pentax 16-45 vs. Sigma 17-70

The 24-90mm also suffers at the wide end, but in practice, with careful composition, is useable for architecture. Mind you, there are degrees of requirement even there, depending upon the final use.

Unfortunately, shooting for Images of England, software solutions are not allowed, so the lens and the use of it become very important.

For other purposes, some defects can be made into advantages. For example, David Hamilton did very well out of poor lenses throughout the 1970s.

This thread has brought out the valid point that lenses do have defects and being aware of them enables us to make good choices.

the store agreed on letting me have a go with the two lenses. I will pick a date in the next 2 weeks and do some tests.
I'll let you guys no the outcome, and I will try to find some ftp space where I can put up some RAW images so you can have a look at them as well.

[edit]
The 16th of december I am going make the testshots.
I am still in doubt which to buy.
If the construction of the Sigma is anything close to my Sigma 50mm macro then it would be hard to beat it in that point, that thing is built rock solid. The Pentax however is more compact and light.

Question to the 16-45 users, is the construction a lot different from the 18-55?
[/edit]

Just came back from the store with a 16-45 and the 50-200.
Sadly they didn't have the sigma on stock with a Pentax mount, so I couldn't judge the optical quality.
I made my decision on the feel of the two units. The Pentax is quite a bit lighter and I must say that the DS feels good with the 16-45 attached to it.

The construction of the 16-45 is quite a bit better then the 18-55. It feels so much better. I didn't know that 2mm extra in the wide range would make such a difference. The 50-200 is great as well. It's nice and compact and it is nice and sharp as well.

So current line-up is:
DA16-45
DA50-200
A50-1.7
Sigma 50mm Macro 2.8 EX
Tamron 28-200
DA18-55

The 18-55 will not be used very much I'm afraid but putting it on ebay is useless as well since the price is so low when you buy it new.
The Tamron will be the lens I will use when going on long walks with a small bag. It's not the best performer, but hauling a complete setup around doesn't work very well.

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.

[quote="Hythloday"]Yes, it's excellent at 200mm.

G

Maybe the 18-200mm Sigma. That has the focal lengths of both Pentax kit lenses in one. Good for travelling.

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.

"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

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.

going back to the original question, one benefit of the Pentax is you can use it on the K10 with MTF program line. I checked with Sigma before, about the 17-35EX and it doesn't contain this data, so the MTF program line is useless.