3rd party Lenses - poor copies.

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chris-red

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Chris
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I'm considering buying a Sigma 17-50, I would prefer a Canon 17-55 but unfortunately cannot justify the extra cost.

I'm concerned about whether I will get a 'bad copy' I see this term bandied about a lot and just wondered what exactly this means and how to check for it?

The closest I got to a bad copy was actually a canon lens, I bought a 35mm f2, It really wasn't sharp and I was quite disappointed then I calibrated the focus using the adjustment on the camera and found it needed to be set to -17 on a scale of -20 to 20. However once this was done it was fine and I was happy with it. Since then I have had the focus system replaced due to accidental damage and I reset the focus adjustment and it seems good at 0.

So can anyone give me an example of a bad copy of a lens and what I should check to make sure I'm not stuck with one.

Cheers,
Chris
 
Trouble is both the lens and the camera are manufactured to a tolerance so the lens you are talking about may not have been a "bad" copy as such just at the extreme edge of tolerance, as perhaps is your camera body, so, combined they needed the large "correction". When the lens went in for repair it may have been at the other end of the tolerance level and combined with your camera meant no adjustment was required and therefore appeared to now be a "good" copy.
Back to the original question - a bad copy may just be at the wrong end of tolerance for your camera body to match up with and in some cases I guess 3rd party manufacturers may have wider tolerances so you cant tune-out the mis-match, you get a new copy which is at the other end and it appears you have a good copy, on another body it might be a bad one.
What to watch out for, is it sharp? Is it sharp across the frame corner to corner? Are you being fair based on price, you cant expect a £300 3rd party lens (or even a camera own-brand cheapo) perhaps to be as good as the camera manufacturer's top of the range £1100 lens or have as good build quality.
 
chris-red said:
I'm concerned about whether I will get a 'bad copy' I see this term bandied about a lot and just wondered what exactly this means and how to check for it?
Click to expand...

I did read that the 17-55mm is Canon's most unreliable lens but that doesn't seem to put people off and yet people worry about buying a Sigma or Tamron and some of these 3rd party lenses come with guarantees that put Canon to shame.

Personally I've never had a bad Sigma or Tamron and if I was in the market for a Canon 17-55mm I don't think I'd let internet panic put me off, just buy from a good reputable dealer and if you think you've got a duff get straight onto them.

Just shoot a few test shots at verious apertures and distance and look at them on your pc. If you're happy... you're happy :D
 
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I have the 2 lenses you are thinking of and extremely happy with both - and noticed that the Sigma suddenly dropped in price a couple of months ago (maybe a promotion by Sigma?) from circa £475 to £315 which makes it a real bargain with superb image quality and get the lens from a UK supplier -

- checking with your retailer that the lens has been imported by Sigma Imaging (UK) Ltd (see camerapricebuster for current prices) and you will enjoy after registering with Sigma, a 3 year warranty - in my opinion a no-brainer, go for it and enjoy. :)
 
agree with MatBin.
sharpness is dependent upon the camera and the body as a combined system.
it could be that your sigma lens is great but the camera is on the limited of QC tolerances.
It's all about price. personally with a 17-55 and 7D I'm sometimes disappointed with the sharpness. but then same system, it can blow me away.
Therefore I put the difference down to my camera technique and lighting (both of which are variable and can be improved! :))
 
Ok my tuppence worth, personally I think a lot of the hype is end user error too.
When I first got my sigma 150/500 I thought I had the so named bad copy, lent to a friend when we were out and wow, his results were amazing so I had to go back and rethink my techniques.
Now I have mastered it I am well pleased with the results I am getting
 
DizMatt said:
personally with a 17-55 and 7D I'm sometimes disappointed with the sharpness. but then same system, it can blow me away.
Therefore I put the difference down to my camera technique and lighting (both of which are variable and can be improved! :))
Click to expand...

+1 (but with my 450d and 17-55)
 
Cool cheers, basically what I thought. I'll think about placing an order!
 
here's an example of the 17-55 with good lighting.
1240_10151261315132993_10135274_n.jpg

if it shows up properly.
however, if you use f2.8 for groups when you shouldn't etc, then it's less forgiving and your shots won't be as good across the subjects.
Still I traded up from a tamron 17-50 non IS which was great for the money, but was slower to focus, noisier and sometimes missed critical shots.
however, that could be down to my perception of course!:shrug:

also they're much cheaper 2nd hand now, and there are always a few floating around from photographers moving to full frame, so they needn't break the bank
 
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