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01-14-2010, 02:36 PM   #1
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Sigma 30mm/1.4 VS any other f1.8 Sigma primes

Anyone here own both the Sigma 30/1.4 and either of the three sigma f1.8 lenses (20, 24, 28) and what they think of their performances wide open at close distances and infinity focus.

Is the 30/1.4 significantly better ?

Thank you

01-14-2010, 02:45 PM   #2
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I don't *own* both, but I've used the 30/1.4 and the 20/1.8 and 28/1.8. I can only say that my 30/1.4 didn't always focus properly, especially at infinity wide open, while the 1.8s always nailed it. The MFD of the 30/1.4 is also really disappointing *if* comparing it directly to the f/1.8 series.
01-14-2010, 03:08 PM   #3
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Heehee. I just got a 28/ 1.8, now. ...from somewhere.

Only had it for a week or so, but I'm quite pleased with the optical performance: the 30 has kind of mixed reviews, and a rep for being a lot sharper in the center than edges: this wouldn't help me a whole lot, cause I like to put my subjects off-center when I use a lens this wide, (Yeah, 28mm equivalent is 'this wide' to me. )



It's really quite big, (that's the only drawback, to my purposes: it's just kind of imposing to subjects. But, then again, it's a full-frame 1.8 wide angle for film, too, heheheheh. ) I get good sharpness, and it certainly does AF well. I don't know that I've tried it wide-open at infinity, yet, though: so far it's meeting with my unqualified approval.

Last edited by Ratmagiclady; 01-14-2010 at 03:15 PM.
01-14-2010, 03:10 PM   #4
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Thank you.

The MTF figures at the sigma website shows extreme softness towards the edges of the 1.8's, and being smaller and 2/3rd stop faster the 30 seems inviting. If it is just the focusing it could be sample variation and I'll get it at a reputable dealer with a good return policy, and MFD doesn't matter much to me.

01-14-2010, 03:22 PM   #5
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QuoteOriginally posted by pcarfan Quote
Thank you.

The MTF figures at the sigma website shows extreme softness towards the edges of the 1.8's, and being smaller and 2/3rd stop faster the 30 seems inviting. If it is just the focusing it could be sample variation and I'll get it at a reputable dealer with a good return policy, and MFD doesn't matter much to me.
Sounds like a plan, there, if you can try one out. I presume that all the controversy about the 30 just means there's bad samples out there. I notice you have that FA 24/2, as well, and if you're planning to keep that, the 30 might prove more useful to have around to choose from.
01-14-2010, 03:43 PM   #6
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QuoteOriginally posted by Ratmagiclady Quote
Sounds like a plan, there, if you can try one out. I presume that all the controversy about the 30 just means there's bad samples out there. I notice you have that FA 24/2, as well, and if you're planning to keep that, the 30 might prove more useful to have around to choose from.
I am also hearing rumors of a Pentax 30/1.4 too......with the 24/2, it's really only the sigma 20/1.8 or 28/1.8, but those two are giants.

Last edited by pcarfan; 01-14-2010 at 03:56 PM.
01-14-2010, 04:10 PM   #7
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I had the 28 1.8 in Nikon mount for a couple days, but it had a FF problem, so I sent it back.

In Nikon land, it's regarded as a good alternative to the uber-$$$ Nikon 28 1.4, and is thought of as having very nice bokeh for a 28.

It is a big lens for a 28mm prime, but it does give you 1.8.

Here are a couple snaps from mine:


f/2.5, f/1.8

f/1.8
01-14-2010, 04:14 PM   #8
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I think the Sigma 1.4/30 has gotten a bad rap partly because consumer dslr AF tolerances are too lax to support the lens speed wide open; thus front and back focus issues. The lens is already legendary sharp; at f/1.8 it is sharper! The barrel distortion correction in this lens is not linear; pp correction is problematic.

I don't own the other Sigmas. From optics viewpoint, as angle of view increases, the lens must refract at greater angles, the circle of confusion grows, lens sharpness decreases. Those principles indicate the 1.8/28 is less sharp than the 1.4/30 at f/1.8, the 1.8/24 is less sharp than the 1.8/28, and the 1.4/20 is least sharp, wide open.

01-15-2010, 01:07 AM   #9
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The Sigma 20/1.8 is a bit soft wide open, this is correct, but you can see this only in 100% view. Already at f2.8 is resolves better than the sensor of the K20.
Keep in mind that it is a full frame 20mm lens!
I consider it a very good lens.

The 30mm is a completely different beast. As Klaus from Photozone puts it: "The Sigma AF 30mm f/1.4 EX DC is a lens with a mission - to achieve the highest center resolution there is without caring too much about the rest."
01-15-2010, 05:30 AM   #10
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Thank you for all the responses. It looks like I just might wait for the Pentax announcements until the end of second quarter before I make a decision.

I am happy with the 24/2, and the 35/2. I wanted something faster, but at the same time not as bulky as the 24 and be a wideangle (wider than the 35)....yeah! a lot to ask, but I am willing to compromise, as what i want is impossible. If I have to compromise a bit, I might, but now that I think about it, 1/3 stop advantage over the 24 isn't much, especially going longer and keeping the size the same. 1 full stop advantage will bring something significant to the table, but I am not entirely satisfied with that either...waiting for now seems to make the most sense.

Let's see what Pentax can do, and hope my funds are still available for me and not used up for other trivial household stuff by then..............

P.S: Ah! Wieland you are calling the 20 a great lens (too early, and I thought it was the 28), now that is very interesting. The photozone review of the Canon mount gives abysmal resolution figures wide open, let me investigate it further...this lens, if it indeed is stellar will be a no brainer......

Last edited by pcarfan; 01-15-2010 at 05:42 AM.
01-15-2010, 06:03 AM   #11
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QuoteOriginally posted by pcarfan Quote
I am also hearing rumors of a Pentax 30/1.4 too......with the 24/2, it's really only the sigma 20/1.8 or 28/1.8, but those two are giants.
Hrm, yeah, it does seem a next logical step for the DA* line, that. Maybe even a 28, to go for the 'true normal' thing. (I wonder about maybe an FA 31 all dressed up in DA* case. ) ( I think they could really stand to make a nice small DA normal, too, (maybe a 35/2 re-dressed: something affordable to get people into the primes. )) Who knows when to expect anything like that, though.

It looks like you have quite a lineup, there, so maybe adding the 1.4 speed is a way to go. The size of the 28 doesn't bother me too much, (apart from the imposingness) cause with my FA 50, two lenses are doing the jobs I divvy up among three on film: an 85, a 50, and a 35. (Makes me wish Canon had ever made a nice 40 or 43mm for FD. ) But I bet you like to carry a lot of those things.
01-15-2010, 06:29 AM   #12
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I have the 20/1.8, 24/1.8 and 30/1.4 lenses in Pentax mount.

The best of the bunch by far is the 24/1.8. It's a very good multi purpose lens, without any major flaw. It's sharp, even wide open, has well controlled chromatic aberrations, nice colors, limited distortion and vignetting. It focuses so close that the front of the lens is almost touching the subject when used at the minimum distance. The only -- minor -- drawback is the bulk of the lens, which takes a lot of space in the bag for a 24mm.

The 30/1.4 is not really a bad lens but I have yet to find a use for it. It is very sharp in the center, but not at all in the corners of the frame, even when stopped down, making it ill suited for architecture or landscape photography. It is not very good at portrait either because 30mm is too short a focal length for tight portraits. As for social photography or street photography in available light, it's almost impossible due to the focusing issues. The minimum focus is not very impressive either for a 30mm lens, thus prohibiting its use for museum photography in low light.

The worst of the bunch is certainly the 20/1.8. It is very soft wide open, getting somewhat sharper at F/4 and above, but without never getting really sharp. This lens can't even be used as a soft focus lens, as the kind of cloudiness that it exhibits is not nice to the eye.

Cheers!

Abbazz
01-15-2010, 08:52 AM   #13
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QuoteOriginally posted by Abbazz Quote
The worst of the bunch is certainly the 20/1.8. It is very soft wide open, getting somewhat sharper at F/4 and above, but without never getting really sharp. This lens can't even be used as a soft focus lens, as the kind of cloudiness that it exhibits is not nice to the eye.
Perhaps your copy is defective?
01-15-2010, 09:23 AM   #14
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QuoteOriginally posted by jsherman999 Quote
I had the 28 1.8 in Nikon mount for a couple days, but it had a FF problem, so I sent it back.
Although I highly doubt any focusing problems of this kind can be blamed solely on the lens. If there is a mechanical problem with the lens, the camera's phase detection AF system (which is at the bottom of the mirror box, not in the lens) should not cause a focus indication at all. If D80 also had contrast measurement AF (in live view), your lens would focus fine, probably.

EDIT: To OP, I have Sigma 24 f/1.8 and it's sharp enough at around f/8 to take landscape photos and fast enough to do indoor photos handheld. Also, barrel distortion is low, especially when compared to 24-70 zooms.

Last edited by asdf; 01-15-2010 at 09:41 AM.
01-15-2010, 10:00 AM   #15
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I own the 24mm f1.8. I like it, somewhat soft at the corners wide open but not egregiously so. Focus speed in normal light is neither fast nor slow, about normal. Like many Sigmas, it doesn't like AF in low light, (K10D and K20D bodies), I've gotten better results with MF. Color rendition is good but not stellar, still no real complaints there. Has good close focus capability. I generally MF close focus shots on all lenses so I can't really comment on the AF capability there. On my copy the inside barrel is a tiny bit loose, it bothers me aesthetically but I don't think it affects IQ much. It's biggest problems are lens flare (I went from a wide angle hood to a standard one, I haven't seen any vignetting, and flare control is MUCH better) and it's BIG, especially compared to Pentax primes. However it can be found at 1/3 the price of the Pentax FA* 24mm on the second hand market, always a major factor for me.
Overall I'd rate it about 8.75 out of 10. Good solid "B+" lens, nothing very wrong with it, but also nothing hugely exciting either. Note that I have never used the Sigma 30mm so I cannot compare the two.

NaCl(gets the job done)H2O
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