Sigma 70-200 2.8 OS

JayB

JayB

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Hey all, having a problem with my Sigma 70-200, I know its not the sharpest lens at 2.8 which I'm a little disappointed at but that's not my issue, trying to zoom in at 200mm at different settings and I cant get a picture that is even a little soft, its just blurred even on a tripod. I read then that I can use the AF-Fine tune in my D7100 but tried different settings and cant seem to get it pin sharp no matter what the F stop is.

I also have noticed on other lens that the images are most of the time a little soft and like not very clear. Like a fog/mist over the pictures? Its not bad but it doesn't seem as clear as the pics from my D80. Tried cleaning the sensor but it didnt make any difference.

Anyone got any ideas?
 
I've deleted most of them but I will take more, I do have 1 here though
http://www.flickr.com/photos/98106232@N02/9557734366/meta/

This one just looks plain blurry as if it was shacking and out of focus. It was on a sturdy tripod, zero wind, and tried to focus on white ball atached to the ship. I also used the remote trigger to limit shake. Now that one is by far the worst one that has came out of my camera. The rest are not as bad as this one but still. And this one was 1 of 3 shots I tried to take and failed at.
 
Definitly not mate, I have it about a month now, always in its padded bag, never out of my sight. Im quite careful with it. I do find however if I manually focus i can get it closer which brings me back to the AF-tune thing in the camera, I downloaded those charts you can get to test focus but it seems to focus fine on it so I'm stumped. lol.
 
Is it the same all the way through the 70-200mm range?

Just asking as I have a lens I dropped and its fine at the lower range but at the max zoom it looks just like that.

As for the Sigma 70-200mm not being sharp at f2.8 .... no problems here.



 
Ive had 2 of these and they are very sharp wide open right through the range.
 
i notice you shot that pic at (1/2000) if the os was on then there is your problem ;) i use to have same prob with high speed and IS when i forgot to turn it off
 
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Thanks for replys guys, Yea OS was on, never thought to turn it off if I'm honest. Mine seems soft at 2.8 through all focal range and upon reading loads of reviews they all said the same so I just assumed that was the way it was. No not through all the focal range is it blurry like that. Id need to take more text shots to see. Those pics all look awesome. I've never been able to get pics as sharp as that with my D7100 since I got it. Was there any editing afterwards to get them that sharp? Also if you look at my Exif data, if there any settings I'm using there that are really silly or not a good idea?

Thanks in advance.
 
There was editing done on mine as I shoot raw and always add a little sharpening etc.

Your settings look fine to me, you should easily get a sharp photo at 1/2000 handheld so take it off the tripod and shoot a few pics through the zoom range.
 
Ok will do, thanks for the help, I'll follow up with some shots tomorrow hopefully.
 
Hmmm seem to recall others having issues with d7100 AF, what are your other lenses like?
 
I will test more tomorrow and come back with results as I deleted most bad ones.
 
Sorry to double post, but can anyone point me in the correct direction to check for back focusing test or even normal focus test? and whats the best way to use it?
 
I wouldnt worry about that yet, if your other lenses produce far better shots than the Sigma the Sigmas at fault, if they all produce poor results its your camera. Try manual focus like Phil suggested.
 
Looking at the Exif detail, it appears that its set for

51-point AF
AF-C

Also that the focus point used is 48 (E1). I'm not sure what point that is though.

Have you tried less AF points (AF-9), on AF-S and ensured the focus point is what you need (centre point maybe?).

However, I may be well off the mark!!
 
Quick way to check for front/back focussing is to AF normally, get focus lock and then switch to live-view and see if it significantly re-focusses.
 
ive heard of a lens focusing ok at one distance, and being off at other end, was a sigma 50mm or 35mm i think.

try manual focus, live view, on something slopped or tip the camera towards the ground, can hopefully see a plane/strip of focus as you adjust.
 
Hey everyone, only getting back to you now, just 2 pics to compare for you. Havnt had much chance to get many others.

Sorry about the can, seen it laying on the ground and thought the writing was plain and of good quality instead of a printed page.

70-200 F8

Saved - 70-200 F8 by jasonboglephotography, on Flickr

70-200 F2.8

Saved - 70-200 F2.8 -2 by jasonboglephotography, on Flickr

The 2.8 isnt as sharp at all. I tried to manual focus to but cant seem to get any better so not sure whats going on.
 
looks ok to me too, dont forget at 2.8 you will have a very narrow depth of field so the whole tin can may not be in focus anyway...

get some shots of a brick wall
 
Oh.. It must be my lack of knowledge I guess. I'll take more pics and see what you guys think, any suggestions along with a textured wall?
 
Try a target like this. Tripod, box square to the camera, 200mm f/2.8, and focus a couple of inches to the side of the ruler with single AF point. You can then see exactly where the sharpest point of focus actually is on the ruler. Adjust accordingly. Re-test a few times to check consistency.

Try other focal lengths too, there may be a slight difference, so set the best compromise. It's usually best to bias a little towards the long end as that's where any errors are most likely to show.

 
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