Tamron 28-75 2.8 aperture comparisons

[KreGg]

So as I learn more and more about my lenses and when to use a given aperture, I decided to take my idle time right now and do some tests.
Having read lots of people experiencing back or front focusing or softness with this camera, I decided I should try mine. It seems that the quality control ain't the best.

I know there was a thread here from 2008,
http://www.thephotoforum.com/forum/photography-equipment-products/117121-tamron-28-75-f-2-8-sharpness-test-wide-open-stopped-down-zoom-extremes.html
with some shots from this lens. But I decided to re-make it to test mine. And since I ve got some pics, I decided to share with anyone who might find it useful.

The subject is a cotton coat. The camera was mounted on a tripod. Aperture priority mode. All shots on the biggest focal length (75mm):

First pic is the smallest aperture it goes, f/32, no crops:

Second pic is of f/8.0, no crops:

Third picture is of f/2.8, no crops:

I think all are pretty sharp. With the edge going to f 8.0. I won't bother posting the other apertures, cause they pretty much look the same with no crops.

Now to the 100% crops. Here we can see great differences on extremes:

f/32, 100% crop:

f/16, 100% crop:

f/8.0, 100% crop:

f/5.6, 100% crop:

f/4.0, 100% crop:

f/2.8, 100% crop:

If we crop that much, we can definitely see that 2.8 is MUCH softer than the other apertures. Though f/32 is close behind. But, to me, both are pretty much acceptable, knowing they are extremes.
But all the other apertures are tack sharp from what I can see.

I was trying some night photography the other night, but I realized I had my aperture at 2.8 on all pictures. Since I have a tripod and I was shooting still objects, now I know I should have closed the aperture a bit more to get a little extra sharpness.

But my eyes are nowhere trained. I know the middle apertures sharpness are good. But how about my 2.8 aperture? Is it too soft? Or I got a good copy?

 

[Ballistics]

I think you need a better subject.

 

[COLTSFANATIC1]

I agree with ballistics,

 

[KreGg]

I think you need a better subject.

hmmm I was just trying to test the sharpness of my lens on its apertures.
I thought a cotton coat would serve the purpose. So how can I best do this test?

 

[Ballistics]

Go outside and find an object that is not too small with defined edges, like a bottle, or ball etc. Place it upon something that allows you to take pictures at a comfortable height, and make sure there is nothing immediately behind it. A shallow DOF will help emphasize the sharpness and make sure you have plenty of light.