Teggy02

I think this is a bad copy. I bought a Tamron 17-50 2.8 from a photographer the other day. I've never purchased a third party lens... and I think I've already learned my lesson. The lens had no fungus, scratches or anything. I took a few test shots, it looked fine... I was wrong.

I uploaded images and was just super disappointed. I went to the park during daylight today to confirm my beliefs. These are all terrible pictures, don't judge me on composition. I was really just trying to see if the autofocus is off. I think it is. Give me you .02. FML.

All of these pictures are about 60% crop of original... and I had to shrink them to fit them on the page.


I feel as if anything shot at any focal length at any speed within 5 feet is always sharp. I took this of myself outside. NX tells me the center focus is my right eye... looks good to me.



This little guy was maybe 6 feet from me. NX tells me my focus point is bottom of his nose and a little bit of his legs.

50mm 1/400th f/5.6

His tail looks sharper to me...


This next guy was maybe 8 feet away from me. NX tells me my center focus is his chest and maybe a little bit of the actual tree.

50mm 1/200th f/2.8

Serious back focusing issues...

sfr002

Looks like a back focusing issue. Sorry bro!

Jake2k

Damn that stinks man, I think my 18-105 has a slight back focus issue too so your not alone haha

Mama Got Boost??

My Sigma 17-50 was the same way. Drove me friggin' batty! Sorry

Teggy02

it seems really hit or miss the more i test the lens.

i guess that's what happens when you buy third party... you can't shop at Payless and call the shoes Nikes, right?

Jake2k

Yea as a rule I always tell myself that I will never buy anything but Nikkor or Sigma. How much did you save buying it locally instead of new or refurb, if you don't mind me asking.

Teggy02

I got it for $350 and it was basically brand new. The guy owns a photography business and he claims that the only shots this particular lens was used for was to test it out before he purchased a bunch of them for his photographers.

The more I test the lens, the more I'm realizing that the back focusing issue usually occurs when my subject is particularly small, active, and further away. I would never dream of doing action shots at this focal point and I'm not big into nature photographer at all. I really just need to try the lens out at an event and see how it works for me.

Teggy02

I kinda clump Sigma into the same category as Tamron and Tokina... You really take a gamble when you buy any third party lenses. Some copies are so clean that you could almost compare them to Nikon and Canon lenses. Others... well, you're seeing first hand the problems that could sometimes occur.

Quality control is usually an issue with these lenses.

.:Chris:.

Call them and see if they will recalibrate it for you. Also backfocus issues can be caused by abuse - ie. dropping. No way to tell whether it was manufacturing or abuse.

Try a backfocus test and see how much it's off.