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09-30-2012, 05:13 PM   #1
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Sigma 30 1.4 vs. Sigma 28 1.8

I'm using a Pentax K20D, and I'm planning to add a fast normal prime to my active collection of lenses (Tamron 17-50 2.8; FA 50 1.4; DA* 50-135 2.8) to round it out for most of the shooting I want to do.

I'm curious to hear some feedback from people who have used these lenses. Each lens is pretty similarly priced, and I feel each has its (slight) advantages.

Sigma 30mm f1.4
- Technically the "right" lens, as it's designed for APS-C
- It's ever so slightly faster
- It's more popular and should be easier to re-sell should I decide I don't need it anymore.

Sigma 28 f1.8
- On a Pentax APS-C camera, it is technically the perfect "normal" length, as the diagonal of the sensor on the camera is 28mm
- If Pentax ever releases a full-frame camera, this lens will work on it.
- This lens will also work on my Pentax ZK-7 film camera. (Though I don't use it much and I already have a nice, sharp manual-focus 28mm lens).

Mostly I'm interested in comments on image quality and bad/good quirks of either lens. I'm not so worried about the fact that one is slightly faster than the other, though I am concerned about depth of field control. I want to be able to blur the background right out, and I do wonder if having a 1.4 lens would give me noticeably more versatility.

P.S. I'm of course aware of the FA31 1.8, and the thought of selling one of these lenses in the next year or so to put the money towards the 31 is in the back of my mind.

09-30-2012, 05:33 PM   #2
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Online Depth of Field Calculator

The 30/1.4 has a DoF of 1.91ft at a distance of 10 feet.

The 28/1.8 has a DoF of 2.8ft at a distance of 10 feet.
09-30-2012, 08:53 PM   #3
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I had the 28/1.8 for a while, and now have the 30/1.4, although it I did just get an FA 31 so I may not have the sigma long. I liked the 30/1.4 much more than the 28/1.8, for reasons that may or may not apply. I thought the 30 had slightly better image quality, especially in the center, and slightly better colors. Plus the 28 was a little too big for me to carry around everywhere. Although I love the ieda of closer focus on the Sigma 28, I didn't use it much at that focal length. I would recommend the 30, but either are fine lenses that can make great pictures.
09-30-2012, 09:21 PM   #4
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I'd recommend the 30, it's technically better. You can always sell it if a FF is released.

10-01-2012, 03:56 AM   #5
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Doesn't the 30mm sigma have triangular bokeh? I think some people were complaining about that, because it can be distracting.
10-01-2012, 08:01 AM   #6
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The Sigma 30mm has the edge over the Sigma 28mm. Not too much difference in coverage but optically it is superior imo.
10-03-2012, 06:56 AM - 1 Like   #7
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QuoteOriginally posted by Na Horuk Quote
Doesn't the 30mm sigma have triangular bokeh? I think some people were complaining about that, because it can be distracting.
Yes, this lens exhibits such a huge amount of coma that the out of focus highlights tend to take this weird triangular shape, especially in the corners of the frame:


For example, see these pictures on Lenstip: http://pliki.optyczne.pl/sig30/sig30_fot9.jpg

http://pliki.optyczne.pl/sig30/sig30_fot14.jpg

Cheers!

Abbazz

Last edited by Abbazz; 10-03-2012 at 07:03 AM.
10-06-2012, 10:53 AM   #8
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I have not owned Sigma 30/1.4 but I have 28/1.8. I was very biased when I bought it as I had read many bad reviews of this lens. Soft, big, heavy, awkward MF/AF switch and so on. But I decided to "gamble" as I found one for 150 euros. I have also DA 35/2.4 but I found it little bit too long for my taste as "normal" lens. So at this price there would not be too much loss if I didn't like the lens.

It surely is bigger and heavier than it needs to be for APS-C but the weight difference is not big compared to sigma 30/1.4 (28 is 480g and 30 is 430g). But it is around 3cm longer. Autofocus is screwdrive so it is "noisy" compared to HSM or so but as I already knew it it didn't bother me. What bothered me most was the somewhat inaccurate focusing with the outermost focusing points of the K-5 (have not experienced this with other lenses) but other 9 focus points worked well. What is also nice is that focusing ring does not rotate during focusing. If it would, the lens would be very hard to use as half of the barrel is focus ring. That said the build quality of the lens is very good IMO, only complain being that the focus ring could be more stiff.

And then the most important part, the image quality. I have not used this lens very long yet but I can say that this lens has it strengths. And one is the close focusing ability and bokeh. Also the sharpness at 1.8 is good if not very good. Here are some examples what this lens is capable of:















As a landscape lens I don't find this lens to "pop out". The sharpness at F5.6-F10 is not better than for example Tamron 17-50/2.8 so it is hard to justify buying this lens for that kind of work instead of the Tamron. That said Sigma 28/1.8 does quite well for that kind of things but could be better IMO (with this I mean that you surely expect prime lens to be very sharp stopped down). Here is one example:



Of course these small images don't show everything but gives the idea. In the end I'm considering selling the DA 35/2.4 as I don't use it much anymore. But the biggest problem with this lens is the size. Only if I could find the lens with this capability in a smaller size. To summarize, the strengths of this lens are in close focusing capabilities and not so much in the "general" take everywhere lens (because of size).

10-06-2012, 09:13 PM   #9
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QuoteOriginally posted by Nick Siebers Quote
I had the 28/1.8 for a while, and now have the 30/1.4, although it I did just get an FA 31 so I may not have the sigma long. I liked the 30/1.4 much more than the 28/1.8, for reasons that may or may not apply. I thought the 30 had slightly better image quality, especially in the center, and slightly better colors. Plus the 28 was a little too big for me to carry around everywhere. Although I love the ieda of closer focus on the Sigma 28, I didn't use it much at that focal length. I would recommend the 30, but either are fine lenses that can make great pictures.
Hey Nick - for low light, which one is quicker to focus? I've got the sigma f1.4/50 but end up missing shots of the kids because it never focuses - probably because I'm too close and it's low light.

Pat
10-06-2012, 09:20 PM   #10
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QuoteOriginally posted by rocksaw Quote
Hey Nick - for low light, which one is quicker to focus? I've got the sigma f1.4/50 but end up missing shots of the kids because it never focuses - probably because I'm too close and it's low light.

Pat
Hi Pat -

Not 100% sure, to be honest. At f/1.4, f/1.8 your DOF is pretty thin. so I accept that a number of shots will be misfocused from that. The "not locking on and refusing to fire" hasn't happened to me much with the 30, unless the kids get too close, which can happen (but you are talking a pretty serious close-up). I don't remember it being an issue with the 28/1.8 either. The 28 does focus much more closely, and would eliminate the "kids getting too close" under most circumstances. The DA 70, that lens gave my AF fits, but neither of these two is bad. Others may have had a different experience, though.

n
10-07-2012, 05:39 AM   #11
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Thanks Nick I think I've always leaned towards the 30 because of the 1.4 vs 1.8, but didn't want to get another camera that zoomed in "too much". I'll probably put the 30 on the Christmas list and see what happens-
10-11-2012, 08:46 AM   #12
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My favorite lens

It's been a while since I have talked about how much i like this lens. I don't have any experience with the competition though. I only know I love this lens. I really enjoy the macro focusing, colors, DOF, out of focus rendition, etc...

My only complaint is I have to adjust the lens and camera to switch from manual to auto focus, but all my Sigma lenses are like that.

Here are some favs of mine that I am sure I have posted before:

f/1.8 (f/1.7)


f/1.8 (f/1.7)


f/2


f/3.5
10-12-2012, 08:05 AM   #13
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Both of these are somewhat soft in the corners at wider apertures. Not a huge deal since with that thin of DOF you're more likely to have your subject in the center of the frame anyway.

If you want better sharpness across the frame then there's the FA 35/2 and DA 35/2.4. They're also a lot smaller & lighter. You do of course give up some speed with either of these.
10-12-2012, 11:43 AM   #14
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I rented the Sigma 28mm macro and really liked it. I was surprised to find myself using it wide open in hotel suites etc during parties. Sure, it's big and I had to use a step-down adapter to mount the LED ring light, but that didn't interfere with the pictures at all. Very nice - I'd like to try it against their 24mm macro, just for comparison. For the right price I'd buy the 28mm.
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