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05-31-2017, 09:31 PM   #1
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The Sigma 10-20mm F4-5.6 EX DC on a Full-Frame (K-1)?

My dad is kindly offering me his Sigma 10-20mm F4-5.6 EX DC. However, he's coming from a APS-C world and I'm now FF with the K-1. I realize the 10-20mm is gonna translate to 16-32mm or so on the K-1 (crop mode), I just wondered if anyone has used this lens on a FF and how it performed? My dad and I live on polar opposite sides of the globe, before we pay for postage there and back I just wanted to get some impressions from any other users. Far be it for me to knock back a free lens but if the general consensus is that it's awful then I think I'll kindly pass on the offer (and save us postage costs).
Thus far my experience with non FF lenses on the K-1 have been a little disappointing (DA 21mm 3.2). Having said that the DA 50 1.8 does perform fantastically... :|

I'll have a gander on flickr for pics, just wondering if anyone here can produce an example of the kinda vignetting i'm likely to see with it paired on the K-1.

Cheers,

Bruce

05-31-2017, 10:17 PM   #2
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The version I have is Sigma 10-20mm F3.5 EX DC, works between 14 and 20mm in K-1 FF mode.
06-01-2017, 02:28 AM   #3
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I have tried it once, at 20 it was fine but at 10 it did vignet when shooting in full frame. I'm at work now but when I get home if nobody else has posted pictures I'll put some up.
06-01-2017, 03:39 AM   #4
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QuoteOriginally posted by KiloHotelphoto Quote
I have tried it once, at 20 it was fine but at 10 it did vignet when shooting in full frame. I'm at work now but when I get home if nobody else has posted pictures I'll put some up.
I would really appreciate that, it doesn't have to be a fancy shot, just to get an idea would be really good

In other regards, do you find it performs well? such as sharpness, bokeh and the rest? I noticed massive improvements for example when I stepped up from using the D FA 100mm 2.8 from the K-50 to the K-1, the increase in bokeh, sharpness and overall quality was very significant. I'm curious if just having the Sigma 10-20mm on a FF (K-1) improves things?

06-01-2017, 05:26 AM   #5
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Hi:

I tried the Sigma 10-20 f/3.5 on my K1 and also my K3.

Long story short, there was vignetting at all focal lengths on the K1 (greater at the wide end, less so at the narrower end). Having said that, there was additional usable space outside of the APS-C area before the lens got really soft and faded into vignette.

I compared the same images on my K1 and K3 and found that the K3 provided better images of the edge field of view when comparing like image to like image. For example, if I used 18mm on the K1 and 12mm on the K3 and shot with both cameras on a tripod, the field of view would be essentially the same, but the K3 provided better images at the edges. It may be the lens (with the wider end of the lens being softer, i.e., 18mm on the K1 is the same field of view as 12mm on the K3, but at 18mm the edge performance may be better) or it may be the newer in body stabilization on the K1 which caused edge degradation, but I found that edge performance, when comparing like image to like image, better on the K3.

This is not to say you will not get additional usable space with the Sigma 10-20 and then you can crop when the lens begins to get really soft.

Kengoh, a very experienced user on this forum, has the 10-20 (I forget if it is the variable aperture or the 3.5). He has posted some amazing images. You might want to send him a message and get his advice.

Good luck.

Last edited by candgpics; 06-01-2017 at 06:42 AM.
06-01-2017, 07:26 AM   #6
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i tried this on my PZ1, ok its film not digital. the lens noticibly vignets to at least 13mm, even when looking at the viewfinder. there may be exposure fall off in corners in the 14-15mm range but this is not uncommon even for full frame lenses especially wide open. note my k50/1.4 has about 1-2 stops exposure fall off in the corners, even on a cropped sensor
06-01-2017, 02:56 PM   #7
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QuoteOriginally posted by candgpics Quote
Hi:

I tried the Sigma 10-20 f/3.5 on my K1 and also my K3.

Long story short, there was vignetting at all focal lengths on the K1 (greater at the wide end, less so at the narrower end). Having said that, there was additional usable space outside of the APS-C area before the lens got really soft and faded into vignette.
Yeah thats my experience with the 10-20 f3.5 too. At first try it looked really promising from 14-20 on the K-1 status screen but then:
* Mushy corners and edges
* Variable vignetting (depending on where the SR sensor was at the time, I see black edges).

I can get some more image than I get with APS-C but not enough for me to bother.
06-01-2017, 03:23 PM   #8
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Vignetting is bad as the DA21mm on the K-1?



06-01-2017, 03:35 PM   #9
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I have it and found it unusable on the K-1, Bruce.

I now have the DA12-24 and it works from 17mm up.

06-01-2017, 05:15 PM   #10
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Sorry it took me this long. I went out after work and took 5 pictures, 10,12,14,18,20mm in TV mode. I did lens correction in Lightroom and just did the auto enhance and converted them to jpeg.

Hope this helps you out.
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06-01-2017, 05:25 PM   #11
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Hi:

Vignetting at the widest end is that bad or slightly worse--it clears up a fair amount by around 14mm, but is always present to some extent. I think the bigger issue is that the quality of the image outside of the APS-C area starts to degrade somewhat quickly. So, you will get some additional image area, but not as much as you likely will want.

For the price of postage--perhaps up to $75 ($US)--I say go for it. If you were looking to purchase it outright than I would suggest Clackers' idea of looking for a DA 12-24. I have heard from others that at about 17mm or 18mm the image is quite good on the K1.

I used to own the Sigma 10-20 variable aperture model you father may send you (and I liked it). I later bought the f/3.5 version after I sold the variable aperture version and wanted a wide zoom again. At full price the f/3.5 lens just did not work for me on the K1, but if postage is reasonable I think it would be worth it so long as you know you will have to do some cropping.
11-06-2018, 02:08 PM   #12
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Resurrecting an old thread..

In square 1:1 mode this looks workable (I stole screenshots for 20mm and half of 18mm tests).
Could someone verify that for me? Thanks!

In the meantime this will work nicely for K∙50 and my 43 kit, for a decent price; how nice.
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11-07-2018, 04:42 PM   #13
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I have tried this lens on my K1-II a few times, and I was really disappointed. Vignetting all over the line and poor image quality. On my K5 it was my favorite lens: sharp pictures, bright colours. I don't know why but on my K1 it is really bad. I never use this lens again. I'm waiting for black Friday, for buying the Irix 15 mm.
11-12-2018, 05:57 PM   #14
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My copy of this lens isn't even working properly on the K-1. AF doesn't work, Exposure is all wrong. Lens works perfectly on the KP however.

My advice is to forget about this lens for any FF work, it's really not usable.
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