Would you say this is sharp?

[futureal33]

Just bought a Sigma 18-50 2.8 Macro and wanted to check if you guys think its a sharp copy...

Im pretty pleased with the IQ... just trying to get other's opinions:

Shot wide open @ 2.8, no PP done.

Original - focussing on the right tip of the spiders web..:


IMG_0216 by futureal33, on Flickr

100% Crop on the area in focus:


IMG_0216 cropped by futureal33, on Flickr

 

[TCR4x4]

Looks alright to me for a shot at f/2.8.

 

[Joe T]

Is that a jpeg? What quality? What level of sharpening set in camera?

 

[futureal33]

Yeah it's a jpeg, shot at full jpeg quality (L). Sharpening in camera is set at +1

 

[scottthehat]

looks fine to me, but to be honest it not the best of subjects,

 

[HoppyUK]

Is it a sharp copy? Probably, the chances are good, but it's impossible to tell without shooting side by side with another identical copy.

One quick way of telling if the lens has been put together properly is to shoot a distant target (to minimise any focusing errors and field flatness isues) like a road sign or car number plate, at a high shutter speed and lowest f/number, and position the target in each of the four corners - in exactly the same position. Focus carefully, then lock it in manual focus.

Zoom in on the LCD and see if each corner is equally sharp. Or perhaps equally unsharp, as this is a very tough test. The level of sharpness is not so important, you are only looking for equality which will show up any decentering, which is the most common problem. Don't look too hard, many lenses show very slight difference - if there's anything wrong, you will see it immediately.

 

[AndyWest]

It is hard to tell with that kind of subject plus it looks a dull day. Try photographing something in the open with nice texture like a fence post or similar, something with a flat surface. I test on brickwork or my obliging model which is my flying pig!

 

[odd jim]

Looks good to me (from whats posted at least) but as long as you're happy with it, who cares?