When is AF fine tune too much on a new Lens?

[redhed17]

I bought a new Sigma 10-20mm lens today and took some pics after I got it in the city centre. When I got the camera home and checked the pics they didn't seem at all sharp at f3.5, and didn't get much better at smaller apertures. I did some test shots outside when I got home on subjects closer to the Lens to try and see if there was a problem. The images were soft and only got marginally better as I went to smaller apertures. So I tried the AF fine tune on my D500 to see if it could improve anything. I haven't had to do it with my other lenses. Anyway, the Lens came out -10, which did improve things, but is a -10 adjustment setting a reasonable change to make, or OTT?

I know btw that this is not the highest quality Lens, and I probably won't be using it wide open, but should it go back or not iyho?

I will be doing more testing tomorrow.

 

[Mark twiglet]

On my old d7000 my sigma was +20! But was great lens

 

[chris malcolm]

Cameras, especially older cameras, often have difficulty getting reliable and accurate AF with very wide angle lenses. Like many others I gave up using AF with this lens, memorised the sharpest setting for infinity, which at f8 had a pretty wide DoF, and otherwise used manual focus. AF was not only often inaccurate, it varied wildly from considerble back focus to considerable front focus -- in other words fine tuning would never have fixed the AF problem. I found f8 a good general aperture for widespread sharpness, and f11 necessary if I wanted the edges as sharp as possible. At f11 the edges sharpened up but the centre softened a bit due to diffraction.

 

[gramps]

is a -10 adjustment setting a reasonable change to make, or OTT?

Nikon gives an adjustment range from +20 to -20 so no, -10 isn't OTT if it solves the problem ... if it doesn't solve the problem then maybe it should go back.