Lack of sharpness: what's the reason?

[springm]

See this picture (which I like very much)



and the 100% crop where I tried to focus:



It is everything else but sharp. But why? It was shot with the current Tamron 70-300 on the A700 at 210mm, f5 and 1/400 s. I know that at this f-stop the lens does not deliver the best sharpness, but is it really so bad? 1/400 s plus SSS should be fast enough to stop even my early morning tremor. If anyone could shed some light on this I would be really glad.

Markus

[Dr. Harout]

Two questions Markus:
1- Is the lens sharp?
2- How did you focus on your subject, was it with the center area and recomposing, or did you use one of the lateral points of focus?

[springm]

1. Yes, I guess the lens is ok, just see this shot:

<a href="http://www.flickr.com/photos/springm/2978893580/" title="Kalmunai students II by springm, on Flickr"><img src="http://farm4.static.flickr.com/3233/297 ... 54c07e.jpg" width="500" height="333" alt="Kalmunai students II" /></a>

2. I used the central sensor. I know that this reframing action can create unsharp pictures, but the focusing point is not so far from the center and it's a tele photo, so I did rule this out as the reason.

BTW, the full size jpeg can be found here: http://farm4.static.flickr.com/3210/298 ... d22e_o.jpg
I shot it as a craw file and converted and sharpened in bibble.

Markus

[David Kilpatrick]

You don't state the temperature or conditions. Even at this distance, rising heat can be sufficient to create unsharpness in a tele shot. Many, many examples of poor sharpness I see from 200mm and over are a result of shooting when the air is not perfectly cold (or perfectly even in temperature) and this affects beach, tropical, humid locations most. A combination of humidity and slight turbulence caused by rising heat on a still day can ruin tele shots at wider apertures. The actual disturbance has most effect when close to the camera - near the subject, it just makes it look a bit wriggly. Near to the camera (i.e. shooting across a blacktop tarmac road to something the other side) can just blur the shot.

David

[springm]

ok, that's a factor I haven't considered yet. It was 6:30 to 7:00 local time, on the beach, with the sun up but not yet really hot. It would explain why my portraits are sharp but this one is not. o.t.o.h.



is sharp, shot with a much longer focal length. O.k. in between was water, so that would strengthen your theorem.

Markus

[01af]

Air turbulences indeed can ruin the sharpness not only in super-telephoto shots but also at moderate focal lengths such as 200 mm. But that particular image (buffaloes at the beach, with green and yellow boats and a cart in the background) seems to suffer from camera shake. With SSS engaged, 1/400 s at 210 mm on APS-C format should be safe. Without, it's not. Are you really sure SSS was active? It looks like the camera was moving up and down with SSS off.

In addition to that there is some lateral chromatic aberration which is surprisingly strong considering how close the cropped area is to the image's centre ... but still, that should not affect sharpness so badly.

-- Olaf

[[SiC]]

There is something with the "grain pattern" (don't know how else to describe it) of the newer Alphas which I don't like... especially with the 100% views I've seen with the 300/350 but sometimes with the 700 too... Is this an effect of in camera jpg?
I don't know how to explain, edges look jagged and sometimes the grain makes patterns instead of being "salt and pepper"-type (see top of image).

A bit disconcerning as I was hoping for a 700 at some point

Do you know what I'm talking about?

As for the particular image... maybe the cow(?) shook his head

BR,
/Zeb!

[springm]

Are you really sure SSS was active? It looks like the camera was moving up and down with SSS off.

Yes, definitely it was on - only when having used a tripod I sometimes forget to switch it on again, but I had none around. But maybe I have moved 'cause I had no stable position for the foot in the sand.

That CA you mentioned is indeed strong and I have no explanation for it as in other shots with this lens it is not so visible.

There is something with the "grain pattern" (don't know how else to describe it) of the newer Alphas which I don't like... especially with the 100% views I've seen with the 300/350 but sometimes with the 700 too... Is this an effect of in camera jpg?
I don't know how to explain, edges look jagged and sometimes the grain makes patterns instead of being "salt and pepper"-type
...
As for the particular image... maybe the cow(?) shook his head

The shot was made as a craw and converted in bibble. At ISO 320 grain is usually invisible, but in this case I intensified sharpening without taking care of the noise that gets intensified, too. However I guess in an 8x12 print it should barely be visible.

And your remark about the head movement of the subject, an ox, well this is possible. And when they shake the head to chase away flies, the movement at the tips of the horns is quite fast.

Markus

[[SiC]]

The shot was made as a craw and converted in bibble. At ISO 320 grain is usually invisible, but in this case I intensified sharpening without taking care of the noise that gets intensified, too. However I guess in an 8x12 print it should barely be visible.

Ok, shouldn't blame the in-camera jpg this time then

/Zeb!

ps. enjoyed your blog and commented some great pics on Flickr