a quick autofocus test that works for me.  I can describe it if anyone wants to know more.

If a lens focuses well with my camera body, then I try to evaluate the sharpness.  Some lenses are sharper than others.  The vast majority of photography that I do involves people, not landscapes, and the photos are almost all posted on the web, not made into prints.  I really don't need lenses that are as crisp as breadsticks and images that hurt the eyes with razor sharp details. 

I may lust in my heart for a lens that blows me away with sharpness on every shot, but in reality it is not worth chasing.  The people who view my photos would not recognize it anyway.

Just my opinion!

Mike in Portland, OR

[Marsu42]

I have developed a quick autofocus test that works for me.  I can describe it if anyone wants to know more.

Please do :-)

I may lust in my heart for a lens that blows me away with sharpness on every shot, but in reality it is not worth chasing.  The people who view my photos would not recognize it anyway.

That's the difference - the only one who views my photos is me :-) ... I am macro-infected and am using it as a microscope with 18MP camera behind it. However, even with a tele lens I would like to see detail at 100% that I wasn't able to see with my bare eyes if possible - that's mostly why I want to get a L lens, not because of any 2.8 aperture or quick af (although a precise af does help getting sharp pictures, just as you wrote).

[Stu_bert]

Marsu42 asked,

...-what is Canon service actually able to do?
* AF adjustment (Do I have to turn in my non-afma body with my lens)?
* sharpness / ca-improvments?
* Do they do it for free on warranty / how bad does a problem have to be to make them do it for free?

I've wondered about that also -- since they took the trouble to remove afma from our 60Ds, can and will they correct a mismatch, and at what cost, post-warranty?

In the UK, when I have my lenses adjusted to the body (started when I had the 5D), Canon do adjustments in the lab which stores it separate to the AFMA data. The technician I spoke to claimed it is more accurate. I can't speak for the lens adjustments as frankly I've only ever asked on one, and it was still rubbish after :-)

[StevenBrianSamuels]

I use to test all my lenses for a few days after buying until I noticed how much I agonized over it and decide to just go out and shoot.  Made life a bit simpler.

[EOBeav]

I know of a couple of landscape pros who 'only' have the 70-200mm f/4 L, non-IS.  I shoot with it, and it's one of my favorite lenses.  My experience on an XSi is that if you're shooting indoor sports or something similar, you'll have a tough time raising the ISO enough to get a decently sharp image. On a tripod, though, that's a whole different story. Some of my best shots have come from this lens, and I'm always amazed at the amount of detail I get with it. If you get it, you won't be sorry.  And you don't have to apologize for having it instead of the f/2.8 IS.  Just sayin'.