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Old Feb 28, 2010, 11:46 PM   #1
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Default Need a recommendation for a telephoto zoom

I've mentioned her before that I have a Sigma 70-300 APO DG zoom lens. I bought that lens shortly after getting my K100D, about 3 years ago. When my wife decided to move up to a DSLR we bought her a K200D and the Pentax 55-300. I've never done any strict controlled tests, but my impression from comparing my pics with hers is that the Pentax is sharper at the long end.

Now I have a K20D, and I definitely have the sense that my Sigma 70-300 is soft at the long end. I had more or less decided to put up with the Sigma for a while longer, until I could afford a really nice, pro grade telephoto zoom, such as the DA* 60-250, or the Sigma 100-300 EX. That would very likely mean waiting several years.

But in the recent thread on BIFs, someone (Scott?) pointed out that there are advantages to using a "consumer grade" zoom, as the smaller maximum aperture gives a greater depth of field when wide open, resulting in quicker autofocusing. Since autofocus speed is considered to be one of the K20's few weak points, this is a significant consideration. That insight has turned my thinking upside down.

So now, I'd like some suggestions: of the "consumer grade" lenses on the market, which do you think is the sharpest? And do you think it's so much sharper than my Sigma that it would be worth my upgrading?
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Old Feb 28, 2010, 11:52 PM   #2
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I would put you wife's DAL 55-300mm to see how you like the results. If you do move to the DA 55-300mm, it is a bit better in build quality and features. If she has the DA 55-300mm you can shear the lens.
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Old Mar 1, 2010, 10:34 AM   #3
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From comparison shots posted here, I'd say the Tamron 70-300 is as sharp as you can get in this class - perhaps a shade sharper than the DA 55-300 (though that could be sample variation rather than actual optic design). However, it does suffer significantly from CA and PF. I ended up deciding on the DA 55-300 because of that and have been really happy with my second copy. It doesn't compare with the DA*300, but then it's a whole lot cheaper and lighter.
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Old Mar 1, 2010, 11:16 AM   #4
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I've only shot with my 55-300 Pentax, but I'm more then happy with it's performance.

I have a buddy with a Canon 70-300 and both lenses seem about equal...picture wise...same birds, same time, same lighting.

As a consumer grade lens...I think the 55-300 is hard to beat. Although I'm hoping that Pentax brings out a 400 mm, F 5.6...similar to the Canon 400 mm L series , F 5.6. A friend has one of these...this lens is a remarkably good lens, robust build....$ 1500 CAD.

But @ $ 1500 , it is close/ maybe a pro lens for outdoor shots.

Last edited by lesmore49; Mar 1, 2010 at 11:22 AM.
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Old Mar 2, 2010, 3:26 PM   #5
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Thanks for the suggestions folks. Sometimes you have to ask a question before you see an answer that should have been clear from the start. After reading your suggestions I realized that all I need to do is borrow my wife's 55-300, set up my K20 on a tripod, then shoot some sample pics using her lens and my sigma 70-300. That way I can compare the pics and decide for myself whether the Pentax is so much better than the Sigma I already have. In either case, I think I have decided to forego a professional grade telephoto, unless I suddenly stumble upon an amazingly good deal.

Thanks for helping me see the rather obvious solution to my dilemma.
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Old Mar 4, 2010, 10:33 PM   #6
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Quote:
Originally Posted by mtngal View Post
From comparison shots posted here, I'd say the Tamron 70-300 is as sharp as you can get in this class - perhaps a shade sharper than the DA 55-300 (though that could be sample variation rather than actual optic design). However, it does suffer significantly from CA and PF. I ended up deciding on the DA 55-300 because of that and have been really happy with my second copy. It doesn't compare with the DA*300, but then it's a whole lot cheaper and lighter.
I think these two lenses are pretty close in IQ (at least mine are), with the 55-300 better at the tele end because of the Tamron's purple fringing (although that hasn't been much of a problem with mine). The Pentax is a better handling lens and has the advantage of the clutch mechanism to allow quick switching between manual and AF (in the DA version only), while the Tamron has a clear advantage at the short end because of it's 1:2 macro ratio, where it clearly excels, and thus is a more versatile lens. I favor the Pentax for BIFs and the Tamron where I think I will need the macro feature - it can be better as a general walk-around lens. The Pentax, however, can be good for not-quite-so close-ups as well. Be aware that pictures shot with consumer grade lenses may require more post-processing than higher grade lenses, but the results can be quite satisfactory if you are going for "slides" and not for super-sized prints..
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Last edited by penolta; Mar 4, 2010 at 10:38 PM.
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