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04-05-2011, 11:25 PM   #1
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Sigma 17-50 real world photos

K-5 + Sigma 17-50 ( plus one FA43 photo)

Photos shot in DNG and processed in LR3.3.

After dozens of photos since my initial indoor test, it does appear that the Sigma front focuses a little bit. Nowhere as bad as the Tamron 17-50 that I got though.





















04-06-2011, 02:36 AM   #2
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Thanks for the share. I'm still contemplating whether to upgrade from my Sigma 18-50mm F2.8 macro. Just quite unsure how much increases optical performance beside the HSM and OS which I don't really care about.
04-06-2011, 04:07 AM   #3
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whats it like wide open at 17mm at its hyper focal distance...does it look soft at the frame edge ..

also Low light and the K5 wide open at 17mm..do you suffer any Front focus issues with your K5 in that scenario with the sigma ?
04-06-2011, 04:41 AM   #4
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Couple of real world photos of the Sigma 17-50 on a K20D

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04-06-2011, 05:39 AM   #5
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QuoteOriginally posted by belrosevj Quote
Couple of real world photos of the Sigma 17-50 on a K20D

the second image looks blurred....
04-06-2011, 02:36 PM   #6
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QuoteOriginally posted by Tommot1965 Quote
whats it like wide open at 17mm at its hyper focal distance...does it look soft at the frame edge ..

also Low light and the K5 wide open at 17mm..do you suffer any Front focus issues with your K5 in that scenario with the sigma ?
I'm a noob, does hyper focal distance mean infinity focus? I don't think I've used 17mm, wide open, at infinity focus yet. I'll try that out.

I didn't suffer any noticeable front focus when I ran the test with the back of the puzzle box. However, yesterday, in even lower light, I did have front focus while taking photos of a magazine. Did not have front focus issues using the 100 WR. Now, this was using firmware 1.01.

I then (finally) upgraded to 1.03. Used the Siggy again, and the front focus was less. I did some adjustments on the K-5, and it seemed ok.

My original puzzle box test had the target subject perpendicular to the lens. The magazine test was done at an angle high above the magazine, which was lying flat on the coffee table. The line of sight was probably 35-45 degrees.
04-06-2011, 08:48 PM   #7
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QuoteOriginally posted by Armanius Quote
I'm a noob, does hyper focal distance mean infinity focus? I don't think I've used 17mm, wide open, at infinity focus yet. I'll try that out.

I didn't suffer any noticeable front focus when I ran the test with the back of the puzzle box. However, yesterday, in even lower light, I did have front focus while taking photos of a magazine. Did not have front focus issues using the 100 WR. Now, this was using firmware 1.01.

I then (finally) upgraded to 1.03. Used the Siggy again, and the front focus was less. I did some adjustments on the K-5, and it seemed ok.

My original puzzle box test had the target subject perpendicular to the lens. The magazine test was done at an angle high above the magazine, which was lying flat on the coffee table. The line of sight was probably 35-45 degrees.
near enough mate
04-07-2011, 05:09 AM   #8
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QuoteOriginally posted by Tommot1965 Quote
the second image looks blurred....
that would be my mistake not the lens.

04-07-2011, 01:55 PM   #9
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QuoteOriginally posted by belrosevj Quote
that would be my mistake not the lens.
you might want to try again..as to get such a blurred picture at a wide FOV as 17mm. is not easy, unless you coughing..LOL

seriously..that image would have had a huge DOF..so much of it should have been in focus...was it shot in Raw ?..if so some post processing sharpening might help..but not much......

my copy of this lens was quite OOF at the wide end with distance objects...yet up close even a 17mm it was fine...it was strange that at two different Focus distances at the wide end {17mm} such a change would happen to my shots..
04-07-2011, 02:09 PM - 1 Like   #10
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QuoteOriginally posted by Armanius Quote
I'm a noob, does hyper focal distance mean infinity focus? I don't think I've used 17mm, wide open, at infinity focus yet. I'll try that out.

I didn't suffer any noticeable front focus when I ran the test with the back of the puzzle box. However, yesterday, in even lower light, I did have front focus while taking photos of a magazine. Did not have front focus issues using the 100 WR. Now, this was using firmware 1.01.

I then (finally) upgraded to 1.03. Used the Siggy again, and the front focus was less. I did some adjustments on the K-5, and it seemed ok.

My original puzzle box test had the target subject perpendicular to the lens. The magazine test was done at an angle high above the magazine, which was lying flat on the coffee table. The line of sight was probably 35-45 degrees.
Ill explain that a little better as I didnt have time in my last post.

the hyper focal distance is a point at which the lens focuses , and from that point to infinity everything will be in focus, and from that point back to a certain distance from the focal plane it will also be in focus...

all the relative distances will change as the lens is stopped down or opened up...also different focal lengths will affect the hyper focal distance...

example...your sigma at 50 F2.8..the HF is 4.657 metres. to infinity , the near point is 2.329 metres.


if I change the lens...to F5.6 ..the DOF increases so the HF distance reduces to 2.331 metres to infinity, and the near limit drops to 1.166 metres.

focusing at the HF distance is handy for doing landscapes and you are unsure if you need to stop the lens down to achieve great DOF..etc

the Iphone has a great App, called DOF master..I use it when I need to ,its a great resource if your out and about shooting .
04-07-2011, 03:35 PM   #11
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@Tommot - thank you so much for the explanation! It was very informative and helpul. I also downloaded the DOFMaster app for my iPhone. It should prove to be a great resource. Now I'm thinking that I shouldn't have returned the DA21 so that I can just set it on F8 and not even worry about focusing! Stupid me ...
04-07-2011, 04:10 PM   #12
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QuoteOriginally posted by Tommot1965 Quote
you might want to try again..as to get such a blurred picture at a wide FOV as 17mm. is not easy, unless you coughing..LOL

seriously..that image would have had a huge DOF..so much of it should have been in focus...was it shot in Raw ?..if so some post processing sharpening might help..but not much......

my copy of this lens was quite OOF at the wide end with distance objects...yet up close even a 17mm it was fine...it was strange that at two different Focus distances at the wide end {17mm} such a change would happen to my shots..
Now to think of it, I wasn't paying much attention when I took the photo. I sort of clicked it. i will test it again at 17mm.
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