TC3
07-05-11, 07:53 AM
lots of new dslr owners on here. sooner or later they will aquire a new lens and i am suggesting to make sure it is not a dud. for example i got a nikon 16-85vr 2 weeks ago. at 85mm the lens was back focusing. this means it was not focusing at the point i chose it to but a few inches behind. this was the case for an item about a meter away. when focusing on a distant subject it was even worse. look at these extreme crops and you will see the difference between my 1st copy of the lens and the 3rd copy. both taken on a tripod with aperture at f5.6
http://tc3.smugmug.com/photos/i-XkDVQLh/0/L/i-XkDVQLh-L.jpg
http://tc3.smugmug.com/photos/i-2BcbDsL/0/L/i-2BcbDsL-L.jpg
i went back to the shop and swapped it for another lens. the 2nd copy of this lens i had had very poor image quality in the bottom right of the image. many lenses have soft corners especially if used at the largest aperture which in this case was f3.5. however the corners should be fairly similar and no one drastically worse than the other corners. these images show extreme crops of the bottom right corner of the 2nd and 3rd lens.
http://tc3.smugmug.com/Other/Bedroom/i-MR6tq5J/0/L/tc3_0428-L.jpg
http://tc3.smugmug.com/Other/Bedroom/i-kHv4SRT/0/L/tc3_0465-L.jpg
these are all extreme crops like i said just to show what can be wrong at times. sometimes these problems will go unnoticed especially to the untrained eye and may only be picked up on later when it is too late to exchange.
i just thought this info may help some dslr newbie. i have never had to exchange any nikon gear up to now and just got unlucky with that lens but now i have a perfect copy of it. in the past i had to return a tokina 11-16, tamron 17-50, sigma 70-300 and sigma 17-70 all for one or both of these faults. however in the past 6 years i must have bought over 25 lenses so for me it has been 1 in 6 that have been at fault.
sorry to bore those of you who are already in the know :)
http://tc3.smugmug.com/photos/i-XkDVQLh/0/L/i-XkDVQLh-L.jpg
http://tc3.smugmug.com/photos/i-2BcbDsL/0/L/i-2BcbDsL-L.jpg
i went back to the shop and swapped it for another lens. the 2nd copy of this lens i had had very poor image quality in the bottom right of the image. many lenses have soft corners especially if used at the largest aperture which in this case was f3.5. however the corners should be fairly similar and no one drastically worse than the other corners. these images show extreme crops of the bottom right corner of the 2nd and 3rd lens.
http://tc3.smugmug.com/Other/Bedroom/i-MR6tq5J/0/L/tc3_0428-L.jpg
http://tc3.smugmug.com/Other/Bedroom/i-kHv4SRT/0/L/tc3_0465-L.jpg
these are all extreme crops like i said just to show what can be wrong at times. sometimes these problems will go unnoticed especially to the untrained eye and may only be picked up on later when it is too late to exchange.
i just thought this info may help some dslr newbie. i have never had to exchange any nikon gear up to now and just got unlucky with that lens but now i have a perfect copy of it. in the past i had to return a tokina 11-16, tamron 17-50, sigma 70-300 and sigma 17-70 all for one or both of these faults. however in the past 6 years i must have bought over 25 lenses so for me it has been 1 in 6 that have been at fault.
sorry to bore those of you who are already in the know :)