[benjikan]

I voted for the Sigma, for its all-around versatility. You can always get a prime wider than 50mm later, for more "specialized" purposes (i.e. macro, wide aperture, whatever).

So did I.

[Rondec]

There have been several that reported that the Sigma is at its weakest from 50-70mm. That doesn't mean that it isn't useable, just softer there. However, there have been the same kind of reports about the Pentax DA 17-70. A lot probably depends on your copy.

As you add primes, I would add them for specific functions -- landscape, macro, portrait, etc., although you certainly could use the 35 as a walk around lens too, you would find yourself taking a lot of macro-type photos with it on the way. The world just looks different through a prime lens.

[JesseDavis]

...The world just looks different through a prime lens.

Mmm, I do 80 percent of my shooting with either 50mm or 100mm primes. I suppose I have been zoom- and digital lens- averse for some philosophical reason, with an engineering background I find it hard to believe that a zoom could compare. Still though this thread and the last few days have been a long slog towards convincing myself that the zoom is the best value and most versatile option for me right now (*sob*).

I slept in again today (was on this forum all night!) but tomorrow I have no work so I will head back down to shinjuku and hope that that sigma is still there. If it's not, I will try to find another and if I can't then I will get the 35 and not have to pine for it, because a new sigma 17-70 is more expensive than a Ltd. even though the OSM is available now too.

Once again, thanks everyone. If you have any other thoughts the deadline approacheth, eveningtime in North America and the zoom will be mine, yessssss.

[JesseDavis]

Well, I bought the sigma, for a great price, and thanks for all the votes and suggestions. However I have a pretty definitive answer to the original question as well (only found by buying the sigma and then taking it to the pentax store ) I am reasonably happy with it for 200 bucks but I will definitely be getting primes, and here is why. Also scroll down to see some of the first pics from my new-to-me sigma

Top DA 40mm Ltd @ F4, Bottom Sigma 17-70mm @40mm / F4; 100% crop of a wall calender taken by the pentax guy with my k10.


Despite the obvious differences, the sigma is much sharper at the wide end, and in the above crops it is also wide open at the longer end, whereas the ltd is stopped down to match it.

I actually found a 17-35 EX with a distance scale on it and actually bought that instead, but after 20 minutes in a coffee shop shooting the menu and realizing that it wasn't at all sharp unless stopped down to F8 or 11, I went back to the store and exchanged it for the 17-70, which is sharper in the corners, close focussing, sharper with much less stopping down, and has more range, but lacks a DOF scale. I had thought that going with EX would assure me better optics but it just goes to show that branding means little.

Then I walked over to the Pentax Forum and looked into whether I could purchase a limited in addition to that without my wife exploding (the answer is no, for now) and ended up with the above stinging reminder of what I am missing for the convenience of the zoom and still having gas money.

Anyway, here are some shots. First, my master and commander (snapshot in the store when we first found the sigma):


And a pretty cool shot I got later in a coffee shop (20 second exposure!)
Smokin':

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Last edited by JesseDavis; 02-27-2010 at 05:41 AM.

[Rondec]

Enjoy. I think planning your next lens purchase increases the enjoyment when you actually get it. Some folks can go out and buy all the limiteds at once, but I have gradually accumulated what I have. At the same time, I think you will enjoy the Sigma. Maybe not as much as primes ever, but sometimes it is just handier to have that range with you.

[code4code5]

Just a quick word about the Sigma. I've found that at 70mm, I didn't need any focus adjustment. After getting some OOF super wide shots, I did some focus testing at 17mm and found that I needed a +6 adjustment. It was a night-and-day difference when shooting wide at f/2.8, and my 70mm shots are still spot on.

[Pentaxor]

Despite the obvious differences, the sigma is much sharper at the wide end, and in the above crops it is also wide open at the longer end, whereas the ltd is stopped down to match it.

why would you compare a prime 40mm lens against something at 17mm and at 70mm with a zoom? it just doesn't make any sense since they are of different focal lens and purpose of shooting. first you have to contend of shooting a particular subject with the same size, thereby difference in shooting distances. 2nd is that the field of view will be different, unless you shoot both lenses at the same focal length at 40mm which should be the right comparison. if you are going to compare a zoom in all focal ranges, you should had tried the Pentax DA17-70 against the Sigma 17-70.

also I see no images for comparison if the Sigma is indeed sharper at wide end and the sigma is not wide open at the long end but closes down at f4.5.

I had thought that going with EX would assure me better optics but it just goes to show that branding means little.

not all EX are built and perform the same. sample variations exist and not all EX lenses means better optical results. what is the most obvious difference with EX lenses is the build quality. branding thus means something. if you compare a Sigma 70-300 against a Sigma 100-300 APO EX, the latter would win hands down.

[JesseDavis]

why would you compare a prime 40mm lens against something at 17mm and at 70mm with a zoom? it just doesn't make any sense...

...because that is the one I bought vs. one of the ones I had been considering the better performance at 17 is just a bonus with the zoom, along with the fact that it shoots at that length

also I see no images for comparison if the Sigma is indeed sharper at wide end and the sigma is not wide open at the long end but closes down...

well, we set the sigma to the 40mm (actually 43 or so as 40 on a zoom doesn't quite equal 40 on a prime) length and it closed itself down to f4 ('wide open' at that focal length). We set the Ltd's Fstop to match the sigma. What the comparison shows is how the sigma performs at 40 mm versus the 40 Ltd at the same aperture. The unfair advantage to the prime comes from it being stopped down to meet the sigma, while the sigma is at its maximum aperture there which will cause softness in almost any lens.

(BTW the above image is being stretched by mobile me, the actual quality of a 100% crop on the 40mm Ltd is a bit better than you see there)

basically I was trying to determine whether I could still justify buying more lenses in those lengths someday now that I have the sigma, and I can (erm.. yay? yes, YAY!)

What I was surprised at was *how much* softness you could see wide open with all the zooms I tried. My FA 100 and my M 50 both spank the pants off my sigma wide open, and match or beat almost any lens I've tried. I've learned here not to lust after extreme aperture numbers so much becuase if you buy a 2.8 lens that needs to be stopped down to 5.6, well, then its not 2.8 when you use it.

My chief aim was really wide usage though, and the sigma seems pretty good there. Much better sharpness in the 17-70 than in the EX 17-30, especially in corners, and it doesn't need to be stopped down as far for a good image either. Unfortunately there is no DOF scale, which was a big letdown for me, but I think I will live.

[tokyoso]

Well, I bought the sigma, for a great price, and thanks for all the votes and suggestions. However I have a pretty definitive answer to the original question as well (only found by buying the sigma and then taking it to the pentax store ) I am reasonably happy with it for 200 bucks but I will definitely be getting primes, and here is why. Also scroll down to see some of the first pics from my new-to-me sigma

Top DA 40mm Ltd @ F4, Bottom Sigma 17-70mm @40mm / F4; 100% crop of a wall calender taken by the pentax guy with my k10.

Despite the obvious differences, the sigma is much sharper at the wide end, and in the above crops it is also wide open at the longer end, whereas the ltd is stopped down to match it.

I actually found a 17-35 EX with a distance scale on it and actually bought that instead, but after 20 minutes in a coffee shop shooting the menu and realizing that it wasn't at all sharp unless stopped down to F8 or 11, I went back to the store and exchanged it for the 17-70, which is sharper in the corners, close focussing, sharper with much less stopping down, and has more range, but lacks a DOF scale. I had thought that going with EX would assure me better optics but it just goes to show that branding means little.

Then I walked over to the Pentax Forum and looked into whether I could purchase a limited in addition to that without my wife exploding (the answer is no, for now) and ended up with the above stinging reminder of what I am missing for the convenience of the zoom and still having gas money.

Congrats on the great buy! wifey looks happy there..