How to assure oneself of a good copy of a lens?


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Canonized

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I have discovered that consistency is not guranteed for many lenses and even for Canon. So getting a good "copy" is key to make sure one does not get upset or fed up with the new lens.

I would like to know if any one has a sure fire (or at the very least some degree of success) way to get a good piece. What tests do you take? Do you ask for more than one copy to test? How many to ask for to test? Which dealer is the most helpful in this process?

Do you know of retailers that allows buyers to change lenses or which retailer refuses to do so? (I note in the US several retailers allow exchanges)

Looking forward to hear from forummers :)
 

fWord

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When I previously purchased a 70-200mm f/4 from CP, which has occasionally been faulted for back-focus issues, I was aware of the risk, so I actually got the salesperson to agree that I can return it in the event that it's unsound. And she said that, sure, I could do that, provided that I return the lens in good condition.

But to add to your question:

How do we know that a copy we buy second-hand (eg. from someone here at CS), is indeed a good copy? We can't possibly shoot charts and brick walls on the spot.
 

adamadam

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n0d3 said something in the chatroom...

I think this translates to some like:
buy with the condition of exchange, then test
but in the end, the composition of the photograph makes a larger impact than the sharpness of the photograph.
 

n0d3

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oi. mai saboh leh.
 

fWord

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n0d3 said:
oi. mai saboh leh.
:bsmilie: Well, it was good advice!

But most people will prefer to know that they're getting exactly what they paid for. Especially when it comes to L lenses when things go in the order of thousands, I want to ensure that I don't buy a lemon.
 

LensView

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Basically, there is no way of ensuring. Unless the lens is each made by hand then the QC is there if not than its just about luck. But I mean how much can you worry about an L lens. Canon service is good. I once had a problem with my lens, sent it back to the shop and they referred me to Canon. Got it changed. I had a speck of dust between the elements. So its really your faith in Canon. Afterall, you are in the Canon forum.
 

Ris Goh

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MScolor do allow exchange (same item) within 7days if its a lemon....... at least that's what they always tells me ;)
 

light

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It really depend how much you trust Canon's service and quality.
I don't really like to buy from shops which allow people to test, play and choose the lens. Cause when I wanna buy the lens, I would think that the copy i am buying may be 'touched' by many window shoppers already.
 

solarii

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I subscribe to the policy "What you don't know won't hurt you..."

I mean, if the fault is not obvious on the onset then it probably isn't serious enough to warrant your frustration. Ok, some people will say that they pay top dollar and they want to get the best out of their equipment... anything less is getting short-changed.

But I feel its pointless to spend hours shooting chart after chart, then peering at magnified shots on screen to spot some minor calibration defects. If the problem isn't obvious to the naked eye in your shots, then I won't bother. Of course if your lens can't focus correctly its pretty serious and warrants your concern. Else just shoot.
 

ykia

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Bring the Canon body with you.

Politely tell the sales person that are seriously considering a purchase and that you would like to test it before you buy.

Mount the potential lens/lenses on the cam, open it to the widest and auto focus cosistantly on the same subject with good details (eg. calculator/telephone key pad) in the shop. Fire off 3~5 shots and repeat for 1 or 2 more lenses of the same kind. Note the serial number of the lens/lenses against the frame numbers taken.

If you have a laptop, upload the frames and do a quick eyeball of the sharpness. If you don't, let the sales person know before hand you need to check the sharpness of the photos and if they could let you have access to their PC, otherwise let them know you have to come back the next day.

Of course you need to balance this against the price of the lens/lenses -- i.e. I would seriously reconsider doing this if the lens costs under $500, unless the sales person doesn't mind.

If one shop doesn't allow it, there's always others you can go to, but the trade off for pre-checking the sharpness is that you may not get it at the lowest possible price, and you'll need to put in the time.
 

user111

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bring card reader, laptop and test chart to the shop
 

Canonized

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ykia said:
Bring the Canon body with you.

Politely tell the sales person that are seriously considering a purchase and that you would like to test it before you buy.

Mount the potential lens/lenses on the cam, open it to the widest and auto focus cosistantly on the same subject with good details (eg. calculator/telephone key pad) in the shop. Fire off 3~5 shots and repeat for 1 or 2 more lenses of the same kind. Note the serial number of the lens/lenses against the frame numbers taken.

If you have a laptop, upload the frames and do a quick eyeball of the sharpness. If you don't, let the sales person know before hand you need to check the sharpness of the photos and if they could let you have access to their PC, otherwise let them know you have to come back the next day.

Of course you need to balance this against the price of the lens/lenses -- i.e. I would seriously reconsider doing this if the lens costs under $500, unless the sales person doesn't mind.

If one shop doesn't allow it, there's always others you can go to, but the trade off for pre-checking the sharpness is that you may not get it at the lowest possible price, and you'll need to put in the time.
EXCELLENT ADVICE!
Will remember to do precisely this. I would add only - to shoot the photos with a scrap of paper with the serial number on it and put it in the photo as you shoot - that way it is easier to find out which is which.

Thanks again.

Still hoping to hear how others do it! :)
 

ykia

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Thanks Canonized! Good idea to shoot the serial no written down!


Canonized said:
EXCELLENT ADVICE!
Will remember to do precisely this. I would add only - to shoot the photos with a scrap of paper with the serial number on it and put it in the photo as you shoot - that way it is easier to find out which is which.

Thanks again.

Still hoping to hear how others do it! :)
 

plato

New Member
There isn't a sure-fire way. What I do is to bring my camera body along and shoot something with detail on it so you can see where the focus point is. Since it boils down to how closely calibrated the lens and your camera body are, you should use your own camera body for testing. And if after you buy the lens and find it's not as sharp as you think it should be, then you can always get Canon to calibrate your body and lens. I doubt the shops would let you exchange unless the lens is damaged or spoilt, but if you have a good relationship with them, who knows?
 

ibs

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plato said:
There isn't a sure-fire way. What I do is to bring my camera body along and shoot something with detail on it so you can see where the focus point is. Since it boils down to how closely calibrated the lens and your camera body are, you should use your own camera body for testing. And if after you buy the lens and find it's not as sharp as you think it should be, then you can always get Canon to calibrate your body and lens. I doubt the shops would let you exchange unless the lens is damaged or spoilt, but if you have a good relationship with them, who knows?

How much do they charge for calibration? I might consider sending one in because there's always something wrong with my photos.. i know its because of my lack of skills.. but i just want to be sure. :bsmilie:
 

freelancer

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I always buy from one particular large photo store and the arrangement is to take the lens home after paying for it and take up to a week to run some tests myself. Usually this means shooting "regular" images and some shots on a lens focus test chart. So far I have yet to return a lens with the exception of the 50/1.8 (which is marginally not as good as my other lenses using the lens focus test chart although with "regular" images it looks fine. Apparently this is a common issue with most of the 50/1.8).

When I have time I also test the lens using a camera from the shop with the lens focus test chart. This helps me to confirm that my camera bodies are all accurate when it comes to focus. The assumption here is that if a lens is accurate with the shop's camera and shows the same results with my own camera, it is quite logical that the lens and the 2 camera bodies are all having the same accurate focus.

Hopes this helps.
 

JediForce4ever

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I would test a few good copies of that particular lens(shops, friends, etc)....
The go test the potential new lens...if image quality is about the same, I would make the purchase.
 

freelancer

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JediForce4ever said:
I would test a few good copies of that particular lens(shops, friends, etc)....
The go test the potential new lens...if image quality is about the same, I would make the purchase.
From my experiences its not necessary as there are plenty of "good copy" images out there that you can look at. Most of the time it has to do with how sharp the focus is with the lens wide open and stopped down one aperture. The first and foremost thing is to make sure your camera body is not front or back focusing coz if it is, you are going to buy a "good copy" which in reality needs adjustment.
 

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