Sigma 30/1.4 EX (full size pics)

Hi.

Just got my Sigma 30/1.4 EX instead of bad copy of 10-20. I found that it has soft top left extreme edge when wide open. Softness almost (IMHO)disappears at f8. The center is really sharp.

So my question - left edge is issue of my copy or it's usual for Sigma? even prime.

f2.8



f5.6



f8



f1.4



f7.1



I really tired of choosing Sigmas. Do you think it's ok&

Sorry to hear about the situation.

Usually it takes only 1-2 stops of stopping down for a lens to reach the sweet spot.

Also lopsided blurrness does not sound like a good thing.

Did you intend the lens for low light or broad daylight usage? That may help you decide.

I going to use it almost daylight.

I checked this
http://www.pbase.com/miljenko/image/50204324
The same problem with left corner.

CA I think, I can remove when RAW converting.
I see, Sigma makes skin color in blue tone - no good.

That left-sided defocus is definitely an issue with your particular copy. I tried three copies of this lens, and all three had different problems, but focus (or mis-focus) was always consistant throughout the image field.

• Mike

Jetroot said:

I going to use it almost daylight.

I checked this
http://www.pbase.com/miljenko/image/50204324
The same problem with left corner.

CA I think, I can remove when RAW converting.
I see, Sigma makes skin color in blue tone - no good.

Click to expand...

Just found some mistake in pp with my sigma examples. Check this one, I think it's sharp enought at 2.8. Am I wrong?

That left edge looks like an issue to me. The right edge is holding sharpness nicely. I'm very impressed with the central area sharpness of this lens.

If a lens is put together properly, their sharpness (or softness) should be symmetrical. Most lenses, especially ultra wides, will soften towards the edges/corners. But that softness should be symmetrical. The upper right corner of a lens should be about as soft as its lower left corner.

I've getting very frustrated with my Sigma experience. I've had two Sigma 12-24s with problems. (I want it for interior architecture photos.) Both have serious softness on one side or the other. The first one had a loose interior element so the softness/smearing could appear on either side or sometimes not at all. The second copy has a fixed softness on the left side. When I use a focus chart the left side of the chart's image indicates severe front focus while the right side a mild back focus. If I compensate with manual focus I can get the left side very sharp, but sharpness falls off the further to the right on the image.

I'm going to try a third copy.

BTW: The copies had a very large difference (delta of 20000) in SN so I doubt if they were from the same batch.

Steve