That is the K version and not the M version!

I had a Tokina 12-24mm on my Canon 300D. Today I bought the Pentax-DA 12-24mm. It had struck me before that the optical design was the same, but now I see that the lens cap and the hood have exactly the same construction. The only difference is the name Pentax on them.

The Pentax is far lighter in weight and is slimmer. The Tokina consists of one barrel and inside the barrel the lens elements changes dependent on the focal lenght. The Pentax makes exactly the same movement but consists of two barrels so the length varies slightly depending on the focal length used.

You can safely use PTLens and select Tokina to correct distortions. The lens hardly suffers from distortions. Just in the range 12-18mm.

I also correct chromatic aberrations. The Pentax and the Tokina behave in exactly the same way. The Pentax 12-24mm is more pleasantly to use than the Tokina 12-24mm because it is far lighter in weight.

When I compared the DA12-24mm to the DA16-45mm, it struck me that the DA12-24mm is slightly sharper (at 24mm) and shows slightly better contrast.

"Interestingly the optical design of the lens is the result of a joint effort by Tokina and Pentax. However, both manufacturers have a different approach regarding the actual mechanical implementation and only the Tokina variant is available for Nikon (and Canon) naturally."

See:

http://www.photozone.de/8Reviews/lenses/tokina_1224_4_nikon/index.htm

and

http://forums.dpreview.com/forums/read.asp?forum=1036&message=19618921

With my Canon 300D I used to have a Sigma 18-125mm. A nice lens but not very fast. I used the range 18-23mm for about 40% of my pictures and hardly used the tele range. When I bought the 17-70mm I found that it has a pleasant range and that it is a reasonably fast lens.

I also have a 17-70mm on my Pentax K100D. It is a nice walkaround lens which can be used for 90% of my pictures. If I want another lens it would be a super wide angle.

My lens line-up:

Pentax-DA 16-45mm
Pentax-DA 50-200mm
Sigma 17-70mm.

Congratulations! Now the shop has neither the Sigma 17-70mm nor the Pentax-DA 16-45mm in stock any more

The 16-45mm is a good lens and in combination with the 50-20mm an excellent choice. The Sigma 17-70mm would have been the best choice as a one lens solution.

If you call the barrel distortions of the Sigma 17-70mm atrocious you should also call the barrel distortions by the Pentax 16-45mm also atrocious. The distortions are slightly better than those produced by the Sigma.

If you use the lenses for architectural purposes both are unsuitable, i.e. as long as you don't correct the distortions.

I have supplied Tom Niemann with pictures for four lenses which he calibrated. Each lens (Sigma 18-125mm, Sigma 18-50mm f2.8 EX, Sigma 17-70mm and the Pentax 28-70mm f4 AL) from (severe) barrel distortions at the extreme WA range.

Just use PTLens or Proxel to remove the distortions. I used to have a Tokina 12-24mm (which is optically the same as the Pentax 12-24mm, I feel) suffers very little from distortions. Only at the edges between the range 12-18mm.

I have used Pentax lenses for nearly 30 years and Pentax has always been proud of its SMC coating. But I still wonder how original the coating of the present Pentax lenses is. The new star lenses will have a special coating, called WP, to protect the front element from rain and dust. The Tokina lenses have the same WP coating according to their site.

I also wonder if Pentax designs its own lenses anymore. It is said that Tokina and Pentax develop the new lenses on a cooperative basis. But I get a feeling that Pentax produces the new lenses under licence, optically speaking. Just have a look at the optical design of the Pentax 12-24mm:

http://www.pentax.de/downloads/lenses/de/DB_SLR-Objektiv_12-24__GER.pdf

and the Tokina 12-24mm:

http://www.thkphoto.com/products/tokina/afl-00.html

Only the lens element after the front element is slightly different. Add to this that the new star lenses will have a WP coating.

It is no more than a thought. Pentax has been busy designing new (and successful) cameras (with new features like SR) but they buy the expertise for new lenses? Has Samsung rescued Pentax?

Don't misunderstand me I like Pentax and will only buy Pentax lenses in the future (like e.g. the Pentax 12-24mm) but I have doubts whether Pentax have designed everything themselves.

I use Focal Blade and find that there is hardly any difference between the Sigma 17-70mm and the Pentax-DA 16-45mm. Both lenses require very little sharpening indeed. Digital images require some sharpening not because of the lens used, but because it is the nature of digital images.

If the Sigma 17-70mm was branded Pentax 17-70mm, everybody would have been very enthousiastic about the lens. I feel there is little or no difference in image quality. I like WA photography and therefore bought the Pentax 16-45mm because it has a very nice range indeed for a wide angle zoom lens. On my Canon 300D I had a Tokina 12-24mm which is wider (some 3 mms in Pentax terms) but lacks the tele of the Pentax lens. The Pentax 16-45mm is just one mm wider than the Sigma, but I feel that one mm is worthwhile.

The weather does not permit it but if I take some 5 pictures and process them, you will hardly recognise the lens. This test has been done before on the Canon forum (recognise the L lens). Nobody had a 100% score.

Before I had my Pentax K100D I had a Canon 300D with a Sigma 17-70mm. The lens is very good indeed. I did not notice any problems with it. But the Sigma 17-70mm on my Pentax K100D is considerably sharper (because of the filter in front of the sensor?). I used this lens for half a year and had no desire to use my other lenses (Sigma 18-125mm and the Sigma 18-50mm f/2.8 EX). For a test of the Sigma 17-70mm on a Canon 350D, see:

http://www.photozone.de/8Reviews/lenses/sigma_1770_2845/index.htm

or the Sigma 17-70mm on a Canon 20D:

http://www.ephotozine.com/equipment/tests/testdetail.cfm?test_id=415

I always use PTLens to correct distortions and chromatic aberrations. The Sigma 17-70mm suffers very little from chromatic aberrations.

You may doubt it, but I can assure you that the Sigma 17-70mm is at least equally sharp as the Pentax 16-45mm in the centre. In fact it is a tad sharper on the edges and in the corners than the DA16-45mm.

The DA16-45mm is more lightweight and starts at 16mm.