Simple test to test lens sharpness.

Hope you don't mind me asking a question in your thread, as I have one of these coming in from ebay as well!

When people describe this lens (or the tamron 17-50) as "soft," is this referring to the lens front or back focusing when snapping a picture or a different problem with the optics?

pwk wrote in post #16783482
Hope you don't mind me asking a question in your thread, as I have one of these coming in from ebay as well!

When people describe this lens (or the tamron 17-50) as "soft," is this referring to the lens front or back focusing when snapping a picture or a different problem with the optics?

They are referring to sharpness in corners. It suppose to be soft at 17mm and 35mm at wide open aperture.

khwaja wrote in post #16779949
Some pics taken so far.

50mm 2.8

IMAGE LINK: https://www.flickr.com​/photos/khwaja76/13160​799784/

Lol that looks like a startup screen of an iPhone game

One more quick test with Yongnuo flash.

50mm 2.8

IMAGE LINK: https://flic.kr/p/mzkS​JJ

IMAGE LINK: https://flic.kr/p/mzjx​dR

I don't think that the 17mm shot looks soft, but it does look like focus is missed by a bit - looks like the plane just behind his face is in focus, it's pretty apparent if you look at his hair, ears and shirt.

khwaja wrote in post #16798351
One more quick test with Yongnuo flash.

Is it looking good? It looks little soft at 17mm compared to 50mm. Converted them using DPP. My next investment is getting processing software and learning to process raw and noise.

Heya,

Looks fine to me for being at it's widest aperture.

The only thing I see is a slightly back focusing going on. Take a test shot and use center point on your AF grid only, not all 9 points. When you focus, put the center point on your son's forehead instead of his eyes (right at his hair line for example). Tap AF. Tap it one more time, then immediately expose.

Very best,

Well, something in your photos beside the lens sharpness. Please look carefully at the shot taken at 17 mm. You had to take it at a close distance, so it really shows the distortion.

Lbsimon wrote in post #16799135
Well, something in your photos beside the lens sharpness. Please look carefully at the shot taken at 17 mm. You had to take it at a close distance, so it really shows the distortion.

Just curious on this- where do you see the distortion at?

Scud49 wrote in post #16799329
Just curious on this- where do you see the distortion at?

I think that he's talking about perspective distortion. Why? Who knows.

WhyFi wrote in post #16799360
I think that he's talking about perspective distortion. Why? Who knows.

Yes, correct. Perspective distortion. On the 18 mm photo the face proportions are distorted as compared with the 50 mm photo.

Lbsimon wrote in post #16799451
Yes, correct. Perspective distortion. On the 18 mm photo the face proportions are distorted as compared with the 50 mm photo.

Who cares? The guy wants to know if his lens is performing well - why bring up a non-related non-issue?

WhyFi wrote in post #16799752
Who cares? The guy wants to know if his lens is performing well - why bring up a non-related non-issue?

You care, otherwise you would have just ignored it. The OP might care, he may not be aware of the wide angle distortion. I care for many reasons.

Lbsimon wrote in post #16800193
You care, otherwise you would have just ignored it.

Why am I not surprised that you're not making any sense? I was responding to someone that posed a question after someone else made a really dumb comment that made it seem as if there was something potentially wrong with the lens in question. Rather than let that possibility linger and add to the OPs unease, I thought it better to point out how irrelevant the comment was.

Lbsimon wrote in post #16800193
The OP might care, he may not be aware of the wide angle distortion.

So you make it a habit of giving people unsolicited advice? Does that make you feel smart? I bet that's really endearing trait to those around you.

Lbsimon wrote in post #16800193
I care for many reasons.

Good for you - it's not your thread, it's completely out of left field and has nothing to do with the OP's issue and introducing another "problem" when the guy is already questioning whether or not his gear is working properly is hardly helpful.

Ok, you won.

Lbsimon, Martin, Bill and Scud49,
Thanks for all the tips. I will try focusing on forehead and check it out. DPP is not recognizing sigma 17-50 to correct lens issues. Is there any workaround with correcting these issues using DPP.
Thanks