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02-01-2016, 03:16 PM   #1
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Sigma 17-70 DC HSM Contemporary

I bought this lens After reading the in depth review. I'm using it with à Pentax K-50. I noticed à lot of chromatic aberration as soon has the sun comes in from an angle, even if it's not in the viewfinder. I would like to know if an body noticed anything like that.

Thank's.

Has you can see, the kit lens shows no abberrations or fringing, while the Sigma lens does.

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Last edited by ygagne1008; 02-01-2016 at 07:52 PM.
02-01-2016, 04:07 PM   #2
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C'mon man. You *gotta* post a picture if you really want help!

I don't own that lens, but it seems like I've only read good things about it.
02-01-2016, 05:22 PM   #3
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QuoteOriginally posted by ygagne1008 Quote
I noticed à lot of chromatic aberration as soon has the sun comes in from an angle, even if it's not in the viewfinder. I would like to know if an body noticed anything like that.
Welcome to the Pentax Forums!

I bought mine Spring of 2014 and it has been a smooth journey so far. The lens is free from both CA and Purple Fringing (they are not the same thing). As noted above, an example photo would be helpful.


Steve

Last edited by stevebrot; 02-01-2016 at 05:28 PM.
02-01-2016, 06:41 PM   #4
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It sounds like he's talking about flaring.

02-02-2016, 12:19 AM   #5
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From pictures you have posted-the is no CA or PurpleFringing at all IMO. Only lens flare.. Photos are not taken from the same angle,focal length, kit was focused on close range object, sigma on distant, and dusty window does not help you with flares-it works as dirty lens that bounces some light even more into your camera. First of all-use lens hood. Second-try to avoid taking pictures from behind other glass that is not parallel with you front lens(if you don't want to use it as flare/reflection screen).
02-02-2016, 03:12 AM   #6
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QuoteOriginally posted by Edgar_in_Indy Quote
It sounds like he's talking about flaring.
That was my thinking as well.
02-02-2016, 03:41 AM   #7
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As others have already said, I see no issue with CAs or purple fringing, but there is flare evident.

Do you have a UV filter (or any other filter) fitted to the lens? I'm generally a fan of UV filters for general walk-about protection on my lenses, but they can introduce (or significantly increase) flare issues. If I'm shooting into the light, or with the light just out of the frame, I always remove my filters...
02-02-2016, 10:37 AM   #8
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Bonjour M. Gagné (Yves?)

this is indeed flare, not CA. Pentax lenses are reputed as being better than most regarding flare, and that's a fine example. However, note that the focal lengths of the two images are different (or you framed differently) so that's bound to influence the result also.

Is there a lot of snow in l'Assomption?

02-02-2016, 05:33 PM   #9
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Pentax coatings have traditionally been superb. Even Zeiss licensed them, AFAIK.
02-02-2016, 07:46 PM   #10
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QuoteOriginally posted by bdery Quote
Bonjour M. Gagné (Yves?)

this is indeed flare, not CA. Pentax lenses are reputed as being better than most regarding flare, and that's a fine example. However, note that the focal lengths of the two images are different (or you framed differently) so that's bound to influence the result also.

Is there a lot of snow in l'Assomption?
Not a lot.

---------- Post added 02-02-16 at 08:00 PM ----------

QuoteOriginally posted by ygagne1008 Quote
I bought this lens After reading the in depth review. I'm using it with à Pentax K-50. I noticed à lot of chromatic aberration as soon has the sun comes in from an angle, even if it's not in the viewfinder. I would like to know if an body noticed anything like that.

Thank's.

Has you can see, the kit lens shows no abberrations or fringing, while the Sigma lens does.

I'm glad to know about the Pentax lens flare beeing better. I took out any kind of filter when shooting.
The problem with the flare problem is that, even with a small amount of sunlight creeping from the side, not even in the frame,
I get some kind of greenish flare on my pictures, making it really frustrating at times.
I'm shooting with a K-50.

Again thank you for your input.

But from reading reviews of this lens, I tend to believe I got a bad copy of it.
02-02-2016, 11:14 PM   #11
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QuoteOriginally posted by ygagne1008 Quote
But from reading reviews of this lens, I tend to believe I got a bad copy of it.
Are you using your hood? Any lens will flare with the sun in the frame and most will if a strong light outside the frame strikes the front lens element. The 17-70 has an exposed front element and consistent use of the hood will pay a dividend. Based on your examples, I don't see that your lens exhibits an unusual amount of veiling flare.


Steve
02-03-2016, 05:34 PM   #12
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My Sigma 17-70C is a bit prone to flare but my 18-55 kit lens flares a lot also. The angle of the two shots into the sun isn't exactly the same and that is likely the reason one lens shows more flare. Shooting into the sun through a window isn't the best way to do a lens test. My DA 15 is my most flare resistant lens and it would likely flare some attempting that shot.
02-03-2016, 05:46 PM   #13
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QuoteOriginally posted by ygagne1008 Quote
But from reading reviews of this lens, I tend to believe I got a bad copy of it.
Honestly, if you'd reported problems with focusing, or lack of sharpness in a specific area of the frame, I'd believe that might be a "bad copy", but for one example of a lens to flare very differently to another is most unusual. Did you buy it used? I'm wondering if there's a chance that someone has over-cleaned the front or rear elements and removed some of the coatings... It just doesn't seem like something that would be due to sample variation between new lenses...
02-04-2016, 05:59 AM   #14
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QuoteOriginally posted by stevebrot Quote
Are you using your hood? Any lens will flare with the sun in the frame and most will if a strong light outside the frame strikes the front lens element. The 17-70 has an exposed front element and consistent use of the hood will pay a dividend. Based on your examples, I don't see that your lens exhibits an unusual amount of veiling flare.


Steve
Yes i always have the hood on. Of course the angles may be differrent in those shots, but i took a bunch of them, and some at the same focal lenghts and angles. The Pentax kit lens always shows less or no flare at all. Of course i'm satisfied with the quality of the Sigma lens, i've taken sharp shots and it's good on all of it's aperture settings,which is not the case with the kit lens.
So i'm taking it back to the seller who will send it back to Sigma for testing.

I also took shots inside with different lighting conditions and again the Pentax is better.This may depend on the quality of fabrication of the lens, more glass, more air gaps may flare more, i'm not a specialist.

So when the lens come back, i will post a short comment, to make a long story short.

I really appreciate all the input i got from everyone, and i'm glad to be in this forum.
02-04-2016, 12:21 PM   #15
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I have this lens and love to take sunset pictures. I cannot use the Sigma for these photos as it flares out the yin-yang. I rely on an older Tamron zoom or Pentax 50mm to take sunset pics - neither one flares like the Sigma does.
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