Testing new lenses when buying from shops

[lexxmexx]

Ok, I have read from many horrifying reviews that many lenses (cheap and expensive) have some defects that need calibration after buying them, eg focus shifts, AF inconsistencies, severe CA, lens mis-alignments etc. Sounds like it is a must to test the lenses thoroughly with those testing charts which is so troublesome. This is really scary that spending hundreds to thousands of dollars can bring more nightmares than having the simple enjoyment of photography.

Are the manufacturers' QC really so bad? I am wondering if this problem is really exagerrated by the internet users where only those people who have experienced lens problems cared to post their comments while the majority of those with the good lens just keep quiet about it.

Do you guys experience QC issues when buying lenses?
Do the shops (eg. at Funan) let people test the lenses using those charts, like the ruler test?

Or can you share your buying experiences?

I hope that such paranoia and kiasu-ness are just probably the result of over-reading from the internet.

 

[gundamseed84]

I think if you are seriously going to buy the lenses if there are no problems most would let you try. For ruler test, just bring your own ruler, shouldn't be too much of a problem. Alternative you can do 'on the field' test shots around the shop, instead of the 'lab-type' of testing using charts.

Canon, Nikon, Pentax, QC should be good, so far no problems. Usually it is the Sigma, Tamron brands that you might want to do more testing. Again, some issues might be due to incompatibility of your body to the lens, as calibration is done specific to your body. Use on another body and another issue might arise.

Bought Sigma from a CS-er doing parallel import, no issues so far as he did some testing for me. I think regardless of what lenses you are buying just do a test. However it might not be nice to spend the whole day testing at the shop and worse if you are not buying.

 

[rhino123]

Basically, look at how many lenses are being sold per days and the complaints in the internet... it was like - 0.X% defective rate. To me, that is pretty good. Even Apple Iphone faces their fare shares of defective units - something like battery burn or blow up... but that was 1 in a few millions sets sold.

Anyway, it is consumer's responsibility to test the product up (don't care if it is lenses or camera body or other accessories) before buying. Of course like what gundamseed had pointed out, simple test like ruler test can be done, don't need the test chart. Even if without ruler, then use the wordings on the boxes in the shops as gauge for you to test the focus accuracy.

But do note that the Live View of your camera can only show so much... so it can only be taken as an indicative of the quality of the lens you are going to buy. Most mid to high end DSLR nowaday came with focus micro adjustment and so accuracy could be calibrated by oneself too.

I mean... don't worry, get the lens you want, test it properly then play with it. Worst come to worst, go down to the service center and had your lens calibrated.

 

[lexxmexx]

My cam does not have AF microadjustment. One of the lens I will be getting is a Tamron, so I guess I will have to spend more time testing it. Thanks for the assurance guys

 

[Octarine]

Ok, I have read from many horrifying reviews that many lenses (cheap and expensive) have some defects that need calibration after buying them, eg focus shifts, AF inconsistencies, severe CA, lens mis-alignments etc. Sounds like it is a must to test the lenses thoroughly with those testing charts which is so troublesome. This is really scary that spending hundreds to thousands of dollars can bring more nightmares than having the simple enjoyment of photography.

I think you mix up issues caused by lens design and those issues where the cause is somewhere between lens and body.
Focus shifts and CA are something in the lens design and you can read reviews about expensive lenses to find focus shift issues. Focus calibration is not an error as long as the focus is spot on within a certain tolerance (which is pretty usual). But: since all lenses have their tolerances and all bodies have it as well it can be either more pronounced or less, or even be zero. If it gets too pronounced then ask the service center for the lens to adjust accordingly.
And one thing to note: people tend to complain about things they perceive as bad. How many people report every week that their lens is perfectly spot on when focusing? How many people report that during last month there was no issue with the USM focus system? And so on ... It helps to read several reviews where it is obvious that they do their own analysis. It's a known fact that reviews get sold and one can find the same words sooner or later on many cheap websites.

 

[lexxmexx]

You could be right on this. With so many people complaining that certain lens cannot AF accurately and have front/back focusing problems, I am wondering if the problem is really exagerrated by unrealistic expectations.

I am intending to buy the Tamron 17-55mm f2.8 and had read that many copies of it have the above mentioned problem and had to recalibrate to improve it. The thing is that, they merely state the focusing problem without elaborating on how bad it is or is it within the DOF.

 

[Octarine]

Another link worth reading: http://www.lensrentals.com/blog/2008/12/this-lens-is-soft-and-other-myths
Especially if your body comes with AF micro adjustments there's little to worry, unless the focus issue is beyond the correctable range. I have an earlier version of the Tamron 17-50 and it works fine.
Also worth noting is the special field curvature of this lens, which might give the wrong impression when looking at the images. http://www.photozone.de/canon-eos/2...pherical-if-canon-test-report--review?start=1

 

[SnagIt]

I think the problem is overrated. There are problem units but I don't think the rate is as high as what the internet has been complaining. Go try for yourself. When the image not sharp, it could be due to user errors (misfocus, handshake, focus shift ...etc). Don't fear third-party lens, they actually made some excellent lens.