Sigma 70-200mm sharpess

greywolf · 6 Feb 2012 at 16:50

D.P. · 6 Feb 2012 at 17:02

The 200mm f/2.8 results would not be acceptable to me. However, it is impossible to know what the issue is with these photos.

What is your tripod? Many times I see people complain at image softness when their tripod and head is widely inadequate with plenty of slop. The shutter speeds you have are right in the target zone of mirror-slap induced oscillations for starters. Did you use mirror up?

Secondly, how were these focused? Did you use AutoFocus, manual focus, or liveview. Try using focus stacking through manual focused images getting an approximation through liveview. Or at least you magnified liveview to verify auto-focus.

Is this the image center or corners?

What distance were these taken from? What happens at larger distances?

To check autofocus issues then use the chart form here. Follow guidelines exactly. Make sure you have chart printed at the correct brightness.
http://regex.info/blog/photo-tech/focus-chart

ElDude · 6 Feb 2012 at 17:10

That's odd. It looks like it's being shot through a sheet of glass. It doesn't have a filter attached does it?

greywolf · 6 Feb 2012 at 17:23

D.P. said:
The 200mm f/2.8 results would not be acceptable to me. However, it is impossible to know what the issue is with these photos.

What is your tripod? Many times I see people complain at image softness when their tripod and head is widely inadequate with plenty of slop. The shutter speeds you have are right in the target zone of mirror-slap induced oscillations for starters. Did you use mirror up?

Secondly, how were these focused? Did you use AutoFocus, manual focus, or liveview. Try using focus stacking through manual focused images getting an approximation through liveview. Or at least you magnified liveview to verify auto-focus.

Is this the image center or corners?

What distance were these taken from? What happens at larger distances?

To check autofocus issues then use the chart form here. Follow guidelines exactly. Make sure you have chart printed at the correct brightness.
http://regex.info/blog/photo-tech/focus-chart

Thanks for the reply DP.

Tripod is a Giottos MTL9251B with MH5011 head.

D90 does not have mirror lock up. Might retake with exposure delay.

Distance was around 1m, although seems to occur at further distances.
Used autofocus, centre focus point.

Will check the chart out tomorrow.

Thanks.

ElDude said:
That's odd. It looks like it's being shot through a sheet of glass. It doesn't have a filter attached does it?

Nope no filter and the glass is clean.

D.P. · 6 Feb 2012 at 21:39

With the lens mounted to the tripod, tap the end of the lens. There should be no visible vibration and everything should be rock solid, even with a fairly strong tap or flick of the finger.

Use the exposure delay, it helps.

The above will check vibration induced softness.

To check focusing issues use liveview with a magnified image. Once the focus is locked you can then also switch to manual focus and try focussing at very slight increments away form the liveview focus point. This will check for focusing issues.