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Cant get sharp enough photos


AB188 Avatar
AB188 10 14 England
26 Mar 2019 9:47AM
Hi, I have a Sigma 583306 17-50mm f2.8 EX DC HSM and use it on a Nikon D7000. I have also used a couple of Nikon lenses and are fine on this camera.
No matter what I do I feel I can never get the photos very sharp with this lens; the photos are in photos but they always seem to lack any substantial sharpness. I have no issue with the focus points using the lens. I use Aperture priority mostly and I do have it set mostly to full aperture of F2.8 (I bought this lens for low light), and I have noticed that it is slightly sharper when set to F4 +. My iso is usually pretty low unless the light is bad, and my shutter speed always fast – at least 300/1 sec + minimum mostly.
Its just bugging me so much that it never seems crisp, or have I been spoilt with the Nikon lenses? Help
234134_1553593650.jpg
Deiqkier Avatar
Deiqkier 13 51 United Kingdom
26 Mar 2019 10:07AM
I have no knowledge of this particular lens, but in general lenses are at their least sharp at 2.8 improve as you decrease the aperture. Try the lens on 5.6 or 8 and compare results. Dont be afraid of using a higher ISO setting to keep a higher shutter speed .
Colin
thewilliam2 Avatar
thewilliam2 6 1.7k United Kingdom
26 Mar 2019 10:40AM
My first thoughts are whether you're standing properly, whether you're focusing in the right place and whether the lens has been dropped.

Correct stance, with the camera pressed lightly to the face, left hand under the lens and elbows tucked in to the body, makes a huge difference.

One of my mentees didn't know about focus lock and many of his shots showed a sharp background between the subject heads.

Was the lens bought new? Has anybody else used it during your ownership? The only Sigma lens that I ever owned, the 15-30mm zoom, was OK-ish when new but it didn't keep its sharpness during professional use. I always did wonder whether my assistant had dropped it and kept quiet.

Nikon lenses, or rather the professional versions, are designed to withstand a hard life!

Umberto_V Avatar
26 Mar 2019 11:04AM
I have this lens for Canon. Had it for about 10 years, I find it quite sharp. Make sure the Optical Stabilisation is on if you are using it hand held.

IIRC Sigma quality control at the time i bought mine was less than perfect but luckily mines is ok.
Dave_Canon Avatar
Dave_Canon 17 2.2k United Kingdom
26 Mar 2019 11:39AM
If I were taking this shot, I would use Aperture Priority but would set f5.6 or even f8. I would set the ISO to suit the light so that I am using a reasonable hand hold speed (almost all my lenses have IS anyway). For focussing I would use a single centre spot and focus on the eyes of one of the people (centre one in this case). Having locked in the focus, I can recompose and take the shot.

If you are using a multiple detection auto-focus, it will focus on the nearest object which would be the front of the table, tent pole or guide rope, all of which would be wrong.

Dave
LenShepherd Avatar
LenShepherd 15 4.7k United Kingdom
26 Mar 2019 12:37PM

Quote:
No matter what I do I feel I can never get the photos very sharp with this lens; the photos are in photos but they always seem to lack any substantial sharpness. on lenses? Help


If you have other lenses which are sharp there is a problem with this lens.
bornstupix2 Avatar
bornstupix2 6 131 1 France
26 Mar 2019 2:10PM
Without sounding elitist you are asking an awful lot of a mid priced wide aperture extreme wide angle zoom if you shoot at f2.8 and expect sharp results. With the restrictions in upload file sizes added to full aperture fall off you will still struggle to maintain sharpness in your finished images. A little tweak in contrast/clarity in a photo processing prog may help but its an old rule....you can soften an image but sharpening?....im not sure. I have an F2.8 17-35 ed Nikkor which despite its squeak in the focus motor I use as my motorbike pannier standard lens on a battered D700 Nikon. I would never use it a f2.8 unless absolutely forced or unless I was looking for a soft image for Adobe CC to work with. Sods law guarantees that pushing your iso settings too far whilst giving you the extra stop down dividend will push you into the limits of sensor quality. My answer would be to look for a used high quality 20mm prime. I have just had a second look at your posted air force image and a vignette on a sepia b&w would perhaps go some way to rescuing the whole thing.
banehawi Avatar
banehawi Plus
19 3.0k 4373 Canada
26 Mar 2019 3:34PM
Ive used this lens also, and got the best results after I had performed AFMA, auto focus iocro adjustments, for the lens. It needed quite a bit of tweaking.

I would recommend you give this a try and see if it helps.








W
AB188 Avatar
AB188 10 14 England
30 Mar 2019 1:46PM
HI, I think the aperture was the problem, ive been testing the sharpness on the same shots. The pic shows at F2.8 and then F5, same zoom in. The dial on the watch is definitely sharper. What a difference, thank you!

234134_1553953606.jpg

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