lucki Posted January 28, 2014 Share Posted January 28, 2014 Hi, I was wondering whether anyone has had similar experiences to myself with this new lens from Sigma. Many people have referred to it as '3 primes in 1' but when I have tested it I have found it can be a bit soft compared to my better prime lenses. I have tested it on my GH2 with a Metabones Nikon to M43 Speed Booster and a Metabones Nikon to M43 basic adapter against my average to stronger primes. The following comparison illustrates what I mean. The Sigma image is at 18mm using a standard Nikon to M43 adapter, the Voigtlander at its fixed focal length of 17.5mm. Both ISO 400, F2, 1/50, NR off, AWB. They are pretty close but I feel the Voigtlander edges it. http://i32.photobucket.com/albums/d7/lucki231/Sigma18-35mmzoom_zps91755d8b.jpg~original http://i32.photobucket.com/albums/d7/lucki231/Voigtlander175mm_zps67a7484c.jpg~original What have other people's experiences been with the Sigma thus far? Can it really substitute for a set of good primes? Quote Link to comment Share on other sites More sharing options...
Julian Posted January 28, 2014 Share Posted January 28, 2014 The only difference I see is the depth of field. The Voigtlander is focussed more to the front, so the bag in front is sharper. The sigma isn't as sharp there because the area is out of focus. That doesn't have anything to do with the sharpness of the lens though. What differences do you see? Btw, I can't see the files in original format, just 1.024px × 577px, or is that what you uploaded? Try focussing on a brick wall or something, so you can see the corner sharpness. I don't know how the Voigtlander performs in this aspect, but the 18-35mm is excellent. Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted January 29, 2014 Administrators Share Posted January 29, 2014 Crap test, focus point is way off. The Sigma is focussed on the red cushion and the Voigtlander on the yellow ribbons almost 30cm further forwards. Totally clueless and therefore - Null and void :) The Sigma 18-35mm is the sharper lens, especially if you're gonna be combining it with a decent adapter - like Speed Booster. I will do a test showing that it is as sharp as the very best primes, even wide open. Julian 1 Quote Link to comment Share on other sites More sharing options...
lucki Posted January 29, 2014 Author Share Posted January 29, 2014 Thank you to the first responder. You are correct that the depth of field appears different for each lens. The Nokton seems to front focus whereas the Sigma back focuses, the actual depth of field being the same. I will test on a brick wall as you suggested. Regarding the second response, 'crap test' and 'clueless' are hardly necessary. I was asking a question based on my limited experience to get some advice from people with better knowledge about this lens. In fact, I came on this site because I previously respected the author and even paid $30 for his GH2 shooting guide. I won't be doing that again. Your overreaction is mean spirited and 'clueless'. I'm sure you can out-test me if you want to. I set focus correctly. And this is precisely my problem, I set focus on exactly the same point on the green and white cushion in both images. This is an issue I have been having repeatedly when comparing the lenses. Thanks to the first responder. My sigma seems has front focus problems, which can happen with a bad copy of the lens. This issue is all over the internet and the dealer I bought it from suggested it is causing the problems. Quote Link to comment Share on other sites More sharing options...
lucki Posted January 29, 2014 Author Share Posted January 29, 2014 Please also ignore the 1024 resolution image, there is a download link on the bottom right hand corner where you can access the full resolution version. Thanks again. Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted January 29, 2014 Administrators Share Posted January 29, 2014 Are you setting focus then stopping the lens down? Back focus / front focus issues can only happen when you change the aperture. Quote Link to comment Share on other sites More sharing options...
maxotics Posted January 29, 2014 Share Posted January 29, 2014 Hi lucki, Andrew is extremely passionate about this stuff and he seems to work 23 hours a day. Anyone who has spent any time on this forum will, at some point, feel a bit insulted by him. My guess is he could say the same thing about us ;) That he answered your post is the highest compliment of all. He wouldn't if he wasn't interested. That he said he might do tests to help with your question is another plus. As far as I'm concerned, Andrew's tests are second-to-none. They are just phenomenal. Sorry you got off to a bad start. Hope you stick around for a bit! Quote Link to comment Share on other sites More sharing options...
Axel Posted January 29, 2014 Share Posted January 29, 2014 An equally unscientific observation: It seems the Sigma is too sharp for my Pocket when stopped down to f3.5 (or so I guess, two stops on the SB): A lot of terrible moire (on brick walls, roof tops and thin lines, all usual suspects, weirdly colored in raw, but also, a little less, in ProRes). This magically disappears once I open the aperture and limit the exposure with the ND fader. Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted January 29, 2014 Administrators Share Posted January 29, 2014 Hi lucki, Andrew is extremely passionate about this stuff and he seems to work 23 hours a day. Anyone who has spent any time on this forum will, at some point, feel a bit insulted by him. My guess is he could say the same thing about us ;) That he answered your post is the highest compliment of all. He wouldn't if he wasn't interested. That he said he might do tests to help with your question is another plus. As far as I'm concerned, Andrew's tests are second-to-none. They are just phenomenal. Sorry you got off to a bad start. Hope you stick around for a bit! Didn't realise it was his test. "Crap" was a bit rude in that light. But alas, there's the problem with the internet in a nutshell :) Quote Link to comment Share on other sites More sharing options...
maxotics Posted January 29, 2014 Share Posted January 29, 2014 An equally unscientific observation: It seems the Sigma is too sharp for my Pocket when stopped down to f3.5 (or so I guess, two stops on the SB): A lot of terrible moire (on brick walls, roof tops and thin lines, all usual suspects, weirdly colored in raw, but also, a little less, in ProRes). This magically disappears once I open the aperture and limit the exposure with the ND fader. Absolutely, I want primes for photography, but video (am I crazy?) I can't see as much a difference and, because you're really dealing with so few pixels (compared to photos) the moire risk is not worth the sharpness. The only reason to use primes in video, for me, is to maximize the aperture you can shoot at. But if you have a zoom with metabones, why limit yourself to one focal length? Anyway, I'm curious about that question, for any lenses? Quote Link to comment Share on other sites More sharing options...
maxotics Posted January 29, 2014 Share Posted January 29, 2014 Didn't realise it was his test. "Crap" was a bit rude in that light. But alas, there's the problem with the internet in a nutshell :) On another forum, which you'll be able to figure out ;) a member said he didn't want to post his photos (on the forum) because they were meant for large-prints. The "personal forum expert" kept saying "a good photo is a good photo no matter what it's displayed on." I said you have to respect the artist's choice of medium, no matter how uptight it might seem to you. But the expert kept telling this guy he didn't know what he was talking about, all the good photographers he knew said it didn't matter. The forum has really gone off the deep end. Quote Link to comment Share on other sites More sharing options...
lucki Posted January 30, 2014 Author Share Posted January 30, 2014 Sorry for the late reply. I'm in Melbourne and posted quite late at night. I understand where the advice was coming from now and can appreciate you were discrediting the test for my benefit, not to dismiss me out of hand. Andrew is right, the internet makes it easy to overlook things and I was mistaken when I perceived his response as criticism. I appreciate everyone's advice. Thanks for the follow-up Andrew, I could easily have made the mistake of stopping down after setting focus and my new humble tests confirm something was likely wrong with my method as the Sigma performed a lot better. I have posted links to them below. The high resolution files can be downloaded from a link on the side. Unfortunately it's way too hot and sunny here at the moment to shoot a brick wall (30-43 degrees celsius the last few weeks), so I grabbed a random newspaper instead. Please note these tests were with a standard Metabones Nikon to M43 adapter, not a speed booster, as I wanted to test the lens without additional glass. The adapter seems to cut a little light so wide open at F1.8 it is about as bright as the Voigtlander at F2 which is why the images are at slightly different apertures. Disclaimer: these tests are designed to help me make decisions about my kit because I have seen no comparisons with the Voigtlander 17.5mm. I hope they might be of use to others but they are not professional tests! Test 1 focus was set to the smaller black and white group photo http://i32.photobucket.com/albums/d7/lucki231/Test1Sigmaat18mmF18ISO400_zps9333702a.jpg~original http://i32.photobucket.com/albums/d7/lucki231/Test1Voigtlander175mmF2ISO400_zpsa0b08ecd.jpg~original Test 2 focus was set on the buckle of the bag http://s32.photobucket.com/user/lucki231/media/Test2Sigmaat18mmF18ISO800_zpsaea451e0.jpg.html http://s32.photobucket.com/user/lucki231/media/Test2Voigtlander175mmF2ISO800_zps1706c1d7.jpg.html Test 3 focus was set on the middle of the green and white cushion. An attempt to replicate my earlier test. It appears there was something off with the earlier one as the Sigma is a lot better here. http://i32.photobucket.com/albums/d7/lucki231/Test3Sigmaat18mmF18ISO400_zps99d8a5b5.jpg~original http://i32.photobucket.com/albums/d7/lucki231/Test3Voigtlander175mmF2ISO400_zps779a4cf9.jpg~original Hopefully these comparisons are of some benefit. Thanks for all the input. Julian 1 Quote Link to comment Share on other sites More sharing options...
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