[Alex00]

exactly my experience.

Ben

Again looking at dpreview.com - Lens Review - Fullscreen
Tokina 12-24 seems to be the winner all around.

Sigma has much better CA but it suffers distortions at both extremes, even little in the center and viginating at wide angles and loses sharpness all around compared to tokina.

[Ben_Edict]

Again looking at dpreview.com - Lens Review - Fullscreen
Tokina 12-24 seems to be the winner all around.

Sigma has much better CA but it suffers distortions at both extremes, even little in the center and viginating at wide angles and loses sharpness all around compared to tokina.

Problem is: there is no Tokina 12-24 for Pentax, you will need to buy the original Pentax 12-24

Ben

[Alex00]

Yes exactly assuming tokina and pentax are the same. Will cost a little more but i would say it's worthed looking at the overall performance.

[Ben_Edict]

Yes exactly assuming tokina and pentax are the same. Will cost a little more but i would say it's worthed looking at the overall performance.

I can understand that. I choose the Sigma because of the additional 2mm on the wide end, which made the decisive difference for me, as I already had the 15-30 and the 15mm prime (and a 16mm fish-eye etc.). I am also not sure, whether the Pentax 12-24 was available, when I bough the Sigma… As I use the Sigma 10-20 only at f/8 and f/11 or (when needed for DOF) at f/16, the corner weakness is basical gone. The colours are very nice and lively for my taste and the distortion - well, what else would I expect from such a wide angle lens?

Ben

[Alex00]

it's nice having the sigma's extra 2mm but 2mm is not necessarily a big deal. Honestly i was first leaning more toward the sigma for it's great CA. But after i went thru the dpreview graphs, i can see why the pentax is a better overall performer and i can understand the additional cost. I'm sure pentax will release an 8mm lens in the future, we can always buy that for extreme wideness. In addition having the 24 on the pentax is also an advantage and at 24mm it seems to be pretty sharp at f8.

[ScooterMaxi Jim]

I had the Sigma 15-30 - an awful, huge lens. Heavy, soft at every f-stop center to corner - and the worst coloring I have ever experienced. So bad that you couldn't fix the RAWs' color enough to look right.

The Tokina 12-24 (I have the Canon mount) is a great build, and sharp in the center - but the problems with it that are well documented - really are under-stated. The flare problem is substantial - especially if you shoot interiors with windows in daylight (no idea if the Pentax version coatings completely fix the problem because you are dealing with a lot of glass surfaces and a lot of bending of light). The CA problem is complex and vast, and not easily corrected entirely - only mitigated. So, middling is best I can say - and mostly appreciated due to center sharpness. The outer 15% of the images are poor if you look closely.

The Zenitar fisheye is easily a class higher - at least the one I got. Sharp edge to edge at f/4, and still decent at f/2.8. Just started using PTAssembler for lens correction (trans merc rectilinear and squeezed rectilinear) gives me much lower distortion with correction than the rectilinear lenses - far more natural result, nearly no light fall-off, and sharp edge to edge (crop sensor). Build and coatings are perfect (caps suck, though). Flare controlled just as well as the better Pentax lenses I've used (such as the FA 35). Corrected, the 16mm fisheye gives you 13mm in width/horizontal and 15mm in height/vertical in landscape mode.

For a good tutorial on fixing perspectives (yes, rectilinear wide lenses also distort heavily unless corrected), look at:
PTAssembler Projections

[tokyoso]

it's nice having the sigma's extra 2mm but 2mm is not necessarily a big deal. Honestly i was first leaning more toward the sigma for it's great CA. But after i went thru the dpreview graphs, i can see why the pentax is a better overall performer and i can understand the additional cost. I'm sure pentax will release an 8mm lens in the future, we can always buy that for extreme wideness. In addition having the 24 on the pentax is also an advantage and at 24mm it seems to be pretty sharp at f8.

did you get pentax 12-24 ?

i'm looking to make a similar purchase

[Jewelltrail]

Alex00: ....... i can see why the pentax is a better overall performer and i can understand the additional cost.

The Tokina 12-24 in Canon mount @ Adorama is just about $500 right now

The Sigma (old Version) 10-20 in Canon mount @ Adorama is about $480 right now

The Tokina 12-24 for Pentax (aka, Da 12-24 f4) is about $720 @ B & H right now.

[Ben_Edict]

it's nice having the sigma's extra 2mm but 2mm is not necessarily a big deal.

That is a matter of personal prefernce. I prefer the additional angel of view, even if it is a small gain. My 16-50 sets in right in the middle of the Sigma and I have no need for the 24mm end on the Pentax WA.

The Pentax DA 16-50, by the way, shows way more distortion, than the Sigma at 16mm.

I'm sure pentax will release an 8mm lens in the future, we can always buy that for extreme wideness.

I never bet on lenses to be released in the future, if I need a certain lens now. If you are willing to wait, that is fine for you - but it is again a personal decision.

Ben

[Ben_Edict]

I had the Sigma 15-30 - an awful, huge lens. Heavy, soft at every f-stop center to corner - and the worst coloring I have ever experienced. So bad that you couldn't fix the RAWs' color enough to look right.

Too bad you seem to have avery bad copy of that lens. Nothing of the shortcomings you describe can be seen in my copy. Instead it is much less prone to flreing, than my old Pentax K 15mm lens, which in terms of contrast and sharpness sure betters the Sigma 15-30, but does not have its versatility.

The Tokina 12-24 (I have the Canon mount) is a great build, and sharp in the center - but the problems with it that are well documented - really are under-stated. The flare problem is substantial - especially if you shoot interiors with windows in daylight (no idea if the Pentax version coatings completely fix the problem because you are dealing with a lot of glass surfaces and a lot of bending of light). The CA problem is complex and vast, and not easily corrected entirely - only mitigated. So, middling is best I can say - and mostly appreciated due to center sharpness. The outer 15% of the images are poor if you look closely.

The Zenitar fisheye is easily a class higher - at least the one I got. Sharp edge to edge at f/4, and still decent at f/2.8. Just started using PTAssembler for lens correction (trans merc rectilinear and squeezed rectilinear) gives me much lower distortion with correction than the rectilinear lenses - far more natural result, nearly no light fall-off, and sharp edge to edge (crop sensor). Build and coatings are perfect (caps suck, though). Flare controlled just as well as the better Pentax lenses I've used (such as the FA 35). Corrected, the 16mm fisheye gives you 13mm in width/horizontal and 15mm in height/vertical in landscape mode.

Wide angle lens projection is a complicated matter and different manufacturers choose different routes to go. I also would expect and can confirm, that high quality prime lenses are better in terms of IQ, than wide angle zoom lenses. But it is always a question of purpose and simply "fit for the job", whether the one or the other is the better choice in a real shooting situation. I rareley take my Pentax 16mm fisheye or even the A 20mm out these days, as the Sigma 10-20 fullfills most of my needs easily and conveniently. There are some occassions, though, when I prefer shooting primes.

Ben

[ScooterMaxi Jim]

Ben,

I agree that the wide angle primes have the potential to be much better than the wides, but all the R&D has gone into zooms these days - for the same reasons you end up primarily using the 10-20.

I don't know if I got a bad copy of the 15-30 - I would think so. The flare control was good. However, the color cast problem is probably universal. It was surprising to me to find that it was so difficult to correct in RAW processing. I am sure that Sigma technology has moved quite a ways forward since that design.

It would not be surprising to me at all to find that the Pentax 12-24 coatings are a huge improvement over Tokina. For instance, the flare control and contrast on the Pentax 16-45 is very good even at 16mm.

As for wide angle projection, I found the Tokina 12-24 particularly troubling at 12-15mm especially in people group shots with the extensive stretching at the edges. The rectilinear accuracy is very good, but I am happy to have found a program that offers many options and user controls to "normalize" extreme wide angle photos from rectilinear and fisheye lenses alike. You have the added advantage that the edges sharpen up nicely due to the compression. Although it is a good stitching program, the lens distortion correction options in the updated PTAssembler program are especially versatile and yield excellent results - worth having even if you don't do any panoramas.

[Jewelltrail]

Ben_Edict: That is a matter of personal prefernce. I prefer the additional angel of view, even if it is a small gain. My 16-50 sets in right in the middle of the Sigma and I have no need for the 24mm end on the Pentax WA.

When I was reviewing my options: either the Sigma 10-20 or the Pentax Da 12-24 I took a good deal of time. There were many factors which pulled me in either direction. I did give the Sgma at least +1 for 10mm, but could not give this to the Da for 20-24mm since my Tamron 17-50mm already covered me from 17 to 24mm. This proved to weigh, decisively, in favor of the Sigma, along with Sigma's excellent handling of CA.

[unixrevolution]

Just chiming in with my USD $0.02.

I had a similar dillema around christmas, selecting an ultra-wide. the 12-24 Pentax was too expensive, so it was down to the Sigma vs. the Tamron.

I went with the Sigma due to its favorable reviews from just about everyone; I couldn't find much on the Tamron at all as far as reviews went.

Now owning the Sigma, I like it a lot, though I haven't tried any of the others to date. it's a good lens, and it's earned a permanent spot in my camera bag.

[Alex00]

Fisheye does not do the job of a wide angle lens even after correction. Right now, the best choice is the pentax 12-24 in overall performance and IQ. Overall Sharpness is what i was looking for initially. If your not too worried about overall sharpness. For the average user all wide angles lenses may not make much difference if you are not pixel peeping every part of your image.

[Marc Sabatella]

Assuming dpreview did there tests correctly, dpreview shows the 15mm at any aparature suffers from sharpness compared to all three lenses sigma 10-20, pentax 12-24 and tamrom 10-24.

OK, *one* reviewer. The rest - including ones like photozone who can put up actual MTF numbers to back up their claims - all say otherwise.

And actually, I don't think dpreview says what you think they say. Here's a direct quote form the review:

"Compared to the Sigma 10-20mm F4-5.6 EX DC HSM (at 14mm), the 15mm F4 comes out on top; it's a hair sharper, and has lower distortion and falloff."

As compared to the Tokina or Tamron, obviously, they didn't test that on the same camera, so results are not directly comparable. Plus they also say:

"it shows distinct curvature of field, which causes problems with our (flat-field) chart tests at the shooting distance used (approx 2m). As with the Sigma, we have chosen to present data that is technically slightly rear-focused, and therefore gives a better impressions of the edge and corner sharpness at the expense of the centre"

So they are deliberately testing out of focus images, and *still* finding it comes out better than the Sigma; if it comes out ever so slightly worse than the Tokina or Tamron, that could be entirely due to the fact that they test OOF images from the Pentax.

In any case, the differences we are talking abut are miniscule and have no real world relevance. There would be no reason to choose the 15 for its marginally higher sharpness if the focal length isn't perfect for you; a zoom clearly makes more sense for people who don't mind the size or weight.