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View Poll Results: Which lens(es) to go for?
Sigma 10-20 + Sigma 24-70 1550.00%
Pentax 16-50 930.00%
Something else - specified in the thread 620.00%
Voters: 30. You may not vote on this poll

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08-02-2009, 11:53 AM   #1
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Sigma 10-20 + 24-70 or Pentax 16-50?

I currently have some money to recklessly spend so I want to buy something I absolutely don't need but badly want. There are alot of things I could spend it on but this is a camera forum so I'm staying with camera accessories.

Options are the Sigma AF 10-20mm f/4-5.6 EX DC and Sigma AF 24-70mm f/2.8 EX DG Macro or the Pentax SMC DA* 16-50mm f/2.8 ED [IF] SDM.
The Tamron 17-50, Tamron 28-75 and Sigma 18-50 start too long and are out of the game. Pentax' (or Samsung) 12-24 would be perfect but it's simply too expensive and hardly available used.

Yes I said I have money but I'm still not willing to buy any of these lenses new - especially not the Pentax. With the recent price increases it costs 700€+. Used I could get the Pentax for 450-550€ and both Sigma lenses for ~700€.
Even buying new is a game of luck so getting a good sample if you can't exchange is crucial. I have thought about this but there's no alternative - buying overseas looks like a solution but with the taxes and fees they are almost as expensive as buying them here.

I should also mention that I haven't even seen one of the lenses in reality. I know they are large and heavy but this is no concern of mine (and it makes me look more "pro").
Going into a store and testing them would be some kind of cheating since I'm not going to buy there.

Here's my evaluation on each lens - mostly based on Photozone's reviews, the reviews on here and general rants. Surprisingly I couldn't find a single thread compariing the Pentax 16-50 and the Sigma 24-70 on the whole internet, not even an image of the 24-70 on a Pentax - and the internet is a pretty big place...

Sigma 10-20mm
++ wide
+ center almost free of distortion
- strong vignetting
- weak border performance until f/8 (though only really bad at 10mm)
- slow aperture
- focus ring turns clockwise - opposite to Pentax
- possible compability issues
-- quality control issues

Sigma 24-70mm
++ very few CAs
+ almost no vignetting
+ maximum magnification 1:3.8 (16-50 only 1:4.88)
(+ full frame lens)
- soft until f/4 (if your copy is sub-par)
- suffers from flare
- wide end worse than long end (so I've read)
- resolution not as high as 16-50 (but more uniform)
- lens hood too short (and doesn't take advantage of the retro-zoom construction)
- focus ring turns clockwise - opposite to Pentax
- possible compability issues
- low light focusing weaknesses - seems to hunt a lot
-- quality control issues

Pentax 16-50mm
++ weathersealed
+ quiet focusing
+ very high resolution
+ "Pentax colour" rendition
+ Quick Shift
(+ cheaper than buying two lenses)
(- not as wide or long as both Sigma lenses combined...)
- vignetting wide open both at 16 and at 50mm
- can exhibit harsh bokeh
- soft at f/2.8
- strong field curvature
- high distortion at 16mm (up to 18mm?)
-- possible SDM failure
-- bad lateral CAs
-- quality control issues

Links to Photozone's tests:
Sigma AF 10-20mm f/4-5.6 EX DC (Pentax K) - Review / Test Report
Sigma AF 24-70mm f/2.8 EX DG macro (Canon) Lab Test Report / Review (unfortunately tested on a Canon)
Pentax SMC DA* 16-50mm f/2.8 ED [IF] SDM - Test Report / Review

The widest lens I'm using now is a Pentax M 3.5/28 - I also have the 18-55 but because of it's build quality and slow aperture I haven't used for some months. I know that I want something wider but I don't know how wide. Especially indoors you can't have something too wide. Still the range of 24-28mm would be the most important to me.
Pentax' Quick Shift is nice but nothing more since the focus throw is very short anyways and focusing manually seems very hard.
Weatherseling however is one of the main reasons I want this lens (although I don't really need it).

But all of its cons really unsettle me - there are so much threads about it's flaws it seems this lens is total junk. However people who get a good copy have nothing but praise for this lens - this seems also to be case with the 24-70.
You can't even spend high class money and be sure you get high class lenses nowadays...sad.

So what is the lesser evil?

Last edited by Egg Salad; 08-06-2009 at 12:48 PM.
08-02-2009, 12:25 PM   #2
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All three great lenses when it's a good copy; all also have some sort of QC problem. Since you are doing this to have fun rather than as a need, I'd say just flip a coin and hope for the best (get a good copy)

On these lenses though I do recommend something you can refund, or one that's already tested by a trusted seller I took a chance on the Tamron 28-75 and got a great copy, but boy, the suspense!
08-02-2009, 12:42 PM   #3
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I also have the Tamron 28-75 and I love it. I bought it used and knew that I had a good copy. I was missing the ultra wide stuff (I have the 10-17 FE, but sometimes you don't want FE), so I just got the 12-24/f4. I think this is going to be the perfect set.

I really wanted the 16-50 to match with my 50-135, but I was just too scared that I would get a bad copy. I will say that weather sealing and HSM are real plusses for the if you can test it out (I can't, no one near Pittsburgh carries them) or buy a good, proved used copy, go for it. On the other hand, if you love super-wide then the Sigma set is for you.

Take a look at what you shoot now, what you want to shoot in the future and decide whether weather sealing/HSM or wide is more important for your style.
08-02-2009, 01:37 PM   #4
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You'll need to get over the fear of getting a bad copy of any lens (yes, it can happen with any lens) since this will stop you from getting the lens that probably best suits you: the 16-50.

With the preference for weather sealing and good IQ, this lens just cannot be beaten. The Tamron 28-75 is too long for your needs and the Sigma 24-70 just falls short on the things you'd value in such a lens, not to mention that you'll find you want to go wider than 24mm at times...

The 10-20 is also a decent lens and not too pricey, although it seems a little too wide for you, Even Pentax's 12-24 just wouldn't suffice. Other choices may include the Tamron 17-50, which isn't weather sealed but has very good IQ, or the Sigma and Pentax offerings of the 17-70, which aren't weather sealed either but are significantly cheaper without too much loss in IQ. Still the 16-50 is the clear winner for me from all these lenses.

08-02-2009, 02:25 PM   #5
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Andi, yes that's also how I would do it: let the seller give me some pictures to judge on (something you can't do with new lenses if you buy online).
Sure you just have to do something but yes, the fear of getting a very expensive lemon is big.
Allison, in my resaearch for lenses I also found Tamron always seems to deliver more sharpness but 28mm at the short end are just too long.
10-20 + 24-70 is very similar to 12-24 + 28-75, though.
Yeah, I'm not so sure about super/ultra-wide lenses: of course having it is nice and there are great things you can only do with ultra-wides but if you don't know if you can work with them it could be money wasted (not really if you buy used and resell there's not much too lose).

I assume I will mostly stay with nature stuff of different kinds - possibly also architecture and abstract things (at least I know that I like it) - portraiture not so much.

Ash, I know you just have to "bite the bullet" and do it but it's a lot of money you could waste - so I'm as cautious as possible.

What really stops my enthusiasm on the 16-50 are it's CAs, distortion and its SDM.
I'd rather have less resolution (which is more even) than bad CAs and louder autofocus than none at all if it fails (probably happens to less than 10% but if it happens it's going to be very expensive).

Thanks, really helped to bias my decision towards the Pentax, though.
08-02-2009, 02:29 PM   #6
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Abstract things actually should sway you toward the Tamron. This is just me but even at 70mm I feel that it's just long enough to compose abstraction in cityscapes Of course you can always crop to make a lens "longer", so going wide might just be a better way.

EDIT: nevermind, I thought you were thinking about the Siggy 24-60!

Last edited by Andi Lo; 08-02-2009 at 03:36 PM.
08-02-2009, 02:35 PM   #7
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Hi there,

I don't have any experience of the Sigma 24-70, but I do read very positive reports of it and I daresay that the odd person has mentioned they prefer it to the Canon equivalent - cheaper than the Canon too.

I have just bought the Sigma 10-20 and i'm just getting to grips with it, but my initial findings of it are very positive indeed. I've knocked up some quick and dirty test shots over here:

Sigma 10-20mm EX DC f/4-f/5.6 Samples - a set on Flickr

I find the contrast and colour rendition very good indeed, sharpness at f/11 is very good from the centre to the corners at 10mm. I haven't tried wide open apertures, but I expect it won't perform nearly as good at f/4 as it does at f/11. That said, I am using the 10-20mm for landscape shots, so it's tripod mounted with a potential long exposure so I'm always working at the sweet spot / optimal DOF. Aberrations are better than my Pentax lenses, there is slight blue/yellow on the Sigma at the very corners, but nothing that post processing in Camera Raw can't clear up. Barrel distortion is minimal.

Negative points of the 10-20mm would be that it's not dust and weather sealed, but I'm not working in the rain, so no problems there . It's also not HSM, so the autofocus chirps when you focus - again no problem if you're outdoors and landscaping. There also appears to be a little light falloff at 10mm, but I tend to add to the vignette in some of my landscape shots to give it some mood. You can correct for this in Camera Raw.

This is my second Sigma lens, I'm very pleased with both of them so far.
08-02-2009, 02:38 PM   #8
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I'll emphasise that if there is that angst about getting a dud lens - buy new from a store with a returns policy that suits. Then go home a try everything you've got on that lens to see if it meets your expectations.

The 16-50's CA and distortion are IMO overrated. The CA is not obvious unless taken wide open and used in those generally unfavourable high contrast shots, and the barrel distortion is barely noticeable in real life shots, and only really exists at the 16-18mm range. Very few other lenses in this range have no distortion. And you're other 'negative' of SDM I'm assuming stems from the fact that it can fail - yes, this may be true, and again, warranty from your store should cover this if it happens within a set time period. If it lasts beyond that, I'm sure it would do well with the caveat that it would probably not withstand a drop from >1 metre or mistreatment of that sort...

08-03-2009, 07:19 AM   #9
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Big G, my concern about the 10-20 is not how good it is but if I will make use its extreme FOV. It's not as sharp as the longer zooms but you can't expect something that extreme to be equally good. Its weaknesses at 10mm aren't that much of a problem as I would mostly use it at 12-16mm then (except when you really want X-treme perspectives).
Wide open performance isn't nonrelevant and there was an occasion where I had to use my 18-55 at 18mm f/3.5 (band shoot right behind the stage) but naturally you use ultra-wides stopped down to f/8 or smaller.

About aberrations: I always shoot RAW (and JPEG) so I can fix some flaws in PP. However I haven't figured out how this CA-removal tool in SilkyPix Studio (the one that came with my GX-20) works. So if someone can help me out the CA plagued 16-50 is a sure choice. No, seriously - I really don't like CAs or PFs and what they are called - so this is really important to me.

Weather sealing is the second one (without order). I like the thought of not having to care how strong the rain is or if something could splash onto the lens. But this is more like how people like SUV - you won't drive offroad but you could.

I'm currently completely without AF so anything will be faster than that. As long as SDM isn't clearly faster as screwdrive driven AF it doesn't matter. Until now there wasn't any event a noisier AF (than USM/HSM/SDM...) was a problem.

Ash, yes as I said I'm a little bit paranoid about getting "valuable scrap" (if can say that this way).
But because this can be the case of any of these 3 lenses this lets me unbiased - yes there are a lot posts about broken 16-50s but there are also a lot more people that own this lens than the 24-70.
Pentax' QC vs Sigma's QC issues - about equal I think.

Nah, still not buying new. It's not on a "canon-esque" level yet but expensive enough. I trust in supplied test images of the seller to decide on. I'm also not going for any lens that has no guarentee left - but the possibilty of a SDM fail keeps my nervous. The distortion isn't nice but only of secondary importance.

I also want to use it wide open when I spend big bucks for a f/2.8 lens so this would be a problem for me. So, how bad is it in normal situations (moderate focal length like 30mm, f/4, sun to your back)? And is the Sigma 24-70 so much better there?

Thanks, will be back later (or not).
08-03-2009, 07:53 AM   #10
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I may have missed it but I haven't seen where you mentioned what this lens will be used for. Do you have a specific use in mind? It's hard to make recommendations without that information. What do you shoot primarily?

Are you looking for something on the wide end of that range, more towards the long end, or a compromise?

For a short while I owned the DA12-24 along with the Sigma 24-60/2.8 lens. Those two lenses (along with the DA*50-135) covered pretty much everything I needed to shoot. Since I shoot events and I'm making the transition to weddings, I found that having to switch back and forth between the 12-24 and 24-60 to be a pain. Since I didn't really use the 12-24 as much, I sold it and picked up a good used copy of the DA*16-50. That way I still have a wideish angle lens with decent range at the long end. The Sigma 24-60 is way sharper wide open, but the range of the 16-50 is what keeps it on the camera. QC issues aside, it's a great lens.

If I was in the market for a general purpose walkabout lens, the Sigma 24-60/2.8 would be at the very top of list. It's sharp at all apertures and has virtually zero CA/PF. It's also a full frame lens if that means anything to you. No weathersealing or SDM, but if that's not a concern then I'd be trying to find a used copy of that lens than a new or used copy of any of the other lenses mentioned.
08-03-2009, 01:04 PM   #11
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No, you are right. I haven't really said what it's for. I forgot.
It will be my main lens (or lenses) so it's going to be used for pretty much everything. Now I only have three manual primes (3.5/28, 1.7/50, 2.5/135) which are very good but not very flexible so I want something more comfortable and wider. Only did it a MTB-Downhill "shoot" twice yet but it won't be the last time - so MTB action shots are another use.
There also were two band concert shoots were I would have needed something wide (and with AF) but I'm not sure there will be more.
Besides nothing that really requires AF or fast apertures but I like to use shallow DOF so f/4 is to slow - especially in low light.

All in all I tend towards the normal to wide end, for anything longer I still have the 135mm (and the 55-300 but I think about selling because I haven't used it enough).

I am quite comfortable with the 3.5/28 so I can't say if I'd feel limited with only 24mm at the wide end (and having to switch for anything wider).

Resolution/sharpness and optical flawlessness is something that really gets me. Near to no CA/PF and even more sharpness sounds very tempting and 60 instead of 70mm wouldn't bother me that much to prevent me from buying one.

Full frame capability is interesting although the chance of Pentax releasing a FF-camera is ~2% maximum.

No weather sealing is a downside - and a pretty big one.
It seems to be great optics vs sealing - .
08-03-2009, 02:08 PM   #12
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Don't forget about the Sigma 17-70 which is another excellent choice. It's a little slower so you may struggle in low light without a flash at the 70mm end, but it's an even better walkaround lens than the 24-60 as far as range is concerned. Still, it's plenty sharp and focuses close enough for some interesting compositions and macro shooting. The only reason I replaced mine was because I needed the speed. The 24-60 replaced it because of the constant 2.8 max aperture.
08-03-2009, 02:17 PM   #13
Damn Brit

I'm another in the 10-20 and the 24-60 (instead of the 24-70) camp.
08-03-2009, 04:32 PM   #14
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QuoteOriginally posted by Damn Brit Quote
I'm another in the 10-20 and the 24-60 (instead of the 24-70) camp.
How's that camp working out for you Gary? :P

It's really entirely subjective and either can work out for you depending on how you shoot. Personally, I find the 16-24 on the wide end so much more useful to have immediate access to than the 50-70 on the telephoto. Besides, I find 16mm wide enough for my purpose. My main combo is the 16-50 and the 77 limited.
08-04-2009, 01:22 PM   #15
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The Sigma 17-70 is "just" a consumer grade zoom and is even worse than the 16-50 since it has even less wide angle - that's the reason Sigma's 18-50 and Tamron's 17-50 are not in this selection.
Close focusing capabilities are interesting but not enough to pick a slower lens over a true "pro" lens.
Nonetheless this is one of the factors I'm not that thrilled by the 24-60 - it's the worst of the bunch (10-20 doesn't count) in respect of maximum magnification. Sure I have a macro lens if I want to go close (actually not, it's just the Vivitar Macro TC) but 1:5.8 really isn't that much.
Another reason I dislike the 24-60 is its zoom ring which also turns clockwise and a silly reason but one after all - it looks somewhat cheap. So if Sigma I'm staying with the 24-70 (the 24-60 doesn't seem to differ that much apart from that).

I think I'm currently 60% Pentax 16-50, 40% Sigma lens team.
(Your votes: 6 Sigma team, 4 Pentax, 4, something else like the 24-60 or 17-70)

Reason is the Pentax looks like a better choice if you don't know what you actually want. So what I need to tighten (or loosen) my decision are definite statements about its optical performance. What about its optical flaws - are they really there?
Or is the 24-70 (or 24-60) so much better optically (less flawed) that it wins over the Pentax' sealing?

As you can see I haven't written that much about the 10-20 after all - so let me start now.
If I stitch 3 vertical images at 48mm together do I get the same FOV as at 16mm?
If this is the case 3 images at 30mm should simulate 10mm, right?

That's the only possibilty to see if I really "need" something that wide or if 16mm would suffice (when the optics part is done).

Thanks again for giving me your advice or opinion.

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