GH2 Sigma 20mm F1.8

Aki_Hartikainen said:
About the focus ring turning to opposite direction, this is a Nikon feature. Most Nikon lenses have the focus and aperture rings running to the opposite direction from Zeiss and others. A 3rd party lens with Nikon mount often follows this principle. Same lens with other camera mount may have rings rotating the usual way.
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While this is true of many third party lenses, none of the focus rings on the Nikon F-mount Sigma lenses I've used have rotated in the Nikon direction. From what I can tell, all Sigma lenses rotate in the Canon/Lumix direction. JKrepner's Zeiss is probably a ZF model, which rotates in the Nikon direction. Zeiss ZE lenses are made to rotate in the Canon direction.

I have the Sigma 20mm f1.8, and I like it very much. It is a very video-friendly lens, with an outer barrel that neither extends nor rotates, and its focus ring has hard stops, unlike the HSM focus ring on the Sigma 30mm and 50mm f1.4. I've used Sigma 20mm, 24mm, 28mm, 30mm, and 50mm primes, and they all mate very well with the GH2. Auto-focus on the 30mm and 50mm Four Thirds models is very slow, however, but works well in low light. The 24mm and 28mm are very close-focusing macro lenses, and their barrels extend slightly as a result.

The weak side of all the Sigma primes is soft corners at wide open apertures. The 30mm is the softest, as it's not designed as a full-frame lens. The 20mm is also very soft at f1.8, but is much sharper at f2.8. In terms of sharpness, I'd rank them best to worst as 50mm, 28mm, 24mm, 20mm, 30mm. The ones I decided to keep are the 50mm, 28mm, and 20mm.
 
That's interesting and good to know. I saw the Sigma 20 mm f1.8 on eBay, and the Nikon mount versions offered seemed to be lower cost than Canon mount versions. But now that it's confirmed that it's the Sigma that focuses to the usual direction, there should be no difference in operation for Nikon or Canon mount version.
 
I guess not everyone is enthusiastic about this lens. A dissenting voice:

Sigma 20mm f/1.8 EX DG Lens Review

A couple of quotes:

"Unfortunately, I consider the Sigma 20mm f/1.8 EX DG Lens to be unusable at f/1.8 unless you are looking for a soft-focus effect. This lens is one of the softest I've seen wide open. Realistically, this will be an f/2.8 lens to most people as the center does not become decently sharp until this aperture. But wait - there goes the Sigma's uniqueness advantage for now there is a direct Canon counterpart, the Canon EF 20mm f/2.8 USM Lens that costs about the same price (price at times is another reason to buy third party lenses)."

"Sigma's own MTF chart even indicates miserable performance outside the center. The corner problem seems to lie in the Sigma having a significantly curved plane of sharp focus - which I suppose no longer qualifies as a "plane"."

"I don't know what they are looking at, but the Sigma 20mm f/1.8 EX DG Lens turned in some of the strongest vignetting I've seen - 5 stops in the full frame corners at f/1.8."

"The Sigma 20mm f/1.8 EX DG Lens is very flare-prone - more so than the Canon 20 and much more so than the Canon EF 16-35mm f/2.8 L USM Lens. Keep the sun behind the large 82mm Sigma objective lens."

"In conclusion, I recommend not buying the Sigma 20mm f/1.8 EX DG Lens. Sorry Sigma, this one is a dud."

Ouch.

I have no opinion, because I've never used this lens, but I got interested after all the raves here, so I went around looking for reviews, and this one was one of the first.

The photozone.de review is not as bad, but not really good either. These above are the first two reviews of the lens when I googled. Maybe sample variation?
 
I don't think so. You have to take into consideration that these are photographers. They're talking stills, not video. And on a full frame camera.

On dslrs most glass won't really make a huge difference in the sharpness category. I mean you either have to have brand new digital glass (panasonic) or some ultra primes (which are too sharp beyond F4 for gh2, speaking from experience. )

The wide open aperture won't be sharp on the sigma at night, but by 2.8 it'll be decent. Plenty decent. Whatever you aren't getting from it wide open you can put back in post. But you can't make up for a slow aperture when you have limited data.
 
So far the only lower cost lenses I have tested that can be considered somewhat sharp below f2.8 are the Russian Helios 44-2 58 mm f2, Minolta MD Rokkor 45 mm f2 and Minolta MD 50 mm f1.7. Everything else has needed to be stopped down for adequate sharpness, but my experience with newer glass is limited. I have yet to get that razor sharp large aperture cinema look from any of the legacy lenses, so I guess there is a reason for very expensive cinema lenses. They are built to perform at large aperture, whereas still photographers can live with a bit longer exposure.

Speaking of full aperture, here is a lens test from last summer. At the bottom of the page are samples from a Minolta MD 50 f1.7 at full aperture taken from Lumix GF1 mjpeg video: http://www.fourseasonshd.com/cgi-bin/csvsearch.pl?db=db4&tp=tp8&search=filmiluuk1
 
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I will say that the two Olympus f2 zooms are damned sharp wide open. F they weren't so huge and loud, as well as hard to use...


Well if they were built differently then I'd try to buy one. Lol.
 
There is also a Minolta 35 mm HH f1.8 legacy lens that could be adequately sharp at full aperture. They move fast if one is available somewhere. Also, since the old Russian 40 dollar lens was nearly adequately sharp at full aperture (very cinematic lens), I plan to try another Soviet classic, the Mir 24N f2 (which is actually ~35 mm focal length). They are a bit more expensive, though.

Then there are the Leicas, of course. They might well be sharp at f1.4 and f2.

I have no experience in modern automated glass, besides a few Panasonic lenses. I have the 14 mm f2.5, but it does not see any action. I must admit I don't much believe in modern glass, the coatings are too powerful and remove any internal reflections that are part of the film look.
 
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I hope the Sigma 20mm F1.8 is better than the 28mm F1.8 version.


Sigma 28 mm f/1.8 EX DG Aspherical Macro
Image resolution :
3061_rozdz1.jpg


Panasonic G 20 mm f/1.7 ASPH.
Image resolution :

3235_roz.jpg
 
lpowell said:
While this is true of many third party lenses, none of the focus rings on the Nikon F-mount Sigma lenses I've used have rotated in the Nikon direction. From what I can tell, all Sigma lenses rotate in the Canon/Lumix direction. JKrepner's Zeiss is probably a ZF model, which rotates in the Nikon direction. Zeiss ZE lenses are made to rotate in the Canon direction.

I have the Sigma 20mm f1.8, and I like it very much. It is a very video-friendly lens, with an outer barrel that neither extends nor rotates, and its focus ring has hard stops, unlike the HSM focus ring on the Sigma 30mm and 50mm f1.4. I've used Sigma 20mm, 24mm, 28mm, 30mm, and 50mm primes, and they all mate very well with the GH2. Auto-focus on the 30mm and 50mm Four Thirds models is very slow, however, but works well in low light. The 24mm and 28mm are very close-focusing macro lenses, and their barrels extend slightly as a result.

The weak side of all the Sigma primes is soft corners at wide open apertures. The 30mm is the softest, as it's not designed as a full-frame lens. The 20mm is also very soft at f1.8, but is much sharper at f2.8. In terms of sharpness, I'd rank them best to worst as 50mm, 28mm, 24mm, 20mm, 30mm. The ones I decided to keep are the 50mm, 28mm, and 20mm.
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lpowell, you are correct and thanks for the clarification. I'm now memorizing this.... Zeiss ZF and most (or all) Nikon made glass rotates the "Nikon Way" and Zeiss ZE, Sigma 20mm, and Lumix all go the "Canon Way". Got it. Ok, so then I guess I need to either go all ZF + Nikon or swap out ZF for ZE. It isn't a terrible deal but there are moments that missing focus can cost money/time so having all roate the same way seems logical from a muscle memory perspective. What direction do other brands such as Oylmpus and Minolta rotate?

I'm looking for a couple of longer lenses (I have 20, 28, 50) and I'd like a 85mm or 100mm as well as a something in the 150mm+ range. Not so much for far away filming but for portrait type shots with shallow DOF. The Minolta 85mm MD Rokkor 1.7 seems like the right ticket to fill out the 85/100mm range. I found one used for about $290 that's in fair shape. Do you, or anyone reading this, know if the Rokkor's are internal focusing? If the filter ring rotates I'll go nuts with my Vari-ND filter spinning everytime I change focus.

I'd like to get the 100mm Zeiss ZF/ZE but $1800 is a bit hard to swallow and Zeiss makes nothing longer (short of Cine) that I know of. I saw some shots from a Red shot on 300mm lens that started this quest for longer glass. I get the sense that many of the affordable 200-300mm photo lenses are built more for shooting action and wildlife where one doesn't want super thin DOF. Does anyone else have thoughts on that and what works well in the longer mm, range?

Sorry for all of the add on Questions to the original poster's question, but I figure this is all fair game since this is a nice discuession on GH2 glass and Kholi already bought his lens.

Thanks
 
Of the MD 85 mm lenses the f2 version has the best sharpness, contrast and colors: http://www.rokkorfiles.com/85mm%20Page%202.htm

I am fairly certain that other than the zoom lenses, all MD lenses have non-rotating front element. They do not have internal focus in the sense that the external dimensions won't change when focusing. If you are already interested in MD lenses, the longer ones could come from there too. 135 f2.8 is a great low cost lens, and the 200 f2.8 is well known for good image. Other than perhaps Leica, I am not sure I would drop a thousand on a lens right now when beautiful legacy glass can be had for little money in many cases.

I had a 90 mm M-Rokkor f4 and it was the best lens I have seen. Obviously not fast enough for many purposes, but the images were truly vivid and alive. http://www.fourseasonshd.com/cgi-bin/csvsearch.pl?db=db3&tp=tp10&search=mrokkor90f4sn2005303
 
joe1946 said:
Panasonic G 20 mm f/1.7 ASPH.
Image resolution :

View attachment 48910
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The Panasonic 20mm f1.7's numbers are artificially enhanced by the sharpening used the firmware distortion correction. Unfortunately, that also enhances the aliasing artifacts, which is what gives that lens its videocam look. I'd like the lens a lot more if there was a way to turn off the firmware enhancement!
 
Got the 20/1.8, it is not 82mm thread it's 77mm. Thank goodness.

Fast, close focus is great, distortion's not as crazy as I thought it would be. Going to play with it today and this weekend.

OldCorpse, after thinking about it and playing with my crap Tamron 17-35/2.8, I would say that you're probably served to at least have something in the 14-17mm range. 12 IMO is still too much distortion but that's up to taste.
 
Kholi thanks for the feedback. Lemme know what you think of the 20/1.8 - I'm relieved to hear it's got 77mm thread... I just ordered the 77mm heliopan variND, and was thinking whether I should have gone for the 82mm, but figured not enough lenses are 82mm thread to deal with step up rings on an 82mm filter... so often you'd have to stack them which sucks.

As to distortion, I still want to test the 17.5/0.95 - I can't wait :)
 
Kholi, I just picked mine up from the post office as well. Gonna play with it a bit tonight and tomorrow.
 
Kholi said:
Got the 20/1.8, it is not 82mm thread it's 77mm. Thank goodness.
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I didn't know they even made different threads... mine is 82 and everything I've read on it mentions the same. My 82mm vari that I ordered is still on it's way, so can't really use this for all my purposes just yet. I wonder why they even make this in 82mm.

Edit: wow, I'm impressed, can't believe how non-existent the distortion is. It's got that same sigma mojo that my 30 1.4 has. As my first 'real' wide that's not a c-mount or wide angle adapter... this is like a breath of fresh air. I don't think I've stopped grinning for the last hour. This is a VERY fine lens.
 
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I knew there was a simple explanation for why this lens A) didn't distort as much as people claimed. B ) wasn't as soft wide open as people said. C) There was a 77mm thread instead of an 82mm

This is the 28/1.8. Sent the wrong one.

LOL

But I must say this 28's a pretty nice lens as well.








Time to call Amazon... and stop staying up so late.
 
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Kholi said:
I knew there was a simple explanation for why this lens A) didn't distort as much as people claimed. B ) wasn't as soft wide open as people said. C) There was a 77mm thread instead of an 82mm

This is the 28/1.8. Sent the wrong one.

LOL

But I must say this 28's a pretty nice lens as well.

Time to call Amazon... and stop staying up so late.
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Oh man lol! I've done a few of those late night orders, mostly on ebay where people don't exactly want to take your returns... haha. I was thinking... 77mm & 82mm for the same lens...? I thought at one time about getting the 28mm, but there's a few vintage primes that have that area covered for cheaper. I'm gonna put up a short test with it tomorrow, loving it so far.
 
Messing with the Canon 28/1.8 more I'm glad we have it. Definitely has a little more mojo.

Still.... want that 20/1.8. Should be here Wednesday. What a headache. xD

Post up some footages.
 
Hey, Kholi, I have that 28/1.8 Sigma in a Nikon mount - I personally love it on the D300... when I can get it away from my wife, that is :) It's also a macro, though you do have to be pretty close. And bummer about the thread size on the 20/1.8 :(

Make sure to post some footy of the 20 - I'm especially interested in how it behaves wide open in low light... but please move it at least a little :) I'd like to compare the IQ to the Panny 20/1.7.
 
Kholi said:
Messing with the Canon 28/1.8 more I'm glad we have it. Definitely has a little more mojo.

Still.... want that 20/1.8. Should be here Wednesday. What a headache. xD

Post up some footages.
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I almost bought the nikon version of the sigma 20mm 1.8 last year, but ended up with the pancake instead. I'd blind buy the Sigma now since I could share it with the scarlet, so I'm interested in your impression of the lens.
 
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