[robbiec]

In the Pentax world the DA55-300 is a no brainer unless cost is a crucial factor. It generally runs an extra €50 - €75 over the Tamron 70-300. I had both at one stage, gave the Tamron away because I did not like its colour rendition and the fact that it was so clumsy compared to the DA.



Some examples with the DA55-300 from earlier this year



K-5, ISO80, f/7.1, FL 87.5mm, 1/640s





K-5, ISO80, f/7.1, FL 170mm, 1/640s





K20D, ISO800, f/4.5, FL170mm, 1/25s





K20D, ISO640, f/5.6, FL260mm, 1/2500s





K20D, ISO800, f/4.5, FL190mm, 1/160s





I've tried to show various examples of the FL and shots that had both good and bad lighting. Its fairly light weight, well built and as an addition to the kit kens a versatile companion without spending mega money. Hope these help and good luck with your purchase.

[boren]

Robbiec, can you comment about the differences in AF speed between the Pentax and the Tamron? If they're not significant and if the OP doesn't need the 1:2 macro, then the Pentax is the obvious choice.



It's also worth noting that there are two versions of the 55-300 - the metal mount DA which comes with a lens hood and pouch and supports quick-shift focusing, and the plastic mount DA-L which doesn't include these features and is usually sold in kit with lower-end bodies. Optically they're supposed to be identical.

[Brightcolours]

[quote name='Vieux loup' timestamp='1314570472' post='11125']

If you were not quite sure, maybe you could have asked. There is only one test of that lens on Photozone and it is on the Pentax and the crops were taken with that lens. You certainly have a lot of knowledge of things photographic, but this time you jumped to conclusions about what I think and talk about. This frankly is a waist of space, but I wish you would just stick to the facts.

[/quote]

Like I pointed out, I did stick to facts (I quoted your post literally). You mentioning that it is considered better than the Nikon 70-300 AND that I "boost" it often, means the USD VC. Now lets leave it at that.

[robbiec]

My lens would be the DA example, with the quick shift and metal mount. The Tamron from what I can remember using it used to hunt a lot during focussing on the K20D. The DA was / is a lot more assured.

I still have access to the Tamron as I gave it to my father in law, I'll see if I can borrow it for a couple of days and pair it off against the DA on my K-5 and report back



Regards,

Robbie

[boren]

A comparison of these two lenses on the K-5 would be very interesting. Thank you.

[Guest]

[quote name='robbiec' timestamp='1314574745' post='11129']

My lens would be the DA example, with the quick shift and metal mount. The Tamron from what I can remember using it used to hunt a lot during focussing on the K20D. The DA was / is a lot more assured.

I still have access to the Tamron as I gave it to my father in law, I'll see if I can borrow it for a couple of days and pair it off against the DA on my K-5 and report back



Regards,

Robbie

[/quote]





I had the same experience with the Tammy and Pentax. The Pentax is round about the same in speed if something a tiny bit quicker, BUT it is a lot better to find the focus.

I never touched the tammy again.



Regards

[Yakim]

Would you consider an old 70-210/4? IQ and BQ are great and it's cheap but it's a MF only.

[finaldesignrb]

[quote name='Bjoern' timestamp='1314645558' post='11147']

I had the same experience with the Tammy and Pentax. The Pentax is round about the same in speed if something a tiny bit quicker, BUT it is a lot better to find the focus. I never touched the [Tamron] again.[/quote]



It just occurred to me, hmm after years of photography, that longitudinal and in some cases lateral chromatic aberrations, as well as spherical aberrations and low contrast, would tend to interfere with fast, accurate autofocusing. Meaning that optically superior lenses would tend to "autofocus better". Regardless or in addition to issues involving the distance the lens elements must move, the mass of the elements, the "gearing" of a screw drive, the power of the driving motor, speed of controlling electronics and the sophistication of the controlling algorithms, loss of light in translucent mirror, lens aperture, etc etc.



As a most simplistic example, have a to-me-worthless old Sigma 80-200 push-pull zoom. Built nicely and compactly, with wonderful handling. But so much longitudinal color aberration that it becomes a philosophical question, what is "the focus point", when you look at a magnified image in the viewfinder. Do you mean the focus point where things are looking reddish around the edges, or the point where they're bluish? Are you focusing on something bluish, that's comes out best where the fringes are reddish? Does God exist? etc. All questions to be pondered by all too mortal autofocus firmware.