How to ensure a sharp copy of lens?

[eng01170]

I've read that even L lenses vary somewhat copy-to-copy. Is the only way to ensure a good copy to buy from somewhere with a very good returns policy and history, or is there a way to 'test in the shop'? For example, I could check the smoothness of operation (mechanical) but how would I ever detect optical problems other than cafefully taking some samples and then looking them 1:1 on a monitor?

Does anyone know which camera shops allow you to have a 1 to 1 exchange without making a fuss?

 

[ipin]

I've read that even L lenses vary somewhat copy-to-copy. Is the only way to ensure a good copy to buy from somewhere with a very good returns policy and history, or is there a way to 'test in the shop'? For example, I could check the smoothness of operation (mechanical) but how would I ever detect optical problems other than cafefully taking some samples and then looking them 1:1 on a monitor?

Does anyone know which camera shops allow you to have a 1 to 1 exchange without making a fuss?

I believe any of these shops listed below offer a 1 to 1 exchange within a week of purchase :

AP - Alan Photo, #01-38 Sim Lim Square, Tel: 6336 0922, e-mail: alanfoto@singnet.com.sg
AP-F - Alan Photo, #05-20 Funan Digitalife Mall, Tel: 6883 0922, e-mail: alanfoto@singnet.com.sg
CP - Cathay Photo, #01-11/14 Peninsula Plaza, Tel: 6337 4274, e-mail: email@cathayphoto.com.sg
CP-M - Cathay Photo, #02-215/216 Marina Square, 6 Raffles Boulevard, Tel: 6339 6188, e-mail: email@cathayphoto.com.sg
John - John 3:16, #05-46 Funan Digitalife Mall, Tel: 6337 2877 / 6337 1897, e-mail: richardgan@pacific.net.sg
Lord's - Lord's Camera, 304 Orchard Road #01-79 Lucky Plaza, Tel: 6235 4605, e-mail: lordscom@singnet.com.sg
MS - MS Colour, Block 711 Ang Mo Kio Avenue 8, #01-3501C, Tel: 6457 6380, e-mail: sales@mscolor.com.sg, web e-quote
TCW - The Camera Workshop, 3 Coleman Street, #01-31, Tel: 6336 1956 / 6336 7808, e-mail: tcwkshop@singnet.com.sg
TK - T K Foto Technic, 100 Beach Rd, #02-45 Shaw Towers, Tel: 6292 4533, e-mail: sales@tkfoto.com.sg

Taken from Nikon Price Guide (Singapore) 2005~2006 [/QUOTE]

As for testing for sharpness, you can bring a laptop to view the pic taken at the largest (smallest f/ stop number), f/8-10 and smallest (largest f/ stop number), nearest to farthest zoom range (that is if you are buying a zoom lens). Hope this helps.

 

[htthach]

remember to test back focus / front focus problems
I got this problem last time, luckily I got exchanged by manufacturer for new set (hence sadly, the warranty is filled haha)

 

[eng01170]

I always had the impression that shops only warrant a 1 to 1 exchange if there are manufacturer's defects or something like that. Has anyone tried exchanging lens, only to get any unpleasant experiences?

 

[Robbo73]

Focus test website here...

http://www.focustestchart.com/chart.html

Suggest you download the pdf file and print out the chart. I did it with my 24-70L to double check that some of my out of focus/less sharp results were down to me... they were, which is good..I think :cry:

 

[simon80]

bring a measuring tape and laptop to view

 

[Denosha]

You actually don't even need a laptop to see the difference (yes, it's that bad). Even on the tiny 1.8" screen on my 20D, it's possible to see the differences in focus/sharpness btw various copies of the same lens, once you zoom in of course. It has helped me to avoid 2 35L duds and 1 17-55 dud.

 

[Garion]

You actually don't even need a laptop to see the difference (yes, it's that bad). Even on the tiny 1.8" screen on my 20D, it's possible to see the differences in focus/sharpness btw various copies of the same lens, once you zoom in of course. It has helped me to avoid 2 35L duds and 1 17-55 dud.

Didn't know an expensive prime like 35L had duds too. :sweat: What kind of defect they had?

Anyone experience duds with long L telephoto primes yet? (ie. 300mm, 400mm, 500mm and up).

 

[Denosha]

Didn't know an expensive prime like 35L had duds too. :sweat: What kind of defect they had?

Yeah, that's what worries me... I posted about it on DPReview: http://forums.dpreview.com/forums/read.asp?forum=1029&message=15463972 and of course as usual there are people that just refuse to believe that their dear L lenses could be bad copies and would rather just blame the user.

Funny thing is that in another thread over at DPReview when i was talking about the bad copy of the EF-S 17-55mm, the weirdos there seem to think that's it's selfish for one to "cherry pick". Instead, they think that if the first lens you test happens to be a bad copy, you should still buy it and send it in for servicing instead of picking another copy and leaving the bad copy with the store. Their rationale is that some poor sod that doesn't test the lens before buying might end up with the bad copy you tested. Strange logic huh? So consumers are suddenly responsible for the lack of due-diligence on the part of others? :dunno:

 

[Garion]

Yeah, that's what worries me... I posted about it on DPReview: http://forums.dpreview.com/forums/read.asp?forum=1029&message=15463972 and of course as usual there are people that just refuse to believe that their dear L lenses could be bad copies and would rather just blame the user.

Read your thread. I believe its all down to luck lar..yes there are definitely a few bad copies out there but then your experience when buying the 35/1.4L is just almost unbelievable...2 straight lemons in a row..maybe the shop suay suay kena both also lemons.

I think the definition of how "sharp" a lens copy can be be is totally up to one's perception... most lenses, even high end ones like L series, are designed to perform within so called factory "tolerance" limits...so there may be some variance in sample copies, even for L primes...some may get average copies while some could get extremely sharp copies...I had a friend who had a 300mm f4 IS which was very very sharp, even when tried with 2x TC on...later he sold it and bought another copy which turn out not to be as sharp as the first one.

Then once in a while you can also get a true "lemon" lens...which at almost all f-stops would suffer from softness, CA, or all sorts of image artifacts.

So far for the L lens which I bought (both new/2nd hand), I am quite satisfied with the sharpness and overall performance...but it may be worthy to note that sometimes its not just an optical defect of the lens, poor image quality could be caused by focusing problems as well (e.g back/front focus), I sent two of my lens in for calibration after I was somwewhat disheartend by the less than sharp results and now they are working pretty fine.

Funny thing is that in another thread over at DPReview when i was talking about the bad copy of the EF-S 17-55mm, the weirdos there seem to think that's it's selfish for one to "cherry pick". Instead, they think that if the first lens you test happens to be a bad copy, you should still buy it and send it in for servicing instead of picking another copy and leaving the bad copy with the store. Their rationale is that some poor sod that doesn't test the lens before buying might end up with the bad copy you tested. Strange logic huh? So consumers are suddenly responsible for the lack of due-diligence on the part of others? :dunno:

Well this is entirely subjective I believe...the consumer still has a choice or decision to test out other lens at the shop if he or she is dissatisfied with the first copy. So why not? Since you have not really actually paid the dough yet...and customer satisfaction is paramount, especially when concerning such pricy items. You'll be surprised that many of these same peeps in DPreview would not hesitate to test multiple copies of the same lens when buying also.

I would say fortunately here at CS we have not reach that kind of level (yet), which is obsessing over 'pixel peeping'...I find it is detrimental to the hobby and one should be out just using the lens and enjoying what it has to offer instead of constantly obssesing over sharp copies and shooting endless test charts and brick walls. The best way to test a lens to your satisfaction is to actually use it in real life situations and then judge its performance from there, if not happy with the end results do a 1 for 1 exchange or send it for calibration or adjustment.

However if one were to buy from overseas (e.g B&H) and from your less than stellar impression, one would have 2nd thoughts about getting such items from overseas too, since we do not have any means at all to test it before buying.

 

[vince123123]

This situation is not confined only to Canon - even for Nikons, there are fanatic zealots who refuse to believe that there are quality control problems with the products made and try to blame the user.

Yeah, that's what worries me... I posted about it on DPReview: http://forums.dpreview.com/forums/read.asp?forum=1029&message=15463972 and of course as usual there are people that just refuse to believe that their dear L lenses could be bad copies and would rather just blame the user.