18-135mm lens advice Pentax or Sigma AF

Hi, I haven't been around here for some time. But basically want to know if there are any AF issues with the Sigma lens compared to the Pentax.

It is a very long winded story but my dog (60kg Newfoundland) ate my *ist DS vintage Sigma 18-125 and it will not AF too well compared to a Pentax 18-55. The dog definitely did damge the lens as the zoom ring is sticky. But focussing to infinity which I did not check before packing for holiday is now dreadful.

I do know there is a weather sealing difference in the lens and that the zooms are not exactly identical but really my deciding factor will be price Vs feedback.

Ian.

Ps if anyone wants a new lens I can send my dog around

you didn't say what sigma .?

Pentax da 18-135 £419
Sigma hsm 18-125 £219
Sigma Hsm 18-250 £399

From what I've seen the Pentax is very good portrait lens due to strong centre performance but weak edges
The Sigma 18-125 solid on all areas but never excels.

The Sigma 18-250 strange one this over corrected optics leads to very linear performance but at the expense of resolution.

Personally I think the Pentax/Tamron 18-250 is still the class leader in K mount genreal purpose superzooms, Pity the 18-270 will never get k-mounted

I sold my Tamron 18-250 to get the 18-135, which I wanted for the WR. I was a bit worried by the so-so reviews of the lens, but found a good price (£359) so took the plunge and have been pleasantly surprised. It is contrasty and certainly seems sharp enough, although the type of photos I tend to take do not need a lot of border sharpness. The lens is quite heavy, but it balances well on my K5. As for AF, that is fast and accurate certainly as good as the HSM on my Sigma 50-150. Best advice-try one if you can, you might like it!
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Everything changes

It's a sharp, contrasty, fast and quiet-focusing, relatively light WR lens. It maintains good contrast even in midday sunlight, similar to the DA limiteds. I'm not sure you'd be able to get that with the Sigma.

It has issues with border performance, but I knew that when I bought it. It's my lens for pictures of my kids at school or the park when I can't chase after them with my DA 70mm. I don't care about the border for that kind of stuff, or flowers either (which are my second most photographed subject).

Don't expect a DA* lens, and it will give you better results than you thought you would get. I find the focal length perfect and a lot of fun. My other zoom is the DA 55-300, which, I think, complements this lens perfectly. Lots of overlap for when I need it.

Good luck.

... I'm still using my Sigma 17-70 as my walk around lens on my K20D or on my K-5. That speaks volumes for my opinion of the 18-135. It was very disappointing. Pentax should have created a great lens in that focal length (18-135 or 17-125) and put a $1200 or so price tag on it. Instead they produced a mediocre piece of glass that's a waste of money (if you care much about image quality and resolution).
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Mike M. (emem)
http://www.veritasmea.com

I care much about image quality and resolution, and I'm satisfied. So are many others on this forum and Pentax forums.

Or are you talking about resolution in the extreme corners?

It seems that there are two extremes on opinions of this lens. It seems that earlier copies tended to be worse than the newer ones.

citrontokyo wrote:

I care much about image quality and resolution, and I'm satisfied. So are many others on this forum and Pentax forums.

Or are you talking about resolution in the extreme corners?

No, I'm talking about overall sharpness and a certain "je ne sais quoi" (that's lacking) about the rendering. And I'm not trying to sound condescending when I say that many on this forum seem to be happy with images that are far from excellent. Perhaps it comes from accepting that their gear is not as expensive as some others so they don't have such high expectations. For example, the DA50-135 is a nice lens - it produces very nice images. Nothing less is acceptable to my eye. The only thing it lacks is a few millimetres at the wide end - hence my hopes for a really good 18-135. So that's my two bobs worth. (or two cents if you prefer).
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Mike M. (emem)
http://www.veritasmea.com

emem wrote:

citrontokyo wrote:

I care much about image quality and resolution, and I'm satisfied. So are many others on this forum and Pentax forums.

Or are you talking about resolution in the extreme corners?

No, I'm talking about overall sharpness and a certain "je ne sais quoi" (that's lacking) about the rendering. And I'm not trying to sound condescending when I say that many on this forum seem to be happy with images that are far from excellent. Perhaps it comes from accepting that their gear is not as expensive as some others so they don't have such high expectations. For example, the DA50-135 is a nice lens - it produces very nice images. Nothing less is acceptable to my eye. The only thing it lacks is a few millimetres at the wide end - hence my hopes for a really good 18-135. So that's my two bobs worth. (or two cents if you prefer).

I do like to argue with you Mike But on this I have to agree.

Both as to IQ and acceptance levels.

Quite a few 'legendary' consumer lens would not have space in my camera bag.

Tends to come across as snobby but guess your like me and can see the difference.

I have one 'rubbish' do it all lens the Tamron 18-250 and don't see any other 'rubbish' lens offering anything better to warrant carrying multiple 'rubbish' lens.

If I'm out taking snaps the 18-250 cuts it, If I'm out taking pictures I'll have 3-4 DA* and couple of Sigma EX with me, I do not confuse flexibility with quality

oh and of cause the 40 limited as its always with me.

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Mike M. (emem)
http://www.veritasmea.com

I have two Sigma 17-70 non HSM ,better in my opinion ( much lighter, smaller and with better MACRO), my the most used lens although in last 6 weeks I took over 3000 photos with the Q ( addictive!) and none with KX or K7.

That will most likely change, purchased used K5 with , guess what (!) , another identical Sigma 17-70 2.8-4.5.

I purchased used Sigma 18-125 HSM but without OS a while ago, it is great lens , much better optically than the old ( like one eaten by your dog - I used to have one) non HSM version but, it is much bigger than 17-70, much slower , wide fast part is more important to me than tele ( + I do have DA55-300) so I do not really use it much, most likely will be selling it soon with one Sigma 17-70.

I am also in Perth , so you could probably get those both Sigma's for the price of Pentax DA18-135 ( can not comment on this lens, never had one, well too expensive for me) , send me PM when you back if you want to.
kind regards
jack

tellem_esdreamin wrote:

Thanks for that. I did mean the sigma 18-125. As I thought the 250 would be a bit large. I am traveling now and think the 18-125 is a better balance. I am in the states for another week ( from Australia ) and the Pentax lens is a couple of hundred dollars cheaper than at home. So wondering whether to pounce!

Sigma lenses seem about the same price.

I went down the middle on this, with the Sigma 18-200. They make a new one now, 200g heavier (and me $200 lighter?) for stuff I don't need = no thanks. My 18-200 outperformed both Tamrons (18-200 and -250) due to equal or better IQ and Zero zoom creep.

I'm watching for the DA 'high-magnification zoom' news later this year; if it does not meet my needs the old 18-200 mark I could be back in my hands. I'd love it to be WR, could tolerate XS if it fits the K-5. That would be a great hiking lens if it were XS and WR! Question is, what will make it enough different from the DA 18-135? We shall see. If it were 17-170 I'd be even happier!

jimrpdx wrote:

I went down the middle on this, with the Sigma 18-200. They make a new one now, 200g heavier (and me $200 lighter?) for stuff I don't need = no thanks. My 18-200 outperformed both Tamrons (18-200 and -250) due to equal or better IQ

I think your suffering owner pride syndrome

and Zero zoom creep.

you either have an exceptional copy or haven't used it enough for it to loosen up..it has a zoom lock for reason

User reviews for Sigma 18-250mm F3.5-6.3 DC OS HSM lens. ... "The only issues I find annoying are it's bulkiness and the zoom creep "

At 35mm the sigma 18-200 has no border resolution at all barely rating 600 lw/ph vs the Tamron 1700

The bokeh is frankly laughable for a superzoom (and that's not a high standard) general optical performance worse than poor.

Not just my opinion

Here photozone gives it a miserable 1.5 for Optical performance personally I think Klaus was feeling generous that day.

http://www.photozone.de/canon-eos/321-sigma-af-18-200mm-f35-63-dc-os-canon-test-report--review?start=1
some user reviews
http://www.dyxum.com/reviews/lenses/reviews.asp?IDLens=226

Unfortunately all the current 18-200 (non OEM) are based on old design and these old designs were not very good.

All the 18-250+ lens completely blow away all the 18-200's demonstratively so.

Never-the less a superzoom is a compromise from beginning to end the good ones are poor and the poor ones should never have been made fooling those who know no better into parting with good money.

If a superzom is what you need then tread carefully and pay close attention to lab results as many owners will tell you things that are just not true, Not through any deliberate lie but rather they've seen nothing better.

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Jim in Oregon -- a200 veteran, now G1 + K-5
talking to myself: http://granitix.blogspot.com

I have just got one of the hated 18-135. And to be frankly, I think it is a great lens. Very fast and precice focus. The only lens I have with no focus error at all. It's extremely sharp in the center the whole way through the zoom-range. It's almost as fast as the 17-70 in it's range. 4,5 at 68mm and a tad faster at 18mm. My copy is even rather sharp in the edges at 135mm... The build quality is great, and it's a WR-lens. I'm going to "love" this lens. I do have several primes, but my main problem with my Pentax-system is a low-light-focusing-problem. But I can say that this lens (18-135) is the only lens I have, or have had; that focus without any problems at all!
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svein wilhelm