How common are 'duff' lenses?


Link Posted 12/04/2011 - 18:44
Every so often in posts you see references to bad copies of lenses (i.e. "A terrific lens if you get a good one..." or "I wasn't impressed with the lens, but maybe I just had a poor copy")

So just how often do you get 'bad' copies of lenses? Just how reliable is the QC??

I'm planning/hoping to slowly get more lenses, particularly DA Ltds, but given the costs wondered what the risks of getting a dodgy copy are (if there are any)? Might influence whether I go second hand or stick to new and warranted...

Thanks for any thoughts


Some of my vaguely better stuff


Link Posted 12/04/2011 - 19:06
Poor lenses are actually quite a low percentage, but what that percentage may be I doubt that anyone knows. In 40 years of buying lenses I haven't had a duff one yet.

New is better because you don't know how the lenses have been treated, how vigorously they have been cleaned or how often they have been dropped.
Best regards, John


Link Posted 12/04/2011 - 19:27
I'd be inclined to go via a recognised dealer if buying an expensive lens used. That way you should be able to give the lens a quick test before handing over the cash, and you're likely to get some sort of warranty.

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.


Link Posted 12/04/2011 - 21:16
Interesting speculation....I have both Mk1 and Mk2 versions of the 18-55 kit lens and rate them quite highly, my 16-45 a good lens but really not much better than the kit lenses. My 55-300 is undeniably a great lens, however I am quite unable to obtain the sharpness I expected from my Sigma 105 when used as a 1:1 macro - but it is rather good when used as a prime!

Perhaps I expect too much? Or perhaps new lenses DO vary, all but my two 18-55s are brand new...I do judge lenses mainly by their sharpness - during my time as an I&T photographer definition was king


Link Posted 12/04/2011 - 21:25
Lenses have different characters and some will appeal more than others. Sharpness is one factor, but that is very often related to contrast and the way that deceives the eye. Resolution is a different quality. Then there's differences in gradation. Even now, with computer design, different lenses do have different uses.

The classic example is after the Korean war, when Nikon cameras and lenses started finding their way to photojournalists. They had high contrast and very high sharpness, but actually lower resolution than the previously used German lenses.

A new taste for contast and sharpness soon evolved and swept photography.
Best regards, John


Link Posted 12/04/2011 - 22:24
I definitely think digital photography has changed things in this respect. Most people didn't bother having their film photos enlarged beyond the standard snapshot prints, so all those cheap 3rd party zooms didn't look too bad. With digital you can crop and enlarge an image to your heart's content, so any deficiencies in lens sharpness will be highlighted mercilessly.

I know I now find myself cursing the printer for its inability to match the sharpness of the images on my computer screen!

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.


Link Posted 13/04/2011 - 10:09
Duff lenses are not at all common.

Do not believe even a fraction of what the internet whingers say. Most so called faulty lenses are simply not being used correctly by the users.

Every mass produced item has a 'failure' rate but with good manufacturers and good QC on production lines the rate is very, very low.


Link Posted 13/04/2011 - 11:32
You guys are mind readers. Just today I was pondering how it would be possible for a lens to be a "bad copy", as so often referred to on the American equivalent of this site. With modern production methods, how can a lens of obviously inferior quality pass any quality control test? I reckon bretbysteve has worked it out. Operator error.
Pentax K7, Sigma 17-70 f2.8-4.5, Sigma 70-200 f2.8 APO EX, Sigma 70-300 APO, Sigma 1.4x TC, Vivitar 2x TC. Takumar 135mm f2.5, SMC Pentax A 50mm 1:1.7, SMC Pentax -M 1:4 200mm, Pentax X70


Link Posted 13/04/2011 - 13:19
Most so called faulty lenses are simply not being used correctly by the users.

I'd second this, I've tried a range of lenses in the couple of years I've used a DSLR and have found that some are much harder to get good results with than others.

One I have found particularly challenging is the Jupiter 9, of which my copy is a pain to focus. When I get it right, it is capable of producing very sharp images, but I get more misses than hits.

The only 'bad' lenses I've come across have been inherently poor designs (an early Sigma 80-200 zoom lens is probably the worst I have owned), I don't think I've ever come across a bad copy of a well regarded lens.

Whether anyone has ever had a really bad copy of a Pentax Limited lens is an interesting question, I'm not sure I've ever heard/read about it.


Link Posted 13/04/2011 - 14:22
Poor lenses are rather unusual. Poor photographers are more common. Some more or less experienced photographers will state that a lens is poor because they have focusing problems (camera body or photographer error) or there is some movement blur (too slow a shutter speed or poor camera handling).

Lens manufacturers go to great length to make sure their lens designs are acceptable for most photographers. And they go to greater trouble to make sure their top of the line lenses will perform better than average.
Yves (another one of those crazy Canucks)


Link Posted 13/04/2011 - 14:25
Dangermouse wrote:
I know I now find myself cursing the printer for its inability to match the sharpness of the images on my computer screen!

Strange. Most printers are way sharper than computer screens. May be you got a duff!
Yves (another one of those crazy Canucks)


Link Posted 13/04/2011 - 14:57
All images being printed need sharpening, so perhaps in the case above they need more sharpening than is being given.
Best regards, John


Link Posted 13/04/2011 - 14:58
Id say duffs are few, but Ive had a lot (Tammy & Sigma) that have all gone back.

I think any AF lens should be tested as soon as you get it to look for obvious problems, and if any are found it should be swapped for a new one (not repaired).

If you stick to that, you will always get good copies, though it may take you a while, its worth it in the end.
Pentax hybrid user - Digital K3 & K200D, film 645 and 35mm SLR and Pentax (&other) lenses adapted to Fuji X digital
Fan of DA limited and old manual lenses


Link Posted 13/04/2011 - 14:58
Shifted quite a lot of lenses through my hands but never really encountered a 'duff' lens. Sure not all of them were top quality when it comes to sharpness or other IQ-factors but considering the amount of new lenses I have had I think it's not that common to encounter a misaligned lens. I test these lenses for sharpness in a controlled enviroment (tripod, indoors, static subject) and if they are not up to par it's more a due to the maximal optical quality of the itself not because the lens is bad.


Link Posted 13/04/2011 - 15:04
I've had a Sigma lens (second hand) that I'm convinced is a poor lens - Possibly due to a knock in it's earlier life, but there's no evidence of one - When I got it it filled the gap in my AF range between the DA18-55 and the F100-300 both of which give great results (unless I mess up).

The sigma really struggled to find a focus outside on a reasonably bright day, and has never given anything remotely as good as either of the others. Even my various MF supertelephoto/mirror lenses produce better images.

I've since got a DA50-200 to replace it which works fine, I don't know what I've done with the sigma but I wouldn't be happy selling it to some other poor fool.

Having seen numerous examples from the Bigma I know sigma can make excellent lenses, but it's left me somewhat wary of them.

Among my other lenses are some that have clearly been abused, but still produce quite reasonable images. I found a link today that gives an idea of just how badly a lens can be damaged & still give fairly reasonable results:
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.

.[size=11:].Flickr WPF Panoramio
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