Tamron 11-18, bad copy? - DPChallenge Forums

Sony DT 18-70mm f/3.5-5.6 Aspherical ED Zoom Lens for Sony Alpha

02/10/2006 06:03:38 PM · #1

I bought this lens on e-bay, got it for 100 pounds cheaper than the cheapest online retailer with still 10 months warranty on it. the seller sold it because (he says) he bought a 5D and it won't work on it. Fine. But I've just noticed that it's very soft in the corners. I did a test, taking pics of my notice board at various apertures and focal lengths with tripod and remote and well, I'm not happy. Take a look:

resized original:

100% crop of centre:

100% crop of top left corner:

what do you think?!

kiwinick

Sony DSLR-A550

02/10/2006 06:13:27 PM · #2

buyer beware? can you return it?

yido

Canon EOS-5D

Sigma 20mm f/1.8 EX Aspherical DG DF RF for Canon

02/10/2006 06:16:21 PM · #3

a bit soft on the corner but all ultrawides suffer from softness in the corner. Couldn't tell if it's a good or a bad copy though

Nikon AF Zoom-Nikkor 28-105mm f/3.5-4.5D

02/10/2006 06:21:24 PM · #4

Originally posted by yido:

a bit soft on the corner but all ultrawides suffer from softness in the corner. Couldn't tell if it's a good or a bad copy though

So that's an acceptable level of softness? Sorry, but this is my first "real" lens(I mean expensive) so I'm in unchartered territory here but I really thought it wouldn't be that bad. I mean even at 18mm it's soft in the corner, worse than the kit lens!

msieglerfr

Nikon D200

02/10/2006 06:22:19 PM · #5

At which aperture did you take this picture?

Sigma 20mm f/1.8 EX Aspherical DG DF RF for Canon

02/10/2006 06:24:18 PM · #6

Originally posted by msieglerfr:

At which aperture did you take this picture?

wide open, 4.5 . it gets a bit better at f8 and f11 but not much

yido

Canon EOS-5D

02/10/2006 06:31:57 PM · #7

The test shot was taken at f11, which causes softness. It would have been better at a lower aperature.
This nice review of the Tammy has 100% crops from center and corner at various ranges. I'd say use a lower f stop and see if it get sharper. If so, then I think it's ok.
//bobatkins.photo.net/photography/reviews/tamron_11_18_review_0.html

Here's on of Tokina
//photo.net/equipment/tokina/12-24-f4//

And one of Canon
//bobatkins.photo.net/photography/reviews/ef-s_10-22_review.html

They all soften up, especially at the corners wide open and past f8 in my view. I think we should all take pixel peeping with a grain of salt, there are few if any lenses that have "tack sharp" center and corner at every aperature and at every focal length.

Message edited by author 2006-02-10 18:37:11.

02/10/2006 06:40:27 PM · #8

Originally posted by yido:

thanks for your help, much appreciated! I've checked the bob atkins site before but I think his sample shots show nowhere near as much softness at mine... The shots I posted where at 4.5 but it doesn't get much better at 5.6.

Azrifel

Fujifilm X100VI

02/10/2006 06:56:25 PM · #9

Shot wide open at 11mm I'd expect that from a Tamron. Corner softness and considerable vignetting. Is it still like this stopped down a stop or 2?

02/10/2006 07:01:43 PM · #10

Originally posted by Azrifel:

Shot wide open at 11mm I'd expect that from a Tamron. Corner softness and considerable vignetting. Is it still like this stopped down a stop or 2?

well, that's what it looks like at f8:

Is that expected then? I thought the canon 10-22 or the sigma (which is cheaper than the tamron) would deliver better results...

Sigma 20mm f/1.8 EX Aspherical DG DF RF for Canon

02/10/2006 07:51:03 PM · #11

So... Is my lens performing normal and I'm just expecting too much or is it softer than the other super wides for 1.6x sensors?
Please advise!

Message edited by author 2006-02-10 19:55:11.

Azrifel

Fujifilm X100VI

02/10/2006 08:09:19 PM · #12

I'm not too familiar with super wides, but I'd not be happy with that corner softeness at f/8. Wide-open I could understand, but stopped down I would expect full frame sharpness.

yido

Canon EOS-5D

02/10/2006 08:24:07 PM · #13

Sorry, I mistook 11mm for f11. Going from f4.5 to f8 seems to have increased corner sharpness. It doesn't look that bad to me. I don't think it's a "bad copy."
I'm of course assuming that the fabric is flat. Perhaps you should take some real life shots and see for yourself at various focal lenghts and at various aperatures.