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02-12-2013, 11:08 AM   #1
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Not happy with my Sigma....but what to get?

I'm not sure if this is where this questions belongs, and I'd just love to hear others opinions. I shoot with a K5 mostly and I use my 50 mm 1.4 and my 50 - 135 the most. Next would be my 35 mm 2.4 when I'm shooting indoors. I have a Sigma DG 28 - 70 mm 2.8 EX lens that I rarely use. I love the range, I hate the image quality. Am I crazy? Did I get a bad copy? or are they generally just not the greatest lens? I used it today at my daughters ballet class, came home and looked at pictures and am dissapointed I chose this lens to take. It happens every time I use it, dissapointed, then I stick it away until I decide to try it again. Anyway, I'm looking to replace it, but not sure how much I want to spend since I do have some nice glass and I don't actually HAVE to have a zoom in this range.

so my questions are, is the Tamron in the same range going to be a better lens? What's the alternative in a Pentax lens? looks to me like it would be the Pentax DA 16 - 50 2.8, but it's more money than I thought I wanted to spend, since I'm not sure how much I'd use it and since it doesn't go quite as far as I was hoping (I like the 70 -ish range) But if it's well worth it, I would buy it.

Anyway, that's probably a lot of babbling and thinking aloud, I'm just curious what you all think about the Sigma vs. Tamron and what would be a good choice if I get rid of my Sigma.

thanks!!

02-12-2013, 11:19 AM   #2
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Can you post some sample images, preferably full size, for us to review? The Sigma 28-70 DG (assuming you are talking about Sigma 28-70mm F2.8 EX DG Lens Reviews - Sigma Lenses - Pentax Lens Review Database) is not the sharpest zoom from Sigma. The Sigma 17-50 and 24-70 are much more renown for their image quality. The price reflects this as well. If you try to compare the 28-70 to the 50 1.4 or the 50-135, you are bound to be disappointed. If you were to compare the Sigma 17-50 or 24-70 instead, they would fare much better.

As far as Tamron vs Sigma - it's price vs silent focusing in that range. The Tamron 17-50 performs very similarly in IQ to the Sigma. The Tamron 28-75 also performs very similar to the Sigma 24-70. It's just a price vs technology (silent focusing motor, quickshift, etc).
02-12-2013, 11:44 AM   #3
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Interesting, thanks. I may look into the Sigma 24 - 70 then.

Here is a picture from today that I'm very disapointed in.

It has had a bit of noise reduction and sharpening done in LR 3.

data on this shot is: ISO 1600 f 2.8 SS 1/320






Click to see full size.

Last edited by BethC; 02-12-2013 at 11:58 AM.
02-12-2013, 11:50 AM   #4
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If its under warranty why not send it to Sigma and see if they can adjust it, before trying another lens??

02-12-2013, 11:51 AM   #5
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To link the full size, please go to the flickr image page and select "Original". Then right click and copy the image URL.

On this forum, you can either direct link it as a link (just paste it), or if you do want it to show, use [.imgwide][./imgwide] tags (without the period in front). Using normal [.img] tag will show the full image, but make it very very big. Imagewide allows us to click the image to load the full size link.
02-12-2013, 11:54 AM   #6
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QuoteOriginally posted by JinDesu Quote
To link the full size, please go to the flickr image page and select "Original". Then right click and copy the image URL.

On this forum, you can either direct link it as a link (just paste it), or if you do want it to show, use [.imgwide][./imgwide] tags (without the period in front). Using normal [.img] tag will show the full image, but make it very very big. Imagewide allows us to click the image to load the full size link.
Thanks so much!! Now you can click to see it huge. appreciate the tip!
02-12-2013, 11:55 AM   #7
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QuoteOriginally posted by PBandJ Quote
If its under warranty why not send it to Sigma and see if they can adjust it, before trying another lens??
I bought this lens 3 years ago (I think... have to go check on that) so I don't think it's under warranty anymore unfortunately. and for all I know, it may be normal for this lens.
02-12-2013, 11:59 AM   #8
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The image does look a bit soft (and a little bit "bloomy"). The higher noise (ISO 1600) and noise reduction software can exacerbate the softness of a lens.

Did you use a hood with that shot? I have found that "bloom" sometimes come from the lack of contrast when not using a hood, and having lots of light coming from an angle.

Can you do some ISO 100/200 test shots with the lens at F2.8? It's difficult to tell if there is any missed focus in that image due to the subject and high ISO. If the lens is somewhat sharp but slightly mis-focused, it can just be a minor focus correction to make the lens acceptable.

02-12-2013, 12:03 PM   #9
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QuoteOriginally posted by JinDesu Quote
The image does look a bit soft (and a little bit "bloomy"). The higher noise (ISO 1600) and noise reduction software can exacerbate the softness of a lens.

Did you use a hood with that shot? I have found that "bloom" sometimes come from the lack of contrast when not using a hood, and having lots of light coming from an angle.

Can you do some ISO 100/200 test shots with the lens at F2.8? It's difficult to tell if there is any missed focus in that image due to the subject and high ISO. If the lens is somewhat sharp but slightly mis-focused, it can just be a minor focus correction to make the lens acceptable.
I can post it before noise reduction too.

Lets see, Yes I did use a lens hood and the light was coming into the room to the camera left (as I'm sure you can tell) so definetly from an angle. along with some lights on the ceiling. I inspected the image at full size to see if it missed focus too but coudln't decide where the focus fell at all, it all looks soft to me.

I will try some test shots at a lower ISO and re post.

thanks!
02-12-2013, 12:08 PM   #10
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No problem, I will try to keep an eye out on this thread. The image is a little difficult to figure out focus because if it front focused slightly, there's nothing really in front of her that we can use to judge by.

To test the lens, use a tripod, aim at a subject, use manual focus and live view, zoom to maximum zoom, and manually focus until it's as sharp as can be. This removes any focus issues from our review.
02-12-2013, 12:25 PM   #11
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Okay, so here it is with no noise reduction and no sharpening. Oh and I shot in RAW



click to see full size

and here is a test shot of my daughter I ran out and took. She was complaining, so dont mind the grumpy face LOL The shot is completely straight out of the camera, nothing done to it. and also shot in RAW at ISO 200 F2.8 (also click to see full size)

02-12-2013, 12:36 PM   #12
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That second shot of her face is very soft. It seems too soft, but I would still like you to try the manual focusing on a tripod test.

I don't think I have a lens that shoots that soft, even my Sigma 17-70.
02-12-2013, 12:44 PM   #13
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QuoteOriginally posted by JinDesu Quote
That second shot of her face is very soft. It seems too soft, but I would still like you to try the manual focusing on a tripod test.

I don't think I have a lens that shoots that soft, even my Sigma 17-70.
yeah, I was focusing on her camera right eye. it's definetly soft. I'll try the manual test on a tripod. thanks
02-12-2013, 01:58 PM   #14
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I think it's slightly front focused on the floor shot. Have you tried shooting in liveview to see if it looks sharper?
02-12-2013, 02:06 PM   #15
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Sigma 28-70mm f/2.8 EX DG Lens Review
QuoteQuote:
The Sigma 28-70mm f/2.8 EX DG Lens is very soft wide open - especially in the upper half of the focal length range. I don't consider the results useable at and above 50mm until the lens is stopped down to at least f/4 where the full frame corners are still soft. Performance at f/5.6 is better. This lens performs best at 28mm where the results are decent.
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.
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