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02-12-2013, 02:19 PM   #16
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QuoteOriginally posted by VisualDarkness Quote
Sigma 28-70mm f/2.8 EX DG Lens Review


Seems to be worse than my Sigma 24-70/2.8 that suffers heavily from bloom at 70/2.8 to an almost unusable level. Still I think your pic is slightly front focused too.

Liveview is when you see the scene on the screen instead of looking through the viewfinder. It uses a completely different focusing system that almost cant suffer from wrong focus, though is slower and has a harder time to lock.
Ok, after reading that it makes me think I just need a different lens.

So if after I shoot in Live view and focus manually, what then? what do I look for? I mean, image in focus I'm sure. If it is front focusing not in Live view, in LV it will not front focus? If this is the case, what can I do?

02-12-2013, 02:25 PM   #17
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QuoteOriginally posted by BethC Quote
Ok, after reading that it makes me think I just need a different lens.

So if after I shoot in Live view and focus manually, what then? what do I look for? I mean, image in focus I'm sure. If it is front focusing not in Live view, in LV it will not front focus? If this is the case, what can I do?
In Live View, you can magnify the image a large amount. Make sure you are in manual focus mode (the AF/MF switch). Under the maximum magnification, I want you to attempt to focus on your subject - whatever it is (choose something with small details). Move the focus around a little to make sure you've reached accurate focus - it's harder with a soft lens, but the magnification will help.

Once you've done that, take a picture, don't process, upload it full size to here.

For even better consideration, choose one shot at F2.8, then F4, then F8.
02-12-2013, 02:52 PM   #18
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I don't think that photo is terribly bad btw, with some post processing you can clear the noise and add some sharpness, contrast. Keep in mind that when you are checking out a photo at 100% all of its flaws get "magnified." If you would make a print of reasonable size, it would look completely fine.
02-12-2013, 04:01 PM   #19
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QuoteOriginally posted by Na Horuk Quote
I don't think that photo is terribly bad btw, with some post processing you can clear the noise and add some sharpness, contrast. Keep in mind that when you are checking out a photo at 100% all of its flaws get "magnified." If you would make a print of reasonable size, it would look completely fine.
Yeah, at a normal size, I know these will look fine. That's the reason why I chose this lens just to take snaps at my daughters ballet practice. I knew they were only for me and would only be printed small. However, after seeing what my other lenses do (Mostly my 50 mm and my 50-135) It' s hard to trust this lens when shooting a wedding or portraits for someone. Maybe I'll try printing one of the shots from today at 11 x 14 just out of curiousity to see what it will look like.

(My husband hates when I'm editing and I'm zoomed in at 100% and complain about how the photo looks that way.)

I'm uploading my photos take in Live view right now. I've learned one thing.... anything at F 2.8 with this lense pretty much sucks!! And that defeats the whole purpose of having this lens for what I want it for, to shoot wide open in low light conditions (weddings etc.... )

will post my pictures as soon as done uploading......stay tuned.

02-12-2013, 04:04 PM   #20
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Sounds bad already! That's really surprising, but reading the review link I guess it's true for this lens. But don't take it to mean that all Sigma's are bad - the 17-50 and the 24-70 are quite good.
02-12-2013, 04:04 PM   #21
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Okay, here they are completely un edited. shot in RAW. The only thing I did was add the aperature to each shot.





02-12-2013, 04:06 PM   #22
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Well, the 50-135 is outstanding and most 50's are quite sharp at F2.8 so I don't think it's really possible to expect something even close to it from a really cheap 28-70/2.8. Though there is a a use still for that kind of lens.
02-12-2013, 04:07 PM   #23
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Ok - in the F2.8 picture, the focus is on the front-most strawberry. It is quite soft, I'm not sure if my Sigma 17-70 will do better, but I suspect it would.

The F4 picture is much better.

The F8 picture is front focused - the wood in front of the bowl is sharp/lacking bloom.

Still a bit of ISO, but at least we can definitely see the difference now.

02-12-2013, 04:51 PM   #24
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So I guess this means the lens is not faulty, it's actually exactly as the review says it would be. I'd love to try a different Sigma lens and see if there is a big difference. Still not sure what I'd get if I replaced this lens. I do like this focal range and I think I'd use it more if I trusted the pictures would be sharp.
02-13-2013, 10:32 PM   #25
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QuoteOriginally posted by BethC Quote
So I guess this means the lens is not faulty, it's actually exactly as the review says it would be. I'd love to try a different Sigma lens and see if there is a big difference. Still not sure what I'd get if I replaced this lens. I do like this focal range and I think I'd use it more if I trusted the pictures would be sharp.
I own a number of Sigma lenses, and while I haven't had to have any adjusted and I'm happy with them, people in this forum have posted that if you contact Sigma you can arrange to have them adjust a lens that's out-of-warranty for a fee. Also, people have mentioned you'll get the best results if you send in your camera body with the lens, so that they can ensure that it will work well with your particular camera. (Pro photographers do this all the time since they use their cameras/lenses a lot and over time some things can get slightly out of alignment.) I think it's worth it giving Sigma a call and see what they say.
02-14-2013, 07:17 AM   #26
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Just go and get a FA* 28 - 70mm - it is absolutely outstanding, it's like shooting with a whole load of primes attached to your camera body. Not cheap but worth every penny. It hardly comes off my K5.
02-14-2013, 07:29 AM   #27
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I would try some "brick wall" shots in live view and not live view to see how the performance is. I do think that most recent picture is front focusing.

If it's just a focusing issue, that's easy enough to adjust in camera (if you have a k7 or k5), but I also have some suspicions that this lens has an issue based on the haze around some of the hair which I *think* should be in focus.

Regardless, on almost all zooms, if you compare them to a good prime, you're going to be underwhelmed. Best case, this lens will look decent at F2.8 vs a F2.8 image out of your 1.4 which will probably be fairly sharp.

Also you've got a cute kiddo.
02-14-2013, 07:40 AM   #28
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I'm going to go out on a limb here, and talk about my opinion of more expensive Pentax glass vs Sigma glass.

As a set of general rules, Pentax glass is sharper than Sigma glass. Pentax glass tends to produce more vibrant colors, where Sigma glass tends to produce more muted colors. Pentax glass performs better wide open. Pentax glass tends to have back focus issues that I have not experienced with Sigma glass.

There are a few lenses where I don't think that's the case. The Sigma 100-300 F4 for example I would put up against the Pentax 60-250 in everything except for color rendition.

In your shoes, I would take a long look at the DA* 16-50 and DA* 50-135 depending on which focal range you shoot the most; or if focus speed is a serious concern, the FA* 28-70 and 80-200. Even so, if you take either of them at 50/2.8 and compare images to the 50/1.4 at 2.8 and pixel peep you're going to find they aren't as sharp.

Based on what appears to be in the lens review on this lens though, It sounds like what you have is a soft focus lens, and that's just how this lens is. A soft focus lens can have it's uses, but you're not going to get the tack sharp performance you're looking for.
02-14-2013, 08:01 AM   #29
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Thanks all for the replies and the help. I've known for a while that this lens just isn't a great one, figured I got what I paid for, and just wasn't sure if what I was seeing (or not seeing, especially wide open) is normal for this lens. I'm thinking I'm going to replace this lens very soon, I'm just not sure with what. I am considering renting a few, trying them all out and going from there. The only other lenses I have are all Pentax. Including one old 35 - 70 1:3.5 - 4.5 manual focus lens that is so unbelievably sharp it blew me away first time I used it for some portraits of my daughter. Just wish it wasnt manual focus, I shoot a lot of kids and have a few weddings coming up and I'd love something in that range that I could use in low light and get sharp images.

I use my DA 50 - 135 a lot, especially right now because I do the photos for my kids wrestling teams. It's so unbelievably quick, the Sigma searches and searches to grab focus sometimes. Even when I think I'm focusing on a high contrast portion of the image.

Oh well, it was really the second lens I bought and at the time didnt' want to spend a lot of money. Live and learn!
02-14-2013, 08:08 AM   #30
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QuoteOriginally posted by Clinton Quote
Also you've got a cute kiddo.
Oh and thanks! She's got 3 older brothers who all play football and wrestle, This girl stuff is foreign to me haha, she keeps me on my toes!
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