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06-22-2015, 05:57 PM   #16
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If you manually focus in LV, in any kind of bright light the camera will stop down somewhat automatically (sensor protection mechanism), which can throw your focus off if you are actually shooting at a wide aperture. So you must either engage optical preview (which will set it to the selected aperture) while you focus or use the focus assist magnify function (which will open it all the way). And if you are using liveview, then your AF adjust settings have no effect at all, which are only for focus through the viewfinder.

In these latest shots you've chosen a subject that you can't really tell what's going on. Avoid things with printing on them (printed materials have built-in aberrations, misaligned inks, etc) -- let's see something with texture like a piece of wood or a fence or some close-up plants or something...

06-22-2015, 06:29 PM   #17
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It's always hard to draw conclusions from other people's photos without knowing all the details, but I'll give it a go. I assume these are 100% crops?

I don't quite understand how you focused - you say that you manually focused in live view, but also mention AF adjustment. AF adjustment shouldn't make any difference if you're focusing manually. What I would recommend is that you focus once (using magnified live view at f2.8) and then leave focus where it is for any subsequent shots. If that's what you did, then the lens seems to be exhibiting substantial focus shift between f2.8 and f4. This has no bearing on optical capability, but the focus shift does make it difficult to compare these two images.

I would say that certainly at f4, the lens looks pretty sharp. At f2.8, the focus appears to be on the 'ol' of 'Whole', and actually also looks pretty sharp, though it's harder to tell due to lack of detail of the appropriate size. This is why I suggest doing tests at a longer focusing distance - the increased depth of field means that you get more image area from which you can assess detail rendition. It's also generally easier to find subjects with details of the appropriate size across a significant area (grass, soil, debris etc).

Based on these images, I don't see any reason to conclude that the lens is flawed optically, though more testing is needed to be certain of this. If you did not re-focus between shots, then the lens may be displaying focus-shift from f2.8 to f4, which could be worth investigating as this can make AF inaccurate. Focus-shift is pretty common in fast lenses, but not really in a 2.8. However, I have observed this in my Samyang 14mm, which does shift significantly between f2.8 and f4.
06-22-2015, 06:30 PM   #18
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QuoteOriginally posted by vonBaloney Quote
If you manually focus in LV, in any kind of bright light the camera will stop down somewhat automatically (sensor protection mechanism), which can throw your focus off if you are actually shooting at a wide aperture. So you must either engage optical preview (which will set it to the selected aperture) while you focus or use the focus assist magnify function (which will open it all the way).
I hit "ok" on the back to zoom in while manually focusing in live view. Is this what you mean?

And if you are using liveview, then your AF adjust settings have no effect at all, which are only for focus through the viewfinder.
I did not know that. So what's the point of being able to adjust the focus if it's disabled in LV? I mean, if the focus is off, it's off. How is it automatically "corrected" while using LV?

In these latest shots you've chosen a subject that you can't really tell what's going on. Avoid things with printing on them (printed materials have built-in aberrations, misaligned inks, etc) -- let's see something with texture like a piece of wood or a fence or some close-up plants or something...
I read a few different places to specifically shoot at text. But I guess that makes sense. I tried a few different things but the text wasn't good. The can looked the best though. But I'll try some other stuff as well. Thanks for all the info. Learn something new every day.
06-22-2015, 06:57 PM   #19
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QuoteOriginally posted by Another dyemention Quote
I read a few different places to specifically shoot at text. But I guess that makes sense. I tried a few different things but the text wasn't good. The can looked the best though. But I'll try some other stuff as well. Thanks for all the info. Learn something new every day.
Crisp black on white charts made specifically for this kind of thing are good, but labels and magazines (multi color process), etc it can be hard to distinguish flaws in the photograph from flaws in the materials.

06-22-2015, 07:14 PM   #20
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I definitely refocused before taking the second shot. So I'll focus and leave it there next time. And I'll try taking my camera to work tomorrow and doing some tests at lunch. It seems it's the only free time I have lately with a two year old running around. And it's always sunny while I'm at work but when I'm home, it's of course raining. That's Cleveland for you though. I'll take some shots tomorrow and repost my results.

---------- Post added 06-22-15 at 07:14 PM ----------

QuoteOriginally posted by vonBaloney Quote
Crisp black on white charts made specifically for this kind of thing are good, but labels and magazines (multi color process), etc it can be hard to distinguish flaws in the photograph from flaws in the materials.
Gotcha. I will avoid that I the future.

---------- Post added 06-22-15 at 07:22 PM ----------

And I'm not sure how to do a 100% crop in lr5. I just cropped it to what you see.
06-23-2015, 09:04 AM   #21
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So I just took some pictures at lunch and not a single one was in focus. I had a tripod and was manually focusing in LV. The focus peaking was highlighting the subject but after taking the picture, the area in focus was 5-10 feet in front. When I'd refocus, it'd be behind. This went on for half an hour. Never once did it focus on my subject which btw was a big rock about 45-50 feet away. I even tried different subjects and the results were the same every time. The area in focus at that distance at 2.8 and 70mm should be 18 feet according to my DOF app. So there shouldn't have been a problem getting my subject in focus even if I was a bit off. But it wasn't even close. I'm bout to toss this lens.

Last edited by Another dyemention; 06-23-2015 at 09:22 AM.
06-23-2015, 09:27 AM   #22
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It needs some attention from Sigma...
06-23-2015, 09:40 AM   #23
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I'll just send it back to keh and bite the 15% restocking fee. I'm done with it. And even if the focusing happened to be operator error, it still back focuses more than I can adjust for. If I had more funds to put into this id consider sending it to sigma but I don't. So back it goes.


Last edited by Another dyemention; 06-23-2015 at 09:52 AM.
06-23-2015, 09:55 AM   #24
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QuoteOriginally posted by Another dyemention Quote
I'll just send it back to keh and bite the 15% restocking fee. I'm done with it. And even if the focusing happened to be operator error, it still back focuses more than I can adjust for. If I had more funds to put into this id consider sending it to sigma but I don't. So back it goes.
When did you buy it? You should be able to return it for a full refund with return shipping on them...
06-23-2015, 10:01 AM   #25
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I paid for it on May 27th. It's 14 day return policy. I haven't had a chance to even try it out till this week. My wife had finals and nursing school graduation so I was pretty preoccupied.
06-23-2015, 10:11 AM   #26
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QuoteOriginally posted by Another dyemention Quote
I paid for it on May 27th. It's 14 day return policy. I haven't had a chance to even try it out till this week. My wife had finals and nursing school graduation so I was pretty preoccupied.
There is still a warranty in play though I think. Tell KEH you can't get a sharp photo out of it and see what they say...
06-23-2015, 10:17 AM   #27
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I bought it used so not sure there's any warranty. But I'll call em today.
06-23-2015, 10:26 AM   #28
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QuoteOriginally posted by Another dyemention Quote
I bought it used so not sure there's any warranty. But I'll call em today.
It's their own warranty on used stuff. I think it is 6 months, but I could be mistaken.
06-23-2015, 10:59 AM   #29
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I just contacted them and they are going to send it for repair. So we shall see what happens.
08-06-2015, 03:49 AM   #30
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Got my lens back from keh yesterday. I didn't do any controlled tests or anything like that but the focus seems to be perfect. Still have to have it at -5 on the fine adjustment but it is spot in every time. Was even able to focus on my wife's eye lashes and her lip ring. Only shot at f2.8 and, while not the sharpest images ever, it is still as sharp as any other lens I own. Excited to see how well it does stopped down.

---------- Post added 08-06-15 at 03:50 AM ----------

Oh and the focus ring feels like they may have fixed it. It seemed pretty loose when I first got it and now it feels like it should. It took 5 weeks to get it back but I'm very happy with the results from keh.
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