Sigma 10-20mm Have i got a bad one??

iconnect

Hi guys bought the lens in october and am finding it a bit hard to use sharpness i find lacking in the lens i have attached two images, tell me what you think. It could be me but i dont know

B0rG

Did anybody posted a lecture on controling sharpness with apperture, shutter speed and iso settings while I was away?

rymus

god no, we were waiting for you to bestow your knowledge on us :rolleyes:

B0rG

lazy b... people!
I knew it. I knew it!

Fenster

Git posting

Roen

iconnect wrote:

Hi guys bought the lens in october and am finding it a bit hard to use sharpness i find lacking in the lens i have attached two images, tell me what you think. It could be me but i dont know

What was the iso setting on this, it looks quite noisy at full size, that could steal some of your resolution away. Other than that what were the shutter speed and aperture settings? Tripod mounted or no? Mirror lock up or not?

You'll have to rule everything out before you return the lens, that said bad copies do exist and it's not beyond the realms of possibility that you were saddled with one!

magicbastarder

hold the lens up to the light and check that there's no contamination on the elements.

iconnect

Roen wrote:

What was the iso setting on this, it looks quite noisy at full size, that could steal some of your resolution away. Other than that what were the shutter speed and aperture settings? Tripod mounted or no? Mirror lock up or not?

second pic iso 1600 shutter 1/30 anfd f22 no tripod mirror not locked
first pic iso 400 same shutter same aperture
I know the iso on the first is high but i still dont think it should be that bad

georgey

Its hard to say without the full file to examine, however I can without doubt your sensor is really really dirty.

DaireQuinlan

Its possible at 1/30 that theres a modicum of camera shake, although given the wide angle it shouldn't be affected that much. However it could be the aperture. Refraction starts setting in around f22 or thereabouts, resulting in softer images, try making a few test shots at different apertures, on a tripod, with mirror lockup if possible, to check if its actually the lens, and not just your technique.

JMcL

As Daire said, the laws of physics tend to kick in when you stop the lens down to f22, and you can run into problems with sharpness. I'd second all his advice. Try testing at f8 - f11, most lenses operate best in this range. Also, with a lens this wide you shouldn't usually need to step down that much if depth of field is what you're after

Roen

Try ƒ8 or ƒ11, you'll be running into the diffraction limit of that lens at anything past that. Also 1/30 is a little slow even for such a FL. Stick it on a tripod with MLU set if possible on you model and use ISO 100 to see if that makes a difference to resolution.

*EDIT* Ahem, what was said above actually!

iconnect

right not the best photo but i stuck the camera on a tripod ang gave the lens a go what do you think it looks better than before.
shot at 100 iso shutter 3.2 sec f11
Focal point was the z in lucozade